Subject: [PATCH 38/49] tcp: purge write queue upon RST

From: Soheil Hassas Yeganeh <[email-masked]>
Date: Tue, 27 Feb 2018 18:32:18 -0500

[ Upstream commit a27fd7a8ed3856faaf5a2ff1c8c5f00c0667aaa0 ]

When the connection is reset, there is no point in
keeping the packets on the write queue until the connection
is closed.

RFC 793 (page 70) and RFC 793-bis (page 64) both suggest
purging the write queue upon RST:
https://tools.ietf.org/html/draft-ietf-tcpm-rfc793bis-07

Moreover, this is essential for a correct MSG_ZEROCOPY
implementation, because userspace cannot call close(fd)
before receiving zerocopy signals even when the connection
is reset.

Fixes: f214f915e7db ("tcp: enable MSG_ZEROCOPY")
Signed-off-by: Soheil Hassas Yeganeh <[email-masked]>
Reviewed-by: Eric Dumazet <[email-masked]>
Signed-off-by: Yuchung Cheng <[email-masked]>
Signed-off-by: Neal Cardwell <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/ipv4/tcp_input.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 93c614138f0f..14474acea0bb 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4011,6 +4011,7 @@ void tcp_reset(struct sock *sk)
 	/* This barrier is coupled with smp_rmb() in tcp_poll() */
 	smp_wmb();
 
+	tcp_write_queue_purge(sk);
 	tcp_done(sk);
 
 	if (!sock_flag(sk, SOCK_DEAD))
-- 
2.14.3