drm: Clear up master tracking booleans

- is_master can be removed, we can compute this by checking allowed_master
  (which really just tracks whether a master struct has been allocated
  for this fpriv in either open or set_master), and whether the fpriv is
  the current master on the device.

- that frees up is_master as a good replacement name for allowed_master.
  With that it's clear that it tracks whether the fpriv is a master (with
  possibly clients attached to it and authenticated against it), and that
  one of those fprivs with is_master set is the current master.

v2: Fix kerneldoc for is_master (Emil).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
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@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1466499262-18717-10-git-send-email-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_auth.c

@@ -116,11 +116,9 @@ static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
 	int ret = 0;
 
 	dev->master = drm_master_get(fpriv->master);
-	fpriv->is_master = 1;
 	if (dev->driver->master_set) {
 		ret = dev->driver->master_set(dev, fpriv, new_master);
 		if (unlikely(ret != 0)) {
-			fpriv->is_master = 0;
 			drm_master_put(&dev->master);
 		}
 	}
@@ -157,7 +155,7 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
 		if (ret)
 			goto out_err;
 	}
-	fpriv->allowed_master = 1;
+	fpriv->is_master = 1;
 	fpriv->authenticated = 1;
 
 	ret = drm_set_master(dev, fpriv, true);
@@ -196,7 +194,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 		goto out_unlock;
 	}
 
-	if (!file_priv->allowed_master) {
+	if (!file_priv->is_master) {
 		ret = drm_new_set_master(dev, file_priv);
 		goto out_unlock;
 	}
@@ -213,7 +211,6 @@ static void drm_drop_master(struct drm_device *dev,
 	if (dev->driver->master_drop)
 		dev->driver->master_drop(dev, fpriv);
 	drm_master_put(&dev->master);
-	fpriv->is_master = 0;
 }
 
 int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
@@ -291,7 +288,7 @@ out:
 
 bool drm_is_current_master(struct drm_file *fpriv)
 {
-	return fpriv->is_master;
+	return fpriv->is_master && fpriv->master == fpriv->minor->dev->master;
 }
 EXPORT_SYMBOL(drm_is_current_master);
 

include/drm/drmP.h

@@ -303,8 +303,6 @@ struct drm_prime_file_private {
 /** File private data */
 struct drm_file {
 	unsigned authenticated :1;
-	/* Whether we're master for a minor. Protected by master_mutex */
-	unsigned is_master :1;
 	/* true when the client has asked us to expose stereo 3D mode flags */
 	unsigned stereo_allowed :1;
 	/*
@@ -315,10 +313,10 @@ struct drm_file {
 	/* true if client understands atomic properties */
 	unsigned atomic:1;
 	/*
-	 * This client is allowed to gain master privileges for @master.
+	 * This client is the creator of @master.
 	 * Protected by struct drm_device::master_mutex.
 	 */
-	unsigned allowed_master:1;
+	unsigned is_master:1;
 
 	struct pid *pid;
 	kuid_t uid;