Re: [PATCH RFC] suspend: Prevent might sleep splats

[Rafael J. Wysocki]

On Thu, May 24, 2018 at 5:45 PM, Sebastian Andrzej Siewior
<bigeasy@xxxxxxxxxxxxx> wrote:
> On 2018-05-24 17:07:16 [+0200], Rafael J. Wysocki wrote:
>> On Thu, May 24, 2018 at 4:24 PM, Sebastian Andrzej Siewior
>> <bigeasy@xxxxxxxxxxxxx> wrote:
>> > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> >
>> > timekeeping suspend/resume calls read_persistent_clock() which takes
>> > rtc_lock. That results in might sleep warnings because at that point
>> > we run with interrupts disabled.
>> >
>> > We cannot convert rtc_lock to a raw spinlock as that would trigger
>> > other might sleep warnings.
>> >
>> > As a workaround we disable the might sleep warnings by setting
>> > system_state to SYSTEM_SUSPEND before calling sysdev_suspend() and
>> > restoring it to SYSTEM_RUNNING afer sysdev_resume().
>> >
>> > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
>>
>> Hmm.  Don't we also need to cover suspend-to-idle?
>
> Well, if you agree with the approach then I would look into it.

As long as the SYSTEM_SUSPEND system state is defined unambiguously, I
don't have a problem with doing this.