netdev - Re: GRO + splice panics in 3.7.0-rc5

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Date:	Sat, 01 Dec 2012 14:32:01 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Willy Tarreau <w@....eu>
Cc:	netdev@...r.kernel.org
Subject: Re: GRO + splice panics in 3.7.0-rc5

On Sat, 2012-12-01 at 13:47 -0800, Eric Dumazet wrote:

> Thanks a lot Willy
> 
> I believe do_tcp_sendpages() needs a fix, I'll send a patch asap 
> 

Could you try the following patch ?

do_tcp_sendpages() looks really wrong, as only one page is provided by
the caller.

Thanks !

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e6eace1..6976dba 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -831,8 +831,8 @@ static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
 	return mss_now;
 }
 
-static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
-			 size_t psize, int flags)
+static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
+				size_t size, int flags)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int mss_now, size_goal;
@@ -859,12 +859,9 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffse
 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 		goto out_err;
 
-	while (psize > 0) {
+	while (size > 0) {
 		struct sk_buff *skb = tcp_write_queue_tail(sk);
-		struct page *page = pages[poffset / PAGE_SIZE];
 		int copy, i;
-		int offset = poffset % PAGE_SIZE;
-		int size = min_t(size_t, psize, PAGE_SIZE - offset);
 		bool can_coalesce;
 
 		if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
@@ -913,8 +910,8 @@ new_segment:
 			TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
 
 		copied += copy;
-		poffset += copy;
-		if (!(psize -= copy))
+		offset += copy;
+		if (!(size -= copy))
 			goto out;
 
 		if (skb->len < size_goal || (flags & MSG_OOB))
@@ -961,7 +958,7 @@ int tcp_sendpage(struct sock *sk, struct page *page, int offset,
 					flags);
 
 	lock_sock(sk);
-	res = do_tcp_sendpages(sk, &page, offset, size, flags);
+	res = do_tcp_sendpages(sk, page, offset, size, flags);
 	release_sock(sk);
 	return res;
 }


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