summaryrefslogtreecommitdiffstats
path: root/net/core/skbuff.c
blob: 5a2a2e887a12ee3d813fa81b0b26ac8c1f0c24d8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
/*
 *	Routines having to do with the 'struct sk_buff' memory handlers.
 *
 *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
 *			Florian La Roche <rzsfl@rz.uni-sb.de>
 *
 *	Fixes:
 *		Alan Cox	:	Fixed the worst of the load
 *					balancer bugs.
 *		Dave Platt	:	Interrupt stacking fix.
 *	Richard Kooijman	:	Timestamp fixes.
 *		Alan Cox	:	Changed buffer format.
 *		Alan Cox	:	destructor hook for AF_UNIX etc.
 *		Linus Torvalds	:	Better skb_clone.
 *		Alan Cox	:	Added skb_copy.
 *		Alan Cox	:	Added all the changed routines Linus
 *					only put in the headers
 *		Ray VanTassle	:	Fixed --skb->lock in free
 *		Alan Cox	:	skb_copy copy arp field
 *		Andi Kleen	:	slabified it.
 *		Robert Olsson	:	Removed skb_head_pool
 *
 *	NOTE:
 *		The __skb_ routines should be called with interrupts
 *	disabled, or you better be *real* sure that the operation is atomic
 *	with respect to whatever list is being frobbed (e.g. via lock_sock()
 *	or via disabling bottom half handlers, etc).
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

/*
 *	The functions in this file will not compile correctly with gcc 2.4.x
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/kmemcheck.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/netdevice.h>
#ifdef CONFIG_NET_CLS_ACT
#include <net/pkt_sched.h>
#endif
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/splice.h>
#include <linux/cache.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/scatterlist.h>
#include <linux/errqueue.h>
#include <linux/prefetch.h>
#include <linux/if_vlan.h>

#include <net/protocol.h>
#include <net/dst.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <net/ip6_checksum.h>
#include <net/xfrm.h>

#include <asm/uaccess.h>
#include <trace/events/skb.h>
#include <linux/highmem.h>

struct kmem_cache *skbuff_head_cache __read_mostly;
static struct kmem_cache *skbuff_fclone_cache __read_mostly;

/**
 *	skb_panic - private function for out-of-line support
 *	@skb:	buffer
 *	@sz:	size
 *	@addr:	address
 *	@msg:	skb_over_panic or skb_under_panic
 *
 *	Out-of-line support for skb_put() and skb_push().
 *	Called via the wrapper skb_over_panic() or skb_under_panic().
 *	Keep out of line to prevent kernel bloat.
 *	__builtin_return_address is not used because it is not always reliable.
 */
static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
		      const char msg[])
{
	pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
		 msg, addr, skb->len, sz, skb->head, skb->data,
		 (unsigned long)skb->tail, (unsigned long)skb->end,
		 skb->dev ? skb->dev->name : "<NULL>");
	BUG();
}

static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
{
	skb_panic(skb, sz, addr, __func__);
}

static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
{
	skb_panic(skb, sz, addr, __func__);
}

/*
 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
 * the caller if emergency pfmemalloc reserves are being used. If it is and
 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
 * may be used. Otherwise, the packet data may be discarded until enough
 * memory is free
 */
#define kmalloc_reserve(size, gfp, node, pfmemalloc) \
	 __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)

static void *__kmalloc_reserve(size_t size, gfp_t flags, int node,
			       unsigned long ip, bool *pfmemalloc)
{
	void *obj;
	bool ret_pfmemalloc = false;

	/*
	 * Try a regular allocation, when that fails and we're not entitled
	 * to the reserves, fail.
	 */
	obj = kmalloc_node_track_caller(size,
					flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
					node);
	if (obj || !(gfp_pfmemalloc_allowed(flags)))
		goto out;

	/* Try again but now we are using pfmemalloc reserves */
	ret_pfmemalloc = true;
	obj = kmalloc_node_track_caller(size, flags, node);

out:
	if (pfmemalloc)
		*pfmemalloc = ret_pfmemalloc;

	return obj;
}

/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
 *	'private' fields and also do memory statistics to find all the
 *	[BEEP] leaks.
 *
 */

struct sk_buff *__alloc_skb_head(gfp_t gfp_mask, int node)
{
	struct sk_buff *skb;

	/* Get the HEAD */
	skb = kmem_cache_alloc_node(skbuff_head_cache,
				    gfp_mask & ~__GFP_DMA, node);
	if (!skb)
		goto out;

	/*
	 * Only clear those fields we need to clear, not those that we will
	 * actually initialise below. Hence, don't put any more fields after
	 * the tail pointer in struct sk_buff!
	 */
	memset(skb, 0, offsetof(struct sk_buff, tail));
	skb->head = NULL;
	skb->truesize = sizeof(struct sk_buff);
	atomic_set(&skb->users, 1);

	skb->mac_header = (typeof(skb->mac_header))~0U;
out:
	return skb;
}

/**
 *	__alloc_skb	-	allocate a network buffer
 *	@size: size to allocate
 *	@gfp_mask: allocation mask
 *	@flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
 *		instead of head cache and allocate a cloned (child) skb.
 *		If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
 *		allocations in case the data is required for writeback
 *	@node: numa node to allocate memory on
 *
 *	Allocate a new &sk_buff. The returned buffer has no headroom and a
 *	tail room of at least size bytes. The object has a reference count
 *	of one. The return is the buffer. On a failure the return is %NULL.
 *
 *	Buffers may only be allocated from interrupts using a @gfp_mask of
 *	%GFP_ATOMIC.
 */
struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
			    int flags, int node)
{
	struct kmem_cache *cache;
	struct skb_shared_info *shinfo;
	struct sk_buff *skb;
	u8 *data;
	bool pfmemalloc;

	cache = (flags & SKB_ALLOC_FCLONE)
		? skbuff_fclone_cache : skbuff_head_cache;

	if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
		gfp_mask |= __GFP_MEMALLOC;

	/* Get the HEAD */
	skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
	if (!skb)
		goto out;
	prefetchw(skb);

	/* We do our best to align skb_shared_info on a separate cache
	 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
	 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
	 * Both skb->head and skb_shared_info are cache line aligned.
	 */
	size = SKB_DATA_ALIGN(size);
	size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
	data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
	if (!data)
		goto nodata;
	/* kmalloc(size) might give us more room than requested.
	 * Put skb_shared_info exactly at the end of allocated zone,
	 * to allow max possible filling before reallocation.
	 */
	size = SKB_WITH_OVERHEAD(ksize(data));
	prefetchw(data + size);

	/*
	 * Only clear those fields we need to clear, not those that we will
	 * actually initialise below. Hence, don't put any more fields after
	 * the tail pointer in struct sk_buff!
	 */
	memset(skb, 0, offsetof(struct sk_buff, tail));
	/* Account for allocated memory : skb + skb->head */
	skb->truesize = SKB_TRUESIZE(size);
	skb->pfmemalloc = pfmemalloc;
	atomic_set(&skb->users, 1);
	skb->head = data;
	skb->data = data;
	skb_reset_tail_pointer(skb);
	skb->end = skb->tail + size;
	skb->mac_header = (typeof(skb->mac_header))~0U;
	skb->transport_header = (typeof(skb->transport_header))~0U;

	/* make sure we initialize shinfo sequentially */
	shinfo = skb_shinfo(skb);
	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
	atomic_set(&shinfo->dataref, 1);
	kmemcheck_annotate_variable(shinfo->destructor_arg);

	if (flags & SKB_ALLOC_FCLONE) {
		struct sk_buff_fclones *fclones;

		fclones = container_of(skb, struct sk_buff_fclones, skb1);

		kmemcheck_annotate_bitfield(&fclones->skb2, flags1);
		skb->fclone = SKB_FCLONE_ORIG;
		atomic_set(&fclones->fclone_ref, 1);

		fclones->skb2.fclone = SKB_FCLONE_CLONE;
		fclones->skb2.pfmemalloc = pfmemalloc;
	}
out:
	return skb;
nodata:
	kmem_cache_free(cache, skb);
	skb = NULL;
	goto out;
}
EXPORT_SYMBOL(__alloc_skb);

/**
 * build_skb - build a network buffer
 * @data: data buffer provided by caller
 * @frag_size: size of fragment, or 0 if head was kmalloced
 *
 * Allocate a new &sk_buff. Caller provides space holding head and
 * skb_shared_info. @data must have been allocated by kmalloc() only if
 * @frag_size is 0, otherwise data should come from the page allocator.
 * The return is the new skb buffer.
 * On a failure the return is %NULL, and @data is not freed.
 * Notes :
 *  Before IO, driver allocates only data buffer where NIC put incoming frame
 *  Driver should add room at head (NET_SKB_PAD) and
 *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
 *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
 *  before giving packet to stack.
 *  RX rings only contains data buffers, not full skbs.
 */
struct sk_buff *build_skb(void *data, unsigned int frag_size)
{
	struct skb_shared_info *shinfo;
	struct sk_buff *skb;
	unsigned int size = frag_size ? : ksize(data);

	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
	if (!skb)
		return NULL;

	size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

	memset(skb, 0, offsetof(struct sk_buff, tail));
	skb->truesize = SKB_TRUESIZE(size);
	skb->head_frag = frag_size != 0;
	atomic_set(&skb->users, 1);
	skb->head = data;
	skb->data = data;
	skb_reset_tail_pointer(skb);
	skb->end = skb->tail + size;
	skb->mac_header = (typeof(skb->mac_header))~0U;
	skb->transport_header = (typeof(skb->transport_header))~0U;

	/* make sure we initialize shinfo sequentially */
	shinfo = skb_shinfo(skb);
	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
	atomic_set(&shinfo->dataref, 1);
	kmemcheck_annotate_variable(shinfo->destructor_arg);

	return skb;
}
EXPORT_SYMBOL(build_skb);

struct netdev_alloc_cache {
	struct page_frag	frag;
	/* we maintain a pagecount bias, so that we dont dirty cache line
	 * containing page->_count every time we allocate a fragment.
	 */
	unsigned int		pagecnt_bias;
};
static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
static DEFINE_PER_CPU(struct netdev_alloc_cache, napi_alloc_cache);

static struct page *__page_frag_refill(struct netdev_alloc_cache *nc,
				       gfp_t gfp_mask)
{
	const unsigned int order = NETDEV_FRAG_PAGE_MAX_ORDER;
	struct page *page = NULL;
	gfp_t gfp = gfp_mask;

	if (order) {
		gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY;
		page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
		nc->frag.size = PAGE_SIZE << (page ? order : 0);
	}

	if (unlikely(!page))
		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);

	nc->frag.page = page;

	return page;
}

static void *__alloc_page_frag(struct netdev_alloc_cache __percpu *cache,
			       unsigned int fragsz, gfp_t gfp_mask)
{
	struct netdev_alloc_cache *nc = this_cpu_ptr(cache);
	struct page *page = nc->frag.page;
	unsigned int size;
	int offset;

	if (unlikely(!page)) {
refill:
		page = __page_frag_refill(nc, gfp_mask);
		if (!page)
			return NULL;

		/* if size can vary use frag.size else just use PAGE_SIZE */
		size = NETDEV_FRAG_PAGE_MAX_ORDER ? nc->frag.size : PAGE_SIZE;

		/* Even if we own the page, we do not use atomic_set().
		 * This would break get_page_unless_zero() users.
		 */
		atomic_add(size - 1, &page->_count);

		/* reset page count bias and offset to start of new frag */
		nc->pagecnt_bias = size;
		nc->frag.offset = size;
	}

	offset = nc->frag.offset - fragsz;
	if (unlikely(offset < 0)) {
		if (!atomic_sub_and_test(nc->pagecnt_bias, &page->_count))
			goto refill;

		/* if size can vary use frag.size else just use PAGE_SIZE */
		size = NETDEV_FRAG_PAGE_MAX_ORDER ? nc->frag.size : PAGE_SIZE;

		/* OK, page count is 0, we can safely set it */
		atomic_set(&page->_count, size);

		/* reset page count bias and offset to start of new frag */
		nc->pagecnt_bias = size;
		offset = size - fragsz;
	}

	nc->pagecnt_bias--;
	nc->frag.offset = offset;

	return page_address(page) + offset;
}

static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
{
	unsigned long flags;
	void *data;

	local_irq_save(flags);
	data = __alloc_page_frag(&netdev_alloc_cache, fragsz, gfp_mask);
	local_irq_restore(flags);
	return data;
}

/**
 * netdev_alloc_frag - allocate a page fragment
 * @fragsz: fragment size
 *
 * Allocates a frag from a page for receive buffer.
 * Uses GFP_ATOMIC allocations.
 */
void *netdev_alloc_frag(unsigned int fragsz)
{
	return __netdev_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
}
EXPORT_SYMBOL(netdev_alloc_frag);

static void *__napi_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
{
	return __alloc_page_frag(&napi_alloc_cache, fragsz, gfp_mask);
}

void *napi_alloc_frag(unsigned int fragsz)
{
	return __napi_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
}
EXPORT_SYMBOL(napi_alloc_frag);

/**
 *	__alloc_rx_skb - allocate an skbuff for rx
 *	@length: length to allocate
 *	@gfp_mask: get_free_pages mask, passed to alloc_skb
 *	@flags:	If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
 *		allocations in case we have to fallback to __alloc_skb()
 *		If SKB_ALLOC_NAPI is set, page fragment will be allocated
 *		from napi_cache instead of netdev_cache.
 *
 *	Allocate a new &sk_buff and assign it a usage count of one. The
 *	buffer has unspecified headroom built in. Users should allocate
 *	the headroom they think they need without accounting for the
 *	built in space. The built in space is used for optimisations.
 *
 *	%NULL is returned if there is no free memory.
 */
static struct sk_buff *__alloc_rx_skb(unsigned int length, gfp_t gfp_mask,
				      int flags)
{
	struct sk_buff *skb = NULL;
	unsigned int fragsz = SKB_DATA_ALIGN(length) +
			      SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

	if (fragsz <= PAGE_SIZE && !(gfp_mask & (__GFP_WAIT | GFP_DMA))) {
		void *data;

		if (sk_memalloc_socks())
			gfp_mask |= __GFP_MEMALLOC;

		data = (flags & SKB_ALLOC_NAPI) ?
			__napi_alloc_frag(fragsz, gfp_mask) :
			__netdev_alloc_frag(fragsz, gfp_mask);

		if (likely(data)) {
			skb = build_skb(data, fragsz);
			if (unlikely(!skb))
				put_page(virt_to_head_page(data));
		}
	} else {
		skb = __alloc_skb(length, gfp_mask,
				  SKB_ALLOC_RX, NUMA_NO_NODE);
	}
	return skb;
}

