diff mbox

tcp: fix FIONREAD/SIOCINQ

Message ID 1350587652.32642.215.camel@edumazet-glaptop
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet Oct. 18, 2012, 7:14 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

tcp_ioctl() tries to take into account if tcp socket received a FIN
to report correct number bytes in receive queue.

But its flaky because if the application ate the last skb,
we return 1 instead of 0.

Correct way to detect that FIN was received is to test SOCK_DONE.

Reported-by: Elliot Hughes <enh@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
---
 net/ipv4/tcp.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)



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Comments

David Miller Oct. 18, 2012, 7:36 p.m. UTC | #1 
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 18 Oct 2012 21:14:12 +0200

> From: Eric Dumazet <edumazet@google.com>
> 
> tcp_ioctl() tries to take into account if tcp socket received a FIN
> to report correct number bytes in receive queue.
> 
> But its flaky because if the application ate the last skb,
> we return 1 instead of 0.
> 
> Correct way to detect that FIN was received is to test SOCK_DONE.
> 
> Reported-by: Elliot Hughes <enh@google.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied and queued up for -stable.
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diff mbox

Patch

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f32c02e..b7c2f43 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -549,14 +549,12 @@  int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 			 !tp->urg_data ||
 			 before(tp->urg_seq, tp->copied_seq) ||
 			 !before(tp->urg_seq, tp->rcv_nxt)) {
-			struct sk_buff *skb;
 
 			answ = tp->rcv_nxt - tp->copied_seq;
 
-			/* Subtract 1, if FIN is in queue. */
-			skb = skb_peek_tail(&sk->sk_receive_queue);
-			if (answ && skb)
-				answ -= tcp_hdr(skb)->fin;
+			/* Subtract 1, if FIN was received */
+			if (answ && sock_flag(sk, SOCK_DONE))
+				answ--;
 		} else
 			answ = tp->urg_seq - tp->copied_seq;
 		release_sock(sk);