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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
4e35e607 NP |
2 | #ifndef _LINUX_LIST_BL_H |
3 | #define _LINUX_LIST_BL_H | |
4 | ||
5 | #include <linux/list.h> | |
1879fd6a | 6 | #include <linux/bit_spinlock.h> |
4e35e607 NP |
7 | |
8 | /* | |
9 | * Special version of lists, where head of the list has a lock in the lowest | |
10 | * bit. This is useful for scalable hash tables without increasing memory | |
11 | * footprint overhead. | |
12 | * | |
13 | * For modification operations, the 0 bit of hlist_bl_head->first | |
14 | * pointer must be set. | |
15 | * | |
16 | * With some small modifications, this can easily be adapted to store several | |
17 | * arbitrary bits (not just a single lock bit), if the need arises to store | |
18 | * some fast and compact auxiliary data. | |
19 | */ | |
20 | ||
32385c7c | 21 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) |
4e35e607 NP |
22 | #define LIST_BL_LOCKMASK 1UL |
23 | #else | |
24 | #define LIST_BL_LOCKMASK 0UL | |
25 | #endif | |
26 | ||
27 | #ifdef CONFIG_DEBUG_LIST | |
28 | #define LIST_BL_BUG_ON(x) BUG_ON(x) | |
29 | #else | |
30 | #define LIST_BL_BUG_ON(x) | |
31 | #endif | |
32 | ||
33 | ||
34 | struct hlist_bl_head { | |
35 | struct hlist_bl_node *first; | |
36 | }; | |
37 | ||
38 | struct hlist_bl_node { | |
39 | struct hlist_bl_node *next, **pprev; | |
40 | }; | |
41 | #define INIT_HLIST_BL_HEAD(ptr) \ | |
42 | ((ptr)->first = NULL) | |
43 | ||
44 | static inline void INIT_HLIST_BL_NODE(struct hlist_bl_node *h) | |
45 | { | |
46 | h->next = NULL; | |
47 | h->pprev = NULL; | |
48 | } | |
49 | ||
50 | #define hlist_bl_entry(ptr, type, member) container_of(ptr,type,member) | |
51 | ||
26a247fd | 52 | static inline bool hlist_bl_unhashed(const struct hlist_bl_node *h) |
4e35e607 NP |
53 | { |
54 | return !h->pprev; | |
55 | } | |
56 | ||
57 | static inline struct hlist_bl_node *hlist_bl_first(struct hlist_bl_head *h) | |
58 | { | |
59 | return (struct hlist_bl_node *) | |
60 | ((unsigned long)h->first & ~LIST_BL_LOCKMASK); | |
61 | } | |
62 | ||
63 | static inline void hlist_bl_set_first(struct hlist_bl_head *h, | |
64 | struct hlist_bl_node *n) | |
65 | { | |
66 | LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK); | |
2c675598 NP |
67 | LIST_BL_BUG_ON(((unsigned long)h->first & LIST_BL_LOCKMASK) != |
68 | LIST_BL_LOCKMASK); | |
4e35e607 NP |
69 | h->first = (struct hlist_bl_node *)((unsigned long)n | LIST_BL_LOCKMASK); |
70 | } | |
71 | ||
26a247fd | 72 | static inline bool hlist_bl_empty(const struct hlist_bl_head *h) |
4e35e607 | 73 | { |
1658d35e | 74 | return !((unsigned long)READ_ONCE(h->first) & ~LIST_BL_LOCKMASK); |
4e35e607 NP |
75 | } |
76 | ||
77 | static inline void hlist_bl_add_head(struct hlist_bl_node *n, | |
78 | struct hlist_bl_head *h) | |
79 | { | |
80 | struct hlist_bl_node *first = hlist_bl_first(h); | |
81 | ||
82 | n->next = first; | |
83 | if (first) | |
84 | first->pprev = &n->next; | |
85 | n->pprev = &h->first; | |
86 | hlist_bl_set_first(h, n); | |
87 | } | |
88 | ||
34191ae8 NT |
89 | static inline void hlist_bl_add_before(struct hlist_bl_node *n, |
90 | struct hlist_bl_node *next) | |
91 | { | |
92 | struct hlist_bl_node **pprev = next->pprev; | |
93 | ||
94 | n->pprev = pprev; | |
95 | n->next = next; | |
96 | next->pprev = &n->next; | |
97 | ||
