blk-mq: fix race between timeout and CPU hotplug

[linux-block.git] / block / blk-mq.c

diff --git a/block/blk-mq.c b/block/blk-mq.c
index ade8a2d1b0aa8600ad31413b59db37392628bffc..1fccb98aa28f53a9a2e218c77c5fda5db1342e01 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -677,8 +677,11 @@ static void blk_mq_rq_timer(unsigned long priv)
                data.next = blk_rq_timeout(round_jiffies_up(data.next));
                mod_timer(&q->timeout, data.next);
        } else {
-               queue_for_each_hw_ctx(q, hctx, i)
-                       blk_mq_tag_idle(hctx);
+               queue_for_each_hw_ctx(q, hctx, i) {
+                       /* the hctx may be unmapped, so check it here */
+                       if (blk_mq_hw_queue_mapped(hctx))
+                               blk_mq_tag_idle(hctx);
+               }
        }
 }
 
@@ -2090,9 +2093,16 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
         */
        list_for_each_entry(q, &all_q_list, all_q_node)
                blk_mq_freeze_queue_start(q);
-       list_for_each_entry(q, &all_q_list, all_q_node)
+       list_for_each_entry(q, &all_q_list, all_q_node) {
                blk_mq_freeze_queue_wait(q);
 
+               /*
+                * timeout handler can't touch hw queue during the
+                * reinitialization
+                */
+               del_timer_sync(&q->timeout);
+       }
+
        list_for_each_entry(q, &all_q_list, all_q_node)
                blk_mq_queue_reinit(q);