linux-kernel - Re: [PATCH] drm/amdgpu: remove unreachable code

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Date:   Tue, 25 May 2021 08:53:16 +0200
From:   Christian König <christian.koenig@....com>
To:     Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>,
        alexander.deucher@....com
Cc:     airlied@...ux.ie, daniel@...ll.ch, sumit.semwal@...aro.org,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH] drm/amdgpu: remove unreachable code

Am 24.05.21 um 12:46 schrieb Jiapeng Chong:
> In the function amdgpu_uvd_cs_msg(), every branch in the switch
> statement will have a return, so the code below the switch statement
> will not be executed.
>
> Eliminate the follow smatch warning:
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c:845 amdgpu_uvd_cs_msg() warn:
> ignoring unreachable code.

Mhm, that is a NAK. IIRC we explicitely added that code because some 
compiler versions complained that we don't return a value at the end of 
the function.

I suggest to drop the return from the default case and the BUG() instead.

Regards,
Christian.

>
> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c | 2 --
>   1 file changed, 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
> index 82f0542..375b346 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
> @@ -842,8 +842,6 @@ static int amdgpu_uvd_cs_msg(struct amdgpu_uvd_cs_ctx *ctx,
>   		DRM_ERROR("Illegal UVD message type (%d)!\n", msg_type);
>   		return -EINVAL;
>   	}
> -	BUG();
> -	return -EINVAL;
>   }
>   
>   /**