Linux Virtualization - Dec 2019 - [PATCH 4/4] 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().

Reorder calls in qxl_device_fini().  Cleaning up gem & ttm
might trigger qxl commands, so we should do that before
releaseing command rings.

Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
 drivers/gpu/drm/qxl/qxl_drv.c | 21 ++++++++++++++-------
 drivers/gpu/drm/qxl/qxl_kms.c |  8 ++++----
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
index 1d601f57a6ba..8044363ba0f2 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 +133,25 @@ 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;
+
+	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 +284,8 @@ static struct drm_driver qxl_driver = {
 	.major = 0,
 	.minor = 1,
 	.patchlevel = 0,
+
+	.release = qxl_drm_release,
 };
 
 static int __init qxl_init(void)
diff --git a/drivers/gpu/drm/qxl/qxl_kms.c b/drivers/gpu/drm/qxl/qxl_kms.c
index bfc1631093e9..70b20ee4741a 100644
--- a/drivers/gpu/drm/qxl/qxl_kms.c
+++ b/drivers/gpu/drm/qxl/qxl_kms.c
@@ -299,12 +299,12 @@ void qxl_device_fini(struct qxl_device *qdev)
 {
 	qxl_bo_unref(&qdev->current_release_bo[0]);
 	qxl_bo_unref(&qdev->current_release_bo[1]);
-	flush_work(&qdev->gc_work);
-	qxl_ring_free(qdev->command_ring);
-	qxl_ring_free(qdev->cursor_ring);
-	qxl_ring_free(qdev->release_ring);
 	qxl_gem_fini(qdev);
 	qxl_bo_fini(qdev);
+	flush_work(&qdev->gc_work);
+	qxl_ring_free(qdev->command_ring);
+	qxl_ring_free(qdev->cursor_ring);
+	qxl_ring_free(qdev->release_ring);
 	io_mapping_free(qdev->surface_mapping);
 	io_mapping_free(qdev->vram_mapping);
 	iounmap(qdev->ram_header);
-- 
2.18.1

> 
> Move final cleanups to qxl_drm_release() callback.
Can you explain in the commit why this is better or preferable?
> Add drm_atomic_helper_shutdown() call to qxl_pci_remove().
I suppose this is to replace the former manual cleanup calls,
which were moved to qxl_drm_release, I think this could be
added in the commit message ("why"), I don't see much value
in describing "how" this was done.
> 
> Reorder calls in qxl_device_fini().  Cleaning up gem & ttm
> might trigger qxl commands, so we should do that before
> releaseing command rings.
Typo: releaseing -> releasing
Why not putting this in a separate commit? Was this behaviour
changed? It does not seem so to me.
> 
> Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
> ---
>  drivers/gpu/drm/qxl/qxl_drv.c | 21 ++++++++++++++-------
>  drivers/gpu/drm/qxl/qxl_kms.c |  8 ++++----
>  2 files changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
> index 1d601f57a6ba..8044363ba0f2 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 +133,25 @@ 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;
> +
> +	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 +284,8 @@ static struct drm_driver qxl_driver = {
>  	.major = 0,
>  	.minor = 1,
>  	.patchlevel = 0,
> +
> +	.release = qxl_drm_release,
>  };
>  
>  static int __init qxl_init(void)
> diff --git a/drivers/gpu/drm/qxl/qxl_kms.c b/drivers/gpu/drm/qxl/qxl_kms.c
> index bfc1631093e9..70b20ee4741a 100644
> --- a/drivers/gpu/drm/qxl/qxl_kms.c
> +++ b/drivers/gpu/drm/qxl/qxl_kms.c
> @@ -299,12 +299,12 @@ void qxl_device_fini(struct qxl_device *qdev)
>  {
>  	qxl_bo_unref(&qdev->current_release_bo[0]);
>  	qxl_bo_unref(&qdev->current_release_bo[1]);
> -	flush_work(&qdev->gc_work);
> -	qxl_ring_free(qdev->command_ring);
> -	qxl_ring_free(qdev->cursor_ring);
> -	qxl_ring_free(qdev->release_ring);
>  	qxl_gem_fini(qdev);
>  	qxl_bo_fini(qdev);
> +	flush_work(&qdev->gc_work);
> +	qxl_ring_free(qdev->command_ring);
> +	qxl_ring_free(qdev->cursor_ring);
> +	qxl_ring_free(qdev->release_ring);
>  	io_mapping_free(qdev->surface_mapping);
>  	io_mapping_free(qdev->vram_mapping);
>  	iounmap(qdev->ram_header);
Frediano

On Fri, Dec 20, 2019 at 07:09:20AM -0500, Frediano Ziglio
wrote:
> > 
> > Move final cleanups to qxl_drm_release() callback.
> 
> Can you explain in the commit why this is better or preferable?
It gets called when the drm device refcount goes down to zero.
It's needed for a proper cleanup in the correct order.
> > Add drm_atomic_helper_shutdown() call to qxl_pci_remove().
> 
> I suppose this is to replace the former manual cleanup calls,
> which were moved to qxl_drm_release, I think this could be
> added in the commit message ("why"), I don't see much value
> in describing "how" this was done.
The call is part of the shutdown sequence for atomic drm drivers
and wasn't present in qxl for some reason.
> > Reorder calls in qxl_device_fini().  Cleaning up gem & ttm
> > might trigger qxl commands, so we should do that before
> > releaseing command rings.
> 
> Typo: releaseing -> releasing
> Why not putting this in a separate commit? Was this behaviour
> changed? It does not seem so to me.
Yes, I can make that a separate commit.

No, behavior didn't change.  qxl_device_fini() is simply broken
without this.

cheers,
  Gerd