A function to be used to check whether a caller has put a ref object (opened) a struct ttm_base_object
Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: Brian Paul brianp@vmware.com --- drivers/gpu/drm/ttm/ttm_object.c | 46 ++++++++++++++++++++++++++++++++++++++ include/drm/ttm/ttm_object.h | 4 ++++ 2 files changed, 50 insertions(+)
diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c index 53b51c4..d2a0533 100644 --- a/drivers/gpu/drm/ttm/ttm_object.c +++ b/drivers/gpu/drm/ttm/ttm_object.c @@ -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) diff --git a/include/drm/ttm/ttm_object.h b/include/drm/ttm/ttm_object.h index 0097cc0..ed953f9 100644 --- a/include/drm/ttm/ttm_object.h +++ b/include/drm/ttm/ttm_object.h @@ -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 *