linux-kernel - Re: [PATCH] drm/amdgpu: Modify error handling in amdgpu

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Date:	Fri, 5 Aug 2016 10:04:03 +0200
From:	Christian König <deathsimple@...afone.de>
To:	Amitoj Kaur Chawla <amitoj1606@...il.com>, airlied@...ux.ie,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:	julia.lawall@...6.fr
Subject: Re: [PATCH] drm/amdgpu: Modify error handling in amdgpu_ttm

Am 04.08.2016 um 17:42 schrieb Amitoj Kaur Chawla:
> To indicate an error, debugfs_create_file can return an ERR_PTR for
> !CONFIG_DEBUG_FS and NULL otherwise, so in case the result is
> dereferenced there should be a previous IS_ERR and a NULL check.
>
> The Coccinelle semantic patch used to find the issue is as follows:
> @@
> expression e;
> identifier f;
> @@
>
> *  e = debugfs_create_file(...);
> ... when != e == NULL
> e->f
>
> Signed-off-by: Amitoj Kaur Chawla <amitoj1606@...il.com>

The whole section is surrounded by CONFIG_DEBUG_FS, so I suggest to just 
replace the check or IS_ERR with a NULL check.

Regards,
Christian.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 8a1752f..9ff70a7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1198,6 +1198,8 @@ static int amdgpu_ttm_debugfs_init(struct amdgpu_device *adev)
>   				  adev, &amdgpu_ttm_vram_fops);
>   	if (IS_ERR(ent))
>   		return PTR_ERR(ent);
> +	if (!ent)
> +		return -ENOMEM;
>   	i_size_write(ent->d_inode, adev->mc.mc_vram_size);
>   	adev->mman.vram = ent;
>   
> @@ -1205,6 +1207,8 @@ static int amdgpu_ttm_debugfs_init(struct amdgpu_device *adev)
>   				  adev, &amdgpu_ttm_gtt_fops);
>   	if (IS_ERR(ent))
>   		return PTR_ERR(ent);
> +	if (!ent)
> +		return -ENOMEM;
>   	i_size_write(ent->d_inode, adev->mc.gtt_size);
>   	adev->mman.gtt = ent;
>