/**
 *	__netdev_alloc_skb - allocate an skbuff for rx on a specific device
 *	@dev: network device to receive on
 *	@length: length to allocate
 *	@gfp_mask: get_free_pages mask, passed to alloc_skb
 *
 *	Allocate a new &sk_buff and assign it a usage count of one. The
 *	buffer has NET_SKB_PAD headroom built in. Users should allocate
 *	the headroom they think they need without accounting for the
 *	built in space. The built in space is used for optimisations.
 *
 *	%NULL is returned if there is no free memory.
 */
struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
				   unsigned int length, gfp_t gfp_mask)
{
	struct sk_buff *skb;

	length += NET_SKB_PAD;
	skb = __alloc_rx_skb(length, gfp_mask, 0);

	if (likely(skb)) {
		skb_reserve(skb, NET_SKB_PAD);
		skb->dev = dev;
	}

	return skb;
}
EXPORT_SYMBOL(__netdev_alloc_skb);

/**
 *	__napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
 *	@napi: napi instance this buffer was allocated for
 *	@length: length to allocate
 *	@gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
 *
 *	Allocate a new sk_buff for use in NAPI receive.  This buffer will
 *	attempt to allocate the head from a special reserved region used
 *	only for NAPI Rx allocation.  By doing this we can save several
 *	CPU cycles by avoiding having to disable and re-enable IRQs.
 *
 *	%NULL is returned if there is no free memory.
 */
struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
				 unsigned int length, gfp_t gfp_mask)
{
	struct sk_buff *skb;

	length += NET_SKB_PAD + NET_IP_ALIGN;
	skb = __alloc_rx_skb(length, gfp_mask, SKB_ALLOC_NAPI);

	if (likely(skb)) {
		skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
		skb->dev = napi->dev;
	}

	return skb;
}
EXPORT_SYMBOL(__napi_alloc_skb);

void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
		     int size, unsigned int truesize)
{
	skb_fill_page_desc(skb, i, page, off, size);
	skb->len += size;
	skb->data_len += size;
	skb->truesize += truesize;
}
EXPORT_SYMBOL(skb_add_rx_frag);

void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
			  unsigned int truesize)
{
	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

	skb_frag_size_add(frag, size);
	skb->len += size;
	skb->data_len += size;
	skb->truesize += truesize;
}
EXPORT_SYMBOL(skb_coalesce_rx_frag);

static void skb_drop_list(struct sk_buff **listp)
{
	kfree_skb_list(*listp);
	*listp = NULL;
}

static inline void skb_drop_fraglist(struct sk_buff *skb)
{
	skb_drop_list(&skb_shinfo(skb)->frag_list);
}

static void skb_clone_fraglist(struct sk_buff *skb)
{
	struct sk_buff *list;

	skb_walk_frags(skb, list)
		skb_get(list);
}

static void skb_free_head(struct sk_buff *skb)
{
	if (skb->head_frag)
		put_page(virt_to_head_page(skb->head));
	else
		kfree(skb->head);
}

static void skb_release_data(struct sk_buff *skb)
{
	struct skb_shared_info *shinfo = skb_shinfo(skb);
	int i;

	if (skb->cloned &&
	    atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
			      &shinfo->dataref))
		return;

	for (i = 0; i < shinfo->nr_frags; i++)
		__skb_frag_unref(&shinfo->frags[i]);

	/*
	 * If skb buf is from userspace, we need to notify the caller
	 * the lower device DMA has done;
	 */
	if (shinfo->tx_flags & SKBTX_DEV_ZEROCOPY) {
		struct ubuf_info *uarg;

		uarg = shinfo->destructor_arg;
		if (uarg->callback)
			uarg->callback(uarg, true);
	}

	if (shinfo->frag_list)
		kfree_skb_list(shinfo->frag_list);

	skb_free_head(skb);
}

/*
 *	Free an skbuff by memory without cleaning the state.
 */
static void kfree_skbmem(struct sk_buff *skb)
{
	struct sk_buff_fclones *fclones;

	switch (skb->fclone) {
	case SKB_FCLONE_UNAVAILABLE:
		kmem_cache_free(skbuff_head_cache, skb);
		return;

	case SKB_FCLONE_ORIG:
		fclones = container_of(skb, struct sk_buff_fclones, skb1);

		/* We usually free the clone (TX completion) before original skb
		 * This test would have no chance to be true for the clone,
		 * while here, branch prediction will be good.
		 */
		if (atomic_read(&fclones->fclone_ref) == 1)
			goto fastpath;
		break;

	default: /* SKB_FCLONE_CLONE */
		fclones = container_of(skb, struct sk_buff_fclones, skb2);
		break;
	}
	if (!atomic_dec_and_test(&fclones->fclone_ref))
		return;
fastpath:
	kmem_cache_free(skbuff_fclone_cache, fclones);
}

static void skb_release_head_state(struct sk_buff *skb)
{
	skb_dst_drop(skb);
#ifdef CONFIG_XFRM
	secpath_put(skb->sp);
#endif
	if (skb->destructor) {
		WARN_ON(in_irq());
		skb->destructor(skb);
	}
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
	nf_conntrack_put(skb->nfct);
#endif
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
	nf_bridge_put(skb->nf_bridge);
#endif
}

/* Free everything but the sk_buff shell. */
static void skb_release_all(struct sk_buff *skb)
{
	skb_release_head_state(skb);
	if (likely(skb->head))
		skb_release_data(skb);
}

/**
 *	__kfree_skb - private function
 *	@skb: buffer
 *
 *	Free an sk_buff. Release anything attached to the buffer.
 *	Clean the state. This is an internal helper function. Users should
 *	always call kfree_skb
 */

void __kfree_skb(struct sk_buff *skb)
{
	skb_release_all(skb);
	kfree_skbmem(skb);
}
EXPORT_SYMBOL(__kfree_skb);

/**
 *	kfree_skb - free an sk_buff
 *	@skb: buffer to free
 *
 *	Drop a reference to the buffer and free it if the usage count has
 *	hit zero.
 */
void kfree_skb(struct sk_buff *skb)
{
	if (unlikely(!skb))
		return;
	if (likely(atomic_read(&skb->users) == 1))
		smp_rmb();
	else if (likely(!atomic_dec_and_test(&skb->users)))
		return;
	trace_kfree_skb(skb, __builtin_return_address(0));
	__kfree_skb(skb);
}
EXPORT_SYMBOL(kfree_skb);

void kfree_skb_list(struct sk_buff *segs)
{
	while (segs) {
		struct sk_buff *next = segs->next;

		kfree_skb(segs);
		segs = next;
	}
}
EXPORT_SYMBOL(kfree_skb_list);

/**
 *	skb_tx_error - report an sk_buff xmit error
 *	@skb: buffer that triggered an error
 *
 *	Report xmit error if a device callback is tracking this skb.
 *	skb must be freed afterwards.
 */
void skb_tx_error(struct sk_buff *skb)
{
	if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
		struct ubuf_info *uarg;

		uarg = skb_shinfo(skb)->destructor_arg;
		if (uarg->callback)
			uarg->callback(uarg, false);
		skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
	}
}
EXPORT_SYMBOL(skb_tx_error);

/**
 *	consume_skb - free an skbuff
 *	@skb: buffer to free
 *
 *	Drop a ref to the buffer and free it if the usage count has hit zero
 *	Functions identically to kfree_skb, but kfree_skb assumes that the frame
 *	is being dropped after a failure and notes that
 */
void consume_skb(struct sk_buff *skb)
{
	if (unlikely(!skb))
		return;
	if (likely(atomic_read(&skb->users) == 1))
		smp_rmb();
	else if (likely(!atomic_dec_and_test(&skb->users)))
		return;
	trace_consume_skb(skb);
	__kfree_skb(skb);
}
EXPORT_SYMBOL(consume_skb);

/* Make sure a field is enclosed inside headers_start/headers_end section */
#define CHECK_SKB_FIELD(field) \
	BUILD_BUG_ON(offsetof(struct sk_buff, field) <		\
		     offsetof(struct sk_buff, headers_start));	\
	BUILD_BUG_ON(offsetof(struct sk_buff, field) >		\
		     offsetof(struct sk_buff, headers_end));	\

static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
	new->tstamp		= old->tstamp;
	/* We do not copy old->sk */
	new->dev		= old->dev;
	memcpy(new->cb, old->cb, sizeof(old->cb));
	skb_dst_copy(new, old);
#ifdef CONFIG_XFRM
	new->sp			= secpath_get(old->sp);
#endif
	__nf_copy(new, old, false);

	/* Note : this field could be in headers_start/headers_end section
	 * It is not yet because we do not want to have a 16 bit hole
	 */
	new->queue_mapping = old->queue_mapping;

	memcpy(&new->headers_start, &old->headers_start,
	       offsetof(struct sk_buff, headers_end) -
	       offsetof(struct sk_buff, headers_start));
	CHECK_SKB_FIELD(protocol);
	CHECK_SKB_FIELD(csum);
	CHECK_SKB_FIELD(hash);
	CHECK_SKB_FIELD(priority);
	CHECK_SKB_FIELD(skb_iif);
	CHECK_SKB_FIELD(vlan_proto);
	CHECK_SKB_FIELD(vlan_tci);
	CHECK_SKB_FIELD(transport_header);
	CHECK_SKB_FIELD(network_header);
	CHECK_SKB_FIELD(mac_header);
	CHECK_SKB_FIELD(inner_protocol);
	CHECK_SKB_FIELD(inner_transport_header);
	CHECK_SKB_FIELD(inner_network_header);
	CHECK_SKB_FIELD(inner_mac_header);
	CHECK_SKB_FIELD(mark);
#ifdef CONFIG_NETWORK_SECMARK
	CHECK_SKB_FIELD(secmark);
#endif
#ifdef CONFIG_NET_RX_BUSY_POLL
	CHECK_SKB_FIELD(napi_id);
#endif
#ifdef CONFIG_NET_SCHED
	CHECK_SKB_FIELD(tc_index);
#ifdef CONFIG_NET_CLS_ACT
	CHECK_SKB_FIELD(tc_verd);
#endif
#endif

}

/*
 * You should not add any new code to this function.  Add it to
 * __copy_skb_header above instead.
 */
static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
{
#define C(x) n->x = skb->x

	n->next = n->prev = NULL;
	n->sk = NULL;
	__copy_skb_header(n, skb);

	C(len);
	C(data_len);
	C(mac_len);
	n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
	n->cloned = 1;
	n->nohdr = 0;
	n->destructor = NULL;
	C(tail);
	C(end);
	C(head);
	C(head_frag);
	C(data);
	C(truesize);
	atomic_set(&n->users, 1);

	atomic_inc(&(skb_shinfo(skb)->dataref));
	skb->cloned = 1;

	return n;
#undef C
}

/**
 *	skb_morph	-	morph one skb into another
 *	@dst: the skb to receive the contents
 *	@src: the skb to supply the contents
 *
 *	This is identical to skb_clone except that the target skb is
 *	supplied by the user.
 *
 *	The target skb is returned upon exit.
 */
struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
{
	skb_release_all(dst);
	return __skb_clone(dst, src);
}
EXPORT_SYMBOL_GPL(skb_morph);

/**
 *	skb_copy_ubufs	-	copy userspace skb frags buffers to kernel
 *	@skb: the skb to modify
 *	@gfp_mask: allocation priority
 *
 *	This must be called on SKBTX_DEV_ZEROCOPY skb.
 *	It will copy all frags into kernel and drop the reference
 *	to userspace pages.
 *
 *	If this function is called from an interrupt gfp_mask() must be
 *	%GFP_ATOMIC.
 *
 *	Returns 0 on success or a negative error code on failure
 *	to allocate kernel memory to copy to.
 */
int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
{
	int i;
	int num_frags = skb_shinfo(skb)->nr_frags;
	struct page *page, *head = NULL;
	struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;

	for (i = 0; i < num_frags; i++) {
		u8 *vaddr;
		skb_frag_t *f = &skb_shinfo(skb)->frags[i];

		page = alloc_page(gfp_mask);
		if (!page) {
			while (head) {
				struct page *next = (struct page *)page_private(head);
				put_page(head);
				head = next;
			}
			return -ENOMEM;
		}
		vaddr = kmap_atomic(skb_frag_page(f));
		memcpy(page_address(page),
		       vaddr + f->page_offset, skb_frag_size(f));
		kunmap_atomic(vaddr);
		set_page_private(page, (unsigned long)head);
		head = page;
	}

	/* skb frags release userspace buffers */
	for (i = 0; i < num_frags; i++)
		skb_frag_unref(skb, i);

	uarg->callback(uarg, false);

	/* skb frags point to kernel buffers */
	for (i = num_frags - 1; i >= 0; i--) {
		__skb_fill_page_desc(skb, i, head, 0,
				     skb_shinfo(skb)->frags[i].size);
		head = (struct page *)page_private(head);
	}

	skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
	return 0;
}
EXPORT_SYMBOL_GPL(skb_copy_ubufs);

/**
 *	skb_clone	-	duplicate an sk_buff
 *	@skb: buffer to clone
 *	@gfp_mask: allocation priority
 *
 *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
 *	copies share the same packet data but not structure. The new
 *	buffer has a reference count of 1. If the allocation fails the
 *	function returns %NULL otherwise the new buffer is returned.
 *
 *	If this function is called from an interrupt gfp_mask() must be
 *	%GFP_ATOMIC.
 */

struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
{
	struct sk_buff_fclones *fclones = container_of(skb,
						       struct sk_buff_fclones,
						       skb1);
	struct sk_buff *n;

	if (skb_orphan_frags(skb, gfp_mask))
		return NULL;

	if (skb->fclone == SKB_FCLONE_ORIG &&
	    atomic_read(&fclones->fclone_ref) == 1) {
		n = &fclones->skb2;
		atomic_set(&fclones->fclone_ref, 2);
	} else {
		if (skb_pfmemalloc(skb))
			gfp_mask |= __GFP_MEMALLOC;

		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
		if (!n)
			return NULL;

		kmemcheck_annotate_bitfield(n, flags1);
		n->fclone = SKB_FCLONE_UNAVAILABLE;
	}

	return __skb_clone(n, skb);
}
EXPORT_SYMBOL(skb_clone);

static void skb_headers_offset_update(struct sk_buff *skb, int off)
{
	/* Only adjust this if it actually is csum_start rather than csum */
	if (skb->ip_summed == CHECKSUM_PARTIAL)
		skb->csum_start += off;
	/* {transport,network,mac}_header and tail are relative to skb->head */
	skb->transport_header += off;
	skb->network_header   += off;
	if (skb_mac_header_was_set(skb))
		skb->mac_header += off;
	skb->inner_transport_header += off;
	skb->inner_network_header += off;
	skb->inner_mac_header += off;
}

static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
	__copy_skb_header(new, old);

