This is a note to let you know that I've just added the patch titled
drm/nouveau/tmr: avoid processing completed alarms when adding a new one
to the 4.9-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-tmr-avoid-processing-completed-alarms-when-adding-a-new-one.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 330bdf62fe6a6c5b99a647f7bf7157107c9348b3 Mon Sep 17 00:00:00 2001
From: Ben Skeggs <bskeggs@xxxxxxxxxx>
Date: Thu, 11 May 2017 17:13:29 +1000
Subject: drm/nouveau/tmr: avoid processing completed alarms when adding a new one
From: Ben Skeggs <bskeggs@xxxxxxxxxx>
commit 330bdf62fe6a6c5b99a647f7bf7157107c9348b3 upstream.
The idea here was to avoid having to "manually" program the HW if there's
a new earliest alarm. This was lazy and bad, as it leads to loads of fun
races between inter-related callers (ie. therm).
Turns out, it's not so difficult after all. Go figure ;)
Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c
@@ -80,12 +80,22 @@ nvkm_timer_alarm(struct nvkm_timer *tmr,
if (list->timestamp > alarm->timestamp)
break;
}
+
list_add_tail(&alarm->head, &list->head);
+
+ /* Update HW if this is now the earliest alarm. */
+ list = list_first_entry(&tmr->alarms, typeof(*list), head);
+ if (list == alarm) {
+ tmr->func->alarm_init(tmr, alarm->timestamp);
+ /* This shouldn't happen if callers aren't stupid.
+ *
+ * Worst case scenario is that it'll take roughly
+ * 4 seconds for the next alarm to trigger.
+ */
+ WARN_ON(alarm->timestamp <= nvkm_timer_read(tmr));
+ }
}
spin_unlock_irqrestore(&tmr->lock, flags);
-
- /* process pending alarms */
- nvkm_timer_alarm_trigger(tmr);
}
void
Patches currently in stable-queue which might be from bskeggs@xxxxxxxxxx are
queue-4.9/drm-nouveau-tmr-ack-interrupt-before-processing-alarms.patch
queue-4.9/drm-nouveau-tmr-fix-corruption-of-the-pending-list-when-rescheduling-an-alarm.patch
queue-4.9/drm-nouveau-tmr-avoid-processing-completed-alarms-when-adding-a-new-one.patch
queue-4.9/drm-nouveau-mmu-nv4a-use-nv04-mmu-rather-than-the-nv44-one.patch
queue-4.9/drm-nouveau-therm-remove-ineffective-workarounds-for-alarm-bugs.patch
queue-4.9/drm-nouveau-tmr-handle-races-with-hw-when-updating-the-next-alarm-time.patch