From 09ea1383126d942a993b0895cec16e0961db5af9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Jan 2013 07:06:10 +0000 Subject: [PATCH] tcp: splice: fix an infinite loop in tcp_read_sock() [ Upstream commit ff905b1e4aad8ccbbb0d42f7137f19482742ff07 ] commit 02275a2ee7c0 (tcp: don't abort splice() after small transfers) added a regression. [ 83.843570] INFO: rcu_sched self-detected stall on CPU [ 83.844575] INFO: rcu_sched detected stalls on CPUs/tasks: { 6} (detected by 0, t=21002 jiffies, g=4457, c=4456, q=13132) [ 83.844582] Task dump for CPU 6: [ 83.844584] netperf R running task 0 8966 8952 0x0000000c [ 83.844587] 0000000000000000 0000000000000006 0000000000006c6c 0000000000000000 [ 83.844589] 000000000000006c 0000000000000096 ffffffff819ce2bc ffffffffffffff10 [ 83.844592] ffffffff81088679 0000000000000010 0000000000000246 ffff880c4b9ddcd8 [ 83.844594] Call Trace: [ 83.844596] [] ? vprintk_emit+0x1c9/0x4c0 [ 83.844601] [] ? schedule+0x29/0x70 [ 83.844606] [] ? tcp_splice_data_recv+0x42/0x50 [ 83.844610] [] ? tcp_read_sock+0xda/0x260 [ 83.844613] [] ? tcp_prequeue_process+0xb0/0xb0 [ 83.844615] [] ? tcp_splice_read+0xc0/0x250 [ 83.844618] [] ? sock_splice_read+0x22/0x30 [ 83.844622] [] ? do_splice_to+0x7b/0xa0 [ 83.844627] [] ? sys_splice+0x59c/0x5d0 [ 83.844630] [] ? putname+0x2b/0x40 [ 83.844633] [] ? do_sys_open+0x174/0x1e0 [ 83.844636] [] ? system_call_fastpath+0x16/0x1b if recv_actor() returns 0, we should stop immediately, because looping wont give a chance to drain the pipe. Signed-off-by: Eric Dumazet Cc: Willy Tarreau Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 91de64d60bf7..6e922338754f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1481,7 +1481,7 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, break; } used = recv_actor(desc, skb, offset, len); - if (used < 0) { + if (used <= 0) { if (!copied) copied = used; break; -- 2.39.5