	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
}

static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
{
	if (skb_pfmemalloc(skb))
		return SKB_ALLOC_RX;
	return 0;
}

/**
 *	skb_copy	-	create private copy of an sk_buff
 *	@skb: buffer to copy
 *	@gfp_mask: allocation priority
 *
 *	Make a copy of both an &sk_buff and its data. This is used when the
 *	caller wishes to modify the data and needs a private copy of the
 *	data to alter. Returns %NULL on failure or the pointer to the buffer
 *	on success. The returned buffer has a reference count of 1.
 *
 *	As by-product this function converts non-linear &sk_buff to linear
 *	one, so that &sk_buff becomes completely private and caller is allowed
 *	to modify all the data of returned buffer. This means that this
 *	function is not recommended for use in circumstances when only
 *	header is going to be modified. Use pskb_copy() instead.
 */

struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
{
	int headerlen = skb_headroom(skb);
	unsigned int size = skb_end_offset(skb) + skb->data_len;
	struct sk_buff *n = __alloc_skb(size, gfp_mask,
					skb_alloc_rx_flag(skb), NUMA_NO_NODE);

	if (!n)
		return NULL;

	/* Set the data pointer */
	skb_reserve(n, headerlen);
	/* Set the tail pointer and length */
	skb_put(n, skb->len);

	if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
		BUG();

	copy_skb_header(n, skb);
	return n;
}
EXPORT_SYMBOL(skb_copy);

/**
 *	__pskb_copy_fclone	-  create copy of an sk_buff with private head.
 *	@skb: buffer to copy
 *	@headroom: headroom of new skb
 *	@gfp_mask: allocation priority
 *	@fclone: if true allocate the copy of the skb from the fclone
 *	cache instead of the head cache; it is recommended to set this
 *	to true for the cases where the copy will likely be cloned
 *
 *	Make a copy of both an &sk_buff and part of its data, located
 *	in header. Fragmented data remain shared. This is used when
 *	the caller wishes to modify only header of &sk_buff and needs
 *	private copy of the header to alter. Returns %NULL on failure
 *	or the pointer to the buffer on success.
 *	The returned buffer has a reference count of 1.
 */

struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
				   gfp_t gfp_mask, bool fclone)
{
	unsigned int size = skb_headlen(skb) + headroom;
	int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
	struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);

	if (!n)
		goto out;

	/* Set the data pointer */
	skb_reserve(n, headroom);
	/* Set the tail pointer and length */
	skb_put(n, skb_headlen(skb));
	/* Copy the bytes */
	skb_copy_from_linear_data(skb, n->data, n->len);

	n->truesize += skb->data_len;
	n->data_len  = skb->data_len;
	n->len	     = skb->len;

	if (skb_shinfo(skb)->nr_frags) {
		int i;

		if (skb_orphan_frags(skb, gfp_mask)) {
			kfree_skb(n);
			n = NULL;
			goto out;
		}
		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
			skb_frag_ref(skb, i);
		}
		skb_shinfo(n)->nr_frags = i;
	}

	if (skb_has_frag_list(skb)) {
		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
		skb_clone_fraglist(n);
	}

	copy_skb_header(n, skb);
out:
	return n;
}
EXPORT_SYMBOL(__pskb_copy_fclone);

/**
 *	pskb_expand_head - reallocate header of &sk_buff
 *	@skb: buffer to reallocate
 *	@nhead: room to add at head
 *	@ntail: room to add at tail
 *	@gfp_mask: allocation priority
 *
 *	Expands (or creates identical copy, if @nhead and @ntail are zero)
 *	header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
 *	reference count of 1. Returns zero in the case of success or error,
 *	if expansion failed. In the last case, &sk_buff is not changed.
 *
 *	All the pointers pointing into skb header may change and must be
 *	reloaded after call to this function.
 */

int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
		     gfp_t gfp_mask)
{
	int i;
	u8 *data;
	int size = nhead + skb_end_offset(skb) + ntail;
	long off;

	BUG_ON(nhead < 0);

	if (skb_shared(skb))
		BUG();

	size = SKB_DATA_ALIGN(size);

	if (skb_pfmemalloc(skb))
		gfp_mask |= __GFP_MEMALLOC;
	data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
			       gfp_mask, NUMA_NO_NODE, NULL);
	if (!data)
		goto nodata;
	size = SKB_WITH_OVERHEAD(ksize(data));

	/* Copy only real data... and, alas, header. This should be
	 * optimized for the cases when header is void.
	 */
	memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);

	memcpy((struct skb_shared_info *)(data + size),
	       skb_shinfo(skb),
	       offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));

	/*
	 * if shinfo is shared we must drop the old head gracefully, but if it
	 * is not we can just drop the old head and let the existing refcount
	 * be since all we did is relocate the values
	 */
	if (skb_cloned(skb)) {
		/* copy this zero copy skb frags */
		if (skb_orphan_frags(skb, gfp_mask))
			goto nofrags;
		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
			skb_frag_ref(skb, i);

		if (skb_has_frag_list(skb))
			skb_clone_fraglist(skb);

		skb_release_data(skb);
	} else {
		skb_free_head(skb);
	}
	off = (data + nhead) - skb->head;

	skb->head     = data;
	skb->head_frag = 0;
	skb->data    += off;
#ifdef NET_SKBUFF_DATA_USES_OFFSET
	skb->end      = size;
	off           = nhead;
#else
	skb->end      = skb->head + size;
#endif
	skb->tail	      += off;
	skb_headers_offset_update(skb, nhead);
	skb->cloned   = 0;
	skb->hdr_len  = 0;
	skb->nohdr    = 0;
	atomic_set(&skb_shinfo(skb)->dataref, 1);
	return 0;

nofrags:
	kfree(data);
nodata:
	return -ENOMEM;
}
EXPORT_SYMBOL(pskb_expand_head);

/* Make private copy of skb with writable head and some headroom */

struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
{
	struct sk_buff *skb2;
	int delta = headroom - skb_headroom(skb);

	if (delta <= 0)
		skb2 = pskb_copy(skb, GFP_ATOMIC);
	else {
		skb2 = skb_clone(skb, GFP_ATOMIC);
		if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
					     GFP_ATOMIC)) {
			kfree_skb(skb2);
			skb2 = NULL;
		}
	}
	return skb2;
}
EXPORT_SYMBOL(skb_realloc_headroom);

/**
 *	skb_copy_expand	-	copy and expand sk_buff
 *	@skb: buffer to copy
 *	@newheadroom: new free bytes at head
 *	@newtailroom: new free bytes at tail
 *	@gfp_mask: allocation priority
 *
 *	Make a copy of both an &sk_buff and its data and while doing so
 *	allocate additional space.
 *
 *	This is used when the caller wishes to modify the data and needs a
 *	private copy of the data to alter as well as more space for new fields.
 *	Returns %NULL on failure or the pointer to the buffer
 *	on success. The returned buffer has a reference count of 1.
 *
 *	You must pass %GFP_ATOMIC as the allocation priority if this function
 *	is called from an interrupt.
 */
struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
				int newheadroom, int newtailroom,
				gfp_t gfp_mask)
{
	/*
	 *	Allocate the copy buffer
	 */
	struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
					gfp_mask, skb_alloc_rx_flag(skb),
					NUMA_NO_NODE);
	int oldheadroom = skb_headroom(skb);
	int head_copy_len, head_copy_off;

	if (!n)
		return NULL;

	skb_reserve(n, newheadroom);

	/* Set the tail pointer and length */
	skb_put(n, skb->len);

	head_copy_len = oldheadroom;
	head_copy_off = 0;
	if (newheadroom <= head_copy_len)
		head_copy_len = newheadroom;
	else
		head_copy_off = newheadroom - head_copy_len;

	/* Copy the linear header and data. */
	if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
			  skb->len + head_copy_len))
		BUG();

	copy_skb_header(n, skb);

	skb_headers_offset_update(n, newheadroom - oldheadroom);

	return n;
}
EXPORT_SYMBOL(skb_copy_expand);

/**
 *	skb_pad			-	zero pad the tail of an skb
 *	@skb: buffer to pad
 *	@pad: space to pad
 *
 *	Ensure that a buffer is followed by a padding area that is zero
 *	filled. Used by network drivers which may DMA or transfer data
 *	beyond the buffer end onto the wire.
 *
 *	May return error in out of memory cases. The skb is freed on error.
 */

int skb_pad(struct sk_buff *skb, int pad)
{
	int err;
	int ntail;

	/* If the skbuff is non linear tailroom is always zero.. */
	if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
		memset(skb->data+skb->len, 0, pad);
		return 0;
	}

	ntail = skb->data_len + pad - (skb->end - skb->tail);
	if (likely(skb_cloned(skb) || ntail > 0)) {
		err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
		if (unlikely(err))
			goto free_skb;
	}

	/* FIXME: The use of this function with non-linear skb's really needs
	 * to be audited.
	 */
	err = skb_linearize(skb);
	if (unlikely(err))
		goto free_skb;

	memset(skb->data + skb->len, 0, pad);
	return 0;

free_skb:
	kfree_skb(skb);
	return err;
}
EXPORT_SYMBOL(skb_pad);

/**
 *	pskb_put - add data to the tail of a potentially fragmented buffer
 *	@skb: start of the buffer to use
 *	@tail: tail fragment of the buffer to use
 *	@len: amount of data to add
 *
 *	This function extends the used data area of the potentially
 *	fragmented buffer. @tail must be the last fragment of @skb -- or
 *	@skb itself. If this would exceed the total buffer size the kernel
 *	will panic. A pointer to the first byte of the extra data is
 *	returned.
 */

unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
{
	if (tail != skb) {
		skb->data_len += len;
		skb->len += len;
	}
	return skb_put(tail, len);
}
EXPORT_SYMBOL_GPL(pskb_put);

/**
 *	skb_put - add data to a buffer
 *	@skb: buffer to use
 *	@len: amount of data to add
 *
 *	This function extends the used data area of the buffer. If this would
 *	exceed the total buffer size the kernel will panic. A pointer to the
 *	first byte of the extra data is returned.
 */
unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
{
	unsigned char *tmp = skb_tail_pointer(skb);
	SKB_LINEAR_ASSERT(skb);
	skb->tail += len;
	skb->len  += len;
	if (unlikely(skb->tail > skb->end))
		skb_over_panic(skb, len, __builtin_return_address(0));
	return tmp;
}
EXPORT_SYMBOL(skb_put);

/**
 *	skb_push - add data to the start of a buffer
 *	@skb: buffer to use
 *	@len: amount of data to add
 *
 *	This function extends the used data area of the buffer at the buffer
 *	start. If this would exceed the total buffer headroom the kernel will
 *	panic. A pointer to the first byte of the extra data is returned.
 */
unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
{
	skb->data -= len;
	skb->len  += len;
	if (unlikely(skb->data<skb->head))
		skb_under_panic(skb, len, __builtin_return_address(0));
	return skb->data;
}
EXPORT_SYMBOL(skb_push);

/**
 *	skb_pull - remove data from the start of a buffer
 *	@skb: buffer to use
 *	@len: amount of data to remove
 *
 *	This function removes data from the start of a buffer, returning
 *	the memory to the headroom. A pointer to the next data in the buffer
 *	is returned. Once the data has been pulled future pushes will overwrite
 *	the old data.
 */
unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
{
	return skb_pull_inline(skb, len);
}
EXPORT_SYMBOL(skb_pull);

/**
 *	skb_trim - remove end from a buffer
 *	@skb: buffer to alter
 *	@len: new length
 *
 *	Cut the length of a buffer down by removing data from the tail. If
 *	the buffer is already under the length specified it is not modified.
 *	The skb must be linear.
 */
void skb_trim(struct sk_buff *skb, unsigned int len)
{
	if (skb->len > len)
		__skb_trim(skb, len);
}
EXPORT_SYMBOL(skb_trim);

/* Trims skb to length len. It can change skb pointers.
 */

int ___pskb_trim(struct sk_buff *skb, unsigned int len)
{
	struct sk_buff **fragp;
	struct sk_buff *frag;
	int offset = skb_headlen(skb);
	int nfrags = skb_shinfo(skb)->nr_frags;
	int i;
	int err;

	if (skb_cloned(skb) &&
	    unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
		return err;

	i = 0;
	if (offset >= len)
		goto drop_pages;

	for (; i < nfrags; i++) {
		int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);

		if (end < len) {
			offset = end;
			continue;
		}

		skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);

drop_pages:
		skb_shinfo(skb)->nr_frags = i;

		for (; i < nfrags; i++)
			skb_frag_unref(skb, i);

		if (skb_has_frag_list(skb))
			skb_drop_fraglist(skb);
		goto done;
	}

	for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
	     fragp = &frag->next) {
		int end = offset + frag->len;

		if (skb_shared(frag)) {
			struct sk_buff *nfrag;

			nfrag = skb_clone(frag, GFP_ATOMIC);
			if (unlikely(!nfrag))
				return -ENOMEM;

			nfrag->next = frag->next;
			consume_skb(frag);
			frag = nfrag;
			*fragp = frag;
		}

		if (end < len) {
			offset = end;
			continue;
		}

		if (end > len &&
		    unlikely((err = pskb_trim(frag, len - offset))))
			return err;

		if (frag->next)
			skb_drop_list(&frag->next);
		break;
	}

done:
	if (len > skb_headlen(skb)) {
		skb->data_len -= skb->len - len;
		skb->len       = len;
	} else {
		skb->len       = len;
		skb->data_len  = 0;
		skb_set_tail_pointer(skb, len);
	}

	return 0;
}
EXPORT_SYMBOL(___pskb_trim);

/**
 *	__pskb_pull_tail - advance tail of skb header
 *	@skb: buffer to reallocate
 *	@delta: number of bytes to advance tail
 *
 *	The function makes a sense only on a fragmented &sk_buff,
 *	it expands header moving its tail forward and copying necessary
 *	data from fragmented part.
 *
 *	&sk_buff MUST have reference count of 1.
 *
 *	Returns %NULL (and &sk_buff does not change) if pull failed
 *	or value of new tail of skb in the case of success.
 *
 *	All the pointers pointing into skb header may change and must be
 *	reloaded after call to this function.
 */

/* Moves tail of skb head forward, copying data from fragmented part,
 * when it is necessary.
 * 1. It may fail due to malloc failure.
 * 2. It may change skb pointers.
 *
 * It is pretty complicated. Luckily, it is called only in exceptional cases.
 */
unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
{
	/* If skb has not enough free space at tail, get new one
	 * plus 128 bytes for future expansions. If we have enough
	 * room at tail, reallocate without expansion only if skb is cloned.
	 */
	int i, k, eat = (skb->tail + delta) - skb->end;

	if (eat > 0 || skb_cloned(skb)) {
		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
				     GFP_ATOMIC))
			return NULL;
	}

	if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
		BUG();

