From 8b70c8612543859173230fbd16a63bacf84ba23a Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 18 Apr 2015 00:01:31 -0400 Subject: [PATCH 2/2] blk-mq: fix CPU hotplug handling Firstly the hctx->tags have to be set as NULL if it is to be disabled no matter if set->tags[i] is NULL or not in blk_mq_map_swqueue() because shared tags can be freed already from another request_queue. The same situation has to be considered in blk_mq_hctx_cpu_online() too. Cc: Reported-by: Dongsu Park Signed-off-by: Ming Lei --- block/blk-mq.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 58a3b4c..612d5c6 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1580,15 +1580,20 @@ 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; + struct blk_mq_tags *tags = set->tags[hctx->queue_num]; - if (set->tags[hctx->queue_num]) + /* tags can be shared by more than one queues */ + if (hctx->tags) 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; + if (!tags) { + tags = blk_mq_init_rq_map(set, hctx->queue_num); + if (!tags) + return NOTIFY_STOP; + set->tags[hctx->queue_num] = tags; + } - hctx->tags = set->tags[hctx->queue_num]; + hctx->tags = tags; return NOTIFY_OK; } @@ -1813,8 +1818,8 @@ static void blk_mq_map_swqueue(struct request_queue *q) 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; } -- 1.9.1