[ 026/133] tcp: fix regression in urgent data handling

Greg Kroah-Hartman
2012-10-10T23:25:26Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 1d57f19539c074105791da6384a8ad674bba8037 ]

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@google.com>
Reported-by: Stephan Springl <springl-k@lar.bfw.de>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/tcp_input.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4818,7 +4818,7 @@ 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;
}
@@ -5680,8 +5680,7 @@ 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;
}
}