Commit e9728f0d authored by Dmitry Torokhov's avatar Dmitry Torokhov
Browse files

Input: pwm-beeper - fix race when suspending



Usually userspace sends SND_BELL and SND_TONE events, and by the time
pwm_beeper_suspend() runs userpsace is already frozen, but theoretically
in-kernel users may send these events too, and that may cause
pwm_beeper_event() scheduling another work after we canceled it.

Let's introduce a "suspended" flag and check it in pwm_beeper_event() to
avoid this race.
Reviewed-by: default avatarThierry Reding <thierry.reding@gmail.com>
Tested-by: default avatarDavid Lechner <david@lechnology.com>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 48a55d7d
......@@ -27,6 +27,7 @@ struct pwm_beeper {
struct pwm_device *pwm;
struct work_struct work;
unsigned long period;
bool suspended;
};
#define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
......@@ -73,7 +74,8 @@ static int pwm_beeper_event(struct input_dev *input,
else
beeper->period = HZ_TO_NANOSECONDS(value);
schedule_work(&beeper->work);
if (!beeper->suspended)
schedule_work(&beeper->work);
return 0;
}
......@@ -154,6 +156,15 @@ static int __maybe_unused pwm_beeper_suspend(struct device *dev)
{
struct pwm_beeper *beeper = dev_get_drvdata(dev);
/*
* Spinlock is taken here is not to protect write to
* beeper->suspended, but to ensure that pwm_beeper_event
* does not re-submit work once flag is set.
*/
spin_lock_irq(&beeper->input->event_lock);
beeper->suspended = true;
spin_unlock_irq(&beeper->input->event_lock);
pwm_beeper_stop(beeper);
return 0;
......@@ -163,8 +174,12 @@ static int __maybe_unused pwm_beeper_resume(struct device *dev)
{
struct pwm_beeper *beeper = dev_get_drvdata(dev);
if (beeper->period)
__pwm_beeper_set(beeper);
spin_lock_irq(&beeper->input->event_lock);
beeper->suspended = false;
spin_unlock_irq(&beeper->input->event_lock);
/* Let worker figure out if we should resume beeping */
schedule_work(&beeper->work);
return 0;
}
......
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