rds: add missing barrier to release_refill

The functions clear_bit and set_bit do not imply a memory barrier, thus it may be possible that the waitqueue_active function (which does not take any locks) is moved before clear_bit and it could miss a wakeup event. Fix this bug by adding a memory barrier after clear_bit. Signed-off-by: Mikulas Patocka <[email protected]> Cc: [email protected] Signed-off-by: David S. Miller <[email protected]>
niw · Aug 12, 2022 · 9f414eb · 9f414eb
1 parent 7ebfc85
commit 9f414eb
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
@@ -363,6 +363,7 @@ static int acquire_refill(struct rds_connection *conn)
 static void release_refill(struct rds_connection *conn)
 {
 	clear_bit(RDS_RECV_REFILL, &conn->c_flags);
+	smp_mb__after_atomic();
 
 	/* We don't use wait_on_bit()/wake_up_bit() because our waking is in a
 	 * hot path and finding waiters is very rare.  We don't want to walk