The request queue uses ->sysfs_dir_lock for protecting the addition/
deletion of kobject entries under sysfs while we register/unregister
blk-mq. However kobject addition/deletion is already protected with
kernfs/sysfs internal synchronization primitives. So use of q->sysfs_
dir_lock seems redundant.
Moreover, q->sysfs_dir_lock is also used at few other callsites along
with q->sysfs_lock for protecting the addition/deletion of kojects.
One such example is when we register with sysfs a set of independent
access ranges for a disk. Here as well we could get rid off q->sysfs_
dir_lock and only use q->sysfs_lock.
The only variable which q->sysfs_dir_lock appears to protect is q->
mq_sysfs_init_done which is set/unset while registering/unregistering
blk-mq with sysfs. But this variable could be easily converted to an
atomic type and used safely without using q->sysfs_dir_lock.
So with this patch we remove q->sysfs_dir_lock from each callsite
and also make q->mq_sysfs_init_done an atomic variable.
Signed-off-by: Nilay Shroff <nilay@xxxxxxxxxxxxx>
---
block/blk-core.c | 1 -
block/blk-ia-ranges.c | 4 ----
block/blk-mq-sysfs.c | 25 +++++++------------------
block/blk-sysfs.c | 5 -----
include/linux/blkdev.h | 3 +--
5 files changed, 8 insertions(+), 30 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 32fb28a6372c..d6c4fa3943b5 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -430,7 +430,6 @@ struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id)
refcount_set(&q->refs, 1);
mutex_init(&q->debugfs_mutex);
mutex_init(&q->sysfs_lock);
- mutex_init(&q->sysfs_dir_lock);
mutex_init(&q->limits_lock);
mutex_init(&q->rq_qos_mutex);
spin_lock_init(&q->queue_lock);
diff --git a/block/blk-ia-ranges.c b/block/blk-ia-ranges.c
index c9eb4241e048..d479f5481b66 100644
--- a/block/blk-ia-ranges.c
+++ b/block/blk-ia-ranges.c
@@ -111,7 +111,6 @@ int disk_register_independent_access_ranges(struct gendisk *disk)
struct request_queue *q = disk->queue;
int i, ret;
- lockdep_assert_held(&q->sysfs_dir_lock);
lockdep_assert_held(&q->sysfs_lock);
if (!iars)
@@ -155,7 +154,6 @@ void disk_unregister_independent_access_ranges(struct gendisk *disk)
struct blk_independent_access_ranges *iars = disk->ia_ranges;
int i;
- lockdep_assert_held(&q->sysfs_dir_lock);
lockdep_assert_held(&q->sysfs_lock);
if (!iars)
@@ -289,7 +287,6 @@ void disk_set_independent_access_ranges(struct gendisk *disk,
{
struct request_queue *q = disk->queue;
- mutex_lock(&q->sysfs_dir_lock);
mutex_lock(&q->sysfs_lock);
if (iars && !disk_check_ia_ranges(disk, iars)) {
kfree(iars);
@@ -313,6 +310,5 @@ void disk_set_independent_access_ranges(struct gendisk *disk,
disk_register_independent_access_ranges(disk);
unlock:
mutex_unlock(&q->sysfs_lock);
- mutex_unlock(&q->sysfs_dir_lock);
}
EXPORT_SYMBOL_GPL(disk_set_independent_access_ranges);
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 156e9bb07abf..0d2226035ab6 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -223,8 +223,6 @@ int blk_mq_sysfs_register(struct gendisk *disk)
unsigned long i, j;
int ret;
- lockdep_assert_held(&q->sysfs_dir_lock);
-
ret = kobject_add(q->mq_kobj, &disk_to_dev(disk)->kobj, "mq");
if (ret < 0)
goto out;
@@ -237,7 +235,7 @@ int blk_mq_sysfs_register(struct gendisk *disk)
goto unreg;
}
- q->mq_sysfs_init_done = true;
+ atomic_set(&q->mq_sysfs_init_done, 1);
