netdev - [PATCH v2] tcp: fix regression in urgent data handling

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Date:	Tue, 18 Sep 2012 09:54:10 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>,
	Stephan Springl <springl-k@...-online.de>,
	Alexander Duyck <alexander.h.duyck@...el.com>
Subject: [PATCH v2] tcp: fix regression in urgent data handling

From: Eric Dumazet <edumazet@...gle.com>

Stephan Springl found that commit 1402d366019fed "tcp: introduce
tcp_try_coalesce" introduced a regression for rlogin

It turns out problem comes from TCP urgent data handling and
a change in behavior in input path.

rlogin sends two one-byte packets with URG ptr set, and when next data
frame is coalesced, we lack sk_data_ready() calls to wakeup consumer.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: Stephan Springl <springl-k@...-online.de>
Cc: Alexander Duyck <alexander.h.duyck@...el.com>
---
v2: Changed Stephan Springl email address in changelog/CC

 net/ipv4/tcp_input.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6e38c6c..d377f48 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4661,7 +4661,7 @@ queue_and_out:
 
 		if (eaten > 0)
 			kfree_skb_partial(skb, fragstolen);
-		else if (!sock_flag(sk, SOCK_DEAD))
+		if (!sock_flag(sk, SOCK_DEAD))
 			sk->sk_data_ready(sk, 0);
 		return;
 	}
@@ -5556,8 +5556,7 @@ no_ack:
 #endif
 			if (eaten)
 				kfree_skb_partial(skb, fragstolen);
-			else
-				sk->sk_data_ready(sk, 0);
+			sk->sk_data_ready(sk, 0);
 			return 0;
 		}
 	}


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