Re: [PATCH v1] PM / sleep: make pm notifier called symmetrically

[Lianwei Wang]

On Wed, May 18, 2016 at 1:34 PM, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
> On Wed, May 18, 2016 at 8:07 AM, Lianwei Wang <lianwei.wang@xxxxxxxxx> wrote:
>> This makes pm notifier PREPARE/POST symmetrical: if PREPARE
>> fails, we will only undo what ever happened on PREPARE.
>>
>> It fixes the unbalanced cpu hotplug enable in cpu pm notifier.
>
> Can you please describe the problem you're trying to address in a bit
> more detail?

It is described in another patch, and it is a common issue. I fixed
the similar issue several times, all because that the CPU_POST_SUSPEND
notifier callback is called without call CPU_SUSPEND_PREPARE notifier
callback before. Something is DO in PM_XXX_PREPARE and UNDO in
POST_XXX. If we don't DO it in XXX_PREPARE then we don't need to UNDO
it in  PM_POST_XXX.

Here is the link for the unbalanced cpu hotplug enable case:
https://lkml.org/lkml/2016/5/6/61 .

Thanks,
Lianwei