This is a note to let you know that I've just added the patch titled
drm/nouveau/pm/fan: drop the fan lock in fan_update() before rescheduling
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-nouveau-pm-fan-drop-the-fan-lock-in-fan_update-before-rescheduling.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 61679fe153b2b9ea5b5e2ab93305419e85e99a9d Mon Sep 17 00:00:00 2001
From: Martin Peres <martin.peres@xxxxxxxx>
Date: Fri, 14 Mar 2014 00:26:52 +0100
Subject: drm/nouveau/pm/fan: drop the fan lock in fan_update() before rescheduling
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From: Martin Peres <martin.peres@xxxxxxxx>
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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from martin.peres@xxxxxxxx are
queue-3.14/drm-nouveau-pm-fan-drop-the-fan-lock-in-fan_update-before-rescheduling.patch
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