Le 24/03/2014 02:03, Martin Peres a écrit :
From: Martin Peres <martin.pe...@labri.fr>
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: <sta...@vger.kernel.org> # 3.9+
Reported-by: Marcin Slusarz <marcin.slus...@gmail.com>
Tested-by: Timothée Ravier <t...@siosm.fr>
Tested-by: Boris Fersing (IRC nick fersingb, email is private)
Signed-off-by: Martin Peres <martin.pe...@free.fr>
---
nvkm/subdev/therm/fan.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/nvkm/subdev/therm/fan.c b/nvkm/subdev/therm/fan.c
index 95f6129..29d4c41 100644
--- a/nvkm/subdev/therm/fan.c
+++ b/nvkm/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;
}
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