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author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2016-06-21 10:54:22 +0200 |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2016-06-21 22:10:55 +0200 |
commit | 3b96a0b1407e08ebebe7a5c586752f7c16754cbd (patch) | |
tree | 6e353aa88a9fbd2b7cfe7a36957c4cb110befb89 /drivers/gpu/drm/drm_auth.c | |
parent | 0aae5920a84469e2bb6795f53157ea9072faef5a (diff) | |
download | linux-3b96a0b1407e08ebebe7a5c586752f7c16754cbd.tar.gz linux-3b96a0b1407e08ebebe7a5c586752f7c16754cbd.tar.bz2 linux-3b96a0b1407e08ebebe7a5c586752f7c16754cbd.zip |
drm: document drm_auth.c
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>
Diffstat (limited to 'drivers/gpu/drm/drm_auth.c')
-rw-r--r-- | drivers/gpu/drm/drm_auth.c | 68 |
1 files changed, 40 insertions, 28 deletions
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 0a23b32e627c..4153e8a193af 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -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); |