Linux Virtualization - Feb 2020 - [PATCH v2 2/2] drm/qxl: add drm_driver.release callback.

Move final cleanups to qxl_drm_release() callback.
Add drm_atomic_helper_shutdown() call to qxl_pci_remove().

Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
 drivers/gpu/drm/qxl/qxl_drv.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
index 1d601f57a6ba..4fda3f9b29f4 100644
--- a/drivers/gpu/drm/qxl/qxl_drv.c
+++ b/drivers/gpu/drm/qxl/qxl_drv.c
@@ -34,6 +34,7 @@
 #include <linux/pci.h>
 
 #include <drm/drm.h>
+#include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
 #include <drm/drm_modeset_helper.h>
@@ -132,21 +133,30 @@ qxl_pci_probe(struct pci_dev *pdev, const struct
pci_device_id *ent)
 	return ret;
 }
 
+static void qxl_drm_release(struct drm_device *dev)
+{
+	struct qxl_device *qdev = dev->dev_private;
+
+	/*
+	 * TODO: qxl_device_fini() call should be in qxl_pci_remove(),
+	 * reodering qxl_modeset_fini() + qxl_device_fini() calls is
+	 * non-trivial though.
+	 */
+	qxl_modeset_fini(qdev);
+	qxl_device_fini(qdev);
+	dev->dev_private = NULL;
+	kfree(qdev);
+}
+
 static void
 qxl_pci_remove(struct pci_dev *pdev)
 {
 	struct drm_device *dev = pci_get_drvdata(pdev);
-	struct qxl_device *qdev = dev->dev_private;
 
 	drm_dev_unregister(dev);
-
-	qxl_modeset_fini(qdev);
-	qxl_device_fini(qdev);
+	drm_atomic_helper_shutdown(dev);
 	if (is_vga(pdev))
 		vga_put(pdev, VGA_RSRC_LEGACY_IO);
-
-	dev->dev_private = NULL;
-	kfree(qdev);
 	drm_dev_put(dev);
 }
 
@@ -279,6 +289,8 @@ static struct drm_driver qxl_driver = {
 	.major = 0,
 	.minor = 1,
 	.patchlevel = 0,
+
+	.release = qxl_drm_release,
 };
 
 static int __init qxl_init(void)
-- 
2.18.1

On Mon, Feb 10, 2020 at 12:37:52PM +0100, Gerd Hoffmann
wrote:
> Move final cleanups to qxl_drm_release() callback.
> Add drm_atomic_helper_shutdown() call to qxl_pci_remove().
> 
> Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
> ---
>  drivers/gpu/drm/qxl/qxl_drv.c | 26 +++++++++++++++++++-------
>  1 file changed, 19 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
> index 1d601f57a6ba..4fda3f9b29f4 100644
> --- a/drivers/gpu/drm/qxl/qxl_drv.c
> +++ b/drivers/gpu/drm/qxl/qxl_drv.c
> @@ -34,6 +34,7 @@
>  #include <linux/pci.h>
>  
>  #include <drm/drm.h>
> +#include <drm/drm_atomic_helper.h>
>  #include <drm/drm_drv.h>
>  #include <drm/drm_file.h>
>  #include <drm/drm_modeset_helper.h>
> @@ -132,21 +133,30 @@ qxl_pci_probe(struct pci_dev *pdev, const struct
pci_device_id *ent)
>  	return ret;
>  }
>  
> +static void qxl_drm_release(struct drm_device *dev)
> +{
> +	struct qxl_device *qdev = dev->dev_private;
> +
> +	/*
> +	 * TODO: qxl_device_fini() call should be in qxl_pci_remove(),
> +	 * reodering qxl_modeset_fini() + qxl_device_fini() calls is
> +	 * non-trivial though.
> +	 */
> +	qxl_modeset_fini(qdev);
So the drm_mode_config_cleanup call in here belongs in ->release, but the
qxl_destroy_monitors_object feels like should be perfectly fine in the
remove hook. You might need to sprinkle a few drm_dev_enter/exit around to
protect code paths thought.

Aside from this lgtm, for the series

Acked-by: Daniel Vetter <daniel.vetter at ffwll.ch>

And up to you whether you want to fix this or not really.

Btw for testing all these patches that add a ->release hook I think it'd
be good if the drm core checks that drm_device->dev is set to NULL, and
that we do this in the remove hook. Since that's guaranteed to be gone at
that point, so anything in ->release that still needs the device is
broken. Ofc maybe do that check only for drivers which have a ->release
hook, and we might need a few fixups.

