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Message-ID: <750643e5-9f24-4e4c-8270-e421a03cf463@suse.de>
Date: Thu, 31 Jul 2025 08:20:39 +0200
From: Hannes Reinecke <hare@...e.de>
To: Yu Kuai <yukuai1@...weicloud.com>, dlemoal@...nel.org, jack@...e.cz,
tj@...nel.org, josef@...icpanda.com, axboe@...nel.dk, yukuai3@...wei.com
Cc: cgroups@...r.kernel.org, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com,
johnny.chenyi@...wei.com
Subject: Re: [PATCH v2 2/5] mq-deadline: switch to use elevator lock
On 7/30/25 10:22, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@...wei.com>
>
> Replace the internal spinlock 'dd->lock' with the new spinlock in
> elevator_queue, there are no functional changes.
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
> block/mq-deadline.c | 58 +++++++++++++++++++++------------------------
> 1 file changed, 27 insertions(+), 31 deletions(-)
>
> diff --git a/block/mq-deadline.c b/block/mq-deadline.c
> index 9ab6c6256695..2054c023e855 100644
> --- a/block/mq-deadline.c
> +++ b/block/mq-deadline.c
> @@ -101,7 +101,7 @@ struct deadline_data {
> u32 async_depth;
> int prio_aging_expire;
>
> - spinlock_t lock;
> + spinlock_t *lock;
> };
>
> /* Maps an I/O priority class to a deadline scheduler priority. */
> @@ -213,7 +213,7 @@ static void dd_merged_requests(struct request_queue *q, struct request *req,
> const u8 ioprio_class = dd_rq_ioclass(next);
> const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
>
> - lockdep_assert_held(&dd->lock);
> + lockdep_assert_held(dd->lock);
>
> dd->per_prio[prio].stats.merged++;
>
> @@ -253,7 +253,7 @@ static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
> {
> const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
>
> - lockdep_assert_held(&dd->lock);
> + lockdep_assert_held(dd->lock);
>
> return stats->inserted - atomic_read(&stats->completed);
> }
> @@ -323,7 +323,7 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd,
> enum dd_prio prio;
> u8 ioprio_class;
>
> - lockdep_assert_held(&dd->lock);
> + lockdep_assert_held(dd->lock);
>
> if (!list_empty(&per_prio->dispatch)) {
> rq = list_first_entry(&per_prio->dispatch, struct request,
> @@ -434,7 +434,7 @@ static struct request *dd_dispatch_prio_aged_requests(struct deadline_data *dd,
> enum dd_prio prio;
> int prio_cnt;
>
> - lockdep_assert_held(&dd->lock);
> + lockdep_assert_held(dd->lock);
>
> prio_cnt = !!dd_queued(dd, DD_RT_PRIO) + !!dd_queued(dd, DD_BE_PRIO) +
> !!dd_queued(dd, DD_IDLE_PRIO);
> @@ -466,10 +466,9 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
> struct request *rq;
> enum dd_prio prio;
>
> - spin_lock(&dd->lock);
> rq = dd_dispatch_prio_aged_requests(dd, now);
> if (rq)
> - goto unlock;
> + return rq;
>
> /*
> * Next, dispatch requests in priority order. Ignore lower priority
> @@ -481,9 +480,6 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
> break;
> }
>
> -unlock:
> - spin_unlock(&dd->lock);
> -
> return rq;
> }
>
> @@ -538,9 +534,9 @@ static void dd_exit_sched(struct elevator_queue *e)
> WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
> WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
>
> - spin_lock(&dd->lock);
> + spin_lock(dd->lock);
> queued = dd_queued(dd, prio);
> - spin_unlock(&dd->lock);
> + spin_unlock(dd->lock);
>
> WARN_ONCE(queued != 0,
> "statistics for priority %d: i %u m %u d %u c %u\n",
Do you still need 'dd->lock'? Can't you just refer to the lock from the
elevator_queue structure directly?
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@...e.de +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
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