Re: [PATCH 2/5] blk-mq: don't pass **hctx to blk_mq_mark_tag_wait()

[Omar Sandoval <osandov@osandov.com>]

On Mon, Jun 25, 2018 at 07:31:46PM +0800, Ming Lei wrote:
> 'hctx' won't be changed at all, so not necessary to pass
> '**hctx' to blk_mq_mark_tag_wait().
> 
> Cc: Andrew Jones <drjones@redhat.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Omar Sandoval <osandov@fb.com>
> Cc: Bart Van Assche <bart.vanassche@wdc.com>

Reviewed-by: Omar Sandoval <osandov@fb.com>

> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  block/blk-mq.c | 23 +++++++++++------------
>  1 file changed, 11 insertions(+), 12 deletions(-)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 62e153eb720c..db2814eb050f 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1009,17 +1009,16 @@ static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
>   * restart. For both cases, take care to check the condition again after
>   * marking us as waiting.
>   */
> -static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
> +static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
>  				 struct request *rq)
>  {
> -	struct blk_mq_hw_ctx *this_hctx = *hctx;
>  	struct sbq_wait_state *ws;
>  	wait_queue_entry_t *wait;
>  	bool ret;
>  
> -	if (!(this_hctx->flags & BLK_MQ_F_TAG_SHARED)) {
> -		if (!test_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state))
> -			set_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state);
> +	if (!(hctx->flags & BLK_MQ_F_TAG_SHARED)) {
> +		if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
> +			set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
>  
>  		/*
>  		 * It's possible that a tag was freed in the window between the
> @@ -1032,17 +1031,17 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
>  		return blk_mq_get_driver_tag(rq);
>  	}
>  
> -	wait = &this_hctx->dispatch_wait;
> +	wait = &hctx->dispatch_wait;
>  	if (!list_empty_careful(&wait->entry))
>  		return false;
>  
> -	spin_lock(&this_hctx->lock);
> +	spin_lock(&hctx->lock);
>  	if (!list_empty(&wait->entry)) {
> -		spin_unlock(&this_hctx->lock);
> +		spin_unlock(&hctx->lock);
>  		return false;
>  	}
>  
> -	ws = bt_wait_ptr(&this_hctx->tags->bitmap_tags, this_hctx);
> +	ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
>  	add_wait_queue(&ws->wait, wait);
>  
>  	/*
> @@ -1052,7 +1051,7 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
>  	 */
>  	ret = blk_mq_get_driver_tag(rq);
>  	if (!ret) {
> -		spin_unlock(&this_hctx->lock);
> +		spin_unlock(&hctx->lock);
>  		return false;
>  	}
>  
> @@ -1063,7 +1062,7 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
>  	spin_lock_irq(&ws->wait.lock);
>  	list_del_init(&wait->entry);
>  	spin_unlock_irq(&ws->wait.lock);
> -	spin_unlock(&this_hctx->lock);
> +	spin_unlock(&hctx->lock);
>  
>  	return true;
>  }
> @@ -1105,7 +1104,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
>  			 * before we add this entry back on the dispatch list,
>  			 * we'll re-run it below.
>  			 */
> -			if (!blk_mq_mark_tag_wait(&hctx, rq)) {
> +			if (!blk_mq_mark_tag_wait(hctx, rq)) {
>  				blk_mq_put_dispatch_budget(hctx);
>  				/*
>  				 * For non-shared tags, the RESTART check
> -- 
> 2.9.5
>