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From:   Daniel Wagner <dwagner@suse.de>
To:     linux-nvme@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org, Daniel Wagner <dwagner@suse.de>
Subject: [RFC v1] nvme-tcp: enable linger socket option on shutdown
Date:   Fri,  3 Sep 2021 14:17:57 +0200
Message-Id: <20210903121757.140357-1-dwagner@suse.de>
MIME-Version: 1.0
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When the no linger is set, the networking stack sends FIN followed by
RST immediately when shutting down the socket. By enabling linger when
shutting down we have a proper shutdown sequence on the wire.

Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
The current shutdown sequence on the wire is a bit harsh and
doesn't let the remote host to react. I suppose we should
introduce a short (how long?) linger pause when shutting down
the connection. Thoughs?

 drivers/nvme/host/tcp.c | 1 +
 include/net/sock.h      | 1 +
 net/core/sock.c         | 8 ++++++++
 3 files changed, 10 insertions(+)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index e2ab12f3f51c..6c6dc465147a 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1558,6 +1558,7 @@ static void nvme_tcp_restore_sock_calls(struct nvme_tcp_queue *queue)
 
 static void __nvme_tcp_stop_queue(struct nvme_tcp_queue *queue)
 {
+	sock_reset_linger(queue->sock->sk);
 	kernel_sock_shutdown(queue->sock, SHUT_RDWR);
 	nvme_tcp_restore_sock_calls(queue);
 	cancel_work_sync(&queue->io_work);
diff --git a/include/net/sock.h b/include/net/sock.h
index 66a9a90f9558..313a6c8ba51c 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2777,6 +2777,7 @@ int sock_set_timestamping(struct sock *sk, int optname,
 
 void sock_enable_timestamps(struct sock *sk);
 void sock_no_linger(struct sock *sk);
+void sock_reset_linger(struct sock *sk);
 void sock_set_keepalive(struct sock *sk);
 void sock_set_priority(struct sock *sk, u32 priority);
 void sock_set_rcvbuf(struct sock *sk, int val);
diff --git a/net/core/sock.c b/net/core/sock.c
index 62627e868e03..23090a01e412 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -755,6 +755,14 @@ void sock_no_linger(struct sock *sk)
 }
 EXPORT_SYMBOL(sock_no_linger);
 
+void sock_reset_linger(struct sock *sk)
+{
+	lock_sock(sk);
+	sock_reset_flag(sk, SOCK_LINGER);
+	release_sock(sk);
+}
+EXPORT_SYMBOL_GPL(sock_reset_linger);
+
 void sock_set_priority(struct sock *sk, u32 priority)
 {
 	lock_sock(sk);
-- 
2.29.2