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>

9 files changed, 27 insertions, 20 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 3c4a62169f28..670b5eb13c87 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -3243,7 +3243,7 @@ int drm_mode_getfb(struct drm_device *dev,
         r->bpp = fb->bits_per_pixel;
         r->pitch = fb->pitches[0];
         if (fb->funcs->create_handle) {
-                if (file_priv->is_master || capable(CAP_SYS_ADMIN) ||
+                if (drm_is_master(file_priv) || capable(CAP_SYS_ADMIN) ||
                     drm_is_control_client(file_priv)) {
                         ret = fb->funcs->create_handle(fb, file_priv,
                                                        &r->handle);
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 0cc182745e31..7aa8121d1323 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -307,7 +307,7 @@ static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv)
                 return -EACCES;
 
         /* MASTER is only for master or control clients */
-        if (unlikely((flags & DRM_MASTER) && !file_priv->is_master &&
+        if (unlikely((flags & DRM_MASTER) && !drm_is_master(file_priv) &&
                      !drm_is_control_client(file_priv)))
                 return -EACCES;
 
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 55143f7747f3..53435e07fa8d 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -233,7 +233,6 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
                         goto out_close;
                 }
 
-                priv->is_master = 1;
                 /* take another reference for the copy in the local file priv */
                 priv->master = drm_master_get(priv->minor->master);
                 priv->authenticated = 1;
@@ -461,7 +460,7 @@ int drm_release(struct inode *inode, struct file *filp)
 
         mutex_lock(&dev->master_mutex);
 
-        if (file_priv->is_master) {
+        if (drm_is_master(file_priv)) {
                 struct drm_master *master = file_priv->master;
                 struct drm_file *temp;
 
@@ -497,7 +496,6 @@ int drm_release(struct inode *inode, struct file *filp)
         /* drop the master reference held by the file priv */
         if (file_priv->master)
                 drm_master_put(&file_priv->master);
-        file_priv->is_master = 0;
         mutex_unlock(&dev->master_mutex);
 
         mutex_lock(&dev->struct_mutex);
diff --git a/drivers/gpu/drm/drm_lock.c b/drivers/gpu/drm/drm_lock.c
index f6452682141b..786401cd5f60 100644
--- a/drivers/gpu/drm/drm_lock.c
+++ b/drivers/gpu/drm/drm_lock.c
@@ -111,7 +111,7 @@ int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
         /* don't set the block all signals on the master process for now 
          * really probably not the correct answer but lets us debug xkb
          * xserver for now */
-        if (!file_priv->is_master) {
+        if (!drm_is_master(file_priv)) {
                 sigemptyset(&dev->sigmask);
                 sigaddset(&dev->sigmask, SIGSTOP);
                 sigaddset(&dev->sigmask, SIGTSTP);
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);
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 60998fc4e5b2..2dd19da6b4b3 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1260,7 +1260,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 
         flags = 0;
         if (args->flags & I915_EXEC_SECURE) {
-                if (!file->is_master || !capable(CAP_SYS_ADMIN))
+                if (!drm_is_master(file) || !capable(CAP_SYS_ADMIN))
                     return -EPERM;
 
                 flags |= I915_DISPATCH_SECURE;
@@ -1369,7 +1369,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
                 ret = i915_parse_cmds(ring,
                                       batch_obj,
                                       args->batch_start_offset,
-                                      file->is_master);
+                                      drm_is_master(file));
                 if (ret)
                         goto err;
 
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index 18b54acacfbb..63c4d6f0281e 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -990,7 +990,7 @@ static struct vmw_master *vmw_master_check(struct drm_device *dev,
         if (unlikely(ret != 0))
                 return ERR_PTR(-ERESTARTSYS);
 
-        if (file_priv->is_master) {
+        if (drm_is_master(file_priv)) {
                 mutex_unlock(&dev->master_mutex);
                 return NULL;
         }
diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c
index 6f54ff4f9372..72913b299047 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -182,7 +182,7 @@ static void imx_drm_driver_preclose(struct drm_device *drm,
 {
         int i;
 
-        if (!file->is_master)
+        if (!drm_is_master(file))
                 return;
 
         for (i = 0; i < MAX_CRTC; i++)
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 */
 /*@{*/