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

From: Eric Dumazet <edumazet@google.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@google.com>
Reported-by: Stephan Springl <redacted>
Cc: Alexander Duyck <redacted>
---
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;
		}
	}