	/* Optimization: no fragments, no reasons to preestimate
	 * size of pulled pages. Superb.
	 */
	if (!skb_has_frag_list(skb))
		goto pull_pages;

	/* Estimate size of pulled pages. */
	eat = delta;
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);

		if (size >= eat)
			goto pull_pages;
		eat -= size;
	}

	/* If we need update frag list, we are in troubles.
	 * Certainly, it possible to add an offset to skb data,
	 * but taking into account that pulling is expected to
	 * be very rare operation, it is worth to fight against
	 * further bloating skb head and crucify ourselves here instead.
	 * Pure masohism, indeed. 8)8)
	 */
	if (eat) {
		struct sk_buff *list = skb_shinfo(skb)->frag_list;
		struct sk_buff *clone = NULL;
		struct sk_buff *insp = NULL;

		do {
			BUG_ON(!list);

			if (list->len <= eat) {
				/* Eaten as whole. */
				eat -= list->len;
				list = list->next;
				insp = list;
			} else {
				/* Eaten partially. */

				if (skb_shared(list)) {
					/* Sucks! We need to fork list. :-( */
					clone = skb_clone(list, GFP_ATOMIC);
					if (!clone)
						return NULL;
					insp = list->next;
					list = clone;
				} else {
					/* This may be pulled without
					 * problems. */
					insp = list;
				}
				if (!pskb_pull(list, eat)) {
					kfree_skb(clone);
					return NULL;
				}
				break;
			}
		} while (eat);

		/* Free pulled out fragments. */
		while ((list = skb_shinfo(skb)->frag_list) != insp) {
			skb_shinfo(skb)->frag_list = list->next;
			kfree_skb(list);
		}
		/* And insert new clone at head. */
		if (clone) {
			clone->next = list;
			skb_shinfo(skb)->frag_list = clone;
		}
	}
	/* Success! Now we may commit changes to skb data. */

pull_pages:
	eat = delta;
	k = 0;
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);

		if (size <= eat) {
			skb_frag_unref(skb, i);
			eat -= size;
		} else {
			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
			if (eat) {
				skb_shinfo(skb)->frags[k].page_offset += eat;
				skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
				eat = 0;
			}
			k++;
		}
	}
	skb_shinfo(skb)->nr_frags = k;

	skb->tail     += delta;
	skb->data_len -= delta;

	return skb_tail_pointer(skb);
}
EXPORT_SYMBOL(__pskb_pull_tail);

/**
 *	skb_copy_bits - copy bits from skb to kernel buffer
 *	@skb: source skb
 *	@offset: offset in source
 *	@to: destination buffer
 *	@len: number of bytes to copy
 *
 *	Copy the specified number of bytes from the source skb to the
 *	destination buffer.
 *
 *	CAUTION ! :
 *		If its prototype is ever changed,
 *		check arch/{*}/net/{*}.S files,
 *		since it is called from BPF assembly code.
 */
int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
{
	int start = skb_headlen(skb);
	struct sk_buff *frag_iter;
	int i, copy;

	if (offset > (int)skb->len - len)
		goto fault;

	/* Copy header. */
	if ((copy = start - offset) > 0) {
		if (copy > len)
			copy = len;
		skb_copy_from_linear_data_offset(skb, offset, to, copy);
		if ((len -= copy) == 0)
			return 0;
		offset += copy;
		to     += copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int end;
		skb_frag_t *f = &skb_shinfo(skb)->frags[i];

		WARN_ON(start > offset + len);

		end = start + skb_frag_size(f);
		if ((copy = end - offset) > 0) {
			u8 *vaddr;

			if (copy > len)
				copy = len;

			vaddr = kmap_atomic(skb_frag_page(f));
			memcpy(to,
			       vaddr + f->page_offset + offset - start,
			       copy);
			kunmap_atomic(vaddr);

			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			to     += copy;
		}
		start = end;
	}

	skb_walk_frags(skb, frag_iter) {
		int end;

		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			if (skb_copy_bits(frag_iter, offset - start, to, copy))
				goto fault;
			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			to     += copy;
		}
		start = end;
	}

	if (!len)
		return 0;

fault:
	return -EFAULT;
}
EXPORT_SYMBOL(skb_copy_bits);

/*
 * Callback from splice_to_pipe(), if we need to release some pages
 * at the end of the spd in case we error'ed out in filling the pipe.
 */
static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
{
	put_page(spd->pages[i]);
}

static struct page *linear_to_page(struct page *page, unsigned int *len,
				   unsigned int *offset,
				   struct sock *sk)
{
	struct page_frag *pfrag = sk_page_frag(sk);

	if (!sk_page_frag_refill(sk, pfrag))
		return NULL;

	*len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);

	memcpy(page_address(pfrag->page) + pfrag->offset,
	       page_address(page) + *offset, *len);
	*offset = pfrag->offset;
	pfrag->offset += *len;

	return pfrag->page;
}

static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
			     struct page *page,
			     unsigned int offset)
{
	return	spd->nr_pages &&
		spd->pages[spd->nr_pages - 1] == page &&
		(spd->partial[spd->nr_pages - 1].offset +
		 spd->partial[spd->nr_pages - 1].len == offset);
}

/*
 * Fill page/offset/length into spd, if it can hold more pages.
 */
static bool spd_fill_page(struct splice_pipe_desc *spd,
			  struct pipe_inode_info *pipe, struct page *page,
			  unsigned int *len, unsigned int offset,
			  bool linear,
			  struct sock *sk)
{
	if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
		return true;

	if (linear) {
		page = linear_to_page(page, len, &offset, sk);
		if (!page)
			return true;
	}
	if (spd_can_coalesce(spd, page, offset)) {
		spd->partial[spd->nr_pages - 1].len += *len;
		return false;
	}
	get_page(page);
	spd->pages[spd->nr_pages] = page;
	spd->partial[spd->nr_pages].len = *len;
	spd->partial[spd->nr_pages].offset = offset;
	spd->nr_pages++;

	return false;
}

static bool __splice_segment(struct page *page, unsigned int poff,
			     unsigned int plen, unsigned int *off,
			     unsigned int *len,
			     struct splice_pipe_desc *spd, bool linear,
			     struct sock *sk,
			     struct pipe_inode_info *pipe)
{
	if (!*len)
		return true;

	/* skip this segment if already processed */
	if (*off >= plen) {
		*off -= plen;
		return false;
	}

	/* ignore any bits we already processed */
	poff += *off;
	plen -= *off;
	*off = 0;

	do {
		unsigned int flen = min(*len, plen);

		if (spd_fill_page(spd, pipe, page, &flen, poff,
				  linear, sk))
			return true;
		poff += flen;
		plen -= flen;
		*len -= flen;
	} while (*len && plen);

	return false;
}

/*
 * Map linear and fragment data from the skb to spd. It reports true if the
 * pipe is full or if we already spliced the requested length.
 */
static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
			      unsigned int *offset, unsigned int *len,
			      struct splice_pipe_desc *spd, struct sock *sk)
{
	int seg;

	/* map the linear part :
	 * If skb->head_frag is set, this 'linear' part is backed by a
	 * fragment, and if the head is not shared with any clones then
	 * we can avoid a copy since we own the head portion of this page.
	 */
	if (__splice_segment(virt_to_page(skb->data),
			     (unsigned long) skb->data & (PAGE_SIZE - 1),
			     skb_headlen(skb),
			     offset, len, spd,
			     skb_head_is_locked(skb),
			     sk, pipe))
		return true;

	/*
	 * then map the fragments
	 */
	for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];

		if (__splice_segment(skb_frag_page(f),
				     f->page_offset, skb_frag_size(f),
				     offset, len, spd, false, sk, pipe))
			return true;
	}

	return false;
}

/*
 * Map data from the skb to a pipe. Should handle both the linear part,
 * the fragments, and the frag list. It does NOT handle frag lists within
 * the frag list, if such a thing exists. We'd probably need to recurse to
 * handle that cleanly.
 */
int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
		    struct pipe_inode_info *pipe, unsigned int tlen,
		    unsigned int flags)
{
	struct partial_page partial[MAX_SKB_FRAGS];
	struct page *pages[MAX_SKB_FRAGS];
	struct splice_pipe_desc spd = {
		.pages = pages,
		.partial = partial,
		.nr_pages_max = MAX_SKB_FRAGS,
		.flags = flags,
		.ops = &nosteal_pipe_buf_ops,
		.spd_release = sock_spd_release,
	};
	struct sk_buff *frag_iter;
	struct sock *sk = skb->sk;
	int ret = 0;

	/*
	 * __skb_splice_bits() only fails if the output has no room left,
	 * so no point in going over the frag_list for the error case.
	 */
	if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
		goto done;
	else if (!tlen)
		goto done;

	/*
	 * now see if we have a frag_list to map
	 */
	skb_walk_frags(skb, frag_iter) {
		if (!tlen)
			break;
		if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
			break;
	}

done:
	if (spd.nr_pages) {
		/*
		 * Drop the socket lock, otherwise we have reverse
		 * locking dependencies between sk_lock and i_mutex
		 * here as compared to sendfile(). We enter here
		 * with the socket lock held, and splice_to_pipe() will
		 * grab the pipe inode lock. For sendfile() emulation,
		 * we call into ->sendpage() with the i_mutex lock held
		 * and networking will grab the socket lock.
		 */
		release_sock(sk);
		ret = splice_to_pipe(pipe, &spd);
		lock_sock(sk);
	}

	return ret;
}

/**
 *	skb_store_bits - store bits from kernel buffer to skb
 *	@skb: destination buffer
 *	@offset: offset in destination
 *	@from: source buffer
 *	@len: number of bytes to copy
 *
 *	Copy the specified number of bytes from the source buffer to the
 *	destination skb.  This function handles all the messy bits of
 *	traversing fragment lists and such.
 */

int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
{
	int start = skb_headlen(skb);
	struct sk_buff *frag_iter;
	int i, copy;

	if (offset > (int)skb->len - len)
		goto fault;

	if ((copy = start - offset) > 0) {
		if (copy > len)
			copy = len;
		skb_copy_to_linear_data_offset(skb, offset, from, copy);
		if ((len -= copy) == 0)
			return 0;
		offset += copy;
		from += copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
		int end;

		WARN_ON(start > offset + len);

		end = start + skb_frag_size(frag);
		if ((copy = end - offset) > 0) {
			u8 *vaddr;

			if (copy > len)
				copy = len;

			vaddr = kmap_atomic(skb_frag_page(frag));
			memcpy(vaddr + frag->page_offset + offset - start,
			       from, copy);
			kunmap_atomic(vaddr);

			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			from += copy;
		}
		start = end;
	}

	skb_walk_frags(skb, frag_iter) {
		int end;

		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			if (skb_store_bits(frag_iter, offset - start,
					   from, copy))
				goto fault;
			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			from += copy;
		}
		start = end;
	}
	if (!len)
		return 0;

fault:
	return -EFAULT;
}
EXPORT_SYMBOL(skb_store_bits);

/* Checksum skb data. */
__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
		      __wsum csum, const struct skb_checksum_ops *ops)
{
	int start = skb_headlen(skb);
	int i, copy = start - offset;
	struct sk_buff *frag_iter;
	int pos = 0;

	/* Checksum header. */
	if (copy > 0) {
		if (copy > len)
			copy = len;
		csum = ops->update(skb->data + offset, copy, csum);
		if ((len -= copy) == 0)
			return csum;
		offset += copy;
		pos	= copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int end;
		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

		WARN_ON(start > offset + len);

		end = start + skb_frag_size(frag);
		if ((copy = end - offset) > 0) {
			__wsum csum2;
			u8 *vaddr;

			if (copy > len)
				copy = len;
			vaddr = kmap_atomic(skb_frag_page(frag));
			csum2 = ops->update(vaddr + frag->page_offset +
					    offset - start, copy, 0);
			kunmap_atomic(vaddr);
			csum = ops->combine(csum, csum2, pos, copy);
			if (!(len -= copy))
				return csum;
			offset += copy;
			pos    += copy;
		}
		start = end;
	}

	skb_walk_frags(skb, frag_iter) {
		int end;

		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			__wsum csum2;
			if (copy > len)
				copy = len;
			csum2 = __skb_checksum(frag_iter, offset - start,
					       copy, 0, ops);
			csum = ops->combine(csum, csum2, pos, copy);
			if ((len -= copy) == 0)
				return csum;
			offset += copy;
			pos    += copy;
		}
		start = end;
	}
	BUG_ON(len);

	return csum;
}
EXPORT_SYMBOL(__skb_checksum);

__wsum skb_checksum(const struct sk_buff *skb, int offset,
		    int len, __wsum csum)
{
	const struct skb_checksum_ops ops = {
		.update  = csum_partial_ext,
		.combine = csum_block_add_ext,
	};

	return __skb_checksum(skb, offset, len, csum, &ops);
}
EXPORT_SYMBOL(skb_checksum);

/* Both of above in one bottle. */

__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
				    u8 *to, int len, __wsum csum)
{
	int start = skb_headlen(skb);
	int i, copy = start - offset;
	struct sk_buff *frag_iter;
	int pos = 0;

	/* Copy header. */
	if (copy > 0) {
		if (copy > len)
			copy = len;
		csum = csum_partial_copy_nocheck(skb->data + offset, to,
						 copy, csum);
		if ((len -= copy) == 0)
			return csum;
		offset += copy;
		to     += copy;
		pos	= copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int end;

		WARN_ON(start > offset + len);

		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
		if ((copy = end - offset) > 0) {
			__wsum csum2;
			u8 *vaddr;
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

			if (copy > len)
				copy = len;
			vaddr = kmap_atomic(skb_frag_page(frag));
			csum2 = csum_partial_copy_nocheck(vaddr +
							  frag->page_offset +
							  offset - start, to,
							  copy, 0);
			kunmap_atomic(vaddr);
			csum = csum_block_add(csum, csum2, pos);
			if (!(len -= copy))
				return csum;
			offset += copy;
			to     += copy;
			pos    += copy;
		}
		start = end;
	}

	skb_walk_frags(skb, frag_iter) {
		__wsum csum2;
		int end;

		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			csum2 = skb_copy_and_csum_bits(frag_iter,
						       offset - start,
						       to, copy, 0);
			csum = csum_block_add(csum, csum2, pos);
			if ((len -= copy) == 0)
				return csum;
			offset += copy;
			to     += copy;
			pos    += copy;
		}
		start = end;
	}
	BUG_ON(len);
	return csum;
}
EXPORT_SYMBOL(skb_copy_and_csum_bits);

