From e4d47d9a03e858f491fe641234bac8c79aa756f4 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 13 May 2021 10:15:29 -0700 Subject: [PATCH] FROMLIST: blk-mq: Swap two calls in blk_mq_exit_queue() If a tag set is shared across request queues (e.g. SCSI LUNs) then the block layer core keeps track of the number of active request queues in tags->active_queues. blk_mq_tag_busy() and blk_mq_tag_idle() update that atomic counter if the hctx flag BLK_MQ_F_TAG_QUEUE_SHARED is set. Make sure that blk_mq_exit_queue() calls blk_mq_tag_idle() before that flag is cleared by blk_mq_del_queue_tag_set(). Cc: Christoph Hellwig Cc: Ming Lei Cc: Hannes Reinecke Fixes: 0d2602ca30e4 ("blk-mq: improve support for shared tags maps") Signed-off-by: Bart Van Assche Bug: 181696921 Link: https://lore.kernel.org/linux-block/d1b1f123-9b47-8805-0b86-2fa9f6b19bb5@kernel.dk/T/#ma8a01d264c59074d3f9b69f833ffe408592cf837 Signed-off-by: Bart Van Assche Change-Id: I3f9ca00fbefec97d1e3c9df85365be0265b8cec6 --- block/blk-mq.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 201890e00f78..2323c4593ee8 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3256,10 +3256,12 @@ EXPORT_SYMBOL(blk_mq_init_allocated_queue); /* tags can _not_ be used after returning from blk_mq_exit_queue */ void blk_mq_exit_queue(struct request_queue *q) { - struct blk_mq_tag_set *set = q->tag_set; + struct blk_mq_tag_set *set = q->tag_set; - blk_mq_del_queue_tag_set(q); + /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */ blk_mq_exit_hw_queues(q, set, set->nr_hw_queues); + /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */ + blk_mq_del_queue_tag_set(q); } static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)