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

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
...@@ -270,6 +270,52 @@ ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key) ...@@ -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); 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, int ttm_ref_object_add(struct ttm_object_file *tfile,
struct ttm_base_object *base, struct ttm_base_object *base,
enum ttm_ref_type ref_type, bool *existed) enum ttm_ref_type ref_type, bool *existed)
......
...@@ -244,6 +244,10 @@ extern void ttm_base_object_unref(struct ttm_base_object **p_base); ...@@ -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, extern int ttm_ref_object_add(struct ttm_object_file *tfile,
struct ttm_base_object *base, struct ttm_base_object *base,
enum ttm_ref_type ref_type, bool *existed); 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 * ttm_ref_object_base_unref
* *
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment