From: bart.vanassche@sandisk.com (Bart Van Assche)
Subject: [PATCH v2 4/7] blk-mq: Introduce blk_quiesce_queue() and blk_resume_queue()
Date: Wed, 5 Oct 2016 07:46:58 -0700 [thread overview]
Message-ID: <b42d5056-c2cb-8f0f-1a65-70740605ff22@sandisk.com> (raw)
In-Reply-To: <CACVXFVO21wDRrZtB0A5qn5KEn-rjnewQxYyN_aAWoQrKSMvmig@mail.gmail.com>
On 10/04/16 21:32, Ming Lei wrote:
> On Wed, Oct 5, 2016 at 12:16 PM, Bart Van Assche
> <bart.vanassche@sandisk.com> wrote:
>> On 10/01/16 15:56, Ming Lei wrote:
>>>
>>> If we just call the rcu/srcu read lock(or the mutex) around .queue_rq(),
>>> the above code needn't to be duplicated any more.
>>
>> Can you have a look at the attached patch? That patch uses an srcu read lock
>> for all queue types, whether or not the BLK_MQ_F_BLOCKING flag has been set.
>
> That is much cleaner now.
>
>> Additionally, I have dropped the QUEUE_FLAG_QUIESCING flag. Just like
>> previous versions, this patch has been tested.
>
> I think the flag of QUEUE_FLAG_QUIESCING is still needed because we
> have to set this flag to prevent new coming .queue_rq() from being run,
> and synchronize_srcu() won't wait for completion of that at all (see
> section of 'Update-Side Primitives' in [1]).
>
> [1] https://lwn.net/Articles/202847/
Hello Ming,
How about using the existing flag BLK_MQ_S_STOPPED instead of
introducing a new QUEUE_FLAG_QUIESCING flag? From the comment above
blk_mq_quiesce_queue() in the patch that was attached to my previous
e-mail: "Additionally, it is not prevented that new queue_rq() calls
occur unless the queue has been stopped first."
Thanks,
Bart.
next prev parent reply other threads:[~2016-10-05 14:46 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-28 23:57 [PATCH v2 0/7] Introduce blk_quiesce_queue() and blk_resume_queue() Bart Van Assche
2016-09-28 23:57 ` [PATCH v2 1/7] blk-mq: Introduce blk_mq_queue_stopped() Bart Van Assche
2016-10-05 17:50 ` Sagi Grimberg
2016-10-11 16:40 ` Christoph Hellwig
2016-09-28 23:59 ` [PATCH v2 4/7] blk-mq: Introduce blk_quiesce_queue() and blk_resume_queue() Bart Van Assche
2016-09-29 5:52 ` Hannes Reinecke
2016-09-29 21:51 ` Ming Lei
2016-09-30 15:55 ` Bart Van Assche
2016-10-01 22:56 ` Ming Lei
2016-10-05 4:16 ` Bart Van Assche
2016-10-05 4:32 ` Ming Lei
2016-10-05 14:46 ` Bart Van Assche [this message]
2016-10-05 16:11 ` Ming Lei
2016-10-05 18:14 ` Sagi Grimberg
2016-10-05 19:05 ` Bart Van Assche
2016-10-05 19:10 ` Sagi Grimberg
2016-10-05 21:08 ` Bart Van Assche
2016-10-05 22:49 ` Ming Lei
2016-10-05 23:00 ` Bart Van Assche
2016-09-29 0:00 ` [PATCH v2 5/7] dm: Fix a race condition related to stopping and starting queues Bart Van Assche
2016-09-29 0:01 ` [PATCH v2 6/7] SRP transport: Port srp_wait_for_queuecommand() to scsi-mq Bart Van Assche
2016-09-29 5:54 ` Hannes Reinecke
2016-10-05 17:38 ` Sagi Grimberg
2016-10-05 21:51 ` Bart Van Assche
2016-10-11 16:44 ` Christoph Hellwig
2016-09-29 0:01 ` [PATCH v2 7/7] [RFC] nvme: Fix a race condition Bart Van Assche
2016-10-05 17:40 ` Sagi Grimberg
2016-10-11 16:46 ` Christoph Hellwig
2016-10-12 0:41 ` Bart Van Assche
2016-09-29 0:02 ` [PATCH v2 2/7] dm: Use BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED in blk-mq code Bart Van Assche
2016-09-29 0:02 ` [PATCH v2 3/7] [RFC] nvme: " Bart Van Assche
2016-10-05 17:43 ` Sagi Grimberg
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