From: Soheil Hassas Yeganeh <soh...@google.com>
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: b75eba76d3d72 (tcp: send in-queue bytes in cmsg upon read)
Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com>
Acked-by: Neal Cardwell <ncardw...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Acked-by: Yuchung Cheng <ych...@google.com>
---
net/ipv4/tcp.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index ad07dd71063da..8b25017e0dc93 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1933,6 +1933,11 @@ 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;
}
--
2.21.0.352.gf09ad66450-goog
