linux-kernel - Re: [PATCH] drm/i915/gt: Handle INTEL_WAKEREF_DEF return value in gen8_ggtt_bind_get

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Message-ID: <87msfjneob.fsf@intel.com>
Date: Wed, 22 Jan 2025 15:47:32 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Krzysztof Karas <krzysztof.karas@...el.com>, Ingyu Jang
 <ingyujang25@...il.com>
Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi
 <rodrigo.vivi@...el.com>, Tvrtko Ursulin <tursulin@...ulin.net>, David
 Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/i915/gt: Handle INTEL_WAKEREF_DEF return value in
 gen8_ggtt_bind_get_ce

On Wed, 22 Jan 2025, Krzysztof Karas <krzysztof.karas@...el.com> wrote:
> Hi Ingyu,
>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
>> index d60a6ca0cae5..8d22d8f2243d 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
>> @@ -311,7 +311,7 @@ static struct intel_context *gen8_ggtt_bind_get_ce(struct i915_ggtt *ggtt, intel
>>  	 * doing rpm_resume().
>>  	 */
>>  	*wakeref = intel_gt_pm_get_if_awake(gt);
>> -	if (!*wakeref)
>> +	if (!*wakeref || *wakeref == INTEL_WAKEREF_DEF)
> INTEL_WAKEREF_DEF is a wrapper for an error pointer - how about
> IS_ERR_OR_NULL() macro? Without going a bit deeper into the code
> it is not apparent that INTEL_WAKEREF_DEF is indicating an error.
>
> Nice catch nevertheless.

It's not a nice catch. It's wrong [1].

BR,
Jani.


[1] https://lore.kernel.org/r/87cyglg9w2.fsf@intel.com


>
> Krzysztof
>
>>  		return NULL;
>>  
>>  	intel_engine_pm_get(ce->engine);
>> -- 
>> 2.34.1
>> 

-- 
Jani Nikula, Intel