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From: Sagi Grimberg <sagig@dev.mellanox.co.il>
To: Wenbo Wang <wenbo.wang@memblaze.com>,
	Keith Busch <keith.busch@intel.com>
Cc: Jens Axboe <axboe@fb.com>, "Wenwei.Tao" <wenwei.tao@memblaze.com>,
	Wenbo Wang <mail_weber_wang@163.com>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended
Date: Sun, 7 Feb 2016 15:41:53 +0200	[thread overview]
Message-ID: <56B749A1.8030504@dev.mellanox.co.il> (raw)
In-Reply-To: <BJXPR01MB19916231021454BD8731EBDE0D30@BJXPR01MB199.CHNPR01.prod.partner.outlook.cn>


> Keith,
>
> Is the following solution OK?
> synchronize_rcu guarantee that no queue_rq is running concurrently with device disable code.
> Together with your another patch (adding blk_sync_queue), both sync/async path shall be handled correctly.

This can be acceptable I think.

> Do you think synchronize_rcu shall be added to blk_sync_queue?

Or, we'll add it to blk_mq_stop_hw_queues() and then scsi
will enjoy it as well.

> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 4c0622f..bfe9132 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -865,7 +865,9 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
>          if (!async) {
>                  int cpu = get_cpu();
>                  if (cpumask_test_cpu(cpu, hctx->cpumask)) {
> +                       rcu_read_lock();
>                          __blk_mq_run_hw_queue(hctx);
> +                       rcu_read_unlock();

I think the rcu is better folded into __blk_mq_run_hw_queue
to cover all the call sites.

WARNING: multiple messages have this Message-ID (diff)
From: sagig@dev.mellanox.co.il (Sagi Grimberg)
Subject: [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended
Date: Sun, 7 Feb 2016 15:41:53 +0200	[thread overview]
Message-ID: <56B749A1.8030504@dev.mellanox.co.il> (raw)
In-Reply-To: <BJXPR01MB19916231021454BD8731EBDE0D30@BJXPR01MB199.CHNPR01.prod.partner.outlook.cn>


> Keith,
>
> Is the following solution OK?
> synchronize_rcu guarantee that no queue_rq is running concurrently with device disable code.
> Together with your another patch (adding blk_sync_queue), both sync/async path shall be handled correctly.

This can be acceptable I think.

> Do you think synchronize_rcu shall be added to blk_sync_queue?

Or, we'll add it to blk_mq_stop_hw_queues() and then scsi
will enjoy it as well.

> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 4c0622f..bfe9132 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -865,7 +865,9 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
>          if (!async) {
>                  int cpu = get_cpu();
>                  if (cpumask_test_cpu(cpu, hctx->cpumask)) {
> +                       rcu_read_lock();
>                          __blk_mq_run_hw_queue(hctx);
> +                       rcu_read_unlock();

I think the rcu is better folded into __blk_mq_run_hw_queue
to cover all the call sites.

  reply	other threads:[~2016-02-07 13:42 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-01 15:42 [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended Wenbo Wang
2016-02-01 15:42 ` Wenbo Wang
2016-02-01 15:59 ` Busch, Keith
2016-02-01 15:59   ` Busch, Keith
2016-02-01 16:17   ` Wenbo Wang
2016-02-01 16:17     ` Wenbo Wang
2016-02-01 16:54 ` Jens Axboe
2016-02-01 16:54   ` Jens Axboe
2016-02-02  7:15   ` Wenbo Wang
2016-02-02 12:41     ` Sagi Grimberg
2016-02-02 12:41       ` Sagi Grimberg
2016-02-02 14:27       ` Keith Busch
2016-02-02 14:27         ` Keith Busch
2016-02-02 14:33         ` Sagi Grimberg
2016-02-02 14:33           ` Sagi Grimberg
2016-02-02 14:46           ` Keith Busch
2016-02-02 14:46             ` Keith Busch
2016-02-02 17:20             ` Sagi Grimberg
2016-02-02 17:20               ` Sagi Grimberg
2016-02-03  0:49               ` Wenbo Wang
2016-02-02 17:25     ` Keith Busch
2016-02-02 17:25       ` Keith Busch
2016-02-03  0:19       ` Wenbo Wang
2016-02-03 14:41     ` Keith Busch
2016-02-03 14:41       ` Keith Busch
2016-02-03 16:35       ` Wenbo Wang
2016-02-03 16:38         ` Keith Busch
2016-02-03 16:38           ` Keith Busch
2016-02-06 14:32           ` Wenbo Wang
2016-02-07 13:41             ` Sagi Grimberg [this message]
2016-02-07 13:41               ` Sagi Grimberg
2016-02-08 15:01             ` Keith Busch
2016-02-08 15:01               ` Keith Busch
2016-02-09 11:22               ` Wenbo Wang
2016-02-09 22:55                 ` Keith Busch
2016-02-09 22:55                   ` Keith Busch

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