linux-kernel - Re: [PATCH v6 02/10] Revert "drm/qxl: do not run release if qxl failed to init"

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Message-Id: <60B8023C-78C9-441D-AA21-A13C4445F666@gmail.com>
Date:   Thu, 4 Feb 2021 13:52:02 -0500
From:   Tong Zhang <ztong0001@...il.com>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     Gerd Hoffmann <kraxel@...hat.com>, dri-devel@...ts.freedesktop.org,
        David Airlie <airlied@...ux.ie>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <spice-devel@...ts.freedesktop.org>,
        Dave Airlie <airlied@...hat.com>
Subject: Re: [PATCH v6 02/10] Revert "drm/qxl: do not run release if qxl
 failed to init"

Hi Thomas,

The original problem was qxl_device_init() can fail,
when it fails there is no need to call 
	qxl_modeset_fini(qdev);
	qxl_device_fini(qdev);
But those two functions are otherwise called in the qxl_drm_release() -

I have posted an updated patch.
The new patch use the following logic

+	if (!qdev->ddev.mode_config.funcs)
+	  return;
	qxl_modeset_fini(qdev);
	qxl_device_fini(qdev);

Thanks,
- Tong


> On Feb 4, 2021, at 1:34 PM, Thomas Zimmermann <tzimmermann@...e.de> wrote:
> 
> Hi
> 
> Am 04.02.21 um 15:57 schrieb Gerd Hoffmann:
>> This reverts commit b91907a6241193465ca92e357adf16822242296d.
> 
> This should be in the correct format, as given by 'dim cite'.
> 
> dim cite b91907a6241193465ca92e357adf16822242296d
> b91907a62411 ("drm/qxl: do not run release if qxl failed to init")
> 
>> Patch is broken, it effectively makes qxl_drm_release() a nop
>> because on normal driver shutdown qxl_drm_release() is called
>> *after* drm_dev_unregister().
>> Cc: Tong Zhang <ztong0001@...il.com>
>> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
>> ---
>>  drivers/gpu/drm/qxl/qxl_drv.c | 2 --
>>  1 file changed, 2 deletions(-)
>> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
>> index 34c8b25b5780..fb5f6a5e81d7 100644
>> --- a/drivers/gpu/drm/qxl/qxl_drv.c
>> +++ b/drivers/gpu/drm/qxl/qxl_drv.c
>> @@ -144,8 +144,6 @@ static void qxl_drm_release(struct drm_device *dev)
>>  	 * reodering qxl_modeset_fini() + qxl_device_fini() calls is
>>  	 * non-trivial though.
>>  	 */
>> -	if (!dev->registered)
>> -		return;
> 
> I'm not sure what the original problem was, but I'm sure that this isn't the fix for it. If there's a problem with shutdown, the operations rather have to be reordered correctly.
> 
> With the citation style address:
> 
> Acked-by: Thomas Zimmermann <tzimmermann@...e.de>
> 
>>  	qxl_modeset_fini(qdev);
>>  	qxl_device_fini(qdev);
>>  }
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>