pytx/list.h

   1 /* Stolen from Linux 2.6.7 */
   2 #ifndef _LINUX_LIST_H
   3 #define _LINUX_LIST_H
   4
   5 #include <stdlib.h>
   6
   7 static inline void prefetch(const void *x)
   8 {
   9 }
  10
  11 /*
  12  * These are non-NULL pointers that will result in page faults
  13  * under normal circumstances, used to verify that nobody uses
  14  * non-initialized list entries.
  15  */
  16 #define LIST_POISON1  ((void *) 0x00100100)
  17 #define LIST_POISON2  ((void *) 0x00200200)
  18
  19 /*
  20  * Simple doubly linked list implementation.
  21  *
  22  * Some of the internal functions ("__xxx") are useful when
  23  * manipulating whole lists rather than single entries, as
  24  * sometimes we already know the next/prev entries and we can
  25  * generate better code by using them directly rather than
  26  * using the generic single-entry routines.
  27  */
  28
  29 struct list_head {
  30         struct list_head *next, *prev;
  31 };
  32
  33 #define LIST_HEAD_INIT(name) { &(name), &(name) }
  34
  35 #define LIST_HEAD(name) \
  36         struct list_head name = LIST_HEAD_INIT(name)
  37
  38 static inline void list_init(struct list_head *head)
  39 {
  40         head->next = head;
  41         head->prev = head;
  42 }
  43
  44 /*
  45  * Insert a new entry between two known consecutive entries.
  46  *
  47  * This is only for internal list manipulation where we know
  48  * the prev/next entries already!
  49  */
  50 static inline void __list_add(struct list_head *new,
  51                               struct list_head *prev,
  52                               struct list_head *next)
  53 {
  54         next->prev = new;
  55         new->next = next;
  56         new->prev = prev;
  57         prev->next = new;
  58 }
  59
  60 /**
  61  * list_add - add a new entry
  62  * @new: new entry to be added
  63  * @head: list head to add it after
  64  *
  65  * Insert a new entry after the specified head.
  66  * This is good for implementing stacks.
  67  */
  68 static inline void list_add(struct list_head *new, struct list_head *head)
  69 {
  70         __list_add(new, head, head->next);
  71 }
  72
  73 /**
  74  * list_add_tail - add a new entry
  75  * @new: new entry to be added
  76  * @head: list head to add it before
  77  *
  78  * Insert a new entry before the specified head.
  79  * This is useful for implementing queues.
  80  */
  81 static inline void list_add_tail(struct list_head *new, struct list_head *head)
  82 {
  83         __list_add(new, head->prev, head);
  84 }
  85
  86 /*
  87  * Delete a list entry by making the prev/next entries
  88  * point to each other.
  89  *
  90  * This is only for internal list manipulation where we know
  91  * the prev/next entries already!
  92  */
  93 static inline void __list_del(struct list_head * prev, struct list_head * next)
  94 {
  95         next->prev = prev;
  96         prev->next = next;
  97 }
  98
  99 /**
 100  * list_del - deletes entry from list.
 101  * @entry: the element to delete from the list.
 102  * Note: list_empty on entry does not return true after this, the entry is
 103  * in an undefined state.
 104  */
 105 static inline void list_del(struct list_head *entry)
 106 {
 107         __list_del(entry->prev, entry->next);
 108         entry->next = LIST_POISON1;
 109         entry->prev = LIST_POISON2;
 110 }
 111
 112 /**
 113  * list_del_init - deletes entry from list and reinitialize it.
 114  * @entry: the element to delete from the list.
 115  */
 116 static inline void list_del_init(struct list_head *entry)
 117 {
 118         __list_del(entry->prev, entry->next);
 119         list_init(entry);
 120 }
 121
 122 /**
 123  * list_move - delete from one list and add as another's head
 124  * @list: the entry to move
 125  * @head: the head that will precede our entry
 126  */
 127 static inline void list_move(struct list_head *list, struct list_head *head)
 128 {
 129         __list_del(list->prev, list->next);
 130         list_add(list, head);
 131 }
 132
 133 /**
 134  * list_move_tail - delete from one list and add as another's tail
 135  * @list: the entry to move
 136  * @head: the head that will follow our entry
 137  */
 138 static inline void list_move_tail(struct list_head *list,
 139                                   struct list_head *head)
 140 {
 141         __list_del(list->prev, list->next);
 142         list_add_tail(list, head);
 143 }
 144
 145 /**
 146  * list_empty - tests whether a list is empty
 147  * @head: the list to test.
 148  */
 149 static inline int list_empty(const struct list_head *head)
 150 {
 151         return head->next == head;
 152 }
 153
 154 static inline void __list_splice(struct list_head *list,
 155                                  struct list_head *head)
 156 {
 157         struct list_head *first = list->next;
 158         struct list_head *last = list->prev;
 159         struct list_head *at = head->next;
 160
 161         first->prev = head;
 162         head->next = first;
 163
 164         last->next = at;
 165         at->prev = last;
 166 }
 167
 168 /**
 169  * list_splice - join two lists
 170  * @list: the new list to add.
 171  * @head: the place to add it in the first list.
 172  */
 173 static inline void list_splice(struct list_head *list, struct list_head *head)
 174 {
 175         if (!list_empty(list))
 176                 __list_splice(list, head);
 177 }
 178
 179 /**
 180  * list_splice_init - join two lists and reinitialise the emptied list.
 181  * @list: the new list to add.
 182  * @head: the place to add it in the first list.
