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Commit 1616c525 authored by David Herrmann's avatar David Herrmann
Browse files

drm: add minor-lookup/release helpers 



Instead of accessing drm_minors_idr directly, this adds a small helper to
hide the internals. This will help us later to remove the drm_global_mutex
requirement for minor-lookup.

Furthermore, this also makes sure that minor->dev is always valid and
takes a reference-count to the device as long as the minor is used in an
open-file. This way, "struct file*"->private_data->dev is guaranteed to be
valid (which it has to, as we cannot reset it).

Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 099d1c29

drivers/gpu/drm/drm_fops.c

+27 −23
Original line number Diff line number Diff line
@@ -79,23 +79,22 @@ static int drm_setup(struct drm_device * dev) 
 */

int drm_open(struct inode *inode, struct file *filp)

{

	struct drm_device *dev = NULL;

	int minor_id = iminor(inode);

	struct drm_device *dev;

	struct drm_minor *minor;

	int retcode = 0;

	int retcode;

	int need_setup = 0;

	struct address_space *old_mapping;

	struct address_space *old_imapping;



	minor = idr_find(&drm_minors_idr, minor_id);

	if (!minor)

		return -ENODEV;



	if (!(dev = minor->dev))

		return -ENODEV;

	minor = drm_minor_acquire(iminor(inode));

	if (IS_ERR(minor))

		return PTR_ERR(minor);



	if (drm_device_is_unplugged(dev))

		return -ENODEV;

	dev = minor->dev;

	if (drm_device_is_unplugged(dev)) {

		retcode = -ENODEV;

		goto err_release;

	}



	if (!dev->open_count++)

		need_setup = 1;
@@ -128,6 +127,8 @@ int drm_open(struct inode *inode, struct file *filp) 
	dev->dev_mapping = old_mapping;

	mutex_unlock(&dev->struct_mutex);

	dev->open_count--;

err_release:

	drm_minor_release(minor);

	return retcode;

}

EXPORT_SYMBOL(drm_open);
@@ -143,33 +144,33 @@ EXPORT_SYMBOL(drm_open); 
 */

int drm_stub_open(struct inode *inode, struct file *filp)

{

	struct drm_device *dev = NULL;

	struct drm_device *dev;

	struct drm_minor *minor;

	int minor_id = iminor(inode);

	int err = -ENODEV;

	const struct file_operations *new_fops;



	DRM_DEBUG("\n");



	mutex_lock(&drm_global_mutex);

	minor = idr_find(&drm_minors_idr, minor_id);

	if (!minor)

		goto out;



	if (!(dev = minor->dev))

		goto out;

	minor = drm_minor_acquire(iminor(inode));

	if (IS_ERR(minor))

		goto out_unlock;



	dev = minor->dev;

	if (drm_device_is_unplugged(dev))

		goto out;

		goto out_release;



	new_fops = fops_get(dev->driver->fops);

	if (!new_fops)

		goto out;

		goto out_release;



	replace_fops(filp, new_fops);

	if (filp->f_op->open)

		err = filp->f_op->open(inode, filp);

out:



out_release:

	drm_minor_release(minor);

out_unlock:

	mutex_unlock(&drm_global_mutex);

	return err;

}
@@ -453,7 +454,8 @@ int drm_lastclose(struct drm_device * dev) 
int drm_release(struct inode *inode, struct file *filp)

{

	struct drm_file *file_priv = filp->private_data;

	struct drm_device *dev = file_priv->minor->dev;

	struct drm_minor *minor = file_priv->minor;

	struct drm_device *dev = minor->dev;

	int retcode = 0;



	mutex_lock(&drm_global_mutex);
@@ -575,6 +577,8 @@ int drm_release(struct inode *inode, struct file *filp) 
	}

	mutex_unlock(&drm_global_mutex);



	drm_minor_release(minor);



	return retcode;

}

EXPORT_SYMBOL(drm_release);

drivers/gpu/drm/drm_stub.c

+39 −0
Original line number Diff line number Diff line
@@ -355,6 +355,45 @@ static void drm_unplug_minor(struct drm_minor *minor) 
	idr_remove(&drm_minors_idr, minor->index);

}



/**

 * drm_minor_acquire - Acquire a DRM minor

 * @minor_id: Minor ID of the DRM-minor

 *

 * Looks up the given minor-ID and returns the respective DRM-minor object. The

 * refence-count of the underlying device is increased so you must release this

 * object with drm_minor_release().

 *

 * As long as you hold this minor, it is guaranteed that the object and the

 * minor->dev pointer will stay valid! However, the device may get unplugged and

 * unregistered while you hold the minor.

 *

 * Returns:

 * Pointer to minor-object with increased device-refcount, or PTR_ERR on

 * failure.

 */

struct drm_minor *drm_minor_acquire(unsigned int minor_id)

{

	struct drm_minor *minor;



	minor = idr_find(&drm_minors_idr, minor_id);

	if (!minor)

		return ERR_PTR(-ENODEV);



	drm_dev_ref(minor->dev);

	return minor;

}



/**

 * drm_minor_release - Release DRM minor

 * @minor: Pointer to DRM minor object

 *

 * Release a minor that was previously acquired via drm_minor_acquire().

 */

void drm_minor_release(struct drm_minor *minor)

{

	drm_dev_unref(minor->dev);

}



/**

 * drm_put_minor - Destroy DRM minor

 * @minor: Minor to destroy

include/drm/drmP.h

+4 −0
Original line number Diff line number Diff line
@@ -1672,6 +1672,10 @@ void drm_dev_ref(struct drm_device *dev); 
void drm_dev_unref(struct drm_device *dev);

int drm_dev_register(struct drm_device *dev, unsigned long flags);

void drm_dev_unregister(struct drm_device *dev);



struct drm_minor *drm_minor_acquire(unsigned int minor_id);

void drm_minor_release(struct drm_minor *minor);



/*@}*/



/* PCI section */