From: Nilay Shroff Date: Tue, 28 Jan 2025 14:34:14 +0000 (+0530) Subject: block: fix nr_hw_queue update racing with disk addition/removal X-Git-Tag: nvme-6.14-2025-03-05~19 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=14ef49657ff3b7156952b2eadcf2e5bafd735795;p=nvme.git block: fix nr_hw_queue update racing with disk addition/removal The nr_hw_queue update could potentially race with disk addtion/removal while registering/unregistering hctx sysfs files. The __blk_mq_update_ nr_hw_queues() runs with q->tag_list_lock held and so to avoid it racing with disk addition/removal we should acquire q->tag_list_lock while registering/unregistering hctx sysfs files. With this patch, blk_mq_sysfs_register() (called during disk addition) and blk_mq_sysfs_unregister() (called during disk removal) now runs with q->tag_list_lock held so that it avoids racing with __blk_mq_update _nr_hw_queues(). Signed-off-by: Nilay Shroff Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Link: https://lore.kernel.org/r/20250128143436.874357-3-nilay@linux.ibm.com Signed-off-by: Jens Axboe --- diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index 6113328abd70..3feeeccf8a99 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -225,25 +225,25 @@ int blk_mq_sysfs_register(struct gendisk *disk) ret = kobject_add(q->mq_kobj, &disk_to_dev(disk)->kobj, "mq"); if (ret < 0) - goto out; + return ret; kobject_uevent(q->mq_kobj, KOBJ_ADD); + mutex_lock(&q->tag_set->tag_list_lock); queue_for_each_hw_ctx(q, hctx, i) { ret = blk_mq_register_hctx(hctx); if (ret) - goto unreg; + goto out_unreg; } + mutex_unlock(&q->tag_set->tag_list_lock); + return 0; - -out: - return ret; - -unreg: +out_unreg: queue_for_each_hw_ctx(q, hctx, j) { if (j < i) blk_mq_unregister_hctx(hctx); } + mutex_unlock(&q->tag_set->tag_list_lock); kobject_uevent(q->mq_kobj, KOBJ_REMOVE); kobject_del(q->mq_kobj); @@ -256,9 +256,10 @@ void blk_mq_sysfs_unregister(struct gendisk *disk) struct blk_mq_hw_ctx *hctx; unsigned long i; - + mutex_lock(&q->tag_set->tag_list_lock); queue_for_each_hw_ctx(q, hctx, i) blk_mq_unregister_hctx(hctx); + mutex_unlock(&q->tag_set->tag_list_lock); kobject_uevent(q->mq_kobj, KOBJ_REMOVE); kobject_del(q->mq_kobj);