[PATCH] ksmbd: keep TCP timers alive for kernel sockets

[Namjae Jeon <linkinjeon@kernel.org>]

ksmbd creates its listening socket with sock_create_kern(). Kernel
sockets do not hold a network namespace reference by default. Accepted
sockets inherit this state.

When an accepted socket is released, tcp_close() clears its pending TCP
timers for a kernel socket after the socket enters an orphaned state. If
the peer is unreachable while ksmbd sends a FIN, this can leave a
FIN-WAIT-1 orphan without a retransmission timer.

Upgrade the listening socket's network namespace reference before
kernel_listen(). Accepted sockets inherit the reference, so the TCP
stack can keep the retransmission timer active and apply its normal
orphan retry policy.

Preserve the existing graceful shutdown behavior.

Link: https://github.com/openwrt/openwrt/issues/24744
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/transport_tcp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/smb/server/transport_tcp.c b/fs/smb/server/transport_tcp.c
index 921e4e86d01c..832e93084605 100644
--- a/fs/smb/server/transport_tcp.c
+++ b/fs/smb/server/transport_tcp.c
@@ -523,6 +523,12 @@ static int create_socket(struct interface *iface)
 		goto out_error;
 	}
 
+	/*
+	 * Accepted sockets inherit the listener's net reference. Keep TCP
+	 * timers alive after a kernel socket is released.
+	 */
+	sk_net_refcnt_upgrade(ksmbd_socket->sk);
+
 	ret = kernel_listen(ksmbd_socket, KSMBD_SOCKET_BACKLOG);
 	if (ret) {
 		pr_err("Port listen() error: %d\n", ret);
-- 
2.25.1