linux-kernel - Re: [PATCH -next v2] drm/amdgpu: return 'ret' in amdgpu_pmu

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Message-ID: <fced7783-1216-ff3f-039f-d7c3a70b4916@huawei.com>
Date:   Mon, 24 Jun 2019 11:16:41 +0800
From:   maowenan <maowenan@...wei.com>
To:     Julia Lawall <julia.lawall@...6.fr>
CC:     <airlied@...ux.ie>, <daniel@...ll.ch>, <alexander.deucher@....com>,
        <christian.koenig@....com>, <David1.Zhou@....com>,
        <dan.carpenter@...cle.com>, <kernel-janitors@...r.kernel.org>,
        <amd-gfx@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next v2] drm/amdgpu: return 'ret' in amdgpu_pmu_init



On 2019/6/22 22:00, Julia Lawall wrote:
> 
> 
> On Sat, 22 Jun 2019, maowenan wrote:
> 
>>
>>
>> On 2019/6/22 21:06, Julia Lawall wrote:
>>>
>>>
>>> On Sat, 22 Jun 2019, Mao Wenan wrote:
>>>
>>>> There is one warning:
>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c: In function ‘amdgpu_pmu_init’:
>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c:249:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
>>>>   int ret = 0;
>>>>       ^
>>>> amdgpu_pmu_init() is called by amdgpu_device_init() in drivers/gpu/drm/amd/amdgpu/amdgpu_device.c,
>>>> which will use the return value. So it returns 'ret' for caller.
>>>> amdgpu_device_init()
>>>> 	r = amdgpu_pmu_init(adev);
>>>>
>>>> Fixes: 9c7c85f7ea1f ("drm/amdgpu: add pmu counters")
>>>>
>>>> Signed-off-by: Mao Wenan <maowenan@...wei.com>
>>>> ---
>>>>  v1->v2: change the subject for this patch; change the indenting when it calls init_pmu_by_type; use the value 'ret' in
>>>>  amdgpu_pmu_init().
>>>>  drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c | 6 +++---
>>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c
>>>> index 0e6dba9..145e720 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c
>>>> @@ -252,8 +252,8 @@ int amdgpu_pmu_init(struct amdgpu_device *adev)
>>>>  	case CHIP_VEGA20:
>>>>  		/* init df */
>>>>  		ret = init_pmu_by_type(adev, df_v3_6_attr_groups,
>>>> -				       "DF", "amdgpu_df", PERF_TYPE_AMDGPU_DF,
>>>> -				       DF_V3_6_MAX_COUNTERS);
>>>> +							   "DF", "amdgpu_df", PERF_TYPE_AMDGPU_DF,
>>>> +							   DF_V3_6_MAX_COUNTERS);
>>>>
>>>>  		/* other pmu types go here*/
>>>
>>> I don't know what is the impact of the other pmu types that are planned
>>> for the future.  Perhaps it would be better to abort the function
>>> immediately in the case of a failure.
>>

OK, v3 will be sent.

>> I guess it would be better to use new function or new switch case clause to process different PMU types
>> in future.
> 
> I don't know.  But normally when an error may occur it is checked for
> immediately, rather than just letting it go until the end of the function.
> But maybe the developer know what is planned for the future for this
> function.
> 
> julia
> 
>>
>>>
>>> julia
>>>
>>>>  		break;
>>>> @@ -261,7 +261,7 @@ int amdgpu_pmu_init(struct amdgpu_device *adev)
>>>>  		return 0;
>>>>  	}
>>>>
>>>> -	return 0;
>>>> +	return ret;
>>>>  }
>>>>
>>>>
>>>> --
>>>> 2.7.4
>>>>
>>>>
>>>
>>
>>
>