[Outreachy kernel] [PATCH 1/2] drm: introduce drm_dev_{get/put} functions
Daniel Vetter
daniel at ffwll.ch
Tue Sep 26 05:22:47 UTC 2017
On Fri, Sep 22, 2017 at 01:17:06AM +0530, Aishwarya Pant wrote:
> Reference counting functions in the kernel typically use get/put suffixes. For
> maintaining coding style consistency, introduce drm_dev_{get/put} functions
> and let the old APIs (with ref/unref suffixes) remain for compatibility.
>
> Signed-off-by: Aishwarya Pant <aishpant at gmail.com>
Excellent idea to fill this gap, we totally overlooked this in the initial
work!
> ---
> drivers/gpu/drm/drm_drv.c | 64 +++++++++++++++++++++++++++++++++--------------
> include/drm/drm_drv.h | 4 ++-
Please also update scripts/coccinelle/api/drm-get-put.cocci with this new
transformation.
> 2 files changed, 48 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index be38ac7..4592314 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -286,13 +286,13 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)
> spin_lock_irqsave(&drm_minor_lock, flags);
> minor = idr_find(&drm_minors_idr, minor_id);
> if (minor)
> - drm_dev_ref(minor->dev);
> + drm_dev_get(minor->dev);
> spin_unlock_irqrestore(&drm_minor_lock, flags);
>
> if (!minor) {
> return ERR_PTR(-ENODEV);
> } else if (drm_dev_is_unplugged(minor->dev)) {
> - drm_dev_unref(minor->dev);
> + drm_dev_put(minor->dev);
> return ERR_PTR(-ENODEV);
> }
>
> @@ -301,7 +301,7 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)
>
> void drm_minor_release(struct drm_minor *minor)
> {
> - drm_dev_unref(minor->dev);
> + drm_dev_put(minor->dev);
> }
>
> /**
> @@ -326,11 +326,11 @@ void drm_minor_release(struct drm_minor *minor)
> * When cleaning up a device instance everything needs to be done in reverse:
> * First unpublish the device instance with drm_dev_unregister(). Then clean up
> * any other resources allocated at device initialization and drop the driver's
> - * reference to &drm_device using drm_dev_unref().
> + * reference to &drm_device using drm_dev_put().
> *
> * Note that the lifetime rules for &drm_device instance has still a lot of
> * historical baggage. Hence use the reference counting provided by
> - * drm_dev_ref() and drm_dev_unref() only carefully.
> + * drm_dev_get() and drm_dev_put() only carefully.
> *
> * It is recommended that drivers embed &struct drm_device into their own device
> * structure, which is supported through drm_dev_init().
> @@ -345,7 +345,7 @@ void drm_minor_release(struct drm_minor *minor)
> * Cleans up all DRM device, calling drm_lastclose().
> *
> * Note: Use of this function is deprecated. It will eventually go away
> - * completely. Please use drm_dev_unregister() and drm_dev_unref() explicitly
> + * completely. Please use drm_dev_unregister() and drm_dev_put() explicitly
> * instead to make sure that the device isn't userspace accessible any more
> * while teardown is in progress, ensuring that userspace can't access an
> * inconsistent state.
> @@ -360,7 +360,7 @@ void drm_put_dev(struct drm_device *dev)
> }
>
> drm_dev_unregister(dev);
> - drm_dev_unref(dev);
> + drm_dev_put(dev);
> }
> EXPORT_SYMBOL(drm_put_dev);
>
> @@ -386,7 +386,7 @@ void drm_dev_unplug(struct drm_device *dev)
> mutex_lock(&drm_global_mutex);
> drm_device_set_unplugged(dev);
> if (dev->open_count == 0)
> - drm_dev_unref(dev);
> + drm_dev_put(dev);
> mutex_unlock(&drm_global_mutex);
> }
> EXPORT_SYMBOL(drm_dev_unplug);
> @@ -475,8 +475,8 @@ static void drm_fs_inode_free(struct inode *inode)
> * initialization sequence to make sure userspace can't access an inconsistent
> * state.
> *
> - * The initial ref-count of the object is 1. Use drm_dev_ref() and
> - * drm_dev_unref() to take and drop further ref-counts.
> + * The initial ref-count of the object is 1. Use drm_dev_get() and
> + * drm_dev_put() to take and drop further ref-counts.
> *
> * Note that for purely virtual devices @parent can be NULL.
> *
> @@ -626,8 +626,8 @@ EXPORT_SYMBOL(drm_dev_fini);
> * initialization sequence to make sure userspace can't access an inconsistent
> * state.
> *
> - * The initial ref-count of the object is 1. Use drm_dev_ref() and
> - * drm_dev_unref() to take and drop further ref-counts.
