include/sys/list.h

   1 /*
   2  *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
   3  *  Copyright (C) 2007 The Regents of the University of California.
   4  *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
   5  *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
   6  *  UCRL-CODE-235197
   7  *
   8  *  This file is part of the SPL, Solaris Porting Layer.
   9  *  For details, see <http://zfsonlinux.org/>.
  10  *
  11  *  The SPL is free software; you can redistribute it and/or modify it
  12  *  under the terms of the GNU General Public License as published by the
  13  *  Free Software Foundation; either version 2 of the License, or (at your
  14  *  option) any later version.
  15  *
  16  *  The SPL is distributed in the hope that it will be useful, but WITHOUT
  17  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  19  *  for more details.
  20  *
  21  *  You should have received a copy of the GNU General Public License along
  22  *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
  23  */
  24
  25 #ifndef _SPL_LIST_H
  26 #define _SPL_LIST_H
  27
  28 #include <sys/types.h>
  29 #include <linux/list.h>
  30
  31 /*
  32  * NOTE: I have implemented the Solaris list API in terms of the native
  33  * linux API.  This has certain advantages in terms of leveraging the linux
  34  * list debugging infrastructure, but it also means that the internals of a
  35  * list differ slightly than on Solaris.  This is not a problem as long as
  36  * all callers stick to the published API.  The two major differences are:
  37  *
  38  * 1) A list_node_t is mapped to a linux list_head struct which changes
  39  *    the name of the list_next/list_prev pointers to next/prev respectively.
  40  *
  41  * 2) A list_node_t which is not attached to a list on Solaris is denoted
  42  *    by having its list_next/list_prev pointers set to NULL.  Under linux
  43  *    the next/prev pointers are set to LIST_POISON1 and LIST_POISON2
  44  *    respectively.  At this moment this only impacts the implementation
  45  *    of the list_link_init() and list_link_active() functions.
  46  */
  47
  48 typedef struct list_head list_node_t;
  49
  50 typedef struct list {
  51         size_t list_size;
  52         size_t list_offset;
  53         list_node_t list_head;
  54 } list_t;
  55
  56 #define list_d2l(a, obj) ((list_node_t *)(((char *)obj) + (a)->list_offset))
  57 #define list_object(a, node) ((void *)(((char *)node) - (a)->list_offset))
  58
  59 static inline int
  60 list_is_empty(list_t *list)
  61 {
  62         return (list_empty(&list->list_head));
  63 }
  64
  65 static inline void
  66 list_link_init(list_node_t *node)
  67 {
  68         node->next = LIST_POISON1;
  69         node->prev = LIST_POISON2;
  70 }
  71
  72 static inline void
  73 list_create(list_t *list, size_t size, size_t offset)
  74 {
  75         ASSERT(list);
  76         ASSERT(size > 0);
  77         ASSERT(size >= offset + sizeof (list_node_t));
  78
  79         list->list_size = size;
  80         list->list_offset = offset;
  81         INIT_LIST_HEAD(&list->list_head);
  82 }
  83
  84 static inline void
  85 list_destroy(list_t *list)
  86 {
  87         ASSERT(list);
  88         ASSERT(list_is_empty(list));
  89
  90         list_del(&list->list_head);
  91 }
  92
  93 static inline void
  94 list_insert_head(list_t *list, void *object)
  95 {
  96         list_add(list_d2l(list, object), &list->list_head);
  97 }
  98
  99 static inline void
 100 list_insert_tail(list_t *list, void *object)
 101 {
 102         list_add_tail(list_d2l(list, object), &list->list_head);
 103 }
 104
 105 static inline void
 106 list_insert_after(list_t *list, void *object, void *nobject)
 107 {
 108         if (object == NULL)
 109                 list_insert_head(list, nobject);
 110         else
 111                 list_add(list_d2l(list, nobject), list_d2l(list, object));
 112 }
 113
 114 static inline void
 115 list_insert_before(list_t *list, void *object, void *nobject)
 116 {
 117         if (object == NULL)
 118                 list_insert_tail(list, nobject);
 119         else
 120                 list_add_tail(list_d2l(list, nobject), list_d2l(list, object));
 121 }
 122
 123 static inline void
 124 list_remove(list_t *list, void *object)
 125 {
 126         ASSERT(!list_is_empty(list));
 127         list_del(list_d2l(list, object));
 128 }
 129
 130 static inline void *
 131 list_remove_head(list_t *list)
 132 {
 133         list_node_t *head = list->list_head.next;
 134         if (head == &list->list_head)
 135                 return (NULL);
 136
 137         list_del(head);
 138         return (list_object(list, head));
 139 }
 140
 141 static inline void *
 142 list_remove_tail(list_t *list)
 143 {
 144         list_node_t *tail = list->list_head.prev;
 145         if (tail == &list->list_head)
 146                 return (NULL);
 147
 148         list_del(tail);
 149         return (list_object(list, tail));
 150 }
 151
 152 static inline void *
 153 list_head(list_t *list)
 154 {
 155         if (list_is_empty(list))
 156                 return (NULL);
 157
 158         return (list_object(list, list->list_head.next));
 159 }
 160
 161 static inline void *
 162 list_tail(list_t *list)
 163 {
 164         if (list_is_empty(list))
 165                 return (NULL);
 166
 167         return (list_object(list, list->list_head.prev));
 168 }
 169
 170 static inline void *
 171 list_next(list_t *list, void *object)
 172 {
 173         list_node_t *node = list_d2l(list, object);
 174
 175         if (node->next != &list->list_head)
 176                 return (list_object(list, node->next));
 177
 178         return (NULL);
 179 }
 180
 181 static inline void *
 182 list_prev(list_t *list, void *object)
 183 {
 184         list_node_t *node = list_d2l(list, object);
 185
 186         if (node->prev != &list->list_head)
 187                 return (list_object(list, node->prev));
 188
 189         return (NULL);
 190 }
 191
 192 static inline int
 193 list_link_active(list_node_t *node)
 194 {
 195         return (node->next != LIST_POISON1) && (node->prev != LIST_POISON2);
 196 }
 197
 198 static inline void
 199 spl_list_move_tail(list_t *dst, list_t *src)
 200 {
 201         list_splice_init(&src->list_head, dst->list_head.prev);
 202 }
 203
 204 #define list_move_tail(dst, src)        spl_list_move_tail(dst, src)
 205
 206 static inline void
 207 list_link_replace(list_node_t *old_node, list_node_t *new_node)
 208 {
 209         ASSERT(list_link_active(old_node));
 210         ASSERT(!list_link_active(new_node));
 211
 212         new_node->next = old_node->next;
 213         new_node->prev = old_node->prev;
 214         old_node->prev->next = new_node;
 215         old_node->next->prev = new_node;
 216         list_link_init(old_node);
 217 }
 218
 219 #endif /* SPL_LIST_H */