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authorBen Skeggs <bskeggs@redhat.com>2017-05-11 17:03:05 +1000
committerBen Skeggs <bskeggs@redhat.com>2017-05-12 08:32:57 +1000
commit9fc64667ee48c9a25e7dca1a6bcb6906fec5bcc5 (patch)
treef6f6d06887a94e9675c51e915bc729f06650801e
parent1b0f84380b10ee97f7d2dd191294de9017e94d1d (diff)
downloadlinux-stericsson-9fc64667ee48c9a25e7dca1a6bcb6906fec5bcc5.tar.gz
drm/nouveau/tmr: fix corruption of the pending list when rescheduling an alarm
At least therm/fantog "attempts" to work around this issue, which could lead to corruption of the pending alarm list. Fix it properly by not updating the timestamp without the lock held, or trying to add an already pending alarm to the pending alarm list.... Signed-off-by: Ben Skeggs <bskeggs@redhat.com> Cc: stable@vger.kernel.org
-rw-r--r--drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c
index 4e696627fdcd..d898787d514c 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c
@@ -71,14 +71,17 @@ nvkm_timer_alarm(struct nvkm_timer *tmr, u32 nsec, struct nvkm_alarm *alarm)
struct nvkm_alarm *list;
unsigned long flags;
- alarm->timestamp = nvkm_timer_read(tmr) + nsec;
-
- /* append new alarm to list, in soonest-alarm-first order */
+ /* Remove alarm from pending list.
+ *
+ * This both protects against the corruption of the list,
+ * and implements alarm rescheduling/cancellation.
+ */
spin_lock_irqsave(&tmr->lock, flags);
- if (!nsec) {
- if (!list_empty(&alarm->head))
- list_del(&alarm->head);
- } else {
+ list_del_init(&alarm->head);
+
+ if (nsec) {
+ /* Insert into pending list, ordered earliest to latest. */
+ alarm->timestamp = nvkm_timer_read(tmr) + nsec;
list_for_each_entry(list, &tmr->alarms, head) {
if (list->timestamp > alarm->timestamp)
break;