Re: [PATCH] amdgpu: fixes memleak issue when init failed

["Christian König" <christian.koenig@amd.com>]

Am 21.04.20 um 15:39 schrieb 赵军奎:
> 发件人："Christian König" <christian.koenig@amd.com>
> 发送日期：2020-04-21 21:02:27
> 收件人："赵军奎" <bernard@vivo.com>
> 抄送人：Alex Deucher <alexander.deucher@amd.com>,"David (ChunMing) Zhou" <David1.Zhou@amd.com>,David Airlie <airlied@linux.ie>,Daniel Vetter <daniel@ffwll.ch>,Tom St Denis <tom.stdenis@amd.com>,Ori Messinger <Ori.Messinger@amd.com>,Sam Ravnborg <sam@ravnborg.org>,amd-gfx@lists.freedesktop.org,dri-devel@lists.freedesktop.org,linux-kernel@vger.kernel.org,opensource.kernel@vivo.com
> 主题：Re: [PATCH] amdgpu: fixes memleak issue when init failed>Am 21.04.20 um 14:09 schrieb 赵军奎:
>>> From: "Christian König" <christian.koenig@amd.com>
>>> Date: 2020-04-21 19:22:49
>>> To:  Bernard Zhao <bernard@vivo.com>,Alex Deucher <alexander.deucher@amd.com>,"David (ChunMing) Zhou" <David1.Zhou@amd.com>,David Airlie <airlied@linux.ie>,Daniel Vetter <daniel@ffwll.ch>,Tom St Denis <tom.stdenis@amd.com>,Ori Messinger <Ori.Messinger@amd.com>,Sam Ravnborg <sam@ravnborg.org>,amd-gfx@lists.freedesktop.org,dri-devel@lists.freedesktop.org,linux-kernel@vger.kernel.org
>>> Cc:  opensource.kernel@vivo.com
>>> Subject: Re: [PATCH] amdgpu: fixes memleak issue when init failed>Am 21.04.20 um 13:17 schrieb Bernard Zhao:
>>>>> VRAM manager and DRM MM when init failed, there is no operaction
>>>>> to free kzalloc memory & remove device file.
>>>>> This will lead to memleak & cause stability issue.
>>>> NAK, failure to create sysfs nodes are not critical.
>>>>
>>>> Christian.
>>>>
>>> OK, get it.
>>> By the way, should i modify this patch to just handle <kfree(mgr)> in error branch, or that it is also unnecessary?
>> What you can do is to drop the "return ret" if anything with the sysfs
>> nodes goes wrong and instead print the error code.
> Emmm, for this part, i am not sure, my modify first print the error, secone release not free memory,
> and last return error, make everything clear to the system.
> I think it`s the same with what you mentioned, is there something that I misunderstood?

Yes, maybe an example makes it more clear what to do here. Currently we 
print and error and return when something with the sysfs files goes wrong:

if (ret) {
     DRM_ERROR("Failed to create device file mem_info_vram_total\n");
     return ret;
}

But what we should do instead is just to print an error and continue and 
in the end return success status:

if (ret)
     DRM_ERROR("Failed to create device file mem_info_vram_total 
(%d)\n", r);

...
return 0;

Regards,
Christian.


>
>> It's really annoying that loading, unloading and loading the driver
>> again sometimes fails because we have a bug in the sysfs files cleanup.
>>
>> We certainly should fix those bugs as well, but they are just not
>> critical for correct driver functionality.
>>
>> Regards,
>> Christian.
>
>>> Regards,
>>> Bernard
>>>
>>>>> Signed-off-by: Bernard Zhao <bernard@vivo.com>
>>>>> ---
>>>>>     drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 24 ++++++++++++++++----
>>>>>     1 file changed, 19 insertions(+), 5 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>> index 82a3299e53c0..4c5fb153e6b4 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>> @@ -175,30 +175,44 @@ static int amdgpu_vram_mgr_init(struct ttm_mem_type_manager *man,
>>>>>     	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_total);
>>>>>     	if (ret) {
>>>>>     		DRM_ERROR("Failed to create device file mem_info_vram_total\n");
>>>>> -		return ret;
>>>>> +		goto VRAM_TOTAL_FAIL;
>>>>>     	}
>>>>>     	ret = device_create_file(adev->dev, &dev_attr_mem_info_vis_vram_total);
>>>>>     	if (ret) {
>>>>>     		DRM_ERROR("Failed to create device file mem_info_vis_vram_total\n");
>>>>> -		return ret;
>>>>> +		goto VIS_VRAM_TOTA_FAIL;
>>>>>     	}
>>>>>     	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_used);
>>>>>     	if (ret) {
>>>>>     		DRM_ERROR("Failed to create device file mem_info_vram_used\n");
>>>>> -		return ret;
>>>>> +		goto VRAM_USED_FAIL;
>>>>>     	}
>>>>>     	ret = device_create_file(adev->dev, &dev_attr_mem_info_vis_vram_used);
>>>>>     	if (ret) {
>>>>>     		DRM_ERROR("Failed to create device file mem_info_vis_vram_used\n");
>>>>> -		return ret;
>>>>> +		goto VIS_VRAM_USED_FAIL;
>>>>>     	}
>>>>>     	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_vendor);
>>>>>     	if (ret) {
>>>>>     		DRM_ERROR("Failed to create device file mem_info_vram_vendor\n");
>>>>> -		return ret;
>>>>> +		goto VRAM_VERDOR_FAIL;
>>>>>     	}
>>>>>     
>>>>>     	return 0;
>>>>> +
>>>>> +VRAM_VERDOR_FAIL:
>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vis_vram_used);
>>>>> +VIS_VRAM_USED_FAIL:
>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vram_used);
>>>>> +RVAM_USED_FAIL:
>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vis_vram_total);
>>>>> +VIS_VRAM_TOTA_FAIL:
>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vram_total);
>>>>> +VRAM_TOTAL_FAIL:
>>>>> +	kfree(mgr);
>>>>> +	man->priv = NULL;
>>>>> +
>>>>> +	return ret;
>>>>>     }
>>>>>     
>>>>>     /**
>