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