 /**
 *	skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
 *	@from: source buffer
 *
 *	Calculates the amount of linear headroom needed in the 'to' skb passed
 *	into skb_zerocopy().
 */
unsigned int
skb_zerocopy_headlen(const struct sk_buff *from)
{
	unsigned int hlen = 0;

	if (!from->head_frag ||
	    skb_headlen(from) < L1_CACHE_BYTES ||
	    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
		hlen = skb_headlen(from);

	if (skb_has_frag_list(from))
		hlen = from->len;

	return hlen;
}
EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);

/**
 *	skb_zerocopy - Zero copy skb to skb
 *	@to: destination buffer
 *	@from: source buffer
 *	@len: number of bytes to copy from source buffer
 *	@hlen: size of linear headroom in destination buffer
 *
 *	Copies up to `len` bytes from `from` to `to` by creating references
 *	to the frags in the source buffer.
 *
 *	The `hlen` as calculated by skb_zerocopy_headlen() specifies the
 *	headroom in the `to` buffer.
 *
 *	Return value:
 *	0: everything is OK
 *	-ENOMEM: couldn't orphan frags of @from due to lack of memory
 *	-EFAULT: skb_copy_bits() found some problem with skb geometry
 */
int
skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
{
	int i, j = 0;
	int plen = 0; /* length of skb->head fragment */
	int ret;
	struct page *page;
	unsigned int offset;

	BUG_ON(!from->head_frag && !hlen);

	/* dont bother with small payloads */
	if (len <= skb_tailroom(to))
		return skb_copy_bits(from, 0, skb_put(to, len), len);

	if (hlen) {
		ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
		if (unlikely(ret))
			return ret;
		len -= hlen;
	} else {
		plen = min_t(int, skb_headlen(from), len);
		if (plen) {
			page = virt_to_head_page(from->head);
			offset = from->data - (unsigned char *)page_address(page);
			__skb_fill_page_desc(to, 0, page, offset, plen);
			get_page(page);
			j = 1;
			len -= plen;
		}
	}

	to->truesize += len + plen;
	to->len += len + plen;
	to->data_len += len + plen;

	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
		skb_tx_error(from);
		return -ENOMEM;
	}

	for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
		if (!len)
			break;
		skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
		skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
		len -= skb_shinfo(to)->frags[j].size;
		skb_frag_ref(to, j);
		j++;
	}
	skb_shinfo(to)->nr_frags = j;

	return 0;
}
EXPORT_SYMBOL_GPL(skb_zerocopy);

void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
{
	__wsum csum;
	long csstart;

	if (skb->ip_summed == CHECKSUM_PARTIAL)
		csstart = skb_checksum_start_offset(skb);
	else
		csstart = skb_headlen(skb);

	BUG_ON(csstart > skb_headlen(skb));

	skb_copy_from_linear_data(skb, to, csstart);

	csum = 0;
	if (csstart != skb->len)
		csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
					      skb->len - csstart, 0);

	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		long csstuff = csstart + skb->csum_offset;

		*((__sum16 *)(to + csstuff)) = csum_fold(csum);
	}
}
EXPORT_SYMBOL(skb_copy_and_csum_dev);

/**
 *	skb_dequeue - remove from the head of the queue
 *	@list: list to dequeue from
 *
 *	Remove the head of the list. The list lock is taken so the function
 *	may be used safely with other locking list functions. The head item is
 *	returned or %NULL if the list is empty.
 */

struct sk_buff *skb_dequeue(struct sk_buff_head *list)
{
	unsigned long flags;
	struct sk_buff *result;

	spin_lock_irqsave(&list->lock, flags);
	result = __skb_dequeue(list);
	spin_unlock_irqrestore(&list->lock, flags);
	return result;
}
EXPORT_SYMBOL(skb_dequeue);

/**
 *	skb_dequeue_tail - remove from the tail of the queue
 *	@list: list to dequeue from
 *
 *	Remove the tail of the list. The list lock is taken so the function
 *	may be used safely with other locking list functions. The tail item is
 *	returned or %NULL if the list is empty.
 */
struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
{
	unsigned long flags;
	struct sk_buff *result;

	spin_lock_irqsave(&list->lock, flags);
	result = __skb_dequeue_tail(list);
	spin_unlock_irqrestore(&list->lock, flags);
	return result;
}
EXPORT_SYMBOL(skb_dequeue_tail);

/**
 *	skb_queue_purge - empty a list
 *	@list: list to empty
 *
 *	Delete all buffers on an &sk_buff list. Each buffer is removed from
 *	the list and one reference dropped. This function takes the list
 *	lock and is atomic with respect to other list locking functions.
 */
void skb_queue_purge(struct sk_buff_head *list)
{
	struct sk_buff *skb;
	while ((skb = skb_dequeue(list)) != NULL)
		kfree_skb(skb);
}
EXPORT_SYMBOL(skb_queue_purge);

/**
 *	skb_queue_head - queue a buffer at the list head
 *	@list: list to use
 *	@newsk: buffer to queue
 *
 *	Queue a buffer at the start of the list. This function takes the
 *	list lock and can be used safely with other locking &sk_buff functions
 *	safely.
 *
 *	A buffer cannot be placed on two lists at the same time.
 */
void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
{
	unsigned long flags;

	spin_lock_irqsave(&list->lock, flags);
	__skb_queue_head(list, newsk);
	spin_unlock_irqrestore(&list->lock, flags);
}
EXPORT_SYMBOL(skb_queue_head);

/**
 *	skb_queue_tail - queue a buffer at the list tail
 *	@list: list to use
 *	@newsk: buffer to queue
 *
 *	Queue a buffer at the tail of the list. This function takes the
 *	list lock and can be used safely with other locking &sk_buff functions
 *	safely.
 *
 *	A buffer cannot be placed on two lists at the same time.
 */
void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
{
	unsigned long flags;

	spin_lock_irqsave(&list->lock, flags);
	__skb_queue_tail(list, newsk);
	spin_unlock_irqrestore(&list->lock, flags);
}
EXPORT_SYMBOL(skb_queue_tail);

/**
 *	skb_unlink	-	remove a buffer from a list
 *	@skb: buffer to remove
 *	@list: list to use
 *
 *	Remove a packet from a list. The list locks are taken and this
 *	function is atomic with respect to other list locked calls
 *
 *	You must know what list the SKB is on.
 */
void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
{
	unsigned long flags;

	spin_lock_irqsave(&list->lock, flags);
	__skb_unlink(skb, list);
	spin_unlock_irqrestore(&list->lock, flags);
}
EXPORT_SYMBOL(skb_unlink);

/**
 *	skb_append	-	append a buffer
 *	@old: buffer to insert after
 *	@newsk: buffer to insert
 *	@list: list to use
 *
 *	Place a packet after a given packet in a list. The list locks are taken
 *	and this function is atomic with respect to other list locked calls.
 *	A buffer cannot be placed on two lists at the same time.
 */
void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
{
	unsigned long flags;

	spin_lock_irqsave(&list->lock, flags);
	__skb_queue_after(list, old, newsk);
	spin_unlock_irqrestore(&list->lock, flags);
}
EXPORT_SYMBOL(skb_append);

/**
 *	skb_insert	-	insert a buffer
 *	@old: buffer to insert before
 *	@newsk: buffer to insert
 *	@list: list to use
 *
 *	Place a packet before a given packet in a list. The list locks are
 * 	taken and this function is atomic with respect to other list locked
 *	calls.
 *
 *	A buffer cannot be placed on two lists at the same time.
 */
void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
{
	unsigned long flags;

	spin_lock_irqsave(&list->lock, flags);
	__skb_insert(newsk, old->prev, old, list);
	spin_unlock_irqrestore(&list->lock, flags);
}
EXPORT_SYMBOL(skb_insert);

static inline void skb_split_inside_header(struct sk_buff *skb,
					   struct sk_buff* skb1,
					   const u32 len, const int pos)
{
	int i;

	skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
					 pos - len);
	/* And move data appendix as is. */
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
		skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];

	skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
	skb_shinfo(skb)->nr_frags  = 0;
	skb1->data_len		   = skb->data_len;
	skb1->len		   += skb1->data_len;
	skb->data_len		   = 0;
	skb->len		   = len;
	skb_set_tail_pointer(skb, len);
}

static inline void skb_split_no_header(struct sk_buff *skb,
				       struct sk_buff* skb1,
				       const u32 len, int pos)
{
	int i, k = 0;
	const int nfrags = skb_shinfo(skb)->nr_frags;

	skb_shinfo(skb)->nr_frags = 0;
	skb1->len		  = skb1->data_len = skb->len - len;
	skb->len		  = len;
	skb->data_len		  = len - pos;

	for (i = 0; i < nfrags; i++) {
		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);

		if (pos + size > len) {
			skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];

			if (pos < len) {
				/* Split frag.
				 * We have two variants in this case:
				 * 1. Move all the frag to the second
				 *    part, if it is possible. F.e.
				 *    this approach is mandatory for TUX,
				 *    where splitting is expensive.
				 * 2. Split is accurately. We make this.
				 */
				skb_frag_ref(skb, i);
				skb_shinfo(skb1)->frags[0].page_offset += len - pos;
				skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
				skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
				skb_shinfo(skb)->nr_frags++;
			}
			k++;
		} else
			skb_shinfo(skb)->nr_frags++;
		pos += size;
	}
	skb_shinfo(skb1)->nr_frags = k;
}

/**
 * skb_split - Split fragmented skb to two parts at length len.
 * @skb: the buffer to split
 * @skb1: the buffer to receive the second part
 * @len: new length for skb
 */
void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
{
	int pos = skb_headlen(skb);

	skb_shinfo(skb1)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
	if (len < pos)	/* Split line is inside header. */
		skb_split_inside_header(skb, skb1, len, pos);
	else		/* Second chunk has no header, nothing to copy. */
		skb_split_no_header(skb, skb1, len, pos);
}
EXPORT_SYMBOL(skb_split);

/* Shifting from/to a cloned skb is a no-go.
 *
 * Caller cannot keep skb_shinfo related pointers past calling here!
 */
static int skb_prepare_for_shift(struct sk_buff *skb)
{
	return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
}

/**
 * skb_shift - Shifts paged data partially from skb to another
 * @tgt: buffer into which tail data gets added
 * @skb: buffer from which the paged data comes from
 * @shiftlen: shift up to this many bytes
 *
 * Attempts to shift up to shiftlen worth of bytes, which may be less than
 * the length of the skb, from skb to tgt. Returns number bytes shifted.
 * It's up to caller to free skb if everything was shifted.
 *
 * If @tgt runs out of frags, the whole operation is aborted.
 *
 * Skb cannot include anything else but paged data while tgt is allowed
 * to have non-paged data as well.
 *
 * TODO: full sized shift could be optimized but that would need
 * specialized skb free'er to handle frags without up-to-date nr_frags.
 */
int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
{
	int from, to, merge, todo;
	struct skb_frag_struct *fragfrom, *fragto;

	BUG_ON(shiftlen > skb->len);
	BUG_ON(skb_headlen(skb));	/* Would corrupt stream */

	todo = shiftlen;
	from = 0;
	to = skb_shinfo(tgt)->nr_frags;
	fragfrom = &skb_shinfo(skb)->frags[from];

	/* Actual merge is delayed until the point when we know we can
	 * commit all, so that we don't have to undo partial changes
	 */
	if (!to ||
	    !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
			      fragfrom->page_offset)) {
		merge = -1;
	} else {
		merge = to - 1;

		todo -= skb_frag_size(fragfrom);
		if (todo < 0) {
			if (skb_prepare_for_shift(skb) ||
			    skb_prepare_for_shift(tgt))
				return 0;

			/* All previous frag pointers might be stale! */
			fragfrom = &skb_shinfo(skb)->frags[from];
			fragto = &skb_shinfo(tgt)->frags[merge];

			skb_frag_size_add(fragto, shiftlen);
			skb_frag_size_sub(fragfrom, shiftlen);
			fragfrom->page_offset += shiftlen;

			goto onlymerged;
		}

		from++;
	}

	/* Skip full, not-fitting skb to avoid expensive operations */
	if ((shiftlen == skb->len) &&
	    (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
		return 0;

	if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
		return 0;

	while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
		if (to == MAX_SKB_FRAGS)
			return 0;

		fragfrom = &skb_shinfo(skb)->frags[from];
		fragto = &skb_shinfo(tgt)->frags[to];

		if (todo >= skb_frag_size(fragfrom)) {
			*fragto = *fragfrom;
			todo -= skb_frag_size(fragfrom);
			from++;
			to++;

		} else {
			__skb_frag_ref(fragfrom);
			fragto->page = fragfrom->page;
			fragto->page_offset = fragfrom->page_offset;
			skb_frag_size_set(fragto, todo);

			fragfrom->page_offset += todo;
			skb_frag_size_sub(fragfrom, todo);
			todo = 0;

			to++;
			break;
		}
	}

	/* Ready to "commit" this state change to tgt */
	skb_shinfo(tgt)->nr_frags = to;

	if (merge >= 0) {
		fragfrom = &skb_shinfo(skb)->frags[0];
		fragto = &skb_shinfo(tgt)->frags[merge];

		skb_frag_size_add(fragto, skb_frag_size(fragfrom));
		__skb_frag_unref(fragfrom);
	}

	/* Reposition in the original skb */
	to = 0;
	while (from < skb_shinfo(skb)->nr_frags)
		skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
	skb_shinfo(skb)->nr_frags = to;

	BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);

onlymerged:
	/* Most likely the tgt won't ever need its checksum anymore, skb on
	 * the other hand might need it if it needs to be resent
	 */
	tgt->ip_summed = CHECKSUM_PARTIAL;
	skb->ip_summed = CHECKSUM_PARTIAL;

	/* Yak, is it really working this way? Some helper please? */
	skb->len -= shiftlen;
	skb->data_len -= shiftlen;
	skb->truesize -= shiftlen;
	tgt->len += shiftlen;
	tgt->data_len += shiftlen;
	tgt->truesize += shiftlen;

	return shiftlen;
}

/**
 * skb_prepare_seq_read - Prepare a sequential read of skb data
 * @skb: the buffer to read
 * @from: lower offset of data to be read
 * @to: upper offset of data to be read
 * @st: state variable
 *
 * Initializes the specified state variable. Must be called before
 * invoking skb_seq_read() for the first time.
 */
void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
			  unsigned int to, struct skb_seq_state *st)
{
	st->lower_offset = from;
	st->upper_offset = to;
	st->root_skb = st->cur_skb = skb;
	st->frag_idx = st->stepped_offset = 0;
	st->frag_data = NULL;
}
EXPORT_SYMBOL(skb_prepare_seq_read);

