From ff905b1e4aad8ccbbb0d42f7137f19482742ff07 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Jan 2013 07:06:10 +0000 Subject: tcp: splice: fix an infinite loop in tcp_read_sock() 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 --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 1ca253635f7..5f173dccd1e 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1482,7 +1482,7 @@ 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; -- cgit v1.2.3-70-g09d2 From f26845b43c75d3f32f98d194c1327b5b1e6b3fb0 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 9 Jan 2013 20:59:09 +0000 Subject: tcp: fix splice() and tcp collapsing interaction Under unusual circumstances, TCP collapse can split a big GRO TCP packet while its being used in a splice(socket->pipe) operation. skb_splice_bits() releases the socket lock before calling splice_to_pipe(). [ 1081.353685] WARNING: at net/ipv4/tcp.c:1330 tcp_cleanup_rbuf+0x4d/0xfc() [ 1081.371956] Hardware name: System x3690 X5 -[7148Z68]- [ 1081.391820] cleanup rbuf bug: copied AD3BCF1 seq AD370AF rcvnxt AD3CF13 To fix this problem, we must eat skbs in tcp_recv_skb(). Remove the inline keyword from tcp_recv_skb() definition since it has three call sites. Reported-by: Christian Becker Cc: Willy Tarreau Signed-off-by: Eric Dumazet Tested-by: Willy Tarreau Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 5f173dccd1e..2aa69c8ae60 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1428,12 +1428,12 @@ static void tcp_service_net_dma(struct sock *sk, bool wait) } #endif -static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) +static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) { struct sk_buff *skb; u32 offset; - skb_queue_walk(&sk->sk_receive_queue, skb) { + while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) { offset = seq - TCP_SKB_CB(skb)->seq; if (tcp_hdr(skb)->syn) offset--; @@ -1441,6 +1441,11 @@ static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) *off = offset; return skb; } + /* This looks weird, but this can happen if TCP collapsing + * splitted a fat GRO packet, while we released socket lock + * in skb_splice_bits() + */ + sk_eat_skb(sk, skb, false); } return NULL; } @@ -1520,8 +1525,10 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, tcp_rcv_space_adjust(sk); /* Clean up data we have read: This will do ACK frames. */ - if (copied > 0) + if (copied > 0) { + tcp_recv_skb(sk, seq, &offset); tcp_cleanup_rbuf(sk, copied); + } return copied; } EXPORT_SYMBOL(tcp_read_sock); -- cgit v1.2.3-70-g09d2