From: Martin Peres <[email protected]> 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: <[email protected]> # 3.9+ Reported-by: Marcin Slusarz <[email protected]> Tested-by: Timothée Ravier <[email protected]> Tested-by: Boris Fersing (IRC nick fersingb, no public email address) Signed-off-by: Martin Peres <[email protected]> Signed-off-by: Ben Skeggs <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> --- 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 stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
