src/notifier.c

   1 /*
   2  * nao-ulib
   3  * Copyright 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>
   4  * Subject to the GPL.
   5  * Nao-Team HTWK,
   6  * Faculty of Computer Science, Mathematics and Natural Sciences,
   7  * Leipzig University of Applied Sciences (HTWK Leipzig)
   8  */
   9
  10 #include <stdint.h>
  11 #include <errno.h>
  12
  13 #include "notifier.h"
  14 #include "comp_x86.h"
  15
  16 /*
  17  * Event notification framework based on the idea of the Linux kernel
  18  * notification chains by Alan Cox which have originally been written
  19  * for event delivery within the networking subsystem.
  20  */
  21
  22 int register_event_hook(struct event_block **head,
  23                         struct event_block *block)
  24 {
  25         if (!block || !head)
  26                 return -EINVAL;
  27         if (!block->hook)
  28                 return -EINVAL;
  29
  30         while ((*head) != NULL) {
  31                 if (block->prio > (*head)->prio)
  32                         break;
  33
  34                 head = &((*head)->next);
  35         }
  36
  37         block->next = (*head);
  38         (*head) = block;
  39         barrier();
  40
  41         return 0;
  42 }
  43
  44 int register_event_hook_once(struct event_block **head,
  45                              struct event_block *block)
  46 {
  47         if (!block || !head)
  48                 return -EINVAL;
  49         if (!block->hook)
  50                 return -EINVAL;
  51
  52         while ((*head) != NULL) {
  53                 if (unlikely(block == (*head)))
  54                         return -EEXIST;
  55
  56                 if (block->prio > (*head)->prio)
  57                         break;
  58
  59                 head = &((*head)->next);
  60         }
  61
  62         block->next = (*head);
  63         (*head) = block;
  64         barrier();
  65
  66         return 0;
  67 }
  68
  69 int unregister_event_hook(struct event_block **head,
  70                           struct event_block *block)
  71 {
  72         if (!block || !head)
  73                 return -EINVAL;
  74
  75         while ((*head) != NULL) {
  76                 if (unlikely(block == (*head))) {
  77                         (*head) = block->next;
  78                         barrier();
  79                         break;
  80                 }
  81
  82                 head = &((*head)->next);
  83         }
  84
  85         return 0;
  86 }
  87
  88 int call_event_hooks(struct event_block **head, unsigned long event,
  89                      const void *arg, int *called)
  90 {
  91         int ret = BLOCK_SUCC_DONE;
  92         struct event_block *block = *head, *next_block;
  93
  94         if (!head || !arg)
  95                 return -EINVAL;
  96         if (called)
  97                 (*called) = 0;
  98
  99         while (block) {
 100                 next_block = block->next;
 101
 102                 ret = block->hook(block, event, arg);
 103                 if (ret & BLOCK_STOP_CHAIN)
 104                         break;
 105
 106                 if(called)
 107                         (*called)++;
 108
 109                 block = next_block;
 110         }
 111
 112         return ret;
 113 }
 114