include/urcu/list.h

   1 // SPDX-FileCopyrightText: 2002 Free Software Foundation, Inc.
   2 // SPDX-FileCopyrightText: 2009 Pierre-Marc Fournier
   3 // SPDX-FileCopyrightText: 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4 //
   5 // SPDX-License-Identifier: LGPL-2.1-or-later
   6
   7 /*
   8  * (originally part of the GNU C Library)
   9  * Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
  10  */
  11
  12 #ifndef _CDS_LIST_H
  13 #define _CDS_LIST_H     1
  14
  15 #include <urcu/compiler.h>
  16
  17 /*
  18  * The definitions of this file are adopted from those which can be
  19  * found in the Linux kernel headers to enable people familiar with the
  20  * latter find their way in these sources as well.
  21  */
  22
  23 /* Basic type for the double-link list. */
  24 struct cds_list_head {
  25         struct cds_list_head *next, *prev;
  26 };
  27
  28 /* Define a variable with the head and tail of the list. */
  29 #define CDS_LIST_HEAD(name) \
  30         struct cds_list_head name = { &(name), &(name) }
  31
  32 /* Initialize a new list head. */
  33 #define CDS_INIT_LIST_HEAD(ptr) \
  34         (ptr)->next = (ptr)->prev = (ptr)
  35
  36 #define CDS_LIST_HEAD_INIT(name) { .next = &(name), .prev = &(name) }
  37
  38 /* Add new element at the head of the list. */
  39 static inline
  40 void cds_list_add(struct cds_list_head *newp, struct cds_list_head *head)
  41 {
  42         head->next->prev = newp;
  43         newp->next = head->next;
  44         newp->prev = head;
  45         head->next = newp;
  46 }
  47
  48 /* Add new element at the tail of the list. */
  49 static inline
  50 void cds_list_add_tail(struct cds_list_head *newp, struct cds_list_head *head)
  51 {
  52         head->prev->next = newp;
  53         newp->next = head;
  54         newp->prev = head->prev;
  55         head->prev = newp;
  56 }
  57
  58 /* Remove element from list. */
  59 static inline
  60 void __cds_list_del(struct cds_list_head *prev, struct cds_list_head *next)
  61 {
  62         next->prev = prev;
  63         prev->next = next;
  64 }
  65
  66 /* Remove element from list. */
  67 static inline
  68 void cds_list_del(struct cds_list_head *elem)
  69 {
  70         __cds_list_del(elem->prev, elem->next);
  71 }
  72
  73 /* Remove element from list, initializing the element's list pointers. */
  74 static inline
  75 void cds_list_del_init(struct cds_list_head *elem)
  76 {
  77         cds_list_del(elem);
  78         CDS_INIT_LIST_HEAD(elem);
  79 }
  80
  81 /* Delete from list, add to another list as head. */
  82 static inline
  83 void cds_list_move(struct cds_list_head *elem, struct cds_list_head *head)
  84 {
  85         __cds_list_del(elem->prev, elem->next);
  86         cds_list_add(elem, head);
  87 }
  88
  89 /* Replace an old entry. */
  90 static inline
  91 void cds_list_replace(const struct cds_list_head *old, struct cds_list_head *_new)
  92 {
  93         _new->next = old->next;
  94         _new->prev = old->prev;
  95         _new->prev->next = _new;
  96         _new->next->prev = _new;
  97 }
  98
  99 /* Join two lists. */
 100 static inline
 101 void cds_list_splice(struct cds_list_head *add, struct cds_list_head *head)
 102 {
 103         /* Do nothing if the list which gets added is empty. */
 104         if (add != add->next) {
 105                 add->next->prev = head;
 106                 add->prev->next = head->next;
 107                 head->next->prev = add->prev;
 108                 head->next = add->next;
 109         }
 110 }
 111
 112 /* Get typed element from list at a given position. */
 113 #define cds_list_entry(ptr, type, member)       caa_container_of(ptr, type, member)
 114
 115
 116 /* Get first entry from a list. */
 117 #define cds_list_first_entry(ptr, type, member) \
 118         cds_list_entry((ptr)->next, type, member)
 119
 120 /* Iterate forward over the elements of the list. */
 121 #define cds_list_for_each(pos, head) \
 122         for (pos = (head)->next; (pos) != (head); pos = (pos)->next)
 123
 124 /*
 125  * Iterate forward over the elements list. The list elements can be
 126  * removed from the list while doing this.
 127  */
 128 #define cds_list_for_each_safe(pos, p, head) \
 129         for (pos = (head)->next, p = (pos)->next; \
 130                 (pos) != (head); \
 131                 pos = (p), p = (pos)->next)
 132
 133 /* Iterate backward over the elements of the list. */
 134 #define cds_list_for_each_prev(pos, head) \
 135         for (pos = (head)->prev; (pos) != (head); pos = (pos)->prev)
 136
 137 /*
 138  * Iterate backwards over the elements list. The list elements can be
 139  * removed from the list while doing this.
 140  */
 141 #define cds_list_for_each_prev_safe(pos, p, head) \
 142         for (pos = (head)->prev, p = (pos)->prev; \
 143                 (pos) != (head); \
 144                 pos = (p), p = (pos)->prev)
 145
 146 #define cds_list_for_each_entry(pos, head, member) \
 147         for (pos = cds_list_entry((head)->next, __typeof__(*(pos)), member); \
 148                 &(pos)->member != (head); \
 149                 pos = cds_list_entry((pos)->member.next, __typeof__(*(pos)), member))
 150
 151 #define cds_list_for_each_entry_reverse(pos, head, member) \
 152         for (pos = cds_list_entry((head)->prev, __typeof__(*(pos)), member); \
 153                 &(pos)->member != (head); \
 154                 pos = cds_list_entry((pos)->member.prev, __typeof__(*(pos)), member))
 155
 156 #define cds_list_for_each_entry_safe(pos, p, head, member) \
 157         for (pos = cds_list_entry((head)->next, __typeof__(*(pos)), member), \
 158                         p = cds_list_entry((pos)->member.next, __typeof__(*(pos)), member); \
 159                 &(pos)->member != (head); \
 160                 pos = (p), p = cds_list_entry((pos)->member.next, __typeof__(*(pos)), member))
 161
 162 /*
 163  * Same as cds_list_for_each_entry_safe, but starts from "pos" which should
 164  * point to an entry within the list.
 165  */
 166 #define cds_list_for_each_entry_safe_from(pos, p, head, member) \
 167         for (p = cds_list_entry((pos)->member.next, __typeof__(*(pos)), member); \
 168                 &(pos)->member != (head); \
 169                 pos = (p), p = cds_list_entry((pos)->member.next, __typeof__(*(pos)), member))
 170
 171 static inline
 172 int cds_list_empty(const struct cds_list_head *head)
 173 {
 174         return head == head->next;
 175 }
 176
 177 static inline
 178 void cds_list_replace_init(struct cds_list_head *old,
 179                 struct cds_list_head *_new)
 180 {
 181         struct cds_list_head *head = old->next;
 182
 183         cds_list_del(old);
 184         cds_list_add_tail(_new, head);
 185         CDS_INIT_LIST_HEAD(old);
 186 }
 187
 188 #endif  /* _CDS_LIST_H */