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drm: use anon-inode instead of relying on cdevs

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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>
This commit is contained in:
David Herrmann
2014-01-03 14:24:19 +01:00
parent 31bbe16f6d
commit 6796cb16c0
15 changed files with 44 additions and 54 deletions
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12
drivers/gpu/drm/drm_stub.c
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@@ -526,8 +526,15 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver,
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 @@ err_ctxbitmap:
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 @@ void drm_dev_free(struct drm_device *dev)
drm_ctxbitmap_cleanup(dev);
drm_ht_remove(&dev->map_hash);
drm_fs_inode_free(dev->anon_inode);
kfree(dev->devname);
kfree(dev);