 183  *
 184  * The list at @list is reinitialised
 185  */
 186 static inline void list_splice_init(struct list_head *list,
 187                                     struct list_head *head)
 188 {
 189         if (!list_empty(list)) {
 190                 __list_splice(list, head);
 191                 list_init(list);
 192         }
 193 }
 194
 195 #undef offsetof
 196 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 197
 198 /**
 199  * container_of - cast a member of a structure out to the containing structure
 200  *
 201  * @ptr:        the pointer to the member.
 202  * @type:       the type of the container struct this is embedded in.
 203  * @member:     the name of the member within the struct.
 204  *
 205  */
 206 #define container_of(ptr, type, member) ({                      \
 207         const __typeof__( ((type *)0)->member ) *__mptr = (ptr);        \
 208         (type *)( (char *)__mptr - offsetof(type,member) );})
 209
 210 /**
 211  * list_entry - get the struct for this entry
 212  * @ptr:        the &struct list_head pointer.
 213  * @type:       the type of the struct this is embedded in.
 214  * @member:     the name of the list_struct within the struct.
 215  */
 216 #define list_entry(ptr, type, member) \
 217         container_of(ptr, type, member)
 218
 219 /**
 220  * list_for_each        -       iterate over a list
 221  * @pos:        the &struct list_head to use as a loop counter.
 222  * @head:       the head for your list.
 223  */
 224 #define list_for_each(pos, head) \
 225         for (pos = (head)->next, prefetch(pos->next); pos != (head); \
 226                 pos = pos->next, prefetch(pos->next))
 227
 228 /**
 229  * __list_for_each      -       iterate over a list
 230  * @pos:        the &struct list_head to use as a loop counter.
 231  * @head:       the head for your list.
 232  *
 233  * This variant differs from list_for_each() in that it's the
 234  * simplest possible list iteration code, no prefetching is done.
 235  * Use this for code that knows the list to be very short (empty
 236  * or 1 entry) most of the time.
 237  */
 238 #define __list_for_each(pos, head) \
 239         for (pos = (head)->next; pos != (head); pos = pos->next)
 240
 241 /**
 242  * list_for_each_prev   -       iterate over a list backwards
 243  * @pos:        the &struct list_head to use as a loop counter.
 244  * @head:       the head for your list.
 245  */
 246 #define list_for_each_prev(pos, head) \
 247         for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
 248                 pos = pos->prev, prefetch(pos->prev))
 249
 250 /**
 251  * list_for_each_safe   -       iterate over a list safe against removal of list entry
 252  * @pos:        the &struct list_head to use as a loop counter.
 253  * @n:          another &struct list_head to use as temporary storage
 254  * @head:       the head for your list.
 255  */
 256 #define list_for_each_safe(pos, n, head) \
 257         for (pos = (head)->next, n = pos->next; pos != (head); \
 258                 pos = n, n = pos->next)
 259
 260 /**
 261  * list_for_each_entry  -       iterate over list of given type
 262  * @pos:        the type * to use as a loop counter.
 263  * @head:       the head for your list.
 264  * @member:     the name of the list_struct within the struct.
 265  */
 266 #define list_for_each_entry(pos, head, member)                          \
 267         for (pos = list_entry((head)->next, __typeof__(*pos), member),  \
 268                      prefetch(pos->member.next);                        \
 269              &pos->member != (head);                                    \
 270              pos = list_entry(pos->member.next, __typeof__(*pos), member),      \
 271                      prefetch(pos->member.next))
 272
 273 /**
 274  * list_for_each_entry_reverse - iterate backwards over list of given type.
 275  * @pos:        the type * to use as a loop counter.
 276  * @head:       the head for your list.
 277  * @member:     the name of the list_struct within the struct.
 278  */
 279 #define list_for_each_entry_reverse(pos, head, member)                  \
 280         for (pos = list_entry((head)->prev, __typeof__(*pos), member),  \
 281                      prefetch(pos->member.prev);                        \
 282              &pos->member != (head);                                    \
 283              pos = list_entry(pos->member.prev, __typeof__(*pos), member),      \
 284                      prefetch(pos->member.prev))
 285
 286 /**
 287  * list_prepare_entry - prepare a pos entry for use as a start point in
 288  *                      list_for_each_entry_continue
 289  * @pos:        the type * to use as a start point
 290  * @head:       the head of the list
 291  * @member:     the name of the list_struct within the struct.
 292  */
 293 #define list_prepare_entry(pos, head, member) \
 294         ((pos) ? : list_entry(head, __typeof__(*pos), member))
 295
 296 /**
 297  * list_for_each_entry_continue -       iterate over list of given type
 298  *                      continuing after existing point
 299  * @pos:        the type * to use as a loop counter.
 300  * @head:       the head for your list.
 301  * @member:     the name of the list_struct within the struct.
 302  */
 303 #define list_for_each_entry_continue(pos, head, member)                 \
 304         for (pos = list_entry(pos->member.next, __typeof__(*pos), member),      \
 305                      prefetch(pos->member.next);                        \
 306              &pos->member != (head);                                    \
 307              pos = list_entry(pos->member.next, __typeof__(*pos), member),      \
 308                      prefetch(pos->member.next))
 309
 310 /**
 311  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 312  * @pos:        the type * to use as a loop counter.
 313  * @n:          another type * to use as temporary storage
 314  * @head:       the head for your list.
 315  * @member:     the name of the list_struct within the struct.
 316  */
 317 #define list_for_each_entry_safe(pos, n, head, member)                  \
 318         for (pos = list_entry((head)->next, __typeof__(*pos), member),  \
 319                 n = list_entry(pos->member.next, __typeof__(*pos), member);     \
 320              &pos->member != (head);                                    \
 321              pos = n, n = list_entry(n->member.next, __typeof__(*n), member))
 322
 323 #endif