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* lib/: rename random32() to prandom_u32()Akinobu Mita2013-04-291-1/+1
| | | | | | | | | Use preferable function name which implies using a pseudo-random number generator. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/list_sort: test: check element addressesArtem Bityutskiy2010-10-261-8/+67
| | | | | | | | | | | | | | Improve 'lib_sort()' test and check that: o 'cmp()' is called only for elements which were present in the original list, i.e., the 'a' and 'b' parameters are valid o the resulted (sorted) list consists onlly of the original elements o intdoruce "poison" fields to make sure data around 'struc list_head' field are not corrupted. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: Don Mullis <don.mullis@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/list_sort: test: unify test messagesArtem Bityutskiy2010-10-261-9/+10
| | | | | | | | | | | This patch unifies 'list_sort_test()' messages a bit and makes sure all of them start with the "list_sort_test:" prefix to make it obvious for users where the messages come from. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: Don Mullis <don.mullis@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/list_sort: test: improve errors handlingArtem Bityutskiy2010-10-261-27/+38
| | | | | | | | | | | | | | | | | | | The 'lib_sort()' test does not free memory if it fails, and it makes the kernel panic if it cannot allocate memory. This patch fixes the problem. This patch also changes several small things: o use 'list_add()' helper instead of adding manually o introduce temporary 'el1' variable to avoid ugly and unreadalbe "if" statement o make 'head' to be stack variable instead of 'kmalloc()'ed, which simplifies code a bit Overall, this patch is of clean-up type. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: Don Mullis <don.mullis@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/list_sort: test: use generic random32Artem Bityutskiy2010-10-261-12/+15
| | | | | | | | | | | | | | | | Instead of using own pseudo-random generator, use generic linux 'random32()' function. Presumably, this should improve test coverage. At the same time, do the following changes: o Use shorter macro name for test list length o Do not use strange 'l_h' name for 'struct list_head' element, use 'list', because it is traditional name and thus, makes the code more obvious and readable. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: Don Mullis <don.mullis@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/list_sort: test: use more reasonable printk levelsArtem Bityutskiy2010-10-261-8/+8
| | | | | | | | | | | I do not see any reason to use KERN_WARN for normal messages and KERN_EMERG for error messages in the lib_sort testing routine. Let's use more reasonable KERN_NORM and KERN_ERR levels. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: Don Mullis <don.mullis@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/Kconfig.debug: add list_sort debugging switchArtem Bityutskiy2010-10-261-2/+2
| | | | | | | | | | | | | | | | | | While hunting a non-existing bug in 'list_sort()', I've improved the 'list_sort_test()' function which tests the 'list_sort()' library call. Although at the end I found a bug in my code, but not in 'list_sort()', I think my clean-ups and improvements are worth merging because they make the test function better. This patch: Make the self-tests selectable via Kconfig rather than by manual enabling of DEBUG_LIST_SORT. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: Don Mullis <don.mullis@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/list_sort: do not pass bad pointers to cmp callbackDon Mullis2010-10-011-1/+1
| | | | | | | | | | | | | | | | If the original list is a POT in length, the first callback from line 73 will pass a==b both pointing to the original list_head. This is dangerous because the 'list_sort()' user can use 'container_of()' and accesses the "containing" object, which does not necessary exist for the list head. So the user can access RAM which does not belong to him. If this is a write access, we can end up with memory corruption. Signed-off-by: Don Mullis <don.mullis@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: revise list_sort() header commentDon Mullis2010-03-061-7/+8
| | | | | | | | | | | | Clarify and correct header comment of list_sort(). Signed-off-by: Don Mullis <don.mullis@gmail.com> Cc: Dave Airlie <airlied@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Artem Bityutskiy <dedekind@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: more scalable list_sort()Don Mullis2010-03-061-69/+183
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | XFS and UBIFS can pass long lists to list_sort(); this alternative implementation scales better, reaching ~3x performance gain when list length exceeds the L2 cache size. Stand-alone program timings were run on a Core 2 duo L1=32KB L2=4MB, gcc-4.4, with flags extracted from an Ubuntu kernel build. Object size is 581 bytes compared to 455 for Mark J. Roberts' code. Worst case for either implementation is a list length just over a power of two, and to roughly the same degree, so here are timing results for a range of 2^N+1 lengths. List elements were 16 bytes each including malloc overhead; initial order was random. time (msec) Tatham-Roberts | generic-Mullis-v2 loop_count length | | ratio 4000000 2 206 294 1.427 2000000 3 176 227 1.289 1000000 5 199 172 0.864 500000 9 235 178 0.757 250000 17 243 182 0.748 125000 33 261 196 0.750 62500 65 277 209 0.754 31250 129 292 219 0.75 15625 257 317 235 0.741 7812 513 340 252 0.741 3906 1025 362 267 0.737 1953 2049 388 283 0.729 ~ L1 size 976 4097 556 323 0.580 488 8193 678 361 0.532 244 16385 773 395 0.510 122 32769 844 418 0.495 61 65537 917 454 0.495 30 131073 1128 543 0.481 15 262145 2355 869 0.369 ~ L2 size 7 524289 5597 1714 0.306 3 1048577 6218 2022 0.325 Mark's code does not actually implement the usual or generic mergesort, but rather a variant from Simon Tatham described here: http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html Simon's algorithm performs O(log N) passes over the entire input list, doing merges of sublists that double in size on each pass. The generic algorithm instead merges pairs of equal length lists as early as possible, in recursive order. For either algorithm, the elements that extend the list beyond power-of-two length are a special case, handled as nearly as possible as a "rounding-up" to a full POT. Some intuition for the locality of reference implications of merge order may be gotten by watching this animation: http://www.sorting-algorithms.com/merge-sort Simon's algorithm requires only O(1) extra space rather than the generic algorithm's O(log N), but in my non-recursive implementation the actual O(log N) data is merely a vector of ~20 pointers, which I've put on the stack. Long-running list_sort() calls: If the list passed in may be long, or the client's cmp() callback function is slow, the client's cmp() may periodically invoke cond_resched() to voluntarily yield the CPU. All inner loops of list_sort() call back to cmp(). Stability of the sort: distinct elements that compare equal emerge from the sort in the same order as with Mark's code, for simple test cases. A boot-time test is provided to verify this and other correctness requirements. A kernel that uses drm.ko appears to run normally with this change; I have no suitable hardware to similarly test the use by UBIFS. [akpm@linux-foundation.org: style tweaks, fix comment, make list_sort_test __init] Signed-off-by: Don Mullis <don.mullis@gmail.com> Cc: Dave Airlie <airlied@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Artem Bityutskiy <dedekind@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: Introduce generic list_sort functionDave Chinner2010-01-121-0/+102
There are two copies of list_sort() in the tree already, one in the DRM code, another in ubifs. Now XFS needs this as well. Create a generic list_sort() function from the ubifs version and convert existing users to it so we don't end up with yet another copy in the tree. Signed-off-by: Dave Chinner <david@fromorbit.com> Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Artem Bityutskiy <dedekind@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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