163 lines
4.2 KiB
C
163 lines
4.2 KiB
C
#ifndef _LINUX_LIST_BL_H
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#define _LINUX_LIST_BL_H
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#include <linux/list.h>
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#include <linux/bit_spinlock.h>
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/*
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* Special version of lists, where head of the list has a lock in the lowest
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* bit. This is useful for scalable hash tables without increasing memory
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* footprint overhead.
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*
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* For modification operations, the 0 bit of hlist_bl_head->first
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* pointer must be set.
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*
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* With some small modifications, this can easily be adapted to store several
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* arbitrary bits (not just a single lock bit), if the need arises to store
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* some fast and compact auxiliary data.
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*/
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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#define LIST_BL_LOCKMASK 1UL
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#else
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#define LIST_BL_LOCKMASK 0UL
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#endif
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#ifdef CONFIG_DEBUG_LIST
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#define LIST_BL_BUG_ON(x) BUG_ON(x)
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#else
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#define LIST_BL_BUG_ON(x)
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#endif
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struct hlist_bl_head {
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struct hlist_bl_node *first;
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};
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struct hlist_bl_node {
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struct hlist_bl_node *next, **pprev;
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};
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#define INIT_HLIST_BL_HEAD(ptr) \
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((ptr)->first = NULL)
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static inline void INIT_HLIST_BL_NODE(struct hlist_bl_node *h)
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{
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h->next = NULL;
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h->pprev = NULL;
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}
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#define hlist_bl_entry(ptr, type, member) container_of(ptr,type,member)
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static inline bool hlist_bl_unhashed(const struct hlist_bl_node *h)
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{
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return !h->pprev;
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}
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static inline struct hlist_bl_node *hlist_bl_first(struct hlist_bl_head *h)
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{
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return (struct hlist_bl_node *)
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((unsigned long)h->first & ~LIST_BL_LOCKMASK);
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}
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static inline void hlist_bl_set_first(struct hlist_bl_head *h,
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struct hlist_bl_node *n)
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{
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LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK);
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LIST_BL_BUG_ON(((unsigned long)h->first & LIST_BL_LOCKMASK) !=
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LIST_BL_LOCKMASK);
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h->first = (struct hlist_bl_node *)((unsigned long)n | LIST_BL_LOCKMASK);
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}
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static inline bool hlist_bl_empty(const struct hlist_bl_head *h)
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{
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return !((unsigned long)READ_ONCE(h->first) & ~LIST_BL_LOCKMASK);
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}
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static inline void hlist_bl_add_head(struct hlist_bl_node *n,
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struct hlist_bl_head *h)
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{
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struct hlist_bl_node *first = hlist_bl_first(h);
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n->next = first;
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if (first)
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first->pprev = &n->next;
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n->pprev = &h->first;
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hlist_bl_set_first(h, n);
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}
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static inline void __hlist_bl_del(struct hlist_bl_node *n)
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{
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struct hlist_bl_node *next = n->next;
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struct hlist_bl_node **pprev = n->pprev;
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LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK);
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/* pprev may be `first`, so be careful not to lose the lock bit */
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WRITE_ONCE(*pprev,
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(struct hlist_bl_node *)
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((unsigned long)next |
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((unsigned long)*pprev & LIST_BL_LOCKMASK)));
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if (next)
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next->pprev = pprev;
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}
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static inline void hlist_bl_del(struct hlist_bl_node *n)
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{
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__hlist_bl_del(n);
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n->next = LIST_POISON1;
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n->pprev = LIST_POISON2;
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}
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static inline void hlist_bl_del_init(struct hlist_bl_node *n)
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{
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if (!hlist_bl_unhashed(n)) {
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__hlist_bl_del(n);
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INIT_HLIST_BL_NODE(n);
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}
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}
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static inline void hlist_bl_lock(struct hlist_bl_head *b)
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{
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bit_spin_lock(0, (unsigned long *)b);
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}
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static inline void hlist_bl_unlock(struct hlist_bl_head *b)
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{
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__bit_spin_unlock(0, (unsigned long *)b);
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}
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static inline bool hlist_bl_is_locked(struct hlist_bl_head *b)
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{
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return bit_spin_is_locked(0, (unsigned long *)b);
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}
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/**
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* hlist_bl_for_each_entry - iterate over list of given type
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* @tpos: the type * to use as a loop cursor.
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* @pos: the &struct hlist_node to use as a loop cursor.
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* @head: the head for your list.
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* @member: the name of the hlist_node within the struct.
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*
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*/
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#define hlist_bl_for_each_entry(tpos, pos, head, member) \
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for (pos = hlist_bl_first(head); \
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pos && \
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({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1;}); \
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pos = pos->next)
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/**
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* hlist_bl_for_each_entry_safe - iterate over list of given type safe against removal of list entry
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* @tpos: the type * to use as a loop cursor.
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* @pos: the &struct hlist_node to use as a loop cursor.
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* @n: another &struct hlist_node to use as temporary storage
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* @head: the head for your list.
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* @member: the name of the hlist_node within the struct.
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*/
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#define hlist_bl_for_each_entry_safe(tpos, pos, n, head, member) \
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for (pos = hlist_bl_first(head); \
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pos && ({ n = pos->next; 1; }) && \
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({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1;}); \
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pos = n)
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#endif
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