linux-kernel - Re: [PATCH] drm/i915/selftests: Fix NULL vs IS_ERR checking for kernel

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Date:   Wed, 12 Jan 2022 09:53:38 -0800
From:   Matthew Brost <matthew.brost@...el.com>
To:     Miaoqian Lin <linmq006@...il.com>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Andi Shyti <andi.shyti@...el.com>,
        Daniele Ceraolo Spurio <daniele.ceraolospurio@...el.com>,
        Jason Ekstrand <jason@...kstrand.net>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/i915/selftests: Fix NULL vs IS_ERR checking for
 kernel_context

On Wed, Dec 22, 2021 at 07:58:29AM +0000, Miaoqian Lin wrote:
> Since i915_gem_create_context() function return error pointers,
> the kernel_context() function does not return null, It returns error
> pointers too. Using IS_ERR() to check the return value to fix this.
> 

Just a nit, err is initialized to -ENOMEM in a bunch of these tests
which isn't needed anymore. If you want to clean that up too, feel free.

With that:
Reviewed-by: Matthew Brost <matthew.brost@...el.com> 

> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
> ---
>  drivers/gpu/drm/i915/gt/selftest_execlists.c | 41 ++++++++++++++------
>  1 file changed, 29 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/selftest_execlists.c b/drivers/gpu/drm/i915/gt/selftest_execlists.c
> index b367ecfa42de..eacfe920afed 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_execlists.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_execlists.c
> @@ -1540,13 +1540,16 @@ static int live_busywait_preempt(void *arg)
>  	 */
>  
>  	ctx_hi = kernel_context(gt->i915, NULL);
> -	if (!ctx_hi)
> -		return -ENOMEM;
> +	if (IS_ERR(ctx_hi))
> +		return IS_ERR(ctx_hi);
> +
>  	ctx_hi->sched.priority = I915_CONTEXT_MAX_USER_PRIORITY;
>  
>  	ctx_lo = kernel_context(gt->i915, NULL);
> -	if (!ctx_lo)
> +	if (IS_ERR(ctx_lo)) {
> +		err = PTR_ERR(ctx_lo);
>  		goto err_ctx_hi;
> +	}
>  	ctx_lo->sched.priority = I915_CONTEXT_MIN_USER_PRIORITY;
>  
>  	obj = i915_gem_object_create_internal(gt->i915, PAGE_SIZE);
> @@ -1742,13 +1745,17 @@ static int live_preempt(void *arg)
>  		goto err_spin_hi;
>  
>  	ctx_hi = kernel_context(gt->i915, NULL);
> -	if (!ctx_hi)
> +	if (IS_ERR(ctx_hi)) {
> +		err = PTR_ERR(ctx_hi);
>  		goto err_spin_lo;
> +	}
>  	ctx_hi->sched.priority = I915_CONTEXT_MAX_USER_PRIORITY;
>  
>  	ctx_lo = kernel_context(gt->i915, NULL);
> -	if (!ctx_lo)
> +	if (IS_ERR(ctx_lo)) {
> +		err = PTR_ERR(ctx_lo);
>  		goto err_ctx_hi;
> +	}
>  	ctx_lo->sched.priority = I915_CONTEXT_MIN_USER_PRIORITY;
>  
>  	for_each_engine(engine, gt, id) {
> @@ -1834,12 +1841,16 @@ static int live_late_preempt(void *arg)
>  		goto err_spin_hi;
>  
>  	ctx_hi = kernel_context(gt->i915, NULL);
> -	if (!ctx_hi)
> +	if (IS_ERR(ctx_hi)) {
> +		err = PTR_ERR(ctx_hi);
>  		goto err_spin_lo;
> +	}
>  
>  	ctx_lo = kernel_context(gt->i915, NULL);
> -	if (!ctx_lo)
> +	if (IS_ERR(ctx_lo)) {
> +		err = PTR_ERR(ctx_lo);
>  		goto err_ctx_hi;
> +	}
>  
>  	/* Make sure ctx_lo stays before ctx_hi until we trigger preemption. */
>  	ctx_lo->sched.priority = 1;
> @@ -1928,8 +1939,8 @@ struct preempt_client {
>  static int preempt_client_init(struct intel_gt *gt, struct preempt_client *c)
>  {
>  	c->ctx = kernel_context(gt->i915, NULL);
> -	if (!c->ctx)
> -		return -ENOMEM;
> +	if (IS_ERR(c->ctx))
> +		return PTR_ERR(c->ctx);
>  
>  	if (igt_spinner_init(&c->spin, gt))
>  		goto err_ctx;
> @@ -3385,13 +3396,17 @@ static int live_preempt_timeout(void *arg)
>  		return -ENOMEM;
>  
>  	ctx_hi = kernel_context(gt->i915, NULL);
> -	if (!ctx_hi)
> +	if (IS_ERR(ctx_hi)) {
> +		err = PTR_ERR(ctx_hi);
>  		goto err_spin_lo;
> +	}
>  	ctx_hi->sched.priority = I915_CONTEXT_MAX_USER_PRIORITY;
>  
>  	ctx_lo = kernel_context(gt->i915, NULL);
> -	if (!ctx_lo)
> +	if (IS_ERR(ctx_lo)) {
> +		err = PTR_ERR(ctx_lo);
>  		goto err_ctx_hi;
> +	}
>  	ctx_lo->sched.priority = I915_CONTEXT_MIN_USER_PRIORITY;
>  
>  	for_each_engine(engine, gt, id) {
> @@ -3683,8 +3698,10 @@ static int live_preempt_smoke(void *arg)
>  
>  	for (n = 0; n < smoke.ncontext; n++) {
>  		smoke.contexts[n] = kernel_context(smoke.gt->i915, NULL);
> -		if (!smoke.contexts[n])
> +		if (IS_ERR(smoke.contexts[n])) {
> +			err = PTR_ERR(smoke.contexts[n]);
>  			goto err_ctx;
> +		}
>  	}
>  
>  	for (n = 0; n < ARRAY_SIZE(phase); n++) {
> -- 
> 2.17.1
>