Cheers, Daniel
> +	qxl_device_fini(qdev);
> +	dev->dev_private = NULL;
> +	kfree(qdev);
> +}
> +
>  static void
>  qxl_pci_remove(struct pci_dev *pdev)
>  {
>  	struct drm_device *dev = pci_get_drvdata(pdev);
> -	struct qxl_device *qdev = dev->dev_private;
>  
>  	drm_dev_unregister(dev);
> -
> -	qxl_modeset_fini(qdev);
> -	qxl_device_fini(qdev);
> +	drm_atomic_helper_shutdown(dev);
>  	if (is_vga(pdev))
>  		vga_put(pdev, VGA_RSRC_LEGACY_IO);
> -
> -	dev->dev_private = NULL;
> -	kfree(qdev);
>  	drm_dev_put(dev);
>  }
>  
> @@ -279,6 +289,8 @@ static struct drm_driver qxl_driver = {
>  	.major = 0,
>  	.minor = 1,
>  	.patchlevel = 0,
> +
> +	.release = qxl_drm_release,
>  };
>  
>  static int __init qxl_init(void)
> -- 
> 2.18.1
> 
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Den 10.02.2020 16.06, skrev Daniel Vetter:
> On Mon, Feb 10, 2020 at 12:37:52PM +0100, Gerd Hoffmann wrote:
>> Move final cleanups to qxl_drm_release() callback.
>> Add drm_atomic_helper_shutdown() call to qxl_pci_remove().
>>
>> Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
>> ---
>>  drivers/gpu/drm/qxl/qxl_drv.c | 26 +++++++++++++++++++-------
>>  1 file changed, 19 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c
b/drivers/gpu/drm/qxl/qxl_drv.c
>> index 1d601f57a6ba..4fda3f9b29f4 100644
>> --- a/drivers/gpu/drm/qxl/qxl_drv.c
>> +++ b/drivers/gpu/drm/qxl/qxl_drv.c
>> @@ -34,6 +34,7 @@
>>  #include <linux/pci.h>
>>  
>>  #include <drm/drm.h>
>> +#include <drm/drm_atomic_helper.h>
>>  #include <drm/drm_drv.h>
>>  #include <drm/drm_file.h>
>>  #include <drm/drm_modeset_helper.h>
>> @@ -132,21 +133,30 @@ qxl_pci_probe(struct pci_dev *pdev, const struct
pci_device_id *ent)
>>  	return ret;
>>  }
>>  
>> +static void qxl_drm_release(struct drm_device *dev)
>> +{
>> +	struct qxl_device *qdev = dev->dev_private;
>> +
>> +	/*
>> +	 * TODO: qxl_device_fini() call should be in qxl_pci_remove(),
>> +	 * reodering qxl_modeset_fini() + qxl_device_fini() calls is
>> +	 * non-trivial though.
>> +	 */
>> +	qxl_modeset_fini(qdev);
> 
> So the drm_mode_config_cleanup call in here belongs in ->release, but
the
> qxl_destroy_monitors_object feels like should be perfectly fine in the
> remove hook. You might need to sprinkle a few drm_dev_enter/exit around to
> protect code paths thought.
> 
> Aside from this lgtm, for the series
> 
> Acked-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> And up to you whether you want to fix this or not really.
> 
> Btw for testing all these patches that add a ->release hook I think
it'd
> be good if the drm core checks that drm_device->dev is set to NULL, and
> that we do this in the remove hook. Since that's guaranteed to be gone
at
> that point, so anything in ->release that still needs the device is
> broken. Ofc maybe do that check only for drivers which have a ->release
> hook, and we might need a few fixups.
> 
We take a ref on the parent device in drm_dev_init() and release it in
drm_dev_fini(). I added this because of the DRM_DEV_* macros we have, to
protect access to the device struct after it was unregistered. Setting
drm_device->dev to NULL in drm_dev_unregister() instead will provide the
same protection I think.

commit 56be6503aab2
drm/drv: Hold ref on parent device during drm_device lifetime

Noralf.
> Cheers, Daniel
> 
>> +	qxl_device_fini(qdev);
>> +	dev->dev_private = NULL;
>> +	kfree(qdev);
>> +}
>> +
>>  static void
>>  qxl_pci_remove(struct pci_dev *pdev)
>>  {
>>  	struct drm_device *dev = pci_get_drvdata(pdev);
>> -	struct qxl_device *qdev = dev->dev_private;
>>  
>>  	drm_dev_unregister(dev);
>> -
>> -	qxl_modeset_fini(qdev);
>> -	qxl_device_fini(qdev);
>> +	drm_atomic_helper_shutdown(dev);
>>  	if (is_vga(pdev))
>>  		vga_put(pdev, VGA_RSRC_LEGACY_IO);
>> -
>> -	dev->dev_private = NULL;
>> -	kfree(qdev);
>>  	drm_dev_put(dev);
>>  }
>>  
>> @@ -279,6 +289,8 @@ static struct drm_driver qxl_driver = {
>>  	.major = 0,
>>  	.minor = 1,
>>  	.patchlevel = 0,
>> +
>> +	.release = qxl_drm_release,
>>  };
>>  
>>  static int __init qxl_init(void)
>> -- 
>> 2.18.1
>>
>