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189 lines
4.8 KiB
189 lines
4.8 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#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_add_before(struct hlist_bl_node *n, |
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struct hlist_bl_node *next) |
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{ |
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struct hlist_bl_node **pprev = next->pprev; |
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n->pprev = pprev; |
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n->next = next; |
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next->pprev = &n->next; |
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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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((uintptr_t)n | ((uintptr_t)*pprev & LIST_BL_LOCKMASK))); |
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} |
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static inline void hlist_bl_add_behind(struct hlist_bl_node *n, |
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struct hlist_bl_node *prev) |
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{ |
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n->next = prev->next; |
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n->pprev = &prev->next; |
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prev->next = n; |
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if (n->next) |
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n->next->pprev = &n->next; |
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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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