drbd: Test cstate while holding req_lock

In case a connection transitions into C_TIMEOUT within the timer
function (request_timer_fn()) we need to make sure that the receiver
thread (potentially running on a different CPU) sees the updated
cstate later on.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/drbd/drbd_nl.c

@@ -442,12 +442,13 @@ bool conn_try_outdate_peer(struct drbd_connection *connection)
 	char *ex_to_string;
 	int r;
 
+	spin_lock_irq(&connection->resource->req_lock);
 	if (connection->cstate >= C_WF_REPORT_PARAMS) {
 		drbd_err(connection, "Expected cstate < C_WF_REPORT_PARAMS\n");
+		spin_unlock_irq(&connection->resource->req_lock);
 		return false;
 	}
 
-	spin_lock_irq(&connection->resource->req_lock);
 	connect_cnt = connection->connect_cnt;
 	spin_unlock_irq(&connection->resource->req_lock);
 

include/linux/drbd.h

@@ -52,7 +52,7 @@
 #endif
 
 extern const char *drbd_buildtag(void);
-#define REL_VERSION "8.4.4"
+#define REL_VERSION "8.4.3"
 #define API_VERSION 1
 #define PRO_VERSION_MIN 86
 #define PRO_VERSION_MAX 101