98 | /* pprev may be `first`, so be careful not to lose the lock bit */ | |
99 | WRITE_ONCE(*pprev, | |
100 | (struct hlist_bl_node *) | |
101 | ((uintptr_t)n | ((uintptr_t)*pprev & LIST_BL_LOCKMASK))); | |
102 | } | |
103 | ||
104 | static inline void hlist_bl_add_behind(struct hlist_bl_node *n, | |
105 | struct hlist_bl_node *prev) | |
106 | { | |
107 | n->next = prev->next; | |
108 | n->pprev = &prev->next; | |
109 | prev->next = n; | |
110 | ||
111 | if (n->next) | |
112 | n->next->pprev = &n->next; | |
113 | } | |
114 | ||
4e35e607 NP |
115 | static inline void __hlist_bl_del(struct hlist_bl_node *n) |
116 | { | |
117 | struct hlist_bl_node *next = n->next; | |
118 | struct hlist_bl_node **pprev = n->pprev; | |
119 | ||
120 | LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK); | |
121 | ||
122 | /* pprev may be `first`, so be careful not to lose the lock bit */ | |
7f5f873c PM |
123 | WRITE_ONCE(*pprev, |
124 | (struct hlist_bl_node *) | |
4e35e607 | 125 | ((unsigned long)next | |
7f5f873c | 126 | ((unsigned long)*pprev & LIST_BL_LOCKMASK))); |
4e35e607 NP |
127 | if (next) |
128 | next->pprev = pprev; | |
129 | } | |
130 | ||
131 | static inline void hlist_bl_del(struct hlist_bl_node *n) | |
132 | { | |
133 | __hlist_bl_del(n); | |
134 | n->next = LIST_POISON1; | |
135 | n->pprev = LIST_POISON2; | |
136 | } | |
137 | ||
138 | static inline void hlist_bl_del_init(struct hlist_bl_node *n) | |
139 | { | |
140 | if (!hlist_bl_unhashed(n)) { | |
141 | __hlist_bl_del(n); | |
142 | INIT_HLIST_BL_NODE(n); | |
143 | } | |
144 | } | |
145 | ||
1879fd6a CH |
146 | static inline void hlist_bl_lock(struct hlist_bl_head *b) |
147 | { | |
148 | bit_spin_lock(0, (unsigned long *)b); | |
149 | } | |
150 | ||
151 | static inline void hlist_bl_unlock(struct hlist_bl_head *b) | |
152 | { | |
153 | __bit_spin_unlock(0, (unsigned long *)b); | |
154 | } | |
155 | ||
49d0de08 SW |
156 | static inline bool hlist_bl_is_locked(struct hlist_bl_head *b) |
157 | { | |
158 | return bit_spin_is_locked(0, (unsigned long *)b); | |
159 | } | |
160 | ||
4e35e607 NP |
161 | /** |
162 | * hlist_bl_for_each_entry - iterate over list of given type | |
163 | * @tpos: the type * to use as a loop cursor. | |
164 | * @pos: the &struct hlist_node to use as a loop cursor. | |
165 | * @head: the head for your list. | |
166 | * @member: the name of the hlist_node within the struct. | |
167 | * | |
168 | */ | |
169 | #define hlist_bl_for_each_entry(tpos, pos, head, member) \ | |
170 | for (pos = hlist_bl_first(head); \ | |
171 | pos && \ | |
172 | ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1;}); \ | |
173 | pos = pos->next) | |
174 | ||
175 | /** | |
176 | * hlist_bl_for_each_entry_safe - iterate over list of given type safe against removal of list entry | |
177 | * @tpos: the type * to use as a loop cursor. | |
178 | * @pos: the &struct hlist_node to use as a loop cursor. | |
179 | * @n: another &struct hlist_node to use as temporary storage | |
180 | * @head: the head for your list. | |
181 | * @member: the name of the hlist_node within the struct. | |
182 | */ | |
183 | #define hlist_bl_for_each_entry_safe(tpos, pos, n, head, member) \ | |
184 | for (pos = hlist_bl_first(head); \ | |
185 | pos && ({ n = pos->next; 1; }) && \ | |
186 | ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1;}); \ | |
187 | pos = n) | |
188 | ||
189 | #endif |