/**
 * skb_seq_read - Sequentially read skb data
 * @consumed: number of bytes consumed by the caller so far
 * @data: destination pointer for data to be returned
 * @st: state variable
 *
 * Reads a block of skb data at @consumed relative to the
 * lower offset specified to skb_prepare_seq_read(). Assigns
 * the head of the data block to @data and returns the length
 * of the block or 0 if the end of the skb data or the upper
 * offset has been reached.
 *
 * The caller is not required to consume all of the data
 * returned, i.e. @consumed is typically set to the number
 * of bytes already consumed and the next call to
 * skb_seq_read() will return the remaining part of the block.
 *
 * Note 1: The size of each block of data returned can be arbitrary,
 *       this limitation is the cost for zerocopy sequential
 *       reads of potentially non linear data.
 *
 * Note 2: Fragment lists within fragments are not implemented
 *       at the moment, state->root_skb could be replaced with
 *       a stack for this purpose.
 */
unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
			  struct skb_seq_state *st)
{
	unsigned int block_limit, abs_offset = consumed + st->lower_offset;
	skb_frag_t *frag;

	if (unlikely(abs_offset >= st->upper_offset)) {
		if (st->frag_data) {
			kunmap_atomic(st->frag_data);
			st->frag_data = NULL;
		}
		return 0;
	}

next_skb:
	block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;

	if (abs_offset < block_limit && !st->frag_data) {
		*data = st->cur_skb->data + (abs_offset - st->stepped_offset);
		return block_limit - abs_offset;
	}

	if (st->frag_idx == 0 && !st->frag_data)
		st->stepped_offset += skb_headlen(st->cur_skb);

	while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
		frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
		block_limit = skb_frag_size(frag) + st->stepped_offset;

		if (abs_offset < block_limit) {
			if (!st->frag_data)
				st->frag_data = kmap_atomic(skb_frag_page(frag));

			*data = (u8 *) st->frag_data + frag->page_offset +
				(abs_offset - st->stepped_offset);

			return block_limit - abs_offset;
		}

		if (st->frag_data) {
			kunmap_atomic(st->frag_data);
			st->frag_data = NULL;
		}

		st->frag_idx++;
		st->stepped_offset += skb_frag_size(frag);
	}

	if (st->frag_data) {
		kunmap_atomic(st->frag_data);
		st->frag_data = NULL;
	}

	if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
		st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
		st->frag_idx = 0;
		goto next_skb;
	} else if (st->cur_skb->next) {
		st->cur_skb = st->cur_skb->next;
		st->frag_idx = 0;
		goto next_skb;
	}

	return 0;
}
EXPORT_SYMBOL(skb_seq_read);

/**
 * skb_abort_seq_read - Abort a sequential read of skb data
 * @st: state variable
 *
 * Must be called if skb_seq_read() was not called until it
 * returned 0.
 */
void skb_abort_seq_read(struct skb_seq_state *st)
{
	if (st->frag_data)
		kunmap_atomic(st->frag_data);
}
EXPORT_SYMBOL(skb_abort_seq_read);

#define TS_SKB_CB(state)	((struct skb_seq_state *) &((state)->cb))

static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
					  struct ts_config *conf,
					  struct ts_state *state)
{
	return skb_seq_read(offset, text, TS_SKB_CB(state));
}

static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
{
	skb_abort_seq_read(TS_SKB_CB(state));
}

/**
 * skb_find_text - Find a text pattern in skb data
 * @skb: the buffer to look in
 * @from: search offset
 * @to: search limit
 * @config: textsearch configuration
 * @state: uninitialized textsearch state variable
 *
 * Finds a pattern in the skb data according to the specified
 * textsearch configuration. Use textsearch_next() to retrieve
 * subsequent occurrences of the pattern. Returns the offset
 * to the first occurrence or UINT_MAX if no match was found.
 */
unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
			   unsigned int to, struct ts_config *config,
			   struct ts_state *state)
{
	unsigned int ret;

	config->get_next_block = skb_ts_get_next_block;
	config->finish = skb_ts_finish;

	skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));

	ret = textsearch_find(config, state);
	return (ret <= to - from ? ret : UINT_MAX);
}
EXPORT_SYMBOL(skb_find_text);

/**
 * skb_append_datato_frags - append the user data to a skb
 * @sk: sock  structure
 * @skb: skb structure to be appended with user data.
 * @getfrag: call back function to be used for getting the user data
 * @from: pointer to user message iov
 * @length: length of the iov message
 *
 * Description: This procedure append the user data in the fragment part
 * of the skb if any page alloc fails user this procedure returns  -ENOMEM
 */
int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
			int (*getfrag)(void *from, char *to, int offset,
					int len, int odd, struct sk_buff *skb),
			void *from, int length)
{
	int frg_cnt = skb_shinfo(skb)->nr_frags;
	int copy;
	int offset = 0;
	int ret;
	struct page_frag *pfrag = &current->task_frag;

	do {
		/* Return error if we don't have space for new frag */
		if (frg_cnt >= MAX_SKB_FRAGS)
			return -EMSGSIZE;

		if (!sk_page_frag_refill(sk, pfrag))
			return -ENOMEM;

		/* copy the user data to page */
		copy = min_t(int, length, pfrag->size - pfrag->offset);

		ret = getfrag(from, page_address(pfrag->page) + pfrag->offset,
			      offset, copy, 0, skb);
		if (ret < 0)
			return -EFAULT;

		/* copy was successful so update the size parameters */
		skb_fill_page_desc(skb, frg_cnt, pfrag->page, pfrag->offset,
				   copy);
		frg_cnt++;
		pfrag->offset += copy;
		get_page(pfrag->page);

		skb->truesize += copy;
		atomic_add(copy, &sk->sk_wmem_alloc);
		skb->len += copy;
		skb->data_len += copy;
		offset += copy;
		length -= copy;

	} while (length > 0);

	return 0;
}
EXPORT_SYMBOL(skb_append_datato_frags);

/**
 *	skb_pull_rcsum - pull skb and update receive checksum
 *	@skb: buffer to update
 *	@len: length of data pulled
 *
 *	This function performs an skb_pull on the packet and updates
 *	the CHECKSUM_COMPLETE checksum.  It should be used on
 *	receive path processing instead of skb_pull unless you know
 *	that the checksum difference is zero (e.g., a valid IP header)
 *	or you are setting ip_summed to CHECKSUM_NONE.
 */
unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
{
	BUG_ON(len > skb->len);
	skb->len -= len;
	BUG_ON(skb->len < skb->data_len);
	skb_postpull_rcsum(skb, skb->data, len);
	return skb->data += len;
}
EXPORT_SYMBOL_GPL(skb_pull_rcsum);

/**
 *	skb_segment - Perform protocol segmentation on skb.
 *	@head_skb: buffer to segment
 *	@features: features for the output path (see dev->features)
 *
 *	This function performs segmentation on the given skb.  It returns
 *	a pointer to the first in a list of new skbs for the segments.
 *	In case of error it returns ERR_PTR(err).
 */
struct sk_buff *skb_segment(struct sk_buff *head_skb,
			    netdev_features_t features)
{
	struct sk_buff *segs = NULL;
	struct sk_buff *tail = NULL;
	struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
	skb_frag_t *frag = skb_shinfo(head_skb)->frags;
	unsigned int mss = skb_shinfo(head_skb)->gso_size;
	unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
	struct sk_buff *frag_skb = head_skb;
	unsigned int offset = doffset;
	unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
	unsigned int headroom;
	unsigned int len;
	__be16 proto;
	bool csum;
	int sg = !!(features & NETIF_F_SG);
	int nfrags = skb_shinfo(head_skb)->nr_frags;
	int err = -ENOMEM;
	int i = 0;
	int pos;
	int dummy;

	__skb_push(head_skb, doffset);
	proto = skb_network_protocol(head_skb, &dummy);
	if (unlikely(!proto))
		return ERR_PTR(-EINVAL);

	csum = !head_skb->encap_hdr_csum &&
	    !!can_checksum_protocol(features, proto);

	headroom = skb_headroom(head_skb);
	pos = skb_headlen(head_skb);

	do {
		struct sk_buff *nskb;
		skb_frag_t *nskb_frag;
		int hsize;
		int size;

		len = head_skb->len - offset;
		if (len > mss)
			len = mss;

		hsize = skb_headlen(head_skb) - offset;
		if (hsize < 0)
			hsize = 0;
		if (hsize > len || !sg)
			hsize = len;

		if (!hsize && i >= nfrags && skb_headlen(list_skb) &&
		    (skb_headlen(list_skb) == len || sg)) {
			BUG_ON(skb_headlen(list_skb) > len);

			i = 0;
			nfrags = skb_shinfo(list_skb)->nr_frags;
			frag = skb_shinfo(list_skb)->frags;
			frag_skb = list_skb;
			pos += skb_headlen(list_skb);

			while (pos < offset + len) {
				BUG_ON(i >= nfrags);

				size = skb_frag_size(frag);
				if (pos + size > offset + len)
					break;

				i++;
				pos += size;
				frag++;
			}

			nskb = skb_clone(list_skb, GFP_ATOMIC);
			list_skb = list_skb->next;

			if (unlikely(!nskb))
				goto err;

			if (unlikely(pskb_trim(nskb, len))) {
				kfree_skb(nskb);
				goto err;
			}

			hsize = skb_end_offset(nskb);
			if (skb_cow_head(nskb, doffset + headroom)) {
				kfree_skb(nskb);
				goto err;
			}

			nskb->truesize += skb_end_offset(nskb) - hsize;
			skb_release_head_state(nskb);
			__skb_push(nskb, doffset);
		} else {
			nskb = __alloc_skb(hsize + doffset + headroom,
					   GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
					   NUMA_NO_NODE);

			if (unlikely(!nskb))
				goto err;

			skb_reserve(nskb, headroom);
			__skb_put(nskb, doffset);
		}

		if (segs)
			tail->next = nskb;
		else
			segs = nskb;
		tail = nskb;

		__copy_skb_header(nskb, head_skb);

		skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
		skb_reset_mac_len(nskb);

		skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
						 nskb->data - tnl_hlen,
						 doffset + tnl_hlen);

		if (nskb->len == len + doffset)
			goto perform_csum_check;

		if (!sg && !nskb->remcsum_offload) {
			nskb->ip_summed = CHECKSUM_NONE;
			nskb->csum = skb_copy_and_csum_bits(head_skb, offset,
							    skb_put(nskb, len),
							    len, 0);
			SKB_GSO_CB(nskb)->csum_start =
			    skb_headroom(nskb) + doffset;
			continue;
		}

		nskb_frag = skb_shinfo(nskb)->frags;

		skb_copy_from_linear_data_offset(head_skb, offset,
						 skb_put(nskb, hsize), hsize);

		skb_shinfo(nskb)->tx_flags = skb_shinfo(head_skb)->tx_flags &
			SKBTX_SHARED_FRAG;

		while (pos < offset + len) {
			if (i >= nfrags) {
				BUG_ON(skb_headlen(list_skb));

				i = 0;
				nfrags = skb_shinfo(list_skb)->nr_frags;
				frag = skb_shinfo(list_skb)->frags;
				frag_skb = list_skb;

				BUG_ON(!nfrags);

				list_skb = list_skb->next;
			}

			if (unlikely(skb_shinfo(nskb)->nr_frags >=
				     MAX_SKB_FRAGS)) {
				net_warn_ratelimited(
					"skb_segment: too many frags: %u %u\n",
					pos, mss);
				goto err;
			}

			if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
				goto err;

			*nskb_frag = *frag;
			__skb_frag_ref(nskb_frag);
			size = skb_frag_size(nskb_frag);

			if (pos < offset) {
				nskb_frag->page_offset += offset - pos;
				skb_frag_size_sub(nskb_frag, offset - pos);
			}

			skb_shinfo(nskb)->nr_frags++;

			if (pos + size <= offset + len) {
				i++;
				frag++;
				pos += size;
			} else {
				skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
				goto skip_fraglist;
			}

			nskb_frag++;
		}

skip_fraglist:
		nskb->data_len = len - hsize;
		nskb->len += nskb->data_len;
		nskb->truesize += nskb->data_len;

perform_csum_check:
		if (!csum && !nskb->remcsum_offload) {
			nskb->csum = skb_checksum(nskb, doffset,
						  nskb->len - doffset, 0);
			nskb->ip_summed = CHECKSUM_NONE;
			SKB_GSO_CB(nskb)->csum_start =
			    skb_headroom(nskb) + doffset;
		}
	} while ((offset += len) < head_skb->len);

	/* Some callers want to get the end of the list.
	 * Put it in segs->prev to avoid walking the list.
	 * (see validate_xmit_skb_list() for example)
	 */
	segs->prev = tail;

	/* Following permits correct backpressure, for protocols
	 * using skb_set_owner_w().
	 * Idea is to tranfert ownership from head_skb to last segment.
	 */
	if (head_skb->destructor == sock_wfree) {
		swap(tail->truesize, head_skb->truesize);
		swap(tail->destructor, head_skb->destructor);
		swap(tail->sk, head_skb->sk);
	}
	return segs;

err:
	kfree_skb_list(segs);
	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(skb_segment);

int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
{
	struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
	unsigned int offset = skb_gro_offset(skb);
	unsigned int headlen = skb_headlen(skb);
	struct sk_buff *nskb, *lp, *p = *head;
	unsigned int len = skb_gro_len(skb);
	unsigned int delta_truesize;
	unsigned int headroom;

	if (unlikely(p->len + len >= 65536))
		return -E2BIG;

	lp = NAPI_GRO_CB(p)->last;
	pinfo = skb_shinfo(lp);

	if (headlen <= offset) {
		skb_frag_t *frag;
		skb_frag_t *frag2;
		int i = skbinfo->nr_frags;
		int nr_frags = pinfo->nr_frags + i;

		if (nr_frags > MAX_SKB_FRAGS)
			goto merge;

		offset -= headlen;
		pinfo->nr_frags = nr_frags;
		skbinfo->nr_frags = 0;

		frag = pinfo->frags + nr_frags;
		frag2 = skbinfo->frags + i;
		do {
			*--frag = *--frag2;
		} while (--i);

		frag->page_offset += offset;
		skb_frag_size_sub(frag, offset);

		/* all fragments truesize : remove (head size + sk_buff) */
		delta_truesize = skb->truesize -
				 SKB_TRUESIZE(skb_end_offset(skb));

		skb->truesize -= skb->data_len;
		skb->len -= skb->data_len;
		skb->data_len = 0;

