bsd/net/init.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <kern/kalloc.h>
  25 #include <libkern/OSAtomic.h>
  26 #include <sys/errno.h>
  27 #include <net/init.h>
  28 #include <libkern/libkern.h>
  29 #include <string.h>
  30
  31 struct init_list_entry {
  32         struct init_list_entry  *next;
  33         net_init_func_ptr               func;
  34 };
  35
  36 #define LIST_RAN ((struct init_list_entry*)0xffffffff)
  37 static struct init_list_entry   *list_head = 0;
  38
  39 errno_t
  40 net_init_add(
  41         net_init_func_ptr init_func)
  42 {
  43         struct init_list_entry  *entry;
  44
  45         if (init_func == 0) {
  46                 return EINVAL;
  47         }
  48
  49         /* Check if we've already started */
  50         if (list_head == LIST_RAN) {
  51                 return EALREADY;
  52         }
  53
  54         entry = kalloc(sizeof(*entry));
  55         if (entry == 0) {
  56                 printf("net_init_add: no memory\n");
  57                 return ENOMEM;
  58         }
  59
  60         bzero(entry, sizeof(*entry));
  61         entry->func = init_func;
  62
  63         do {
  64                 entry->next = list_head;
  65
  66                 if (entry->next == LIST_RAN) {
  67                         /* List already ran, cleanup and call the function */
  68                         kfree(entry, sizeof(*entry));
  69                         return EALREADY;
  70                 }
  71         } while(!OSCompareAndSwap((UInt32)entry->next, (UInt32)entry,
  72                                                           (UInt32*)&list_head));
  73
  74         return 0;
  75 }
  76
  77 __private_extern__ void
  78 net_init_run(void)
  79 {
  80         struct init_list_entry  *backward_head = 0;
  81         struct init_list_entry  *forward_head = 0;
  82         struct init_list_entry  *current = 0;
  83
  84         /*
  85          * Grab the list, replacing the head with 0xffffffff to indicate
  86          * that we've already run.
  87          */
  88         do {
  89                 backward_head = list_head;
  90         } while (!OSCompareAndSwap((UInt32)backward_head, (UInt32)LIST_RAN,
  91                                                            (UInt32*)&list_head));
  92
  93         /* Reverse the order of the list */
  94         while (backward_head != 0) {
  95                 current = backward_head;
  96                 backward_head = current->next;
  97                 current->next = forward_head;
  98                 forward_head = current;
  99         }
 100
 101         /* Call each function pointer registered */
 102         while (forward_head != 0) {
 103                 current = forward_head;
 104                 forward_head = current->next;
 105                 current->func();
 106                 kfree(current, sizeof(*current));
 107         }
 108 }