1 files changed, 36 insertions, 24 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index ade8a2d1b0aa..e68b71b85a7e 100644
--- 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);
+		}
 	}
 }
 
@@ -855,6 +858,16 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 		spin_lock(&hctx->lock);
 		list_splice(&rq_list, &hctx->dispatch);
 		spin_unlock(&hctx->lock);
+		/*
+		 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
+		 * it's possible the queue is stopped and restarted again
+		 * before this. Queue restart will dispatch requests. And since
+		 * requests in rq_list aren't added into hctx->dispatch yet,
+		 * the requests in rq_list might get lost.
+		 *
+		 * blk_mq_run_hw_queue() already checks the STOPPED bit
+		 **/
+		blk_mq_run_hw_queue(hctx, true);
 	}
 }
 
@@ -1571,22 +1584,6 @@ static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
 	return NOTIFY_OK;
 }
 
-static int blk_mq_hctx_cpu_online(struct blk_mq_hw_ctx *hctx, int cpu)
-{
-	struct request_queue *q = hctx->queue;
-	struct blk_mq_tag_set *set = q->tag_set;
-
-	if (set->tags[hctx->queue_num])
-		return NOTIFY_OK;
-
-	set->tags[hctx->queue_num] = blk_mq_init_rq_map(set, hctx->queue_num);
-	if (!set->tags[hctx->queue_num])
-		return NOTIFY_STOP;
-
-	hctx->tags = set->tags[hctx->queue_num];
-	return NOTIFY_OK;
-}
-
 static int blk_mq_hctx_notify(void *data, unsigned long action,
 			      unsigned int cpu)
 {
@@ -1594,8 +1591,11 @@ static int blk_mq_hctx_notify(void *data, unsigned long action,
 
 	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
 		return blk_mq_hctx_cpu_offline(hctx, cpu);
-	else if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
-		return blk_mq_hctx_cpu_online(hctx, cpu);
+
+	/*
+	 * In case of CPU online, tags may be reallocated
+	 * in blk_mq_map_swqueue() after mapping is updated.
+	 */
 
 	return NOTIFY_OK;
 }
@@ -1775,6 +1775,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 	unsigned int i;
 	struct blk_mq_hw_ctx *hctx;
 	struct blk_mq_ctx *ctx;
+	struct blk_mq_tag_set *set = q->tag_set;
 
 	queue_for_each_hw_ctx(q, hctx, i) {
 		cpumask_clear(hctx->cpumask);
@@ -1803,16 +1804,20 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 		 * disable it and free the request entries.
 		 */
 		if (!hctx->nr_ctx) {
-			struct blk_mq_tag_set *set = q->tag_set;
-
 			if (set->tags[i]) {
 				blk_mq_free_rq_map(set, set->tags[i], i);
 				set->tags[i] = NULL;
-				hctx->tags = NULL;
 			}
+			hctx->tags = NULL;
 			continue;
 		}
 
+		/* unmapped hw queue can be remapped after CPU topo changed */
+		if (!set->tags[i])
+			set->tags[i] = blk_mq_init_rq_map(set, i);
+		hctx->tags = set->tags[i];
+		WARN_ON(!hctx->tags);
+
 		/*
 		 * Set the map size to the number of mapped software queues.
 		 * This is more accurate and more efficient than looping
@@ -2090,9 +2095,16 @@ 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);