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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <226048f7-6ad3-a625-c2ed-d9d13e096803@acm.org>
Date:   Thu, 30 Apr 2020 18:50:03 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Can Guo <cang@...eaurora.org>
Cc:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        hongwus@...eaurora.org, rnayak@...eaurora.org,
        stanley.chu@...iatek.com, alim.akhtar@...sung.com,
        beanhuo@...ron.com, Avri.Altman@....com,
        bjorn.andersson@...aro.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/1] scsi: pm: Balance pm_only counter of request queue
 during system resume

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.