netdev - [PATCH net 2/6] mptcp: fix poll after shutdown

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Message-Id: <20210211233042.304878-3-mathew.j.martineau@linux.intel.com>
Date:   Thu, 11 Feb 2021 15:30:38 -0800
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org
Cc:     Paolo Abeni <pabeni@...hat.com>, davem@...emloft.net,
        kuba@...nel.org, mptcp@...ts.01.org, matthieu.baerts@...sares.net,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>
Subject: [PATCH net 2/6] mptcp: fix poll after shutdown

From: Paolo Abeni <pabeni@...hat.com>

The current mptcp_poll() implementation gives unexpected
results after shutdown(SEND_SHUTDOWN) and when the msk
status is TCP_CLOSE.

Set the correct mask.

Fixes: 8edf08649eed ("mptcp: rework poll+nospace handling")
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 net/mptcp/protocol.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 9eecd1383d24..42ca49954bdd 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3321,7 +3321,7 @@ static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
 	struct sock *sk = (struct sock *)msk;
 
 	if (unlikely(sk->sk_shutdown & SEND_SHUTDOWN))
-		return 0;
+		return EPOLLOUT | EPOLLWRNORM;
 
 	if (sk_stream_is_writeable(sk))
 		return EPOLLOUT | EPOLLWRNORM;
@@ -3354,6 +3354,8 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 		mask |= mptcp_check_readable(msk);
 		mask |= mptcp_check_writeable(msk);
 	}
+	if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
+		mask |= EPOLLHUP;
 	if (sk->sk_shutdown & RCV_SHUTDOWN)
 		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
 
-- 
2.30.1