include/urcu/list.h

   1 /*
   2  * Copyright (C) 2002 Free Software Foundation, Inc.
   3  * (originally part of the GNU C Library)
   4  * Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   5  *
   6  * Copyright (C) 2009 Pierre-Marc Fournier
   7  * Conversion to RCU list.
   8  * Copyright (C) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * This library is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * This library is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with this library; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #ifndef _CDS_LIST_H
  26 #define _CDS_LIST_H     1
  27
  28 /*
  29  * The definitions of this file are adopted from those which can be
  30  * found in the Linux kernel headers to enable people familiar with the
  31  * latter find their way in these sources as well.
  32  */
  33
  34 /* Basic type for the double-link list. */
  35 struct cds_list_head {
  36         struct cds_list_head *next, *prev;
  37 };
  38
  39 /* Define a variable with the head and tail of the list. */
  40 #define CDS_LIST_HEAD(name) \
  41         struct cds_list_head name = { &(name), &(name) }
  42
  43 /* Initialize a new list head. */
  44 #define CDS_INIT_LIST_HEAD(ptr) \
  45         (ptr)->next = (ptr)->prev = (ptr)
  46
  47 #define CDS_LIST_HEAD_INIT(name) { .prev = &(name), .next = &(name) }
  48
  49 /* Add new element at the head of the list. */
  50 static inline
  51 void cds_list_add(struct cds_list_head *newp, struct cds_list_head *head)
  52 {
  53         head->next->prev = newp;
  54         newp->next = head->next;
  55         newp->prev = head;
  56         head->next = newp;
  57 }
  58
  59 /* Add new element at the tail of the list. */
  60 static inline
  61 void cds_list_add_tail(struct cds_list_head *newp, struct cds_list_head *head)
  62 {
  63         head->prev->next = newp;
  64         newp->next = head;
  65         newp->prev = head->prev;
  66         head->prev = newp;
  67 }
  68
  69 /* Remove element from list. */
  70 static inline
  71 void __cds_list_del(struct cds_list_head *prev, struct cds_list_head *next)
  72 {
  73         next->prev = prev;
  74         prev->next = next;
  75 }
  76
  77 /* Remove element from list. */
  78 static inline
  79 void cds_list_del(struct cds_list_head *elem)
  80 {
  81         __cds_list_del(elem->prev, elem->next);
  82 }
  83
  84 /* Remove element from list, initializing the element's list pointers. */
  85 static inline
  86 void cds_list_del_init(struct cds_list_head *elem)
  87 {
  88         cds_list_del(elem);
  89         CDS_INIT_LIST_HEAD(elem);
  90 }
  91
  92 /* Delete from list, add to another list as head. */
  93 static inline
  94 void cds_list_move(struct cds_list_head *elem, struct cds_list_head *head)
  95 {
  96         __cds_list_del(elem->prev, elem->next);
  97         cds_list_add(elem, head);
  98 }
  99
 100 /* Replace an old entry. */
 101 static inline
 102 void cds_list_replace(struct cds_list_head *old, struct cds_list_head *_new)
 103 {
 104         _new->next = old->next;
 105         _new->prev = old->prev;
 106         _new->prev->next = _new;
 107         _new->next->prev = _new;
 108 }
 109
 110 /* Join two lists. */
 111 static inline
 112 void cds_list_splice(struct cds_list_head *add, struct cds_list_head *head)
 113 {
 114         /* Do nothing if the list which gets added is empty. */
 115         if (add != add->next) {
 116                 add->next->prev = head;
 117                 add->prev->next = head->next;
 118                 head->next->prev = add->prev;
 119                 head->next = add->next;
 120         }
 121 }
 122
 123 /* Get typed element from list at a given position. */
 124 #define cds_list_entry(ptr, type, member) \
 125         ((type *) ((char *) (ptr) - (unsigned long) (&((type *) 0)->member)))
 126
 127
 128 /* Get first entry from a list. */
 129 #define cds_list_first_entry(ptr, type, member) \
 130         cds_list_entry((ptr)->next, type, member)
 131
 132 /* Iterate forward over the elements of the list. */
 133 #define cds_list_for_each(pos, head) \
 134         for (pos = (head)->next; pos != (head); pos = pos->next)
 135
 136 /*
 137  * Iterate forward over the elements list. The list elements can be
 138  * removed from the list while doing this.
 139  */
 140 #define cds_list_for_each_safe(pos, p, head) \
 141         for (pos = (head)->next, p = pos->next; \
 142                 pos != (head); \
 143                 pos = p, p = pos->next)
 144
 145 /* Iterate backward over the elements of the list. */
 146 #define cds_list_for_each_prev(pos, head) \
 147         for (pos = (head)->prev; pos != (head); pos = pos->prev)
 148
 149 /*
 150  * Iterate backwards over the elements list. The list elements can be
 151  * removed from the list while doing this.
 152  */
 153 #define cds_list_for_each_prev_safe(pos, p, head) \
 154         for (pos = (head)->prev, p = pos->prev; \
 155                 pos != (head); \
 156                 pos = p, p = pos->prev)
 157
 158 #define cds_list_for_each_entry(pos, head, member) \
 159         for (pos = cds_list_entry((head)->next, __typeof__(*pos), member); \
 160                 &pos->member != (head); \
 161                 pos = cds_list_entry(pos->member.next, __typeof__(*pos), member))
 162
 163 #define cds_list_for_each_entry_reverse(pos, head, member) \
 164         for (pos = cds_list_entry((head)->prev, __typeof__(*pos), member); \
 165                 &pos->member != (head); \
 166                 pos = cds_list_entry(pos->member.prev, __typeof__(*pos), member))
 167
 168 #define cds_list_for_each_entry_safe(pos, p, head, member) \
 169         for (pos = cds_list_entry((head)->next, __typeof__(*pos), member), \
 170                         p = cds_list_entry(pos->member.next, __typeof__(*pos), member); \
 171                 &pos->member != (head); \
 172                 pos = p, p = cds_list_entry(pos->member.next, __typeof__(*pos), member))
 173
 174 /*
 175  * Same as cds_list_for_each_entry_safe, but starts from "pos" which should
 176  * point to an entry within the list.
 177  */
 178 #define cds_list_for_each_entry_safe_from(pos, p, head, member) \
 179         for (p = cds_list_entry(pos->member.next, __typeof__(*pos), member); \
 180                 &pos->member != (head); \
 181                 pos = p, p = cds_list_entry(pos->member.next, __typeof__(*pos), member))
 182
 183 static inline
 184 int cds_list_empty(struct cds_list_head *head)
 185 {
 186         return head == head->next;
 187 }
 188
 189 static inline
 190 void cds_list_replace_init(struct cds_list_head *old,
 191                 struct cds_list_head *_new)
 192 {
 193         struct cds_list_head *head = old->next;
 194
 195         cds_list_del(old);
 196         cds_list_add_tail(_new, head);
 197         CDS_INIT_LIST_HEAD(old);
 198 }
 199
 200 #endif  /* _CDS_LIST_H */