Re: [PATCH 1/5] blk-mq: cleanup __blk_mq_sched_dispatch_requests

[Jens Axboe <axboe@kernel.dk>]

On 4/13/23 12:06?AM, Christoph Hellwig wrote:
> __blk_mq_sched_dispatch_requests currently has duplicated logic
> for the cases where requests are on the hctx dispatch list or not.
> Merge the two with a new need_dispatch variable and remove a few
> pointless local variables.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  block/blk-mq-sched.c | 31 ++++++++++++++-----------------
>  1 file changed, 14 insertions(+), 17 deletions(-)
> 
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index 06b312c691143f..f3257e1607a00c 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -271,9 +271,7 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
>  
>  static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
>  {
> -	struct request_queue *q = hctx->queue;
> -	const bool has_sched = q->elevator;
> -	int ret = 0;
> +	bool need_dispatch = false;
>  	LIST_HEAD(rq_list);
>  
>  	/*
> @@ -302,23 +300,22 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
>  	 */
>  	if (!list_empty(&rq_list)) {
>  		blk_mq_sched_mark_restart_hctx(hctx);
> -		if (blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) {
> -			if (has_sched)
> -				ret = blk_mq_do_dispatch_sched(hctx);
> -			else
> -				ret = blk_mq_do_dispatch_ctx(hctx);
> -		}
> -	} else if (has_sched) {
> -		ret = blk_mq_do_dispatch_sched(hctx);
> -	} else if (hctx->dispatch_busy) {
> -		/* dequeue request one by one from sw queue if queue is busy */
> -		ret = blk_mq_do_dispatch_ctx(hctx);
> +		if (!blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) 

There's some trailing whitespace here. Patch 5 also doesn't seem to
apply, but I'll see what that's about and comment there if there's a
concern.

-- 
Jens Axboe