| From 61679fe153b2b9ea5b5e2ab93305419e85e99a9d Mon Sep 17 00:00:00 2001 |
| From: Martin Peres <martin.peres@labri.fr> |
| Date: Fri, 14 Mar 2014 00:26:52 +0100 |
| Subject: drm/nouveau/pm/fan: drop the fan lock in fan_update() before rescheduling |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| From: Martin Peres <martin.peres@labri.fr> |
| |
| commit 61679fe153b2b9ea5b5e2ab93305419e85e99a9d upstream. |
| |
| 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: Marcin Slusarz <marcin.slusarz@gmail.com> |
| Tested-by: Timothée Ravier <tim@siosm.fr> |
| Tested-by: Boris Fersing (IRC nick fersingb, no public email address) |
| Signed-off-by: Martin Peres <martin.peres@free.fr> |
| Signed-off-by: Ben Skeggs <bskeggs@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/gpu/drm/nouveau/core/subdev/therm/fan.c | 19 +++++++++++++------ |
| 1 file changed, 13 insertions(+), 6 deletions(-) |
| |
| --- a/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c |
| +++ b/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c |
| @@ -54,8 +54,10 @@ nouveau_fan_update(struct nouveau_fan *f |
| |
| /* 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 *f |
| |
| 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 *f |
| ptimer->alarm(ptimer, delay * 1000 * 1000, &fan->alarm); |
| } |
| |
| -done: |
| - spin_unlock_irqrestore(&fan->lock, flags); |
| return ret; |
| } |
| |