Re: [PATCH 08/18] blk-mq: fold __blk_mq_insert_req_list into blk_mq_insert_request

[Damien Le Moal <dlemoal@kernel.org>]

On 4/12/23 14:32, Christoph Hellwig wrote:
> Remove this very small helper and fold it into the only caller.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  block/blk-mq.c | 25 +++++++------------------
>  1 file changed, 7 insertions(+), 18 deletions(-)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 103caf1bae2769..7e9f7d00452f11 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2446,23 +2446,6 @@ static void blk_mq_run_work_fn(struct work_struct *work)
>  	__blk_mq_run_hw_queue(hctx);
>  }
>  
> -static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
> -					    struct request *rq,
> -					    bool at_head)
> -{
> -	struct blk_mq_ctx *ctx = rq->mq_ctx;
> -	enum hctx_type type = hctx->type;
> -
> -	lockdep_assert_held(&ctx->lock);
> -
> -	trace_block_rq_insert(rq);
> -
> -	if (at_head)
> -		list_add(&rq->queuelist, &ctx->rq_lists[type]);
> -	else
> -		list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
> -}
> -
>  /**
>   * blk_mq_request_bypass_insert - Insert a request at dispatch list.
>   * @rq: Pointer to request to be inserted.
> @@ -2586,8 +2569,14 @@ static void blk_mq_insert_request(struct request *rq, bool at_head,
>  		list_add(&rq->queuelist, &list);
>  		e->type->ops.insert_requests(hctx, &list, at_head);
>  	} else {
> +		trace_block_rq_insert(rq);

Shouldn't we keep the trace call under ctx->lock to preserve precise tracing ?

> +
>  		spin_lock(&ctx->lock);
> -		__blk_mq_insert_req_list(hctx, rq, at_head);
> +		if (at_head)
> +			list_add(&rq->queuelist, &ctx->rq_lists[hctx->type]);
> +		else
> +			list_add_tail(&rq->queuelist,
> +				      &ctx->rq_lists[hctx->type]);
>  		blk_mq_hctx_mark_pending(hctx, ctx);
>  		spin_unlock(&ctx->lock);
>  	}