linux-kernel - Re: [PATCH] PM / Sleep: Print last wakeup source on failed wakeup

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Date:	Wed, 12 Jun 2013 00:00:18 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Julius Werner <jwerner@...omium.org>
Cc:	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Todd Poynor <toddpoynor@...gle.com>, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Sameer Nanda <snanda@...omium.org>
Subject: Re: [PATCH] PM / Sleep: Print last wakeup source on failed wakeup_count write

On Thursday, May 30, 2013 01:02:17 PM Julius Werner wrote:
> Commit a938da06 introduced a useful little log message to tell
> users/debuggers which wakeup source aborted a suspend. However, this
> message is only printed if the abort happens during the in-kernel
> suspend path (after writing /sys/power/state).
> 
> The full specification of the /sys/power/wakeup_count facility allows
> user-space power managers to double-check if wakeups have already
> happened before it actually tries to suspend (e.g. while it was running
> user-space pre-suspend hooks), by writing the last known wakeup_count
> value to /sys/power/wakeup_count. This patch changes the sysfs handler
> for that node to also print said log message if that write fails, so
> that we can figure out the offending wakeup source for both kinds of
> suspend aborts.
> 
> Signed-off-by: Julius Werner <jwerner@...omium.org>
> ---
>  drivers/base/power/wakeup.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
> index 79715e7..b0b7886 100644
> --- a/drivers/base/power/wakeup.c
> +++ b/drivers/base/power/wakeup.c
> @@ -772,6 +772,8 @@ bool pm_save_wakeup_count(unsigned int count)
>  		events_check_enabled = true;
>  	}
>  	spin_unlock_irqrestore(&events_lock, flags);
> +	if (!events_check_enabled)
> +		print_active_wakeup_sources();

This is going to be done in the autosleep case too, which I'm slightly
concerned about.

If you wanted to cover /sys/power/wakeup_count only, it would be better
to put that into wakeup_count_store(), but perhaps you wanted to cover
autosleep too?

>  	return events_check_enabled;
>  }

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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