Commit 8196738e authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Yu Kuai
Browse files

block: serialize all debugfs operations using q->debugfs_mutex 

mainline inclusion
from mainline-v5.19-rc4
commit 5cf9c91b
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/IAGRKP
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5cf9c91ba927119fc6606b938b1895bb2459d3bc



--------------------------------

Various places like I/O schedulers or the QOS infrastructure try to
register debugfs files on demans, which can race with creating and
removing the main queue debugfs directory.  Use the existing
debugfs_mutex to serialize all debugfs operations that rely on
q->debugfs_dir or the directories hanging off it.

To make the teardown code a little simpler declare all debugfs dentry
pointers and not just the main one uncoditionally in blkdev.h.

Move debugfs_mutex next to the dentries that it protects and document
what it is used for.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220614074827.458955-3-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Conflicts:
	block/blk-mq-debugfs.h
	block/blk-mq-debugfs.c
	block/blk-mq-sched.c
	block/blk-rq-qos.c
	block/blk-rq-qos.h
	block/blk-sysfs.c
	block/blk-io-hierarchy/debugfs.c
	block/blk-io-hierarchy/stats.c
	include/linux/blkdev.h
	kernel/trace/blktrace.c
[Context conflicts]
Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
parent 9134f0c1

block/blk-io-hierarchy/debugfs.c

+6 −0
Original line number Diff line number Diff line
@@ -198,6 +198,8 @@ void blk_mq_debugfs_register_hierarchy(struct request_queue *q, 
	struct blk_io_hierarchy_stats *stats =

		queue_to_wrapper(q)->io_hierarchy_stats;



	lockdep_assert_held(&q->debugfs_mutex);



	if (!blk_mq_hierarchy_registered(q, stage) ||

	    !blk_mq_debugfs_enabled(q))

		return;
@@ -211,6 +213,8 @@ void blk_mq_debugfs_unregister_hierarchy(struct request_queue *q, 
	struct blk_io_hierarchy_stats *stats =

		queue_to_wrapper(q)->io_hierarchy_stats;



	lockdep_assert_held(&q->debugfs_mutex);



	if (!blk_mq_hierarchy_registered(q, stage) ||

	    !blk_mq_debugfs_enabled(q))

		return;
@@ -223,6 +227,8 @@ void blk_mq_debugfs_create_default_hierarchy_attr(struct request_queue *q) 
	struct blk_io_hierarchy_stats *stats =

		queue_to_wrapper(q)->io_hierarchy_stats;



	lockdep_assert_held(&q->debugfs_mutex);



	if (!blk_mq_debugfs_enabled(q))

		return;

block/blk-io-hierarchy/stats.c

+8 −0
Original line number Diff line number Diff line
@@ -33,6 +33,8 @@ void blk_mq_debugfs_register_hierarchy_stats(struct request_queue *q) 
	struct blk_io_hierarchy_stats *stats;

	enum stage_group stage;



	lockdep_assert_held(&q->debugfs_mutex);



	stats = queue_to_wrapper(q)->io_hierarchy_stats;

	if (!stats || !blk_mq_debugfs_enabled(q))

		return;
@@ -203,8 +205,10 @@ void blk_mq_register_hierarchy(struct request_queue *q, enum stage_group stage) 


	blk_mq_freeze_queue(q);



	mutex_lock(&q->debugfs_mutex);

	WRITE_ONCE(stats->hstage[stage], hstage);

	blk_mq_debugfs_register_hierarchy(q, stage);

	mutex_unlock(&q->debugfs_mutex);



	blk_mq_unfreeze_queue(q);

}
@@ -220,6 +224,8 @@ void blk_mq_unregister_hierarchy(struct request_queue *q, 
	if (!blk_mq_hierarchy_registered(q, stage))

		return;



	mutex_lock(&q->debugfs_mutex);



	blk_mq_debugfs_unregister_hierarchy(q, stage);

	blk_io_hierarchy_iodump_exit(q, stage);
@@ -230,6 +236,8 @@ void blk_mq_unregister_hierarchy(struct request_queue *q, 
	spin_unlock(&stats->hstage_lock);



	kfree(hstage);



	mutex_unlock(&q->debugfs_mutex);

}

EXPORT_SYMBOL_GPL(blk_mq_unregister_hierarchy);

block/blk-mq-debugfs.c

+12 −5
Original line number Diff line number Diff line
@@ -862,11 +862,6 @@ void blk_mq_debugfs_register(struct request_queue *q) 
	blk_mq_debugfs_register_hierarchy_stats(q);

