From a3374c42aa5f7237e87ff3b0622018636b0c847e Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Thu, 18 Oct 2012 09:14:12 +0000
Subject: [PATCH] tcp: fix FIONREAD/SIOCINQ
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/tcp.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f32c02e2a5434..b7c2f439b54f9 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);
--
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