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drm/ttm: ttm object security fixes for render nodes

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When a client looks up a ttm object, don't look it up through the device hash
table, but rather from the file hash table. That makes sure that the client
has indeed put a reference on the object, or in gem terms, has opened
the object; either using prime or using the global "name".

To avoid a performance loss, make sure the file hash table entries can be
looked up from under an RCU lock, and as a consequence, replace the rwlock
with a spinlock, since we never need to take it in read mode only anymore.

Finally add a ttm object lookup function for the device hash table, that is
intended to be used when we put a ref object on a base object or, in  gem terms,
when we open the object.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
This commit is contained in:
Thomas Hellstrom
2013-12-18 14:13:29 +01:00
parent 859ae233cd
commit 05efb1abec
4 changed files with 76 additions and 42 deletions
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18
include/drm/ttm/ttm_object.h
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@@ -190,13 +190,25 @@ extern int ttm_base_object_init(struct ttm_object_file *tfile,
* @key: Hash key
*
* Looks up a struct ttm_base_object with the key @key.
* Also verifies that the object is visible to the application, by
* comparing the @tfile argument and checking the object shareable flag.
*/
extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
*tfile, uint32_t key);
/**
* ttm_base_object_lookup_for_ref
*
* @tdev: Pointer to a struct ttm_object_device.
* @key: Hash key
*
* Looks up a struct ttm_base_object with the key @key.
* This function should only be used when the struct tfile associated with the
* caller doesn't yet have a reference to the base object.
*/
extern struct ttm_base_object *
ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key);
/**
* ttm_base_object_unref
*
@@ -218,6 +230,8 @@ extern void ttm_base_object_unref(struct ttm_base_object **p_base);
* @existed: Upon completion, indicates that an identical reference object
* already existed, and the refcount was upped on that object instead.
*
* Checks that the base object is shareable and adds a ref object to it.
*
* Adding a ref object to a base object is basically like referencing the
* base object, but a user-space application holds the reference. When the
* file corresponding to @tfile is closed, all its reference objects are