On Thu, Feb 02, 2017 at 09:36:32AM +0000, Chris Wilson wrote:
> Some state is coupled into the device lifetime outside of the
> load/unload timeframe and requires teardown during final unreference
> from drm_dev_release(). For example, dmabufs hold both a device and
> module reference and may live longer than expected (i.e. the current
> pattern of the driver tearing down its state and then releasing a
> reference to the drm device) and yet touch driver private state when
> destroyed.
>
> v2: Export drm_dev_fini() and move the responsibility for finalizing the
> drm_device and freeing it to the release callback. (If no callback is
> provided, the core will call drm_dev_fini() and kfree(dev) as before.)
> v3: Remember to add drm_dev_fini() to drm_drv.h
> v4: Tidy language for kerneldoc
> v5: Cross reference from drm_dev_init() to note that driver->release()
> allows for arbitrary embedding.
> v6: Refer to driver data rather than driver state, as state is now
> becoming associated with the struct drm_atomic_state and friends.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_drv.c | 65 ++++++++++++++++++++++++++++++++---------------
> include/drm/drm_drv.h | 13 ++++++++++
> 2 files changed, 58 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index a8ce3179c07c..e122e4d022f8 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -465,7 +465,10 @@ static void drm_fs_inode_free(struct inode *inode)
> * that do embed &struct drm_device it must be placed first in the overall
> * structure, and the overall structure must be allocated using kmalloc(): The
> * drm core's release function unconditionally calls kfree() on the @dev pointer
> - * when the final reference is released.
> + * when the final reference is released. To override this behaviour, and so
> + * allow embedding of the drm_device inside the driver's device struct at an
> + * arbitrary offset, you must supply a driver->release() callback and control
The new official way to reference a struct member is &foo.bar. I've
applied this polish to both places and applied your patch, thanks a lot.
-Daniel
> + * the finalization explicitly.
> *
> * RETURNS:
> * 0 on success, or error code on failure.
> @@ -553,6 +556,41 @@ int drm_dev_init(struct drm_device *dev,
> EXPORT_SYMBOL(drm_dev_init);
>
> /**
> + * drm_dev_fini - Finalize a dead DRM device
> + * @dev: DRM device
> + *
> + * Finalize a dead DRM device. This is the converse to drm_dev_init() and
> + * frees up all data allocated by it. All driver private data should be
> + * finalized first. Note that this function does not free the @dev, that is
> + * left to the caller.
> + *
> + * The ref-count of @dev must be zero, and drm_dev_fini() should only be called
> + * from a drm_driver->release() callback.
> + */
> +void drm_dev_fini(struct drm_device *dev)
> +{
> + drm_vblank_cleanup(dev);
> +
> + if (drm_core_check_feature(dev, DRIVER_GEM))
> + drm_gem_destroy(dev);
> +
> + drm_legacy_ctxbitmap_cleanup(dev);
> + drm_ht_remove(&dev->map_hash);
> + drm_fs_inode_free(dev->anon_inode);
> +
> + drm_minor_free(dev, DRM_MINOR_PRIMARY);
> + drm_minor_free(dev, DRM_MINOR_RENDER);
> + drm_minor_free(dev, DRM_MINOR_CONTROL);
> +
> + mutex_destroy(&dev->master_mutex);
> + mutex_destroy(&dev->ctxlist_mutex);
> + mutex_destroy(&dev->filelist_mutex);
> + mutex_destroy(&dev->struct_mutex);
> + kfree(dev->unique);
> +}
> +EXPORT_SYMBOL(drm_dev_fini);
> +
> +/**
> * drm_dev_alloc - Allocate new DRM device
> * @driver: DRM driver to allocate device for
> * @parent: Parent device object
> @@ -598,25 +636,12 @@ static void drm_dev_release(struct kref *ref)
> {
> struct drm_device *dev = container_of(ref, struct drm_device, ref);
>
> - drm_vblank_cleanup(dev);
> -
> - if (drm_core_check_feature(dev, DRIVER_GEM))
> - drm_gem_destroy(dev);
> -
> - drm_legacy_ctxbitmap_cleanup(dev);
> - drm_ht_remove(&dev->map_hash);
> - drm_fs_inode_free(dev->anon_inode);
> -
> - drm_minor_free(dev, DRM_MINOR_PRIMARY);
> - drm_minor_free(dev, DRM_MINOR_RENDER);
> - drm_minor_free(dev, DRM_MINOR_CONTROL);
> -
> - mutex_destroy(&dev->master_mutex);
> - mutex_destroy(&dev->ctxlist_mutex);
> - mutex_destroy(&dev->filelist_mutex);
> - mutex_destroy(&dev->struct_mutex);
> - kfree(dev->unique);
> - kfree(dev);
> + if (dev->driver->release) {
> + dev->driver->release(dev);
> + } else {
> + drm_dev_fini(dev);
> + kfree(dev);
> + }
> }
>
> /**
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 732e85652d1e..5699f42195fe 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -102,6 +102,17 @@ struct drm_driver {
> *
> */
> void (*unload) (struct drm_device *);
> +
> + /**
> + * @release:
> + *
> + * Optional callback for destroying device data after the final
> + * reference is released, i.e. the device is being destroyed. Drivers
> + * using this callback are responsible for calling drm_dev_fini()
> + * to finalize the device and then freeing the struct themselves.
> + */
> + void (*release) (struct drm_device *);
> +
> int (*set_busid)(struct drm_device *dev, struct drm_master *master);
>
> /**
> @@ -437,6 +448,8 @@ extern unsigned int drm_debug;
> int drm_dev_init(struct drm_device *dev,
> struct drm_driver *driver,
> struct device *parent);
> +void drm_dev_fini(struct drm_device *dev);
> +
> struct drm_device *drm_dev_alloc(struct drm_driver *driver,
> struct device *parent);
> int drm_dev_register(struct drm_device *dev, unsigned long flags);
> --
> 2.11.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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