tcp: purge write queue upon RST

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 <soheil@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 8d480542aa07a3a423a76072c3d52e9b3547e637..9a1b3c1c1c1473829e6d975f97a864b9acd4a6d6 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3992,6 +3992,7 @@ 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))