linux-kernel - Re: [PATCH] drm/hisilicon: Remove redundant null check

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Message-ID: <f41cbcb3-d08a-7d3f-530c-a0cb3f9e3801@huawei.com>
Date:   Mon, 2 Nov 2020 16:46:48 +0800
From:   "tiantao (H)" <tiantao6@...wei.com>
To:     Thomas Zimmermann <tzimmermann@...e.de>,
        Tian Tao <tiantao6@...ilicon.com>, <airlied@...ux.ie>,
        <daniel@...ll.ch>, <kraxel@...hat.com>,
        <alexander.deucher@....com>, <tglx@...utronix.de>,
        <dri-devel@...ts.freedesktop.org>, <xinliang.liu@...aro.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/hisilicon: Remove redundant null check



在 2020/11/2 16:32, Thomas Zimmermann 写道:
> Hi
> 
> Am 30.10.20 um 10:27 schrieb Tian Tao:
>> drm_irq_uninstall can handle the case where dev->irq_enable is false,
>> so Remove redundant null check.
>>
>> Signed-off-by: Tian Tao <tiantao6@...ilicon.com>
>> ---
>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>> index 0c1b40d..b71589b1 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>> @@ -246,13 +246,13 @@ static int hibmc_unload(struct drm_device *dev)
>>   
>>   	drm_atomic_helper_shutdown(dev);
>>   
>> -	if (dev->irq_enabled)
>> -		drm_irq_uninstall(dev);
>> -
>> +	drm_irq_uninstall(dev);
> 
> Removing this check would at least result in an error, [1] so rather
> leave it in for now.
> 
Now there seems to be no driver to check the return value of 
drm_irq_uninstall
> Instead, we could discuss if drm_irq_install() should become a managed
> interface.

Codes like the following
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 09d6e9e..572357c 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -172,6 +172,9 @@ int drm_irq_uninstall(struct drm_device *dev)
         bool irq_enabled;
         int i;

+       if(!dev->irq_enabled || !dev)
+               return 0;

> 
> Best regards
> Thomas
> 
> [1]
> https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/drm_irq.c#L201
> 
>>   	pci_disable_msi(dev->pdev);
>> +
>>   	hibmc_kms_fini(priv);
>>   	hibmc_mm_fini(priv);
>>   	dev->dev_private = NULL;
>> +
>>   	return 0;
>>   }
>>   
>>
>