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authorChristoph Hellwig <hch@lst.de>2022-06-14 10:48:25 +0300
committerJens Axboe <axboe@kernel.dk>2022-06-17 16:31:05 +0300
commit5cf9c91ba927119fc6606b938b1895bb2459d3bc (patch)
treec6d3d7b1806f35e8fff9c439285324c6feeddad5 /block/blk-mq-debugfs.c
parent50e34d78815e474d410f342fbe783b18192ca518 (diff)
downloadlinux-5cf9c91ba927119fc6606b938b1895bb2459d3bc.tar.xz
block: serialize all debugfs operations using q->debugfs_mutex
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: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220614074827.458955-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-mq-debugfs.c')
-rw-r--r--block/blk-mq-debugfs.c25
1 files changed, 20 insertions, 5 deletions
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 7e4136a60e1c..f0fcfe1387cb 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -711,11 +711,6 @@ void blk_mq_debugfs_register(struct request_queue *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)
{
@@ -746,6 +741,8 @@ 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;
@@ -773,6 +770,8 @@ 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.
@@ -790,6 +789,8 @@ 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;
}
@@ -811,6 +812,10 @@ static const char *rq_qos_id_to_name(enum rq_qos_id id)
void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
{
+ lockdep_assert_held(&rqos->q->debugfs_mutex);
+
+ if (!rqos->q->debugfs_dir)
+ return;
debugfs_remove_recursive(rqos->debugfs_dir);
rqos->debugfs_dir = NULL;
}
@@ -820,6 +825,8 @@ void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
struct request_queue *q = rqos->q;
const char *dir_name = rq_qos_id_to_name(rqos->id);
+ lockdep_assert_held(&q->debugfs_mutex);
+
if (rqos->debugfs_dir || !rqos->ops->debugfs_attrs)
return;
@@ -835,6 +842,8 @@ void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
void blk_mq_debugfs_unregister_queue_rqos(struct request_queue *q)
{
+ lockdep_assert_held(&q->debugfs_mutex);
+
debugfs_remove_recursive(q->rqos_debugfs_dir);
q->rqos_debugfs_dir = NULL;
}
@@ -844,6 +853,8 @@ 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
@@ -863,6 +874,10 @@ 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;
}