[RFC v1] nvme-tcp: enable linger socket option on shutdown

From: Daniel Wagner
Date: Fri Sep 03 2021 - 08:18:03 EST


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@xxxxxxx>
---
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