drm: Add a hash-tab rcu-safe API
While hashtab should now be RCU-safe, Add a drm_ht_xxx_api for consumers
to use to make it obvious what locking mechanism is used.
Document the way the rcu-safe interface should be used.
Don't use rcu-safe list traversal in modify operations where we should use
a spinlock / mutex anyway.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_hashtab.c b/drivers/gpu/drm/drm_hashtab.c
index 5729e39..8025454 100644
--- a/drivers/gpu/drm/drm_hashtab.c
+++ b/drivers/gpu/drm/drm_hashtab.c
@@ -67,7 +67,7 @@
hashed_key = hash_long(key, ht->order);
DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
h_list = &ht->table[hashed_key];
- hlist_for_each_entry_rcu(entry, list, h_list, head)
+ hlist_for_each_entry(entry, list, h_list, head)
DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
}
@@ -81,6 +81,25 @@
hashed_key = hash_long(key, ht->order);
h_list = &ht->table[hashed_key];
+ hlist_for_each_entry(entry, list, h_list, head) {
+ if (entry->key == key)
+ return list;
+ if (entry->key > key)
+ break;
+ }
+ return NULL;
+}
+
+static struct hlist_node *drm_ht_find_key_rcu(struct drm_open_hash *ht,
+ unsigned long key)
+{
+ struct drm_hash_item *entry;
+ struct hlist_head *h_list;
+ struct hlist_node *list;
+ unsigned int hashed_key;
+
+ hashed_key = hash_long(key, ht->order);
+ h_list = &ht->table[hashed_key];
hlist_for_each_entry_rcu(entry, list, h_list, head) {
if (entry->key == key)
return list;
@@ -90,7 +109,6 @@
return NULL;
}
-
int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item)
{
struct drm_hash_item *entry;
@@ -102,7 +120,7 @@
hashed_key = hash_long(key, ht->order);
h_list = &ht->table[hashed_key];
parent = NULL;
- hlist_for_each_entry_rcu(entry, list, h_list, head) {
+ hlist_for_each_entry(entry, list, h_list, head) {
if (entry->key == key)
return -EINVAL;
if (entry->key > key)
@@ -152,7 +170,7 @@
{
struct hlist_node *list;
- list = drm_ht_find_key(ht, key);
+ list = drm_ht_find_key_rcu(ht, key);
if (!list)
return -EINVAL;