linux-kernel - Re: [PATCH] drm_aux-dev: fix error handling in drm_dp_aux_dev_init()

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Date:   Fri, 23 Sep 2016 12:26:05 +0200
From:   Alexey Khoroshilov <khoroshilov@...ras.ru>
To:     David Airlie <airlied@...ux.ie>, ldv-project@...uxtesting.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm_aux-dev: fix error handling in drm_dp_aux_dev_init()

Dear Daniel,

Sorry for long response.

> Applied to drm-misc, thanks for the patch. Out of curiosity, how
> exactly did you spot this bug?

We use static analysis tools that check various rules on correct usage
of kernel core API. An example of error trace for the rm_dp_aux_dev case
you can see here [1].

Some addition details are described in a paper [2].

[1]
http://linuxtesting.org/results/impl_reports_admin?action=preview&num=137
[2]
http://www.ispras.ru/en/publications/configurable_toolset_for_static_verification_of_operating_systems_kernel_modules.pdf

Best regards,
Alexey

On 12.07.2016 14:11, Daniel Vetter wrote:
> On Thu, Jun 30, 2016 at 12:52:15AM +0300, Alexey Khoroshilov wrote:
>> If class_create() fails, there is no need for class_destroy().
>>
>> Found by Linux Driver Verification project (linuxtesting.org).
>>
>> Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
> 
> Applied to drm-misc, thanks for the patch. Out of curiosity, how exactly
> did you spot this bug?
> -Daniel
> 
>> ---
>>  drivers/gpu/drm/drm_dp_aux_dev.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c
>> index 3334baacf43d..734f86a345f6 100644
>> --- a/drivers/gpu/drm/drm_dp_aux_dev.c
>> +++ b/drivers/gpu/drm/drm_dp_aux_dev.c
>> @@ -355,8 +355,7 @@ int drm_dp_aux_dev_init(void)
>>  
>>  	drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
>>  	if (IS_ERR(drm_dp_aux_dev_class)) {
>> -		res = PTR_ERR(drm_dp_aux_dev_class);
>> -		goto out;
>> +		return PTR_ERR(drm_dp_aux_dev_class);
>>  	}
>>  	drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
>>  
>> -- 
>> 1.9.1
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@...ts.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

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