block: add comment in blk_rq_timed_out() about why next can not be 0

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 116bbf3..99c3efc 100644 (file)
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -132,7 +132,12 @@ void blk_rq_timed_out_timer(unsigned long data)
                }
        }
 
-       if (next_set && !list_empty(&q->timeout_list))
+       /*
+        * next can never be 0 here with the list non-empty, since we always
+        * bump ->deadline to 1 so we can detect if the timer was ever added
+        * or not. See comment in blk_add_timer()
+        */
+       if (next)
                mod_timer(&q->timeout, round_jiffies_up(next));
 
        spin_unlock_irqrestore(q->queue_lock, flags);