drm: use anon-inode instead of relying on cdevs
DRM drivers share a common address_space across all character-devices of a
single DRM device. This allows simple buffer eviction and mapping-control.
However, DRM core currently waits for the first ->open() on any char-dev
to mark the underlying inode as backing inode of the device. This delayed
initialization causes ugly conditions all over the place:
if (dev->dev_mapping)
do_sth();
To avoid delayed initialization and to stop reusing the inode of the
char-dev, we allocate an anonymous inode for each DRM device and reset
filp->f_mapping to it on ->open().
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index f2903d7..04c25ce 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -526,8 +526,15 @@
mutex_init(&dev->struct_mutex);
mutex_init(&dev->ctxlist_mutex);
- if (drm_ht_create(&dev->map_hash, 12))
+ dev->anon_inode = drm_fs_inode_new();
+ if (IS_ERR(dev->anon_inode)) {
+ ret = PTR_ERR(dev->anon_inode);
+ DRM_ERROR("Cannot allocate anonymous inode: %d\n", ret);
goto err_free;
+ }
+
+ if (drm_ht_create(&dev->map_hash, 12))
+ goto err_inode;
ret = drm_ctxbitmap_init(dev);
if (ret) {
@@ -549,6 +556,8 @@
drm_ctxbitmap_cleanup(dev);
err_ht:
drm_ht_remove(&dev->map_hash);
+err_inode:
+ drm_fs_inode_free(dev->anon_inode);
err_free:
kfree(dev);
return NULL;
@@ -576,6 +585,7 @@
drm_ctxbitmap_cleanup(dev);
drm_ht_remove(&dev->map_hash);
+ drm_fs_inode_free(dev->anon_inode);
kfree(dev->devname);
kfree(dev);