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

[Mika Kuoppala]

Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com> writes:

> 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>

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
> 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
>
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