From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Tue, 18 Sep 2018 15:42:47 +0800
From: Ming Lei <ming.lei@redhat.com>
To: "jianchao.wang" <jianchao.w.wang@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org
Subject: Re: [PATCH V3 00/17] SCSI: introduce per-host admin queue & enable
 runtime PM
Message-ID: <20180918074245.GC4805@ming.t460p>
References: <20180913121546.5710-1-ming.lei@redhat.com>
 <f9ba3c11-21ac-d963-3f24-cb83744014e1@oracle.com>
 <20180916130918.GA9947@ming.t460p>
 <7e9cfa7a-292a-0c26-0da8-187d961d974a@oracle.com>
 <20180917120727.GC28349@ming.t460p>
 <0475ffa4-be81-e35f-efe8-6821bada104c@oracle.com>
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On Tue, Sep 18, 2018 at 09:17:12AM +0800, jianchao.wang wrote:
> Hi Ming
> 
> On 09/17/2018 08:07 PM, Ming Lei wrote:
> >>> This way will delay runtime pm or system suspend until the queue is unfrozen,
> >>> but it isn't reasonable.
> >> This interface is for the __scsi_execute only, before we call into function, we should have
> >> get the device resumed synchronously.
> > I mean when the queue is frozen, it is reasonable to runtime suspend the queue. However,
> > blk_queue_preempt_enter() is still waiting for queue becoming unfreezing first.
> 
> We don't freeze the queue, but set preempt-only mode when suspend the queue. :)

But the queue can be frozen by other paths. Even though it is frozen, the queue
should be allowed to suspend too.

Thanks,
Ming