smb: server: split ksmbd_rdma_stop_listening() out of ksmbd_rdma_destroy()

We can't call destroy_workqueue(smb_direct_wq); before stop_sessions()!

Otherwise already existing connections try to use smb_direct_wq as
a NULL pointer.

Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Fixes: 0626e6641f ("cifsd: add server handler for central processing and tranport layers")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/connection.c

@@ -504,7 +504,8 @@ void ksmbd_conn_transport_destroy(void)
 {
 	mutex_lock(&init_lock);
 	ksmbd_tcp_destroy();
-	ksmbd_rdma_destroy();
+	ksmbd_rdma_stop_listening();
 	stop_sessions();
+	ksmbd_rdma_destroy();
 	mutex_unlock(&init_lock);
 }

fs/smb/server/transport_rdma.c

@@ -2194,7 +2194,7 @@ int ksmbd_rdma_init(void)
 	return 0;
 }
 
-void ksmbd_rdma_destroy(void)
+void ksmbd_rdma_stop_listening(void)
 {
 	if (!smb_direct_listener.cm_id)
 		return;
@@ -2203,7 +2203,10 @@ void ksmbd_rdma_destroy(void)
 	rdma_destroy_id(smb_direct_listener.cm_id);
 
 	smb_direct_listener.cm_id = NULL;
+}
 
+void ksmbd_rdma_destroy(void)
+{
 	if (smb_direct_wq) {
 		destroy_workqueue(smb_direct_wq);
 		smb_direct_wq = NULL;

fs/smb/server/transport_rdma.h

@@ -54,13 +54,15 @@ struct smb_direct_data_transfer {
 
 #ifdef CONFIG_SMB_SERVER_SMBDIRECT
 int ksmbd_rdma_init(void);
+void ksmbd_rdma_stop_listening(void);
 void ksmbd_rdma_destroy(void);
 bool ksmbd_rdma_capable_netdev(struct net_device *netdev);
 void init_smbd_max_io_size(unsigned int sz);
 unsigned int get_smbd_max_read_write_size(void);
 #else
 static inline int ksmbd_rdma_init(void) { return 0; }
-static inline int ksmbd_rdma_destroy(void) { return 0; }
+static inline void ksmbd_rdma_stop_listening(void) { }
+static inline void ksmbd_rdma_destroy(void) { }
 static inline bool ksmbd_rdma_capable_netdev(struct net_device *netdev) { return false; }
 static inline void init_smbd_max_io_size(unsigned int sz) { }
 static inline unsigned int get_smbd_max_read_write_size(void) { return 0; }