linux-kernel - Re: [PATCH v2 1/3] power: validate wakeup source before activating it.

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Date:	Wed, 6 May 2015 15:11:48 -0700
From:	Jin Qian <jinqian@...roid.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] power: validate wakeup source before activating it.

Hi Rafael,

I kept braces since checkpatch.pl didn't report error or warning. The
if condition has two lines, a brace make the statement more clear I
think.

I removed the format string since ws->name can be random strings if
the wakeup_source is not registered (i.e. using prepare functions).
It's not very useful to print name if we have stack dump from
WARN_ONCE.

Thanks,
jin

On Wed, May 6, 2015 at 3:00 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> On Wednesday, May 06, 2015 11:51:07 AM Jin Qian wrote:
>> A rogue wakeup source not registered in wakeup_sources list is not visible
>> from wakeup_sources_stats_show. Check if the wakeup source is registered
>> properly by looking at the timer struct.
>>
>> Signed-off-by: Jin Qian <jinqian@...roid.com>
>> ---
>>  drivers/base/power/wakeup.c | 19 +++++++++++++++++++
>>  1 file changed, 19 insertions(+)
>>
>> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
>> index 7726200..aead738 100644
>> --- a/drivers/base/power/wakeup.c
>> +++ b/drivers/base/power/wakeup.c
>> @@ -351,6 +351,20 @@ int device_set_wakeup_enable(struct device *dev, bool enable)
>>  }
>>  EXPORT_SYMBOL_GPL(device_set_wakeup_enable);
>>
>> +/**
>> + * wakeup_source_not_registered - validate the given wakeup source.
>> + * @ws: Wakeup source to be validated.
>> + */
>> +static bool wakeup_source_not_registered(struct wakeup_source *ws)
>> +{
>> +     /*
>> +      * Use timer struct to check if the given source is initialized
>> +      * by wakeup_source_add.
>> +      */
>> +     return ws->timer.function != pm_wakeup_timer_fn ||
>> +                ws->timer.data != (unsigned long)ws;
>> +}
>> +
>>  /*
>>   * The functions below use the observation that each wakeup event starts a
>>   * period in which the system should not be suspended.  The moment this period
>> @@ -391,6 +405,11 @@ static void wakeup_source_activate(struct wakeup_source *ws)
>>  {
>>       unsigned int cec;
>>
>> +     if (WARN_ONCE(wakeup_source_not_registered(ws),
>> +                     "unregistered wakeup source\n")) {
>> +             return;
>> +     }
>
> The braces are not necessary and you can use format strings with WARN_ONCE()
> too IIRC.
>
>> +
>>       /*
>>        * active wakeup source should bring the system
>>        * out of PM_SUSPEND_FREEZE state
>>
>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
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