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, 3 insertions, 7 deletions

diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index 233ea208c9fe..18c9b3d8201e 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -177,7 +177,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
         int ret = 0;
 
         mutex_lock(&dev->master_mutex);
-        if (file_priv->is_master)
+        if (drm_is_master(file_priv))
                 goto out_unlock;
 
         if (file_priv->minor->master) {
@@ -191,13 +191,10 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
         }
 
         file_priv->minor->master = drm_master_get(file_priv->master);
-        file_priv->is_master = 1;
         if (dev->driver->master_set) {
                 ret = dev->driver->master_set(dev, file_priv, false);
-                if (unlikely(ret != 0)) {
-                        file_priv->is_master = 0;
+                if (unlikely(ret != 0))
                         drm_master_put(&file_priv->minor->master);
-                }
         }
 
 out_unlock:
@@ -211,7 +208,7 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
         int ret = -EINVAL;
 
         mutex_lock(&dev->master_mutex);
-        if (!file_priv->is_master)
+        if (!drm_is_master(file_priv))
                 goto out_unlock;
 
         if (!file_priv->minor->master)
@@ -221,7 +218,6 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
         if (dev->driver->master_drop)
                 dev->driver->master_drop(dev, file_priv, false);
         drm_master_put(&file_priv->minor->master);
-        file_priv->is_master = 0;
 
 out_unlock:
         mutex_unlock(&dev->master_mutex);