On Tue, Jun 14, 2016 at 08:51:07PM +0200, Daniel Vetter wrote:
> There can only be one current master, and it's for the overall device.
> Render/control minors don't support master-based auth at all.
>
> This simplifies the master logic a lot, at least in my eyes: All these
> additional pointer chases are just confusing.
One master for the device, on the struct drm_device, as opposed to hidden
behind the first of three minors, makes sense.
> @@ -128,13 +128,13 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
> lockdep_assert_held_once(&dev->master_mutex);
>
> /* create a new master */
> - fpriv->minor->master = drm_master_create(fpriv->minor->dev);
> - if (!fpriv->minor->master)
> + dev->master = drm_master_create(dev);
> + if (!dev->master)
> return -ENOMEM;
>
> /* take another reference for the copy in the local file priv */
> old_master = fpriv->master;
> - fpriv->master = drm_master_get(fpriv->minor->master);
> + fpriv->master = drm_master_get(dev->master);
>
> if (dev->driver->master_create) {
> ret = dev->driver->master_create(dev, fpriv->master);
> @@ -234,10 +234,10 @@ int drm_master_open(struct drm_file *file_priv)
> /* if there is no current master make this fd it, but do not create
> * any master object for render clients */
> mutex_lock(&dev->master_mutex);
> - if (!file_priv->minor->master)
> + if (!dev->master)
> ret = drm_new_set_master(dev, file_priv);
> else
> - file_priv->master = drm_master_get(file_priv->minor->master);
> + file_priv->master = drm_master_get(dev->master);
> mutex_unlock(&dev->master_mutex);
You could take the opportunity to make this a bit simpler:
if (!READ_ONCE(dev->master)) {
int ret;
ret = 0;
mutex_lock(&dev->master_mutex);
if (!dev->master)
ret = drm_new_master(dev);
mutex_unlock(&dev->master_mutex);
if (ret)
return ret;
}
file_priv->master = drm_master_get(dev->master);
return 0;
Just to straighten out the kref dance.
>
> return ret;
> @@ -271,11 +271,11 @@ void drm_master_release(struct drm_file *file_priv)
> mutex_unlock(&dev->struct_mutex);
> }
>
> - if (file_priv->minor->master == file_priv->master) {
> + if (dev->master == file_priv->master) {
> /* drop the reference held my the minor */
> if (dev->driver->master_drop)
> dev->driver->master_drop(dev, file_priv, true);
> - drm_master_put(&file_priv->minor->master);
> + drm_master_put(&dev->master);
This still makes me uneasy. This is not equivalent to dropmaster_ioctl
and subsequent setmaster_ioctl will fail as dev->master is still
assigned (but the owner has gone).
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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