lkml.org 
[lkml]   [2014]   [Jun]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.12 081/146] drm/nouveau/pm/fan: drop the fan lock in fan_update() before rescheduling
Date
From: Martin Peres <martin.peres@labri.fr>

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@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: Jiri Slaby <jslaby@suse.cz>
---
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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2014-06-09 11:41    [W:0.830 / U:0.360 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site