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Commit 0d3215e3 authored by Thomas Hellstrom's avatar Thomas Hellstrom
Browse files

drm/ttm: Add a ttm_ref_object_exists function 



A function to be used to check whether a caller has put a ref object
(opened) a struct ttm_base_object

Signed-off-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: default avatarBrian Paul <brianp@vmware.com>
parent 6d10aab8

drivers/gpu/drm/ttm/ttm_object.c

+46 −0
Original line number Diff line number Diff line
@@ -270,6 +270,52 @@ ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key) 
}

EXPORT_SYMBOL(ttm_base_object_lookup_for_ref);



/**

 * ttm_ref_object_exists - Check whether a caller has a valid ref object

 * (has opened) a base object.

 *

 * @tfile: Pointer to a struct ttm_object_file identifying the caller.

 * @base: Pointer to a struct base object.

 *

 * Checks wether the caller identified by @tfile has put a valid USAGE

 * reference object on the base object identified by @base.

 */

bool ttm_ref_object_exists(struct ttm_object_file *tfile,

			   struct ttm_base_object *base)

{

	struct drm_open_hash *ht = &tfile->ref_hash[TTM_REF_USAGE];

	struct drm_hash_item *hash;

	struct ttm_ref_object *ref;



	rcu_read_lock();

	if (unlikely(drm_ht_find_item_rcu(ht, base->hash.key, &hash) != 0))

		goto out_false;



	/*

	 * Verify that the ref object is really pointing to our base object.

	 * Our base object could actually be dead, and the ref object pointing

	 * to another base object with the same handle.

	 */

	ref = drm_hash_entry(hash, struct ttm_ref_object, hash);

	if (unlikely(base != ref->obj))

		goto out_false;



	/*

	 * Verify that the ref->obj pointer was actually valid!

	 */

	rmb();

	if (unlikely(atomic_read(&ref->kref.refcount) == 0))

		goto out_false;



	rcu_read_unlock();

	return true;



 out_false:

	rcu_read_unlock();

	return false;

}

EXPORT_SYMBOL(ttm_ref_object_exists);



int ttm_ref_object_add(struct ttm_object_file *tfile,

		       struct ttm_base_object *base,

		       enum ttm_ref_type ref_type, bool *existed)

include/drm/ttm/ttm_object.h

+4 −0
Original line number Diff line number Diff line
@@ -244,6 +244,10 @@ extern void ttm_base_object_unref(struct ttm_base_object **p_base); 
extern int ttm_ref_object_add(struct ttm_object_file *tfile,

			      struct ttm_base_object *base,

			      enum ttm_ref_type ref_type, bool *existed);



extern bool ttm_ref_object_exists(struct ttm_object_file *tfile,

				  struct ttm_base_object *base);



/**

 * ttm_ref_object_base_unref

 *