}
/**
+ * hlist_del_init_rcu - deletes entry from hash list with re-initialization
+ * @n: the element to delete from the hash list.
+ *
+ * Note: list_unhashed() on the node return true after this. It is
+ * useful for RCU based read lockfree traversal if the writer side
+ * must know if the list entry is still hashed or already unhashed.
+ *
+ * In particular, it means that we can not poison the forward pointers
+ * that may still be used for walking the hash list and we can only
+ * zero the pprev pointer so list_unhashed() will return true after
+ * this.
+ *
+ * The caller must take whatever precautions are necessary (such as
+ * holding appropriate locks) to avoid racing with another
+ * list-mutation primitive, such as hlist_add_head_rcu() or
+ * hlist_del_rcu(), running on this same list. However, it is
+ * perfectly legal to run concurrently with the _rcu list-traversal
+ * primitives, such as hlist_for_each_entry_rcu().
+ */
+static inline void hlist_del_init_rcu(struct hlist_node *n)
+{
+ if (!hlist_unhashed(n)) {
+ __hlist_del(n);
+ n->pprev = NULL;
+ }
+}
+
+/**
* list_replace_rcu - replace old entry by new one
* @old : the element to be replaced
* @new : the new element to insert
}
/**
- * list_for_each_rcu - iterate over an rcu-protected list
- * @pos: the &struct list_head to use as a loop cursor.
- * @head: the head for your list.
+ * list_entry_rcu - get the struct for this entry
+ * @ptr: the &struct list_head pointer.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
*
- * This list-traversal primitive may safely run concurrently with
- * the _rcu list-mutation primitives such as list_add_rcu()
- * as long as the traversal is guarded by rcu_read_lock().
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
*/
-#define list_for_each_rcu(pos, head) \
- for (pos = (head)->next; \
- prefetch(rcu_dereference(pos)->next), pos != (head); \
- pos = pos->next)
-
-#define __list_for_each_rcu(pos, head) \
- for (pos = (head)->next; \
- rcu_dereference(pos) != (head); \
- pos = pos->next)
+#define list_entry_rcu(ptr, type, member) \
+ container_of(rcu_dereference(ptr), type, member)
/**
- * list_for_each_safe_rcu
- * @pos: the &struct list_head to use as a loop cursor.
- * @n: another &struct list_head to use as temporary storage
- * @head: the head for your list.
+ * list_first_entry_rcu - get the first element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
*
- * Iterate over an rcu-protected list, safe against removal of list entry.
+ * Note, that list is expected to be not empty.
*
- * This list-traversal primitive may safely run concurrently with
- * the _rcu list-mutation primitives such as list_add_rcu()
- * as long as the traversal is guarded by rcu_read_lock().
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
*/
-#define list_for_each_safe_rcu(pos, n, head) \
- for (pos = (head)->next; \
- n = rcu_dereference(pos)->next, pos != (head); \
- pos = n)
+#define list_first_entry_rcu(ptr, type, member) \
+ list_entry_rcu((ptr)->next, type, member)
+
+#define __list_for_each_rcu(pos, head) \
+ for (pos = rcu_dereference((head)->next); \
+ pos != (head); \
+ pos = rcu_dereference(pos->next))
/**
* list_for_each_entry_rcu - iterate over rcu list of given type
* as long as the traversal is guarded by rcu_read_lock().
*/
#define list_for_each_entry_rcu(pos, head, member) \
- for (pos = list_entry((head)->next, typeof(*pos), member); \
- prefetch(rcu_dereference(pos)->member.next), \
- &pos->member != (head); \
- pos = list_entry(pos->member.next, typeof(*pos), member))
+ for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
+ prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
/**
* as long as the traversal is guarded by rcu_read_lock().
*/
#define list_for_each_continue_rcu(pos, head) \
- for ((pos) = (pos)->next; \
- prefetch(rcu_dereference((pos))->next), (pos) != (head); \
- (pos) = (pos)->next)
+ for ((pos) = rcu_dereference((pos)->next); \
+ prefetch((pos)->next), (pos) != (head); \
+ (pos) = rcu_dereference((pos)->next))
+
+/**
+ * list_for_each_entry_continue_rcu - continue iteration over list of given type
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue_rcu(pos, head, member) \
+ for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \
+ prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
/**
* hlist_del_rcu - deletes entry from hash list without re-initialization
* as long as the traversal is guarded by rcu_read_lock().
*/
#define hlist_for_each_entry_rcu(tpos, pos, head, member) \
- for (pos = (head)->first; \
- rcu_dereference(pos) && ({ prefetch(pos->next); 1; }) && \
+ for (pos = rcu_dereference((head)->first); \
+ pos && ({ prefetch(pos->next); 1; }) && \
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
- pos = pos->next)
+ pos = rcu_dereference(pos->next))
#endif /* __KERNEL__ */
#endif
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff