From 9d186cac7ffb1831e9f34cb4a3a8b22abb9dd9d4 Mon Sep 17 00:00:00 2001 From: Andrey Vagin Date: Wed, 13 Aug 2014 16:03:10 +0400 Subject: tcp: don't use timestamp from repaired skb-s to calculate RTT (v2) We don't know right timestamp for repaired skb-s. Wrong RTT estimations isn't good, because some congestion modules heavily depends on it. This patch adds the TCPCB_REPAIRED flag, which is included in TCPCB_RETRANS. Thanks to Eric for the advice how to fix this issue. This patch fixes the warning: [ 879.562947] WARNING: CPU: 0 PID: 2825 at net/ipv4/tcp_input.c:3078 tcp_ack+0x11f5/0x1380() [ 879.567253] CPU: 0 PID: 2825 Comm: socket-tcpbuf-l Not tainted 3.16.0-next-20140811 #1 [ 879.567829] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 879.568177] 0000000000000000 00000000c532680c ffff880039643d00 ffffffff817aa2d2 [ 879.568776] 0000000000000000 ffff880039643d38 ffffffff8109afbd ffff880039d6ba80 [ 879.569386] ffff88003a449800 000000002983d6bd 0000000000000000 000000002983d6bc [ 879.569982] Call Trace: [ 879.570264] [] dump_stack+0x4d/0x66 [ 879.570599] [] warn_slowpath_common+0x7d/0xa0 [ 879.570935] [] warn_slowpath_null+0x1a/0x20 [ 879.571292] [] tcp_ack+0x11f5/0x1380 [ 879.571614] [] tcp_rcv_established+0x1ed/0x710 [ 879.571958] [] tcp_v4_do_rcv+0x10a/0x370 [ 879.572315] [] release_sock+0x89/0x1d0 [ 879.572642] [] do_tcp_setsockopt.isra.36+0x120/0x860 [ 879.573000] [] ? rcu_read_lock_held+0x6e/0x80 [ 879.573352] [] tcp_setsockopt+0x32/0x40 [ 879.573678] [] sock_common_setsockopt+0x14/0x20 [ 879.574031] [] SyS_setsockopt+0x80/0xf0 [ 879.574393] [] system_call_fastpath+0x16/0x1b [ 879.574730] ---[ end trace a17cbc38eb8c5c00 ]--- v2: moving setting of skb->when for repaired skb-s in tcp_write_xmit, where it's set for other skb-s. Fixes: 431a91242d8d ("tcp: timestamp SYN+DATA messages") Fixes: 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution") Cc: Eric Dumazet Cc: Pavel Emelyanov Cc: "David S. Miller" Signed-off-by: Andrey Vagin Signed-off-by: David S. Miller --- include/net/tcp.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/tcp.h b/include/net/tcp.h index dafa1cbc149b..36f55254573f 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -705,8 +705,10 @@ struct tcp_skb_cb { #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ #define TCPCB_LOST 0x04 /* SKB is lost */ #define TCPCB_TAGBITS 0x07 /* All tag bits */ +#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ -#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS) +#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ + TCPCB_REPAIRED) __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ /* 1 byte hole */ -- cgit v1.2.3