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drm: document drm_auth.c

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Also extract drm_auth.h for nicer grouping.

v2: Nuke the other comments since they don't really explain a lot, and
within the drm core we generally only document functions exported to
drivers: The main audience for these docs are driver writers.

v3: Limit the exposure of drm_master internals by only including
drm_auth.h where it is neede (Chris).

v4: Spelling polish (Emil).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
This commit is contained in:
Daniel Vetter
2016-06-21 10:54:22 +02:00
parent 0aae5920a8
commit 3b96a0b140
9 changed files with 119 additions and 57 deletions
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68
drivers/gpu/drm/drm_auth.c
View File

@@ -33,17 +33,27 @@
#include "drm_legacy.h"
/**
* drm_getmagic - Get unique magic of a client
* @dev: DRM device to operate on
* @data: ioctl data containing the drm_auth object
* @file_priv: DRM file that performs the operation
* DOC: master and authentication
*
* This looks up the unique magic of the passed client and returns it. If the
* client did not have a magic assigned, yet, a new one is registered. The magic
* is stored in the passed drm_auth object.
* struct &drm_master is used to track groups of clients with open
* primary/legacy device nodes. For every struct &drm_file which has had at
* least once successfully became the device master (either through the
* SET_MASTER IOCTL, or implicitly through opening the primary device node when
* no one else is the current master that time) there exists one &drm_master.
* This is noted in the is_master member of &drm_file. All other clients have
* just a pointer to the &drm_master they are associated with.
*
* Returns: 0 on success, negative error code on failure.
* In addition only one &drm_master can be the current master for a &drm_device.
* It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
* implicitly through closing/openeing the primary device node. See also
* drm_is_current_master().
*
* Clients can authenticate against the current master (if it matches their own)
* using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
* this allows controlled access to the device for an entire group of mutually
* trusted clients.
*/
int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
struct drm_auth *auth = data;
@@ -64,16 +74,6 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
return ret < 0 ? ret : 0;
}
/**
* drm_authmagic - Authenticate client with a magic
* @dev: DRM device to operate on
* @data: ioctl data containing the drm_auth object
* @file_priv: DRM file that performs the operation
*
* This looks up a DRM client by the passed magic and authenticates it.
*
* Returns: 0 on success, negative error code on failure.
*/
int drm_authmagic(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
@@ -126,16 +126,6 @@ static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
return ret;
}
/*
* drm_new_set_master - Allocate a new master object and become master for the
* associated master realm.
*
* @dev: The associated device.
* @fpriv: File private identifying the client.
*
* This function must be called with dev::master_mutex held.
* Returns negative error code on failure. Zero on success.
*/
static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
{
struct drm_master *old_master;
@@ -286,12 +276,28 @@ out:
mutex_unlock(&dev->master_mutex);
}
/**
* drm_is_current_master - checks whether @priv is the current master
* @fpriv: DRM file private
*
* Checks whether @fpriv is current master on its device. This decides whether a
* client is allowed to run DRM_MASTER IOCTLs.
*
* Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
* - the current master is assumed to own the non-shareable display hardware.
*/
bool drm_is_current_master(struct drm_file *fpriv)
{
return fpriv->is_master && fpriv->master == fpriv->minor->dev->master;
}
EXPORT_SYMBOL(drm_is_current_master);
/**
* drm_master_get - reference a master pointer
* @master: struct &drm_master
*
* Increments the reference count of @master and returns a pointer to @master.
*/
struct drm_master *drm_master_get(struct drm_master *master)
{
kref_get(&master->refcount);
@@ -314,6 +320,12 @@ static void drm_master_destroy(struct kref *kref)
kfree(master);
}
/**
* drm_master_put - unreference and clear a master pointer
* @master: pointer to a pointer of struct &drm_master
*
* This decrements the &drm_master behind @master and sets it to NULL.
*/
void drm_master_put(struct drm_master **master)
{
kref_put(&(*master)->refcount, drm_master_destroy);