Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1#ifndef _LINUX_LIST_BL_H
2#define _LINUX_LIST_BL_H
3
4#include <linux/list.h>
5
6/*
7 * Special version of lists, where head of the list has a lock in the lowest
8 * bit. This is useful for scalable hash tables without increasing memory
9 * footprint overhead.
10 *
11 * For modification operations, the 0 bit of hlist_bl_head->first
12 * pointer must be set.
13 *
14 * With some small modifications, this can easily be adapted to store several
15 * arbitrary bits (not just a single lock bit), if the need arises to store
16 * some fast and compact auxiliary data.
17 */
18
19#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
20#define LIST_BL_LOCKMASK 1UL
21#else
22#define LIST_BL_LOCKMASK 0UL
23#endif
24
25#ifdef CONFIG_DEBUG_LIST
26#define LIST_BL_BUG_ON(x) BUG_ON(x)
27#else
28#define LIST_BL_BUG_ON(x)
29#endif
30
31
32struct hlist_bl_head {
33 struct hlist_bl_node *first;
34};
35
36struct hlist_bl_node {
37 struct hlist_bl_node *next, **pprev;
38};
39#define INIT_HLIST_BL_HEAD(ptr) \
40 ((ptr)->first = NULL)
41
42static inline void INIT_HLIST_BL_NODE(struct hlist_bl_node *h)
43{
44 h->next = NULL;
45 h->pprev = NULL;
46}
47
48#define hlist_bl_entry(ptr, type, member) container_of(ptr,type,member)
49
50static inline int hlist_bl_unhashed(const struct hlist_bl_node *h)
51{
52 return !h->pprev;
53}
54
55static inline struct hlist_bl_node *hlist_bl_first(struct hlist_bl_head *h)
56{
57 return (struct hlist_bl_node *)
58 ((unsigned long)h->first & ~LIST_BL_LOCKMASK);
59}
60
61static inline void hlist_bl_set_first(struct hlist_bl_head *h,
62 struct hlist_bl_node *n)
63{
64 LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK);
65 LIST_BL_BUG_ON(((unsigned long)h->first & LIST_BL_LOCKMASK) !=
66 LIST_BL_LOCKMASK);
67 h->first = (struct hlist_bl_node *)((unsigned long)n | LIST_BL_LOCKMASK);
68}
69
70static inline int hlist_bl_empty(const struct hlist_bl_head *h)
71{
72 return !((unsigned long)h->first & ~LIST_BL_LOCKMASK);
73}
74
75static inline void hlist_bl_add_head(struct hlist_bl_node *n,
76 struct hlist_bl_head *h)
77{
78 struct hlist_bl_node *first = hlist_bl_first(h);
79
80 n->next = first;
81 if (first)
82 first->pprev = &n->next;
83 n->pprev = &h->first;
84 hlist_bl_set_first(h, n);
85}
86
87static inline void __hlist_bl_del(struct hlist_bl_node *n)
88{
89 struct hlist_bl_node *next = n->next;
90 struct hlist_bl_node **pprev = n->pprev;
91
92 LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK);
93
94 /* pprev may be `first`, so be careful not to lose the lock bit */
95 *pprev = (struct hlist_bl_node *)
96 ((unsigned long)next |
97 ((unsigned long)*pprev & LIST_BL_LOCKMASK));
98 if (next)
99 next->pprev = pprev;
100}
101
102static inline void hlist_bl_del(struct hlist_bl_node *n)
103{
104 __hlist_bl_del(n);
105 n->next = LIST_POISON1;
106 n->pprev = LIST_POISON2;
107}
108
109static inline void hlist_bl_del_init(struct hlist_bl_node *n)
110{
111 if (!hlist_bl_unhashed(n)) {
112 __hlist_bl_del(n);
113 INIT_HLIST_BL_NODE(n);
114 }
115}
116
117/**
118 * hlist_bl_for_each_entry - iterate over list of given type
119 * @tpos: the type * to use as a loop cursor.
120 * @pos: the &struct hlist_node to use as a loop cursor.
121 * @head: the head for your list.
122 * @member: the name of the hlist_node within the struct.
123 *
124 */
125#define hlist_bl_for_each_entry(tpos, pos, head, member) \
126 for (pos = hlist_bl_first(head); \
127 pos && \
128 ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1;}); \
129 pos = pos->next)
130
131/**
132 * hlist_bl_for_each_entry_safe - iterate over list of given type safe against removal of list entry
133 * @tpos: the type * to use as a loop cursor.
134 * @pos: the &struct hlist_node to use as a loop cursor.
135 * @n: another &struct hlist_node to use as temporary storage
136 * @head: the head for your list.
137 * @member: the name of the hlist_node within the struct.
138 */
139#define hlist_bl_for_each_entry_safe(tpos, pos, n, head, member) \
140 for (pos = hlist_bl_first(head); \
141 pos && ({ n = pos->next; 1; }) && \
142 ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1;}); \
143 pos = n)
144
145#endif