From 2d0364c8c1a97a1d44760895a982221c06af0f35 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 26 Apr 2017 13:47:48 -0700 Subject: [PATCH] blk-mq: Register /queue/mq after having registered /queue A later patch in this series will modify blk_mq_debugfs_register() such that it uses q->kobj.parent to determine the name of a request queue. Hence make sure that that pointer is initialized before blk_mq_debugfs_register() is called. To avoid lock inversion, protect sysfs / debugfs registration with the queue sysfs_lock instead of the global mutex all_q_mutex. Signed-off-by: Bart Van Assche Reviewed-by: Hannes Reinecke Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe --- block/blk-mq-sysfs.c | 35 ++++++++++++++++++++++++++++------- block/blk-mq.h | 1 + block/blk-sysfs.c | 6 +++--- 3 files changed, 32 insertions(+), 10 deletions(-) diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index d745ab81033a..a2dbb1a48e72 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -253,6 +253,8 @@ static void __blk_mq_unregister_dev(struct device *dev, struct request_queue *q) struct blk_mq_hw_ctx *hctx; int i; + lockdep_assert_held(&q->sysfs_lock); + queue_for_each_hw_ctx(q, hctx, i) blk_mq_unregister_hctx(hctx); @@ -267,9 +269,9 @@ static void __blk_mq_unregister_dev(struct device *dev, struct request_queue *q) void blk_mq_unregister_dev(struct device *dev, struct request_queue *q) { - blk_mq_disable_hotplug(); + mutex_lock(&q->sysfs_lock); __blk_mq_unregister_dev(dev, q); - blk_mq_enable_hotplug(); + mutex_unlock(&q->sysfs_lock); } void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx) @@ -302,12 +304,13 @@ void blk_mq_sysfs_init(struct request_queue *q) } } -int blk_mq_register_dev(struct device *dev, struct request_queue *q) +int __blk_mq_register_dev(struct device *dev, struct request_queue *q) { struct blk_mq_hw_ctx *hctx; int ret, i; - blk_mq_disable_hotplug(); + WARN_ON_ONCE(!q->kobj.parent); + lockdep_assert_held(&q->sysfs_lock); ret = kobject_add(&q->mq_kobj, kobject_get(&dev->kobj), "%s", "mq"); if (ret < 0) @@ -327,8 +330,18 @@ int blk_mq_register_dev(struct device *dev, struct request_queue *q) __blk_mq_unregister_dev(dev, q); else q->mq_sysfs_init_done = true; + out: - blk_mq_enable_hotplug(); + return ret; +} + +int blk_mq_register_dev(struct device *dev, struct request_queue *q) +{ + int ret; + + mutex_lock(&q->sysfs_lock); + ret = __blk_mq_register_dev(dev, q); + mutex_unlock(&q->sysfs_lock); return ret; } @@ -339,13 +352,17 @@ void blk_mq_sysfs_unregister(struct request_queue *q) struct blk_mq_hw_ctx *hctx; int i; + mutex_lock(&q->sysfs_lock); if (!q->mq_sysfs_init_done) - return; + goto unlock; blk_mq_debugfs_unregister_hctxs(q); queue_for_each_hw_ctx(q, hctx, i) blk_mq_unregister_hctx(hctx); + +unlock: + mutex_unlock(&q->sysfs_lock); } int blk_mq_sysfs_register(struct request_queue *q) @@ -353,8 +370,9 @@ int blk_mq_sysfs_register(struct request_queue *q) struct blk_mq_hw_ctx *hctx; int i, ret = 0; + mutex_lock(&q->sysfs_lock); if (!q->mq_sysfs_init_done) - return ret; + goto unlock; blk_mq_debugfs_register_hctxs(q); @@ -364,5 +382,8 @@ int blk_mq_sysfs_register(struct request_queue *q) break; } +unlock: + mutex_unlock(&q->sysfs_lock); + return ret; } diff --git a/block/blk-mq.h b/block/blk-mq.h index 524f44742816..7d955c756810 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -78,6 +78,7 @@ static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, */ extern void blk_mq_sysfs_init(struct request_queue *q); extern void blk_mq_sysfs_deinit(struct request_queue *q); +extern int __blk_mq_register_dev(struct device *dev, struct request_queue *q); extern int blk_mq_sysfs_register(struct request_queue *q); extern void blk_mq_sysfs_unregister(struct request_queue *q); extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx); diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index f85723332288..3f37813ccbaf 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -877,9 +877,6 @@ int blk_register_queue(struct gendisk *disk) if (ret) return ret; - if (q->mq_ops) - blk_mq_register_dev(dev, q); - /* Prevent changes through sysfs until registration is completed. */ mutex_lock(&q->sysfs_lock); @@ -889,6 +886,9 @@ int blk_register_queue(struct gendisk *disk) goto unlock; } + if (q->mq_ops) + __blk_mq_register_dev(dev, q); + kobject_uevent(&q->kobj, KOBJ_ADD); wbt_enable_default(q); -- 2.20.1