linux-kernel - Re:Re: [PATCH V2] amdgpu: remove unnecessary condition check

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Date:   Tue, 21 Apr 2020 12:53:47 +0800 (GMT+08:00)
From:   赵军奎 <bernard@...o.com>
To:     Felix Kuehling <felix.kuehling@....com>
Cc:     alexander.deucher@....com,
        Christian König <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        opensource.kernel@...o.com
Subject: Re:Re: [PATCH V2] amdgpu: remove unnecessary condition check


From: Felix Kuehling <felix.kuehling@....com>
Date: 2020-04-21 12:24:19
To:  1587180037-113840-1-git-send-email-bernard@...o.com,Alex Deucher <alexander.deucher@....com>,"Christian König" <christian.koenig@....com>,"David (ChunMing) Zhou" <David1.Zhou@....com>,David Airlie <airlied@...ux.ie>,Daniel Vetter <daniel@...ll.ch>,amd-gfx@...ts.freedesktop.org,dri-devel@...ts.freedesktop.org,linux-kernel@...r.kernel.org
Cc:  opensource.kernel@...o.com,Bernard Zhao <bernard@...o.com>
Subject: Re: [PATCH V2] amdgpu: remove unnecessary condition check>Hi Bernard,
>
>Please see comments inline.
>
>Am 2020-04-20 um 10:41 p.m. schrieb Bernard Zhao:
>> There is no need to if check again, maybe we could merge
>> into the above else branch.
>>
>> Signed-off-by: Bernard Zhao <bernard@...o.com>
>>
>> ---
>> Changes since V1:
>> *commit message improve
>> *code style refactoring
>>
>> Link for V1:
>> * https://lore.kernel.org/patchwork/patch/1226587/
>> ---
>>  drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 16 +++++++++-------
>>  1 file changed, 9 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> index 9dff792c9290..a64eeb07bec4 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> @@ -660,13 +660,15 @@ static int reserve_bo_and_vm(struct kgd_mem *mem,
>>  
>>  	ret = ttm_eu_reserve_buffers(&ctx->ticket, &ctx->list,
>>  				     false, &ctx->duplicates);
>> -	if (!ret)
>> -		ctx->reserved = true;
>> -	else {
>> +
>> +	if (ret) {
>>  		pr_err("Failed to reserve buffers in ttm\n");
>>  		kfree(ctx->vm_pd);
>>  		ctx->vm_pd = NULL;
>>  	}
>> +	else {
>> +		ctx->reserved = true;
>> +	}
>
>Here you're just reversing the if and else branches. This change looks
>completely superfluous to me.
>
>You're also breaking coding style conventions. The "else" should be on
>the same line as the closing brace "}". I'm pretty sure checkpatch.pl
>will complain about this.
>

In this file, only these two functions are <if (! Condition)... else .... > format. 
So in V2, after improve the commit  info, 
I refer to the following code style suggestions and modify it to <if (condition)...else... > format
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=90280eaa88ac1a9140dc759941123530d5545bb6#n191
(refer from Markus Elfring`s suggestion).

>>  
>>  	return ret;
>>  }
>> @@ -733,15 +735,15 @@ static int reserve_bo_and_cond_vms(struct kgd_mem *mem,
>>  
>>  	ret = ttm_eu_reserve_buffers(&ctx->ticket, &ctx->list,
>>  				     false, &ctx->duplicates);
>> -	if (!ret)
>> -		ctx->reserved = true;
>> -	else
>> -		pr_err("Failed to reserve buffers in ttm.\n");
>>  
>>  	if (ret) {
>> +		pr_err("Failed to reserve buffers in ttm.\n");
>>  		kfree(ctx->vm_pd);
>>  		ctx->vm_pd = NULL;
>>  	}
>> +	else {
>> +		ctx->reserved = true;
>> +	}
>
>Same as above regarding coding style.
>
>To minimize unnecessary code changes, you can merge the "if (ret) ..."
>code into the else-branch of the previous if.
>
>Regards,
>  Felix
>
>
>>  
>>  	return ret;
>>  }