From: Martin Peres <martin.peres@xxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
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@xxxxxxxxxxxxxxx> # 3.9+
Reported-by: Marcin Slusarz <marcin.slusarz@xxxxxxxxx>
Tested-by: Timothée Ravier <tim@xxxxxxxx>
Tested-by: Boris Fersing (IRC nick fersingb, no public email address)
Signed-off-by: Martin Peres <martin.peres@xxxxxxx>
Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/gpu/drm/nouveau/core/subdev/therm/fan.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c b/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c
index 39f47b950ad1..c14cb093a64e 100644
--- 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 *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;
}
--
1.9.3
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