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1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_RCULIST_BL_H
3 #define _LINUX_RCULIST_BL_H
6 * RCU-protected bl list version. See include/linux/list_bl.h.
8 #include <linux/list_bl.h>
9 #include <linux/rcupdate.h>
11 static inline void hlist_bl_set_first_rcu(struct hlist_bl_head
*h
,
12 struct hlist_bl_node
*n
)
14 LIST_BL_BUG_ON((unsigned long)n
& LIST_BL_LOCKMASK
);
15 LIST_BL_BUG_ON(((unsigned long)h
->first
& LIST_BL_LOCKMASK
) !=
17 rcu_assign_pointer(h
->first
,
18 (struct hlist_bl_node
*)((unsigned long)n
| LIST_BL_LOCKMASK
));
21 static inline struct hlist_bl_node
*hlist_bl_first_rcu(struct hlist_bl_head
*h
)
23 return (struct hlist_bl_node
*)
24 ((unsigned long)rcu_dereference_check(h
->first
, hlist_bl_is_locked(h
)) & ~LIST_BL_LOCKMASK
);
28 * hlist_bl_del_rcu - deletes entry from hash list without re-initialization
29 * @n: the element to delete from the hash list.
31 * Note: hlist_bl_unhashed() on entry does not return true after this,
32 * the entry is in an undefined state. It is useful for RCU based
35 * In particular, it means that we can not poison the forward
36 * pointers that may still be used for walking the hash list.
38 * The caller must take whatever precautions are necessary
39 * (such as holding appropriate locks) to avoid racing
40 * with another list-mutation primitive, such as hlist_bl_add_head_rcu()
41 * or hlist_bl_del_rcu(), running on this same list.
42 * However, it is perfectly legal to run concurrently with
43 * the _rcu list-traversal primitives, such as
44 * hlist_bl_for_each_entry().
46 static inline void hlist_bl_del_rcu(struct hlist_bl_node
*n
)
49 n
->pprev
= LIST_POISON2
;
53 * hlist_bl_add_head_rcu
54 * @n: the element to add to the hash list.
55 * @h: the list to add to.
58 * Adds the specified element to the specified hlist_bl,
59 * while permitting racing traversals.
61 * The caller must take whatever precautions are necessary
62 * (such as holding appropriate locks) to avoid racing
63 * with another list-mutation primitive, such as hlist_bl_add_head_rcu()
64 * or hlist_bl_del_rcu(), running on this same list.
65 * However, it is perfectly legal to run concurrently with
66 * the _rcu list-traversal primitives, such as
67 * hlist_bl_for_each_entry_rcu(), used to prevent memory-consistency
68 * problems on Alpha CPUs. Regardless of the type of CPU, the
69 * list-traversal primitive must be guarded by rcu_read_lock().
71 static inline void hlist_bl_add_head_rcu(struct hlist_bl_node
*n
,
72 struct hlist_bl_head
*h
)
74 struct hlist_bl_node
*first
;
76 /* don't need hlist_bl_first_rcu because we're under lock */
77 first
= hlist_bl_first(h
);
81 first
->pprev
= &n
->next
;
84 /* need _rcu because we can have concurrent lock free readers */
85 hlist_bl_set_first_rcu(h
, n
);
88 * hlist_bl_for_each_entry_rcu - iterate over rcu list of given type
89 * @tpos: the type * to use as a loop cursor.
90 * @pos: the &struct hlist_bl_node to use as a loop cursor.
91 * @head: the head for your list.
92 * @member: the name of the hlist_bl_node within the struct.
95 #define hlist_bl_for_each_entry_rcu(tpos, pos, head, member) \
96 for (pos = hlist_bl_first_rcu(head); \
98 ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1; }); \
99 pos = rcu_dereference_raw(pos->next))