Re: [PATCH V2 04/20] block: add two helpers for registering/un-registering sched debugfs

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

在 2025/04/19 0:36, Ming Lei 写道:
> Add blk_mq_sched_reg_debugfs()/blk_mq_sched_unreg_debugfs() to clean up
> sched init/exit code a bit.
>
> Register & unregister debugfs for sched & sched_hctx order is changed a
> bit, but it is safe because sched & sched_hctx is guaranteed to be ready
> when exporting via debugfs.
>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
>   block/blk-mq-sched.c | 45 +++++++++++++++++++++++++++++---------------
>   1 file changed, 30 insertions(+), 15 deletions(-)
LGTM
Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>

> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index 9b81771774ef..2abc5e0704e8 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -434,6 +434,30 @@ static int blk_mq_init_sched_shared_tags(struct request_queue *queue)
>   	return 0;
>   }
>   
> +static void blk_mq_sched_reg_debugfs(struct request_queue *q)
> +{
> +	struct blk_mq_hw_ctx *hctx;
> +	unsigned long i;
> +
> +	mutex_lock(&q->debugfs_mutex);
> +	blk_mq_debugfs_register_sched(q);
> +	queue_for_each_hw_ctx(q, hctx, i)
> +		blk_mq_debugfs_register_sched_hctx(q, hctx);
> +	mutex_unlock(&q->debugfs_mutex);
> +}
> +
> +static void blk_mq_sched_unreg_debugfs(struct request_queue *q)
> +{
> +	struct blk_mq_hw_ctx *hctx;
> +	unsigned long i;
> +
> +	mutex_lock(&q->debugfs_mutex);
> +	queue_for_each_hw_ctx(q, hctx, i)
> +		blk_mq_debugfs_unregister_sched_hctx(hctx);
> +	blk_mq_debugfs_unregister_sched(q);
> +	mutex_unlock(&q->debugfs_mutex);
> +}
> +
>   /* caller must have a reference to @e, will grab another one if successful */
>   int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
>   {
> @@ -467,10 +491,6 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
>   	if (ret)
>   		goto err_free_map_and_rqs;
>   
> -	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.init_hctx) {
>   			ret = e->ops.init_hctx(hctx, i);
> @@ -482,11 +502,11 @@ 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);
>   	}
>   
> +	/* sched is initialized, it is ready to export it via debugfs */
> +	blk_mq_sched_reg_debugfs(q);
> +
>   	return 0;
>   
>   err_free_map_and_rqs:
> @@ -524,11 +544,10 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
>   	unsigned long i;
>   	unsigned int flags = 0;
>   
> -	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);
> +	/* unexport via debugfs before exiting sched */
> +	blk_mq_sched_unreg_debugfs(q);
>   
> +	queue_for_each_hw_ctx(q, hctx, i) {
>   		if (e->type->ops.exit_hctx && hctx->sched_data) {
>   			e->type->ops.exit_hctx(hctx, i);
>   			hctx->sched_data = NULL;
> @@ -536,10 +555,6 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
>   		flags = hctx->flags;
>   	}
>   
> -	mutex_lock(&q->debugfs_mutex);
> -	blk_mq_debugfs_unregister_sched(q);
> -	mutex_unlock(&q->debugfs_mutex);
> -
>   	if (e->type->ops.exit_sched)
>   		e->type->ops.exit_sched(e);
>   	blk_mq_sched_tags_teardown(q, flags);