1 /* SPDX-License-Identifier: GPL-2.0 */
5 #include <linux/poison.h>
6 #include <linux/const.h>
9  * Special version of lists, where end of list is not a NULL pointer,
10  * but a 'nulls' marker, which can have many different values.
13  * In the standard hlist, termination of a list is the NULL pointer.
15  * a list are aligned on a word (4 or 8 bytes alignment).
17  * Set to 1 : This is a 'nulls' end-of-list marker (ptr >> 1)
18  * Set to 0 : This is a pointer to some object (ptr)
30 	((ptr)->first = (struct hlist_nulls_node *) NULLS_MARKER(nulls))
39  * ptr_is_a_nulls - Test if a ptr is a nulls
49  * get_nulls_value - Get the 'nulls' value of the end of chain
60  * hlist_nulls_unhashed - Has node been removed and reinitialized?
61  * @h: Node to be checked
63  * Not that not all removal functions will leave a node in unhashed state.
67 static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h)  in hlist_nulls_unhashed()  argument
69 	return !h->pprev;  in hlist_nulls_unhashed()
73  * hlist_nulls_unhashed_lockless - Has node been removed and reinitialized?
74  * @h: Node to be checked
76  * Not that not all removal functions will leave a node in unhashed state.
81 static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h)  in hlist_nulls_unhashed_lockless()  argument
83 	return !READ_ONCE(h->pprev);  in hlist_nulls_unhashed_lockless()
86 static inline int hlist_nulls_empty(const struct hlist_nulls_head *h)  in hlist_nulls_empty()  argument
88 	return is_a_nulls(READ_ONCE(h->first));  in hlist_nulls_empty()
92 					struct hlist_nulls_head *h)  in hlist_nulls_add_head()  argument
94 	struct hlist_nulls_node *first = h->first;  in hlist_nulls_add_head()
96 	n->next = first;  in hlist_nulls_add_head()
97 	WRITE_ONCE(n->pprev, &h->first);  in hlist_nulls_add_head()
98 	h->first = n;  in hlist_nulls_add_head()
100 		WRITE_ONCE(first->pprev, &n->next);  in hlist_nulls_add_head()
105 	struct hlist_nulls_node *next = n->next;  in __hlist_nulls_del()
106 	struct hlist_nulls_node **pprev = n->pprev;  in __hlist_nulls_del()
110 		WRITE_ONCE(next->pprev, pprev);  in __hlist_nulls_del()
116 	WRITE_ONCE(n->pprev, LIST_POISON2);  in hlist_nulls_del()
120  * hlist_nulls_for_each_entry	- iterate over list of given type
121  * @tpos:	the type * to use as a loop cursor.
122  * @pos:	the &struct hlist_node to use as a loop cursor.
128 	for (pos = (head)->first;					       \
131 	     pos = pos->next)
134  * hlist_nulls_for_each_entry_from - iterate over a hlist continuing from current point
135  * @tpos:	the type * to use as a loop cursor.
136  * @pos:	the &struct hlist_node to use as a loop cursor.
143 	     pos = pos->next)