drm: drop redundant drm_file->is_master

The drm_file->is_master field is redundant as it's equivalent to:
    drm_file->master && drm_file->master == drm_file->minor->master

1) "=>"
  Whenever we set drm_file->is_master, we also set:
      drm_file->minor->master = drm_file->master;

  Whenever we clear drm_file->is_master, we also call:
      drm_master_put(&drm_file->minor->master);
  which implicitly clears it to NULL.

2) "<="
  minor->master cannot be set if it is non-NULL. Therefore, it stays as
  is unless a file drops it.

  If minor->master is NULL, it is only set by places that also adjust
  drm_file->is_master.

Therefore, we can safely drop is_master and replace it by an inline helper
that matches:
    drm_file->master && drm_file->master == drm_file->minor->master

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

1 files changed, 16 insertions, 3 deletions

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 80889982d196..6ede53712d7b 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -387,8 +387,6 @@ struct drm_prime_file_private {
 struct drm_file {
 	unsigned always_authenticated :1;
 	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;
 	/*
@@ -1034,7 +1032,7 @@ struct drm_device {
 	/** \name Locks */
 	/*@{ */
 	struct mutex struct_mutex;	/**< For others */
-	struct mutex master_mutex;      /**< For drm_minor::master and drm_file::is_master */
+	struct mutex master_mutex;      /**< For drm_minor::master */
 	/*@} */
 
 	/** \name Usage Counters */
@@ -1172,6 +1170,21 @@ static inline bool drm_is_primary_client(const struct drm_file *file_priv)
 	return file_priv->minor->type == DRM_MINOR_LEGACY;
 }
 
+/**
+ * drm_is_master() - Check whether a DRM open-file is DRM-Master
+ * @file: DRM open-file context
+ *
+ * This checks whether a DRM open-file context is owner of the master context
+ * attached to it. If a file owns a master context, it's called DRM-Master.
+ * Per DRM device, only one such file can be DRM-Master at a time.
+ *
+ * Returns: True if the file is DRM-Master, otherwise false.
+ */
+static inline bool drm_is_master(const struct drm_file *file)
+{
+	return file->master && file->master == file->minor->master;
+}
+
 /******************************************************************/
 /** \name Internal function definitions */
 /*@{*/