out:
return ret;
@@ -259,15 +257,13 @@ void blk_mq_sysfs_unregister(struct gendisk *disk)
struct blk_mq_hw_ctx *hctx;
unsigned long i;
- lockdep_assert_held(&q->sysfs_dir_lock);
-
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_unregister_hctx(hctx);
kobject_uevent(q->mq_kobj, KOBJ_REMOVE);
kobject_del(q->mq_kobj);
- q->mq_sysfs_init_done = false;
+ atomic_set(&q->mq_sysfs_init_done, 0);
}
void blk_mq_sysfs_unregister_hctxs(struct request_queue *q)
@@ -275,15 +271,11 @@ void blk_mq_sysfs_unregister_hctxs(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
unsigned long i;
- mutex_lock(&q->sysfs_dir_lock);
- if (!q->mq_sysfs_init_done)
- goto unlock;
+ if (!atomic_read(&q->mq_sysfs_init_done))
+ return;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_unregister_hctx(hctx);
-
-unlock:
- mutex_unlock(&q->sysfs_dir_lock);
}
int blk_mq_sysfs_register_hctxs(struct request_queue *q)
@@ -292,9 +284,8 @@ int blk_mq_sysfs_register_hctxs(struct request_queue *q)
unsigned long i;
int ret = 0;
- mutex_lock(&q->sysfs_dir_lock);
- if (!q->mq_sysfs_init_done)
- goto unlock;
+ if (!atomic_read(&q->mq_sysfs_init_done))
+ goto out;
queue_for_each_hw_ctx(q, hctx, i) {
ret = blk_mq_register_hctx(hctx);
@@ -302,8 +293,6 @@ int blk_mq_sysfs_register_hctxs(struct request_queue *q)
break;
}
-unlock:
- mutex_unlock(&q->sysfs_dir_lock);
-
+out:
return ret;
}
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 368c2f6f5c85..6f548a4376aa 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -762,7 +762,6 @@ int blk_register_queue(struct gendisk *disk)
struct request_queue *q = disk->queue;
int ret;
- mutex_lock(&q->sysfs_dir_lock);
kobject_init(&disk->queue_kobj, &blk_queue_ktype);
ret = kobject_add(&disk->queue_kobj, &disk_to_dev(disk)->kobj, "queue");
if (ret < 0)
@@ -803,7 +802,6 @@ int blk_register_queue(struct gendisk *disk)
if (q->elevator)
kobject_uevent(&q->elevator->kobj, KOBJ_ADD);
mutex_unlock(&q->sysfs_lock);
- mutex_unlock(&q->sysfs_dir_lock);
/*
* SCSI probing may synchronously create and destroy a lot of
@@ -828,7 +826,6 @@ int blk_register_queue(struct gendisk *disk)
mutex_unlock(&q->sysfs_lock);
out_put_queue_kobj:
kobject_put(&disk->queue_kobj);
- mutex_unlock(&q->sysfs_dir_lock);
return ret;
}
@@ -859,7 +856,6 @@ void blk_unregister_queue(struct gendisk *disk)
blk_queue_flag_clear(QUEUE_FLAG_REGISTERED, q);
mutex_unlock(&q->sysfs_lock);
- mutex_lock(&q->sysfs_dir_lock);
/*
* Remove the sysfs attributes before unregistering the queue data
* structures that can be modified through sysfs.
@@ -876,7 +872,6 @@ void blk_unregister_queue(struct gendisk *disk)
/* Now that we've deleted all child objects, we can delete the queue. */
kobject_uevent(&disk->queue_kobj, KOBJ_REMOVE);
kobject_del(&disk->queue_kobj);
- mutex_unlock(&q->sysfs_dir_lock);
blk_debugfs_remove(disk);
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 76f0a4e7c2e5..1502970eefff 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -561,7 +561,6 @@ struct request_queue {
struct list_head flush_list;
struct mutex sysfs_lock;
- struct mutex sysfs_dir_lock;
struct mutex limits_lock;
/*
@@ -606,7 +605,7 @@ struct request_queue {
*/
struct mutex debugfs_mutex;
- bool mq_sysfs_init_done;
+ atomic_t mq_sysfs_init_done;
};
/* Keep blk_queue_flag_name[] in sync with the definitions below */
--
2.47.1