}



void blk_mq_debugfs_unregister(struct request_queue *q)

{

	q->sched_debugfs_dir = NULL;

}



static void blk_mq_debugfs_register_ctx(struct blk_mq_hw_ctx *hctx,

					struct blk_mq_ctx *ctx)

{
@@ -900,6 +895,8 @@ void blk_mq_debugfs_register_hctx(struct request_queue *q, 


void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)

{

	if (!hctx->queue->debugfs_dir)

		return;

	debugfs_remove_recursive(hctx->debugfs_dir);

	hctx->sched_debugfs_dir = NULL;

	hctx->debugfs_dir = NULL;
@@ -927,6 +924,8 @@ void blk_mq_debugfs_register_sched(struct request_queue *q) 
{

	struct elevator_type *e = q->elevator->type;



	lockdep_assert_held(&q->debugfs_mutex);



	/*

	 * If the parent directory has not been created yet, return, we will be

	 * called again later on and the directory/files will be created then.
@@ -944,6 +943,8 @@ void blk_mq_debugfs_register_sched(struct request_queue *q) 


void blk_mq_debugfs_unregister_sched(struct request_queue *q)

{

	lockdep_assert_held(&q->debugfs_mutex);



	debugfs_remove_recursive(q->sched_debugfs_dir);

	q->sched_debugfs_dir = NULL;

}
@@ -953,6 +954,8 @@ void blk_mq_debugfs_register_sched_hctx(struct request_queue *q, 
{

	struct elevator_type *e = q->elevator->type;



	lockdep_assert_held(&q->debugfs_mutex);



	/*

	 * If the parent debugfs directory has not been created yet, return;

	 * We will be called again later on with appropriate parent debugfs
@@ -972,6 +975,10 @@ void blk_mq_debugfs_register_sched_hctx(struct request_queue *q, 


void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)

{

	lockdep_assert_held(&hctx->queue->debugfs_mutex);



	if (!hctx->queue->debugfs_dir)

		return;

	debugfs_remove_recursive(hctx->sched_debugfs_dir);

	hctx->sched_debugfs_dir = NULL;

}

block/blk-mq-debugfs.h

+0 −5
Original line number Diff line number Diff line
@@ -20,7 +20,6 @@ int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq); 
int blk_mq_debugfs_rq_show(struct seq_file *m, void *v);



void blk_mq_debugfs_register(struct request_queue *q);

void blk_mq_debugfs_unregister(struct request_queue *q);

void blk_mq_debugfs_register_hctx(struct request_queue *q,

				 struct blk_mq_hw_ctx *hctx);

void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx);
@@ -46,10 +45,6 @@ static inline void blk_mq_debugfs_register(struct request_queue *q) 
{

}



static inline void blk_mq_debugfs_unregister(struct request_queue *q)

{

}



static inline void blk_mq_debugfs_register_hctx(struct request_queue *q,

						struct blk_mq_hw_ctx *hctx)

{

block/blk-mq-sched.c

+11 −0
Original line number Diff line number Diff line
@@ -609,7 +609,9 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e) 
	if (ret)

		goto err;



	mutex_lock(&q->debugfs_mutex);

	blk_mq_debugfs_register_sched(q);

	mutex_unlock(&q->debugfs_mutex);



	queue_for_each_hw_ctx(q, hctx, i) {

		if (e->ops.mq.init_hctx) {
@@ -621,7 +623,9 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e) 
				return ret;

			}

		}

		mutex_lock(&q->debugfs_mutex);

		blk_mq_debugfs_register_sched_hctx(q, hctx);

		mutex_unlock(&q->debugfs_mutex);

	}



	return 0;
@@ -638,13 +642,20 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e) 
	unsigned int i;



	queue_for_each_hw_ctx(q, hctx, i) {

		mutex_lock(&q->debugfs_mutex);

		blk_mq_debugfs_unregister_sched_hctx(hctx);

		mutex_unlock(&q->debugfs_mutex);



		if (e->type->ops.mq.exit_hctx && hctx->sched_data) {

			e->type->ops.mq.exit_hctx(hctx, i);

			hctx->sched_data = NULL;

		}

	}



	mutex_lock(&q->debugfs_mutex);

	blk_mq_debugfs_unregister_sched(q);

	mutex_unlock(&q->debugfs_mutex);



	if (e->type->ops.mq.exit_sched)

		e->type->ops.mq.exit_sched(e);

	blk_mq_sched_tags_teardown(q);