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;