[PATCH] drm/i915: Take request reference before arming the watchdog timer

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Reference needs to be taken before arming the timer. Luckily, given the
default timer period of 20s, the potential to hit the race is extremely
unlikely.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Fixes: 9b4d0598ee94 ("drm/i915: Request watchdog infrastructure")
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
Test-with: 20210318162400.2065097-1-tvrtko.ursulin at linux.intel.com
---
 drivers/gpu/drm/i915/i915_request.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 9165971c3c47..bec9c3652188 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -350,6 +350,8 @@ static void __rq_arm_watchdog(struct i915_request *rq)
 	if (!ce->watchdog.timeout_us)
 		return;
 
+	i915_request_get(rq);
+
 	hrtimer_init(&wdg->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	wdg->timer.function = __rq_watchdog_expired;
 	hrtimer_start_range_ns(&wdg->timer,
@@ -357,7 +359,6 @@ static void __rq_arm_watchdog(struct i915_request *rq)
 					   NSEC_PER_USEC),
 			       NSEC_PER_MSEC,
 			       HRTIMER_MODE_REL);
-	i915_request_get(rq);
 }
 
 static void __rq_cancel_watchdog(struct i915_request *rq)
-- 
2.27.0