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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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C
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147/* SPDX-License-Identifier: GPL-2.0 */#ifndef _LINUX_LIST_NULLS_H#define _LINUX_LIST_NULLS_H
#include <linux/poison.h>#include <linux/const.h>
/* * Special version of lists, where end of list is not a NULL pointer, * but a 'nulls' marker, which can have many different values. * (up to 2^31 different values guaranteed on all platforms) * * In the standard hlist, termination of a list is the NULL pointer. * In this special 'nulls' variant, we use the fact that objects stored in * a list are aligned on a word (4 or 8 bytes alignment). * We therefore use the last significant bit of 'ptr' : * Set to 1 : This is a 'nulls' end-of-list marker (ptr >> 1) * Set to 0 : This is a pointer to some object (ptr) */
struct hlist_nulls_head { struct hlist_nulls_node *first;};
struct hlist_nulls_node { struct hlist_nulls_node *next, **pprev;};#define NULLS_MARKER(value) (1UL | (((long)value) << 1))#define INIT_HLIST_NULLS_HEAD(ptr, nulls) \ ((ptr)->first = (struct hlist_nulls_node *) NULLS_MARKER(nulls))#define HLIST_NULLS_HEAD_INIT(nulls) {.first = (struct hlist_nulls_node *)NULLS_MARKER(nulls)}
#define hlist_nulls_entry(ptr, type, member) container_of(ptr,type,member)
#define hlist_nulls_entry_safe(ptr, type, member) \ ({ typeof(ptr) ____ptr = (ptr); \ !is_a_nulls(____ptr) ? hlist_nulls_entry(____ptr, type, member) : NULL; \ })/** * ptr_is_a_nulls - Test if a ptr is a nulls * @ptr: ptr to be tested * */static inline int is_a_nulls(const struct hlist_nulls_node *ptr){ return ((unsigned long)ptr & 1);}
/** * get_nulls_value - Get the 'nulls' value of the end of chain * @ptr: end of chain * * Should be called only if is_a_nulls(ptr); */static inline unsigned long get_nulls_value(const struct hlist_nulls_node *ptr){ return ((unsigned long)ptr) >> 1;}
/** * hlist_nulls_unhashed - Has node been removed and reinitialized? * @h: Node to be checked * * Not that not all removal functions will leave a node in unhashed state. * For example, hlist_del_init_rcu() leaves the node in unhashed state, * but hlist_nulls_del() does not. */static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h){ return !h->pprev;}
/** * hlist_nulls_unhashed_lockless - Has node been removed and reinitialized? * @h: Node to be checked * * Not that not all removal functions will leave a node in unhashed state. * For example, hlist_del_init_rcu() leaves the node in unhashed state, * but hlist_nulls_del() does not. Unlike hlist_nulls_unhashed(), this * function may be used locklessly. */static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h){ return !READ_ONCE(h->pprev);}
static inline int hlist_nulls_empty(const struct hlist_nulls_head *h){ return is_a_nulls(READ_ONCE(h->first));}
static inline void hlist_nulls_add_head(struct hlist_nulls_node *n, struct hlist_nulls_head *h){ struct hlist_nulls_node *first = h->first;
n->next = first; WRITE_ONCE(n->pprev, &h->first); h->first = n; if (!is_a_nulls(first)) WRITE_ONCE(first->pprev, &n->next);}
static inline void __hlist_nulls_del(struct hlist_nulls_node *n){ struct hlist_nulls_node *next = n->next; struct hlist_nulls_node **pprev = n->pprev;
WRITE_ONCE(*pprev, next); if (!is_a_nulls(next)) WRITE_ONCE(next->pprev, pprev);}
static inline void hlist_nulls_del(struct hlist_nulls_node *n){ __hlist_nulls_del(n); WRITE_ONCE(n->pprev, LIST_POISON2);}
/** * hlist_nulls_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_nulls_for_each_entry(tpos, pos, head, member) \ for (pos = (head)->first; \ (!is_a_nulls(pos)) && \ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1;}); \ pos = pos->next)
/** * hlist_nulls_for_each_entry_from - iterate over a hlist continuing from current point * @tpos: the type * to use as a loop cursor. * @pos: the &struct hlist_node to use as a loop cursor. * @member: the name of the hlist_node within the struct. * */#define hlist_nulls_for_each_entry_from(tpos, pos, member) \ for (; (!is_a_nulls(pos)) && \ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1;}); \ pos = pos->next)
#endif