net/rds/xlist.h

   1 #ifndef _LINUX_XLIST_H
   2 #define _LINUX_XLIST_H
   3
   4 #include <linux/stddef.h>
   5 #include <linux/poison.h>
   6 #include <linux/prefetch.h>
   7 #include <asm/system.h>
   8
   9 struct xlist_head {
  10         struct xlist_head *next;
  11 };
  12
  13 static inline void INIT_XLIST_HEAD(struct xlist_head *list)
  14 {
  15         list->next = NULL;
  16 }
  17
  18 static inline int xlist_empty(struct xlist_head *head)
  19 {
  20         return head->next == NULL;
  21 }
  22
  23 static inline void xlist_add(struct xlist_head *new, struct xlist_head *tail,
  24                              struct xlist_head *head)
  25 {
  26         struct xlist_head *cur;
  27         struct xlist_head *check;
  28
  29         while (1) {
  30                 cur = head->next;
  31                 tail->next = cur;
  32                 check = cmpxchg(&head->next, cur, new);
  33                 if (check == cur)
  34                         break;
  35         }
  36 }
  37
  38 static inline struct xlist_head *xlist_del_head(struct xlist_head *head)
  39 {
  40         struct xlist_head *cur;
  41         struct xlist_head *check;
  42         struct xlist_head *next;
  43
  44         while (1) {
  45                 cur = head->next;
  46                 if (!cur)
  47                         goto out;
  48
  49                 next = cur->next;
  50                 check = cmpxchg(&head->next, cur, next);
  51                 if (check == cur)
  52                         goto out;
  53         }
  54 out:
  55         return cur;
  56 }
  57
  58 static inline struct xlist_head *xlist_del_head_fast(struct xlist_head *head)
  59 {
  60         struct xlist_head *cur;
  61
  62         cur = head->next;
  63         if (!cur)
  64                 return NULL;
  65
  66         head->next = cur->next;
  67         return cur;
  68 }
  69
  70 static inline void xlist_splice(struct xlist_head *list,
  71                                 struct xlist_head *head)
  72 {
  73         struct xlist_head *cur;
  74
  75         WARN_ON(head->next);
  76         cur = xchg(&list->next, NULL);
  77         head->next = cur;
  78 }
  79
  80 #endif