> + * The initial ref-count of the object is 1. Use drm_dev_get() and
> + * drm_dev_put() to take and drop further ref-counts.
> *
> * Note that for purely virtual devices @parent can be NULL.
> *
> @@ -670,36 +670,62 @@ static void drm_dev_release(struct kref *ref)
> }
>
> /**
> - * drm_dev_ref - Take reference of a DRM device
> + * drm_dev_get - Take reference of a DRM device
> * @dev: device to take reference of or NULL
> *
> * This increases the ref-count of @dev by one. You *must* already own a
> - * reference when calling this. Use drm_dev_unref() to drop this reference
> + * reference when calling this. Use drm_dev_put() to drop this reference
> * again.
> *
> * This function never fails. However, this function does not provide *any*
> * guarantee whether the device is alive or running. It only provides a
> * reference to the object and the memory associated with it.
> */
> -void drm_dev_ref(struct drm_device *dev)
> +void drm_dev_get(struct drm_device *dev)
> {
> if (dev)
> kref_get(&dev->ref);
> }
> -EXPORT_SYMBOL(drm_dev_ref);
> +EXPORT_SYMBOL(drm_dev_get);
>
> /**
> - * drm_dev_unref - Drop reference of a DRM device
> + * drm_dev_put - Drop reference of a DRM device
> * @dev: device to drop reference of or NULL
> *
> * This decreases the ref-count of @dev by one. The device is destroyed if the
> * ref-count drops to zero.
> */
> -void drm_dev_unref(struct drm_device *dev)
> +void drm_dev_put(struct drm_device *dev)
> {
> if (dev)
> kref_put(&dev->ref, drm_dev_release);
> }
> +EXPORT_SYMBOL(drm_dev_put);
> +
> +/**
> + * drm_dev_ref - Take reference of a DRM device
> + * @dev: device to take reference of or NULL
> + *
> + * This is a compatibility alias for drm_dev_get() and should not be used by new
> + * code.
> + */
> +void drm_dev_ref(struct drm_device *dev)
> +{
> + drm_dev_get(dev);
> +}
> +EXPORT_SYMBOL(drm_dev_ref);
I think you've already converted all callers for drm_dev_ref() with this
patch here, so no need to add the compat function and risk getting new
callers. Once a conversion is done in upstream we should remove these.
Please remove.
With those 2 nits addressed I think your patch is ready for merging,
please resend with those changes.
Thanks, Daniel
> +
> +/**
> + * drm_dev_unref - Drop reference of a DRM device
> + * @dev: device to drop reference of or NULL
> + *
> + * This is a compatibility alias for drm_dev_put() and should not be used by new
> + * code.
> + */
> +void drm_dev_unref(struct drm_device *dev)
> +{
> + drm_dev_put(dev);
> +}
> EXPORT_SYMBOL(drm_dev_unref);
>
> static int create_compat_control_link(struct drm_device *dev)
> @@ -839,7 +865,7 @@ EXPORT_SYMBOL(drm_dev_register);
> *
> * Unregister the DRM device from the system. This does the reverse of
> * drm_dev_register() but does not deallocate the device. The caller must call
> - * drm_dev_unref() to drop their final reference.
> + * drm_dev_put() to drop their final reference.
> *
> * A special form of unregistering for hotpluggable devices is drm_dev_unplug(),
> * which can be called while there are still open users of @dev.
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 71bbaae..e574fa0 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -155,7 +155,7 @@ struct drm_driver {
> * reverse order of the initialization. Similarly to the load
> * hook, this handler is deprecated and its usage should be
> * dropped in favor of an open-coded teardown function at the
> - * driver layer. See drm_dev_unregister() and drm_dev_unref()
> + * driver layer. See drm_dev_unregister() and drm_dev_put()
> * for the proper way to remove a &struct drm_device.
> *
> * The unload() hook is called right after unregistering
> @@ -611,6 +611,8 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver,
> int drm_dev_register(struct drm_device *dev, unsigned long flags);
> void drm_dev_unregister(struct drm_device *dev);
>
> +void drm_dev_get(struct drm_device *dev);
> +void drm_dev_put(struct drm_device *dev);
> void drm_dev_ref(struct drm_device *dev);
> void drm_dev_unref(struct drm_device *dev);
> void drm_put_dev(struct drm_device *dev);
> --
> 2.7.4
>
> --
> You received this message because you are subscribed to the Google Groups "outreachy-kernel" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe at googlegroups.com.
> To post to this group, send email to outreachy-kernel at googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/33c3c79daa7a8f9c52ee87f4d78f3a551ab96b54.1506023126.git.aishpant%40gmail.com.
> For more options, visit https://groups.google.com/d/optout.
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
More information about the dri-devel
mailing list