		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
		goto done;
	} else if (skb->head_frag) {
		int nr_frags = pinfo->nr_frags;
		skb_frag_t *frag = pinfo->frags + nr_frags;
		struct page *page = virt_to_head_page(skb->head);
		unsigned int first_size = headlen - offset;
		unsigned int first_offset;

		if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
			goto merge;

		first_offset = skb->data -
			       (unsigned char *)page_address(page) +
			       offset;

		pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;

		frag->page.p	  = page;
		frag->page_offset = first_offset;
		skb_frag_size_set(frag, first_size);

		memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
		/* We dont need to clear skbinfo->nr_frags here */

		delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
		goto done;
	}
	/* switch back to head shinfo */
	pinfo = skb_shinfo(p);

	if (pinfo->frag_list)
		goto merge;
	if (skb_gro_len(p) != pinfo->gso_size)
		return -E2BIG;

	headroom = skb_headroom(p);
	nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
	if (unlikely(!nskb))
		return -ENOMEM;

	__copy_skb_header(nskb, p);
	nskb->mac_len = p->mac_len;

	skb_reserve(nskb, headroom);
	__skb_put(nskb, skb_gro_offset(p));

	skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
	skb_set_network_header(nskb, skb_network_offset(p));
	skb_set_transport_header(nskb, skb_transport_offset(p));

	__skb_pull(p, skb_gro_offset(p));
	memcpy(skb_mac_header(nskb), skb_mac_header(p),
	       p->data - skb_mac_header(p));

	skb_shinfo(nskb)->frag_list = p;
	skb_shinfo(nskb)->gso_size = pinfo->gso_size;
	pinfo->gso_size = 0;
	__skb_header_release(p);
	NAPI_GRO_CB(nskb)->last = p;

	nskb->data_len += p->len;
	nskb->truesize += p->truesize;
	nskb->len += p->len;

	*head = nskb;
	nskb->next = p->next;
	p->next = NULL;

	p = nskb;

merge:
	delta_truesize = skb->truesize;
	if (offset > headlen) {
		unsigned int eat = offset - headlen;

		skbinfo->frags[0].page_offset += eat;
		skb_frag_size_sub(&skbinfo->frags[0], eat);
		skb->data_len -= eat;
		skb->len -= eat;
		offset = headlen;
	}

	__skb_pull(skb, offset);

	if (NAPI_GRO_CB(p)->last == p)
		skb_shinfo(p)->frag_list = skb;
	else
		NAPI_GRO_CB(p)->last->next = skb;
	NAPI_GRO_CB(p)->last = skb;
	__skb_header_release(skb);
	lp = p;

done:
	NAPI_GRO_CB(p)->count++;
	p->data_len += len;
	p->truesize += delta_truesize;
	p->len += len;
	if (lp != p) {
		lp->data_len += len;
		lp->truesize += delta_truesize;
		lp->len += len;
	}
	NAPI_GRO_CB(skb)->same_flow = 1;
	return 0;
}

void __init skb_init(void)
{
	skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
					      sizeof(struct sk_buff),
					      0,
					      SLAB_HWCACHE_ALIGN|SLAB_PANIC,
					      NULL);
	skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
						sizeof(struct sk_buff_fclones),
						0,
						SLAB_HWCACHE_ALIGN|SLAB_PANIC,
						NULL);
}

/**
 *	skb_to_sgvec - Fill a scatter-gather list from a socket buffer
 *	@skb: Socket buffer containing the buffers to be mapped
 *	@sg: The scatter-gather list to map into
 *	@offset: The offset into the buffer's contents to start mapping
 *	@len: Length of buffer space to be mapped
 *
 *	Fill the specified scatter-gather list with mappings/pointers into a
 *	region of the buffer space attached to a socket buffer.
 */
static int
__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
{
	int start = skb_headlen(skb);
	int i, copy = start - offset;
	struct sk_buff *frag_iter;
	int elt = 0;

	if (copy > 0) {
		if (copy > len)
			copy = len;
		sg_set_buf(sg, skb->data + offset, copy);
		elt++;
		if ((len -= copy) == 0)
			return elt;
		offset += copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int end;

		WARN_ON(start > offset + len);

		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
		if ((copy = end - offset) > 0) {
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

			if (copy > len)
				copy = len;
			sg_set_page(&sg[elt], skb_frag_page(frag), copy,
					frag->page_offset+offset-start);
			elt++;
			if (!(len -= copy))
				return elt;
			offset += copy;
		}
		start = end;
	}

	skb_walk_frags(skb, frag_iter) {
		int end;

		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
					      copy);
			if ((len -= copy) == 0)
				return elt;
			offset += copy;
		}
		start = end;
	}
	BUG_ON(len);
	return elt;
}

/* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
 * sglist without mark the sg which contain last skb data as the end.
 * So the caller can mannipulate sg list as will when padding new data after
 * the first call without calling sg_unmark_end to expend sg list.
 *
 * Scenario to use skb_to_sgvec_nomark:
 * 1. sg_init_table
 * 2. skb_to_sgvec_nomark(payload1)
 * 3. skb_to_sgvec_nomark(payload2)
 *
 * This is equivalent to:
 * 1. sg_init_table
 * 2. skb_to_sgvec(payload1)
 * 3. sg_unmark_end
 * 4. skb_to_sgvec(payload2)
 *
 * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
 * is more preferable.
 */
int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
			int offset, int len)
{
	return __skb_to_sgvec(skb, sg, offset, len);
}
EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);

int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
{
	int nsg = __skb_to_sgvec(skb, sg, offset, len);

	sg_mark_end(&sg[nsg - 1]);

	return nsg;
}
EXPORT_SYMBOL_GPL(skb_to_sgvec);

/**
 *	skb_cow_data - Check that a socket buffer's data buffers are writable
 *	@skb: The socket buffer to check.
 *	@tailbits: Amount of trailing space to be added
 *	@trailer: Returned pointer to the skb where the @tailbits space begins
 *
 *	Make sure that the data buffers attached to a socket buffer are
 *	writable. If they are not, private copies are made of the data buffers
 *	and the socket buffer is set to use these instead.
 *
 *	If @tailbits is given, make sure that there is space to write @tailbits
 *	bytes of data beyond current end of socket buffer.  @trailer will be
 *	set to point to the skb in which this space begins.
 *
 *	The number of scatterlist elements required to completely map the
 *	COW'd and extended socket buffer will be returned.
 */
int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
{
	int copyflag;
	int elt;
	struct sk_buff *skb1, **skb_p;

	/* If skb is cloned or its head is paged, reallocate
	 * head pulling out all the pages (pages are considered not writable
	 * at the moment even if they are anonymous).
	 */
	if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
	    __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
		return -ENOMEM;

	/* Easy case. Most of packets will go this way. */
	if (!skb_has_frag_list(skb)) {
		/* A little of trouble, not enough of space for trailer.
		 * This should not happen, when stack is tuned to generate
		 * good frames. OK, on miss we reallocate and reserve even more
		 * space, 128 bytes is fair. */

		if (skb_tailroom(skb) < tailbits &&
		    pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
			return -ENOMEM;

		/* Voila! */
		*trailer = skb;
		return 1;
	}

	/* Misery. We are in troubles, going to mincer fragments... */

	elt = 1;
	skb_p = &skb_shinfo(skb)->frag_list;
	copyflag = 0;

	while ((skb1 = *skb_p) != NULL) {
		int ntail = 0;

		/* The fragment is partially pulled by someone,
		 * this can happen on input. Copy it and everything
		 * after it. */

		if (skb_shared(skb1))
			copyflag = 1;

		/* If the skb is the last, worry about trailer. */

		if (skb1->next == NULL && tailbits) {
			if (skb_shinfo(skb1)->nr_frags ||
			    skb_has_frag_list(skb1) ||
			    skb_tailroom(skb1) < tailbits)
				ntail = tailbits + 128;
		}

		if (copyflag ||
		    skb_cloned(skb1) ||
		    ntail ||
		    skb_shinfo(skb1)->nr_frags ||
		    skb_has_frag_list(skb1)) {
			struct sk_buff *skb2;

			/* Fuck, we are miserable poor guys... */
			if (ntail == 0)
				skb2 = skb_copy(skb1, GFP_ATOMIC);
			else
				skb2 = skb_copy_expand(skb1,
						       skb_headroom(skb1),
						       ntail,
						       GFP_ATOMIC);
			if (unlikely(skb2 == NULL))
				return -ENOMEM;

			if (skb1->sk)
				skb_set_owner_w(skb2, skb1->sk);

			/* Looking around. Are we still alive?
			 * OK, link new skb, drop old one */

			skb2->next = skb1->next;
			*skb_p = skb2;
			kfree_skb(skb1);
			skb1 = skb2;
		}
		elt++;
		*trailer = skb1;
		skb_p = &skb1->next;
	}

	return elt;
}
EXPORT_SYMBOL_GPL(skb_cow_data);

static void sock_rmem_free(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;

	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
}

/*
 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
 */
int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
{
	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
	    (unsigned int)sk->sk_rcvbuf)
		return -ENOMEM;

	skb_orphan(skb);
	skb->sk = sk;
	skb->destructor = sock_rmem_free;
	atomic_add(skb->truesize, &sk->sk_rmem_alloc);

	/* before exiting rcu section, make sure dst is refcounted */
	skb_dst_force(skb);

	skb_queue_tail(&sk->sk_error_queue, skb);
	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_data_ready(sk);
	return 0;
}
EXPORT_SYMBOL(sock_queue_err_skb);

struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
{
	struct sk_buff_head *q = &sk->sk_error_queue;
	struct sk_buff *skb, *skb_next;
	int err = 0;

	spin_lock_bh(&q->lock);
	skb = __skb_dequeue(q);
	if (skb && (skb_next = skb_peek(q)))
		err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
	spin_unlock_bh(&q->lock);

	sk->sk_err = err;
	if (err)
		sk->sk_error_report(sk);

	return skb;
}
EXPORT_SYMBOL(sock_dequeue_err_skb);

/**
 * skb_clone_sk - create clone of skb, and take reference to socket
 * @skb: the skb to clone
 *
 * This function creates a clone of a buffer that holds a reference on
 * sk_refcnt.  Buffers created via this function are meant to be
 * returned using sock_queue_err_skb, or free via kfree_skb.
 *
 * When passing buffers allocated with this function to sock_queue_err_skb
 * it is necessary to wrap the call with sock_hold/sock_put in order to
 * prevent the socket from being released prior to being enqueued on
 * the sk_error_queue.
 */
struct sk_buff *skb_clone_sk(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;
	struct sk_buff *clone;

	if (!sk || !atomic_inc_not_zero(&sk->sk_refcnt))
		return NULL;

	clone = skb_clone(skb, GFP_ATOMIC);
	if (!clone) {
		sock_put(sk);
		return NULL;
	}

	clone->sk = sk;
	clone->destructor = sock_efree;

	return clone;
}
EXPORT_SYMBOL(skb_clone_sk);

static void __skb_complete_tx_timestamp(struct sk_buff *skb,
					struct sock *sk,
					int tstype)
{
	struct sock_exterr_skb *serr;
	int err;

	serr = SKB_EXT_ERR(skb);
	memset(serr, 0, sizeof(*serr));
	serr->ee.ee_errno = ENOMSG;
	serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
	serr->ee.ee_info = tstype;
	if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
		serr->ee.ee_data = skb_shinfo(skb)->tskey;
		if (sk->sk_protocol == IPPROTO_TCP)
			serr->ee.ee_data -= sk->sk_tskey;
	}

	err = sock_queue_err_skb(sk, skb);

	if (err)
		kfree_skb(skb);
}

void skb_complete_tx_timestamp(struct sk_buff *skb,
			       struct skb_shared_hwtstamps *hwtstamps)
{
	struct sock *sk = skb->sk;

	/* take a reference to prevent skb_orphan() from freeing the socket */
	sock_hold(sk);

	*skb_hwtstamps(skb) = *hwtstamps;
	__skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);

	sock_put(sk);
}
EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);

void __skb_tstamp_tx(struct sk_buff *orig_skb,
		     struct skb_shared_hwtstamps *hwtstamps,
		     struct sock *sk, int tstype)
{
	struct sk_buff *skb;

	if (!sk)
		return;

	if (hwtstamps)
		*skb_hwtstamps(orig_skb) = *hwtstamps;
	else
		orig_skb->tstamp = ktime_get_real();

	skb = skb_clone(orig_skb, GFP_ATOMIC);
	if (!skb)
		return;

	__skb_complete_tx_timestamp(skb, sk, tstype);
}
EXPORT_SYMBOL_GPL(__skb_tstamp_tx);

void skb_tstamp_tx(struct sk_buff *orig_skb,
		   struct skb_shared_hwtstamps *hwtstamps)
{
	return __skb_tstamp_tx(orig_skb, hwtstamps, orig_skb->sk,
			       SCM_TSTAMP_SND);
}
EXPORT_SYMBOL_GPL(skb_tstamp_tx);

void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
{
	struct sock *sk = skb->sk;
	struct sock_exterr_skb *serr;
	int err;

	skb->wifi_acked_valid = 1;
	skb->wifi_acked = acked;

	serr = SKB_EXT_ERR(skb);
	memset(serr, 0, sizeof(*serr));
	serr->ee.ee_errno = ENOMSG;
	serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;

	/* take a reference to prevent skb_orphan() from freeing the socket */
	sock_hold(sk);

	err = sock_queue_err_skb(sk, skb);
	if (err)
		kfree_skb(skb);

	sock_put(sk);
}
EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);


/**
 * skb_partial_csum_set - set up and verify partial csum values for packet
 * @skb: the skb to set
 * @start: the number of bytes after skb->data to start checksumming.
 * @off: the offset from start to place the checksum.
 *
 * For untrusted partially-checksummed packets, we need to make sure the values
 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
 *
 * This function checks and sets those values and skb->ip_summed: if this
 * returns false you should drop the packet.
 */
bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
{
	if (unlikely(start > skb_headlen(skb)) ||
	    unlikely((int)start + off > skb_headlen(skb) - 2)) {
		net_warn_ratelimited("bad partial csum: csum=%u/%u len=%u\n",
				     start, off, skb_headlen(skb));
		return false;
	}
	skb->ip_summed = CHECKSUM_PARTIAL;
	skb->csum_start = skb_headroom(skb) + start;
	skb->csum_offset = off;
	skb_set_transport_header(skb, start);
	return true;
}
EXPORT_SYMBOL_GPL(skb_partial_csum_set);

static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
			       unsigned int max)
{
	if (skb_headlen(skb) >= len)
		return 0;

