Re: [PATCH v3 1/1] scsi: pm: Balance pm_only counter of request queue during system resume

[Bart Van Assche]

On 2020-04-30 18:42, Can Guo wrote:
> On 2020-05-01 04:32, Bart Van Assche wrote:
> > Has it been considered to test directly whether a SCSI device has been
> > runtime suspended instead of relying on blk_queue_pm_only()? How about
> > using pm_runtime_status_suspended() or adding a function in
> > block/blk-pm.h that checks whether q->rpm_status == RPM_SUSPENDED?
> 
> Yes, I used to make the patch like that way, and it also worked well, as
> both ways are equal actually. I kinda like the current code because we
> should be confident that after scsi_dev_type_resume() returns, pm_only
> must be 0. Different reviewers may have different opinions, either way
> works well anyways.

Hi Can,

Please note that this is not a matter of personal preferences of a
reviewer but a matter of correctness. blk_queue_pm_only() does not only
return a value > 0 if a SCSI device has been runtime suspended but also
returns true if scsi_device_quiesce() was called for another reason.
Hence my request to test the "runtime suspended" status directly and not
to rely on blk_queue_pm_only().

Thanks,

Bart.