Re: [PATCH] power: Do not clear events_check_enabled in pm_wakeup_pending()

From: Ravi Chandra Sadineni <ravisadineni@chromium.org>
To: rjw@rjwysocki.net, len.brown@intel.com, pavel@ucw.cz,
	gregkh@linuxfoundation.org, linux-pm@vger.kernel.org,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Todd Broch <tbroch@google.com>,
	Ravi Chandra Sadineni <ravisadineni@chromium.org>,
	Rajat Jain <rajatja@google.com>
Subject: Re: [PATCH] power: Do not clear events_check_enabled in pm_wakeup_pending()
Date: Mon, 24 Jun 2019 16:25:12 -0700	[thread overview]
Message-ID: <CAEZbON4e1=w6G4KEqq2qP0nTD4z00fcqHErWTBVGFGb17f=+1Q@mail.gmail.com> (raw)
In-Reply-To: <20190619175142.237794-1-ravisadineni@chromium.org>

Hi,

Just wanted to check if this is o.k.

Thanks,
Ravi

On Wed, Jun 19, 2019 at 10:52 AM Ravi Chandra Sadineni
<ravisadineni@chromium.org> wrote:
>
> events_check_enabled bool is set when wakeup_count sysfs attribute
> is written. User level daemon is expected to write this attribute
> just before suspend.
>
> When this boolean is set, calls to pm_wakeup_event() will result in
> increment of per device and global wakeup count that helps in
> identifying the wake source. global wakeup count is also used by
> pm_wakeup_pending() to identify if there are any pending events that
> should result in an suspend abort.
>
> Currently calls to pm_wakeup_pending() also clears events_check_enabled.
> This can be a problem when there are multiple wake events or when the
> suspend is aborted due to an interrupt on a shared interrupt line.
> For example an Mfd device can create several platform devices which
> might fetch the state on resume in the driver resume method and increment
> the wakeup count if needed. But if events_check_enabled is cleared before
> resume methods get to execute, wakeup count will not be incremented. Thus
> let us not reset the bool here.
>
> Note that events_check_enabled is also cleared in suspend.c/enter_state()
> on every resume at the end.
>
> Signed-off-by: Ravi Chandra Sadineni <ravisadineni@chromium.org>
> ---
>  drivers/base/power/wakeup.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
> index 5b2b6a05a4f3..88aade871589 100644
> --- a/drivers/base/power/wakeup.c
> +++ b/drivers/base/power/wakeup.c
> @@ -838,7 +838,6 @@ bool pm_wakeup_pending(void)
>
>                 split_counters(&cnt, &inpr);
>                 ret = (cnt != saved_count || inpr > 0);
> -               events_check_enabled = !ret;
>         }
>         raw_spin_unlock_irqrestore(&events_lock, flags);
>
> --
> 2.20.1
>