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Commit 61679fe1 authored by Martin Peres's avatar Martin Peres Committed by Ben Skeggs
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drm/nouveau/pm/fan: drop the fan lock in fan_update() before rescheduling 



This should fix a deadlock that has been reported to us where fan_update()
would hold the fan lock and try to grab the alarm_program_lock to reschedule
an update. On an other CPU, the alarm_program_lock would have been taken
before calling fan_update(), leading to a deadlock.

We should Cc: <stable@vger.kernel.org> # 3.9+

Reported-by: default avatarMarcin Slusarz <marcin.slusarz@gmail.com>
Tested-by: default avatarTimothée Ravier <tim@siosm.fr>
Tested-by: Boris Fersing (IRC nick fersingb, no public email address)
Signed-off-by: default avatarMartin Peres <martin.peres@free.fr>
Signed-off-by: default avatarBen Skeggs <bskeggs@redhat.com>
parent 6c3252bc

drivers/gpu/drm/nouveau/core/subdev/therm/fan.c

+13 −6
Original line number Diff line number Diff line
@@ -54,8 +54,10 @@ nouveau_fan_update(struct nouveau_fan *fan, bool immediate, int target) 


	/* check that we're not already at the target duty cycle */

	duty = fan->get(therm);

	if (duty == target)

		goto done;

	if (duty == target) {

		spin_unlock_irqrestore(&fan->lock, flags);

		return 0;

	}



	/* smooth out the fanspeed increase/decrease */

	if (!immediate && duty >= 0) {
@@ -73,8 +75,15 @@ nouveau_fan_update(struct nouveau_fan *fan, bool immediate, int target) 


	nv_debug(therm, "FAN update: %d\n", duty);

	ret = fan->set(therm, duty);

	if (ret)

		goto done;

	if (ret) {

		spin_unlock_irqrestore(&fan->lock, flags);

		return ret;

	}



	/* fan speed updated, drop the fan lock before grabbing the

	 * alarm-scheduling lock and risking a deadlock

	 */

	spin_unlock_irqrestore(&fan->lock, flags);



	/* schedule next fan update, if not at target speed already */

	if (list_empty(&fan->alarm.head) && target != duty) {
@@ -92,8 +101,6 @@ nouveau_fan_update(struct nouveau_fan *fan, bool immediate, int target) 
		ptimer->alarm(ptimer, delay * 1000 * 1000, &fan->alarm);

	}



done:

	spin_unlock_irqrestore(&fan->lock, flags);

	return ret;

}