linux-kernel - Re: [PATCH] i2c: designware: Fix unbalanced suspended flag

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: <e8b6733c-33b8-cb28-a62b-21dad9bd6466@opensource.cirrus.com>
Date:   Fri, 9 Dec 2022 13:36:07 +0000
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     Hans de Goede <hdegoede@...hat.com>, <wsa@...nel.org>,
        <jarkko.nikula@...ux.intel.com>,
        <andriy.shevchenko@...ux.intel.com>,
        <mika.westerberg@...ux.intel.com>, <jsd@...ihalf.com>
CC:     <linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>
Subject: Re: [PATCH] i2c: designware: Fix unbalanced suspended flag

On 9/12/22 12:15, Hans de Goede wrote:
> Hi Richard,
> 
> On 12/9/22 12:40, Richard Fitzgerald wrote:
>> Ensure that i2c_mark_adapter_suspended() is always balanced by a call to
>> i2c_mark_adapter_resumed().

<snip>

> 
> It is not entirely clear to me where the unbalance you claim to see comes
> from? When runtime-suspended SMART_SUSPEND should keep it suspended at which point
> the system suspend callback will never run ?
> 
> Are you sure that you are not maybe seeing a suspend/resume ordering issue?
> 
> Did you add printk messages to the suspend/resume callbacks of
> i2c-designware-platdrv.c which show the system suspend callback
> being called but not the system resume one ?
> 

With messages in strategic places.

[  169.607358] i2c_designware i2c_designware.2: PM: dev_pm_skip_suspend: 
SMART_SUSPEND=0 pm_runtime_status_suspended=1
[  169.607361] i2c_designware i2c_designware.2: PM: 
__device_suspend_late: dev_pm_skip_suspend:false
[  169.607364] i2c_designware i2c_designware.2: dw_i2c_plat_suspend
...
[  169.702511] i2c_designware i2c_designware.2: PM: dev_pm_skip_resume: 
1 because !power.must_resume
[  169.706241] i2c_designware i2c_designware.2: PM: dev_pm_skip_resume: 
1 because !power.must_resume
[  169.706244] i2c_designware i2c_designware.2: PM: device_resume_early: 
dev_pm_skip_resume:true
...
[  175.254832] i2c i2c-2: Transfer while suspended

(Just to prove my logging isn't lying, for i2c3 it reports
SMART_SUSPEND=1)

So it can skip the resume even if it didn't skip the suspend.
The SMART_SUSPEND flag is not set on i2c2 and the driver core can
skip resume even if it didn't skip suspend.