	/* If we need to pullup then pullup to the max, so we
	 * won't need to do it again.
	 */
	if (max > skb->len)
		max = skb->len;

	if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
		return -ENOMEM;

	if (skb_headlen(skb) < len)
		return -EPROTO;

	return 0;
}

#define MAX_TCP_HDR_LEN (15 * 4)

static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
				      typeof(IPPROTO_IP) proto,
				      unsigned int off)
{
	switch (proto) {
		int err;

	case IPPROTO_TCP:
		err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
					  off + MAX_TCP_HDR_LEN);
		if (!err && !skb_partial_csum_set(skb, off,
						  offsetof(struct tcphdr,
							   check)))
			err = -EPROTO;
		return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;

	case IPPROTO_UDP:
		err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
					  off + sizeof(struct udphdr));
		if (!err && !skb_partial_csum_set(skb, off,
						  offsetof(struct udphdr,
							   check)))
			err = -EPROTO;
		return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
	}

	return ERR_PTR(-EPROTO);
}

/* This value should be large enough to cover a tagged ethernet header plus
 * maximally sized IP and TCP or UDP headers.
 */
#define MAX_IP_HDR_LEN 128

static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
{
	unsigned int off;
	bool fragment;
	__sum16 *csum;
	int err;

	fragment = false;

	err = skb_maybe_pull_tail(skb,
				  sizeof(struct iphdr),
				  MAX_IP_HDR_LEN);
	if (err < 0)
		goto out;

	if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
		fragment = true;

	off = ip_hdrlen(skb);

	err = -EPROTO;

	if (fragment)
		goto out;

	csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
	if (IS_ERR(csum))
		return PTR_ERR(csum);

	if (recalculate)
		*csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
					   ip_hdr(skb)->daddr,
					   skb->len - off,
					   ip_hdr(skb)->protocol, 0);
	err = 0;

out:
	return err;
}

/* This value should be large enough to cover a tagged ethernet header plus
 * an IPv6 header, all options, and a maximal TCP or UDP header.
 */
#define MAX_IPV6_HDR_LEN 256

#define OPT_HDR(type, skb, off) \
	(type *)(skb_network_header(skb) + (off))

static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
{
	int err;
	u8 nexthdr;
	unsigned int off;
	unsigned int len;
	bool fragment;
	bool done;
	__sum16 *csum;

	fragment = false;
	done = false;

	off = sizeof(struct ipv6hdr);

	err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
	if (err < 0)
		goto out;

	nexthdr = ipv6_hdr(skb)->nexthdr;

	len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
	while (off <= len && !done) {
		switch (nexthdr) {
		case IPPROTO_DSTOPTS:
		case IPPROTO_HOPOPTS:
		case IPPROTO_ROUTING: {
			struct ipv6_opt_hdr *hp;

			err = skb_maybe_pull_tail(skb,
						  off +
						  sizeof(struct ipv6_opt_hdr),
						  MAX_IPV6_HDR_LEN);
			if (err < 0)
				goto out;

			hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
			nexthdr = hp->nexthdr;
			off += ipv6_optlen(hp);
			break;
		}
		case IPPROTO_AH: {
			struct ip_auth_hdr *hp;

			err = skb_maybe_pull_tail(skb,
						  off +
						  sizeof(struct ip_auth_hdr),
						  MAX_IPV6_HDR_LEN);
			if (err < 0)
				goto out;

			hp = OPT_HDR(struct ip_auth_hdr, skb, off);
			nexthdr = hp->nexthdr;
			off += ipv6_authlen(hp);
			break;
		}
		case IPPROTO_FRAGMENT: {
			struct frag_hdr *hp;

			err = skb_maybe_pull_tail(skb,
						  off +
						  sizeof(struct frag_hdr),
						  MAX_IPV6_HDR_LEN);
			if (err < 0)
				goto out;

			hp = OPT_HDR(struct frag_hdr, skb, off);

			if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
				fragment = true;

			nexthdr = hp->nexthdr;
			off += sizeof(struct frag_hdr);
			break;
		}
		default:
			done = true;
			break;
		}
	}

	err = -EPROTO;

	if (!done || fragment)
		goto out;

	csum = skb_checksum_setup_ip(skb, nexthdr, off);
	if (IS_ERR(csum))
		return PTR_ERR(csum);

	if (recalculate)
		*csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
					 &ipv6_hdr(skb)->daddr,
					 skb->len - off, nexthdr, 0);
	err = 0;

out:
	return err;
}

/**
 * skb_checksum_setup - set up partial checksum offset
 * @skb: the skb to set up
 * @recalculate: if true the pseudo-header checksum will be recalculated
 */
int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
{
	int err;

	switch (skb->protocol) {
	case htons(ETH_P_IP):
		err = skb_checksum_setup_ipv4(skb, recalculate);
		break;

	case htons(ETH_P_IPV6):
		err = skb_checksum_setup_ipv6(skb, recalculate);
		break;

	default:
		err = -EPROTO;
		break;
	}

	return err;
}
EXPORT_SYMBOL(skb_checksum_setup);

void __skb_warn_lro_forwarding(const struct sk_buff *skb)
{
	net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
			     skb->dev->name);
}
EXPORT_SYMBOL(__skb_warn_lro_forwarding);

void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
{
	if (head_stolen) {
		skb_release_head_state(skb);
		kmem_cache_free(skbuff_head_cache, skb);
	} else {
		__kfree_skb(skb);
	}
}
EXPORT_SYMBOL(kfree_skb_partial);

/**
 * skb_try_coalesce - try to merge skb to prior one
 * @to: prior buffer
 * @from: buffer to add
 * @fragstolen: pointer to boolean
 * @delta_truesize: how much more was allocated than was requested
 */
bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
		      bool *fragstolen, int *delta_truesize)
{
	int i, delta, len = from->len;

	*fragstolen = false;

	if (skb_cloned(to))
		return false;

	if (len <= skb_tailroom(to)) {
		if (len)
			BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
		*delta_truesize = 0;
		return true;
	}

	if (skb_has_frag_list(to) || skb_has_frag_list(from))
		return false;

	if (skb_headlen(from) != 0) {
		struct page *page;
		unsigned int offset;

		if (skb_shinfo(to)->nr_frags +
		    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
			return false;

		if (skb_head_is_locked(from))
			return false;

		delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));

		page = virt_to_head_page(from->head);
		offset = from->data - (unsigned char *)page_address(page);

		skb_fill_page_desc(to, skb_shinfo(to)->nr_frags,
				   page, offset, skb_headlen(from));
		*fragstolen = true;
	} else {
		if (skb_shinfo(to)->nr_frags +
		    skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS)
			return false;

		delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
	}

	WARN_ON_ONCE(delta < len);

	memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags,
	       skb_shinfo(from)->frags,
	       skb_shinfo(from)->nr_frags * sizeof(skb_frag_t));
	skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags;

	if (!skb_cloned(from))
		skb_shinfo(from)->nr_frags = 0;

	/* if the skb is not cloned this does nothing
	 * since we set nr_frags to 0.
	 */
	for (i = 0; i < skb_shinfo(from)->nr_frags; i++)
		skb_frag_ref(from, i);

	to->truesize += delta;
	to->len += len;
	to->data_len += len;

	*delta_truesize = delta;
	return true;
}
EXPORT_SYMBOL(skb_try_coalesce);

/**
 * skb_scrub_packet - scrub an skb
 *
 * @skb: buffer to clean
 * @xnet: packet is crossing netns
 *
 * skb_scrub_packet can be used after encapsulating or decapsulting a packet
 * into/from a tunnel. Some information have to be cleared during these
 * operations.
 * skb_scrub_packet can also be used to clean a skb before injecting it in
 * another namespace (@xnet == true). We have to clear all information in the
 * skb that could impact namespace isolation.
 */
void skb_scrub_packet(struct sk_buff *skb, bool xnet)
{
	if (xnet)
		skb_orphan(skb);
	skb->tstamp.tv64 = 0;
	skb->pkt_type = PACKET_HOST;
	skb->skb_iif = 0;
	skb->ignore_df = 0;
	skb_dst_drop(skb);
	skb->mark = 0;
	skb_init_secmark(skb);
	secpath_reset(skb);
	nf_reset(skb);
	nf_reset_trace(skb);
}
EXPORT_SYMBOL_GPL(skb_scrub_packet);

/**
 * skb_gso_transport_seglen - Return length of individual segments of a gso packet
 *
 * @skb: GSO skb
 *
 * skb_gso_transport_seglen is used to determine the real size of the
 * individual segments, including Layer4 headers (TCP/UDP).
 *
 * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
 */
unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
{
	const struct skb_shared_info *shinfo = skb_shinfo(skb);
	unsigned int thlen = 0;

	if (skb->encapsulation) {
		thlen = skb_inner_transport_header(skb) -
			skb_transport_header(skb);

		if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
			thlen += inner_tcp_hdrlen(skb);
	} else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
		thlen = tcp_hdrlen(skb);
	}
	/* UFO sets gso_size to the size of the fragmentation
	 * payload, i.e. the size of the L4 (UDP) header is already
	 * accounted for.
	 */
	return thlen + shinfo->gso_size;
}
EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);

static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
{
	if (skb_cow(skb, skb_headroom(skb)) < 0) {
		kfree_skb(skb);
		return NULL;
	}

	memmove(skb->data - ETH_HLEN, skb->data - VLAN_ETH_HLEN, 2 * ETH_ALEN);
	skb->mac_header += VLAN_HLEN;
	return skb;
}

struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
{
	struct vlan_hdr *vhdr;
	u16 vlan_tci;

	if (unlikely(vlan_tx_tag_present(skb))) {
		/* vlan_tci is already set-up so leave this for another time */
		return skb;
	}

	skb = skb_share_check(skb, GFP_ATOMIC);
	if (unlikely(!skb))
		goto err_free;

	if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
		goto err_free;

	vhdr = (struct vlan_hdr *)skb->data;
	vlan_tci = ntohs(vhdr->h_vlan_TCI);
	__vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);

	skb_pull_rcsum(skb, VLAN_HLEN);
	vlan_set_encap_proto(skb, vhdr);

	skb = skb_reorder_vlan_header(skb);
	if (unlikely(!skb))
		goto err_free;

	skb_reset_network_header(skb);
	skb_reset_transport_header(skb);
	skb_reset_mac_len(skb);

	return skb;

err_free:
	kfree_skb(skb);
	return NULL;
}
EXPORT_SYMBOL(skb_vlan_untag);

int skb_ensure_writable(struct sk_buff *skb, int write_len)
{
	if (!pskb_may_pull(skb, write_len))
		return -ENOMEM;

	if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
		return 0;

	return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
}
EXPORT_SYMBOL(skb_ensure_writable);

/* remove VLAN header from packet and update csum accordingly. */
static int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
{
	struct vlan_hdr *vhdr;
	unsigned int offset = skb->data - skb_mac_header(skb);
	int err;

	__skb_push(skb, offset);
	err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
	if (unlikely(err))
		goto pull;

	skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);

	vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
	*vlan_tci = ntohs(vhdr->h_vlan_TCI);

	memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
	__skb_pull(skb, VLAN_HLEN);

	vlan_set_encap_proto(skb, vhdr);
	skb->mac_header += VLAN_HLEN;

	if (skb_network_offset(skb) < ETH_HLEN)
		skb_set_network_header(skb, ETH_HLEN);

	skb_reset_mac_len(skb);
pull:
	__skb_pull(skb, offset);

	return err;
}

int skb_vlan_pop(struct sk_buff *skb)
{
	u16 vlan_tci;
	__be16 vlan_proto;
	int err;

	if (likely(vlan_tx_tag_present(skb))) {
		skb->vlan_tci = 0;
	} else {
		if (unlikely((skb->protocol != htons(ETH_P_8021Q) &&
			      skb->protocol != htons(ETH_P_8021AD)) ||
			     skb->len < VLAN_ETH_HLEN))
			return 0;

		err = __skb_vlan_pop(skb, &vlan_tci);
		if (err)
			return err;
	}
	/* move next vlan tag to hw accel tag */
	if (likely((skb->protocol != htons(ETH_P_8021Q) &&
		    skb->protocol != htons(ETH_P_8021AD)) ||
		   skb->len < VLAN_ETH_HLEN))
		return 0;

	vlan_proto = skb->protocol;
	err = __skb_vlan_pop(skb, &vlan_tci);
	if (unlikely(err))
		return err;

	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
	return 0;
}
EXPORT_SYMBOL(skb_vlan_pop);

int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
{
	if (vlan_tx_tag_present(skb)) {
		unsigned int offset = skb->data - skb_mac_header(skb);
		int err;

		/* __vlan_insert_tag expect skb->data pointing to mac header.
		 * So change skb->data before calling it and change back to
		 * original position later
		 */
		__skb_push(skb, offset);
		err = __vlan_insert_tag(skb, skb->vlan_proto,
					vlan_tx_tag_get(skb));
		if (err)
			return err;
		skb->protocol = skb->vlan_proto;
		skb->mac_len += VLAN_HLEN;
		__skb_pull(skb, offset);

		if (skb->ip_summed == CHECKSUM_COMPLETE)
			skb->csum = csum_add(skb->csum, csum_partial(skb->data
					+ (2 * ETH_ALEN), VLAN_HLEN, 0));
	}
	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
	return 0;
}
EXPORT_SYMBOL(skb_vlan_push);

/**
 * alloc_skb_with_frags - allocate skb with page frags
 *
 * @header_len: size of linear part
 * @data_len: needed length in frags
 * @max_page_order: max page order desired.
 * @errcode: pointer to error code if any
 * @gfp_mask: allocation mask
 *
 * This can be used to allocate a paged skb, given a maximal order for frags.
 */
struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
				     unsigned long data_len,
				     int max_page_order,
				     int *errcode,
				     gfp_t gfp_mask)
{
	int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
	unsigned long chunk;
	struct sk_buff *skb;
	struct page *page;
	gfp_t gfp_head;
	int i;

	*errcode = -EMSGSIZE;
	/* Note this test could be relaxed, if we succeed to allocate
	 * high order pages...
	 */
	if (npages > MAX_SKB_FRAGS)
		return NULL;

	gfp_head = gfp_mask;
	if (gfp_head & __GFP_WAIT)
		gfp_head |= __GFP_REPEAT;

	*errcode = -ENOBUFS;
	skb = alloc_skb(header_len, gfp_head);
	if (!skb)
		return NULL;

	skb->truesize += npages << PAGE_SHIFT;

	for (i = 0; npages > 0; i++) {
		int order = max_page_order;

		while (order) {
			if (npages >= 1 << order) {
				page = alloc_pages(gfp_mask |
						   __GFP_COMP |
						   __GFP_NOWARN |
						   __GFP_NORETRY,
						   order);
				if (page)
					goto fill_page;
				/* Do not retry other high order allocations */
				order = 1;
				max_page_order = 0;
			}
			order--;
		}
		page = alloc_page(gfp_mask);
		if (!page)
			goto failure;
fill_page:
		chunk = min_t(unsigned long, data_len,
			      PAGE_SIZE << order);
		skb_fill_page_desc(skb, i, page, 0, chunk);
		data_len -= chunk;
		npages -= 1 << order;
	}
	return skb;

failure:
	kfree_skb(skb);
	return NULL;
}
EXPORT_SYMBOL(alloc_skb_with_frags);