tcp: do not report TCP_CM_INQ of 0 for closed connections

[ Upstream commit 6466e71565 ]

Returning 0 as inq to userspace indicates there is no more data to
read, and the application needs to wait for EPOLLIN. For a connection
that has received FIN from the remote peer, however, the application
must continue reading until getting EOF (return value of 0
from tcp_recvmsg) or an error, if edge-triggered epoll (EPOLLET) is
being used. Otherwise, the application will never receive a new
EPOLLIN, since there is no epoll edge after the FIN.

Return 1 when there is no data left on the queue but the
connection has received FIN, so that the applications continue
reading.

Fixes: b75eba76d3 (tcp: send in-queue bytes in cmsg upon read)
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This commit is contained in:

Soheil Hassas Yeganeh

2019-03-06 13:01:36 -05:00

committed by

Greg Kroah-Hartman

parent 0e6b33fa9a

commit 8accd04eb9

1 changed files with 5 additions and 0 deletions

									
										net/ipv4/tcp.c
									
		+5
		
												View File
												
				@@ -1901,6 +1901,11 @@ static int tcp_inq_hint(struct sock *sk)

						inq = tp->rcv_nxt - tp->copied_seq;

						release_sock(sk);

					}

					/* After receiving a FIN, tell the user-space to continue reading

					 * by returning a non-zero inq.

					 */

					if (inq == 0 && sock_flag(sk, SOCK_DONE))

						inq = 1;

					return inq;

				}