rcu: Add a hlist_nulls_unhashed_lockless() function (02b99b38) · Commits · 戴 / test

include/linux/list_nulls.h

+22 −0

Original line number	Diff line number	Diff line
		@@ -56,11 +56,33 @@ static inline unsigned long get_nulls_value(const struct hlist_nulls_node *ptr)
		return ((unsigned long)ptr) >> 1;
		}

		/**
		* hlist_nulls_unhashed - Has node been removed and reinitialized?
		* @h: Node to be checked
		*
		* Not that not all removal functions will leave a node in unhashed state.
		* For example, hlist_del_init_rcu() leaves the node in unhashed state,
		* but hlist_nulls_del() does not.
		*/
		static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h)
		{
		return !h->pprev;
		}

		/**
		* hlist_nulls_unhashed_lockless - Has node been removed and reinitialized?
		* @h: Node to be checked
		*
		* Not that not all removal functions will leave a node in unhashed state.
		* For example, hlist_del_init_rcu() leaves the node in unhashed state,
		* but hlist_nulls_del() does not. Unlike hlist_nulls_unhashed(), this
		* function may be used locklessly.
		*/
		static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h)
		{
		return !READ_ONCE(h->pprev);
		}

		static inline int hlist_nulls_empty(const struct hlist_nulls_head *h)
		{
		return is_a_nulls(READ_ONCE(h->first));