kernel/intermodule.c

   1 /* Deprecated, do not use.  Moved from module.c to here. --RR */
   2
   3 /* Written by Keith Owens <kaos@ocs.com.au> Oct 2000 */
   4 #include <linux/module.h>
   5 #include <linux/kmod.h>
   6 #include <linux/spinlock.h>
   7 #include <linux/list.h>
   8 #include <linux/slab.h>
   9
  10 /* inter_module functions are always available, even when the kernel is
  11  * compiled without modules.  Consumers of inter_module_xxx routines
  12  * will always work, even when both are built into the kernel, this
  13  * approach removes lots of #ifdefs in mainline code.
  14  */
  15
  16 static struct list_head ime_list = LIST_HEAD_INIT(ime_list);
  17 static DEFINE_SPINLOCK(ime_lock);
  18 static int kmalloc_failed;
  19
  20 struct inter_module_entry {
  21         struct list_head list;
  22         const char *im_name;
  23         struct module *owner;
  24         const void *userdata;
  25 };
  26
  27 /**
  28  * inter_module_register - register a new set of inter module data.
  29  * @im_name: an arbitrary string to identify the data, must be unique
  30  * @owner: module that is registering the data, always use THIS_MODULE
  31  * @userdata: pointer to arbitrary userdata to be registered
  32  *
  33  * Description: Check that the im_name has not already been registered,
  34  * complain if it has.  For new data, add it to the inter_module_entry
  35  * list.
  36  */
  37 void inter_module_register(const char *im_name, struct module *owner, const void *userdata)
  38 {
  39         struct list_head *tmp;
  40         struct inter_module_entry *ime, *ime_new;
  41
  42         if (!(ime_new = kzalloc(sizeof(*ime), GFP_KERNEL))) {
  43                 /* Overloaded kernel, not fatal */
  44                 printk(KERN_ERR
  45                         "Aiee, inter_module_register: cannot kmalloc entry for '%s'\n",
  46                         im_name);
  47                 kmalloc_failed = 1;
  48                 return;
  49         }
  50         ime_new->im_name = im_name;
  51         ime_new->owner = owner;
  52         ime_new->userdata = userdata;
  53
  54         spin_lock(&ime_lock);
  55         list_for_each(tmp, &ime_list) {
  56                 ime = list_entry(tmp, struct inter_module_entry, list);
  57                 if (strcmp(ime->im_name, im_name) == 0) {
  58                         spin_unlock(&ime_lock);
  59                         kfree(ime_new);
  60                         /* Program logic error, fatal */
  61                         printk(KERN_ERR "inter_module_register: duplicate im_name '%s'", im_name);
  62                         BUG();
  63                 }
  64         }
  65         list_add(&(ime_new->list), &ime_list);
  66         spin_unlock(&ime_lock);
  67 }
  68
  69 /**
  70  * inter_module_unregister - unregister a set of inter module data.
  71  * @im_name: an arbitrary string to identify the data, must be unique
  72  *
  73  * Description: Check that the im_name has been registered, complain if
  74  * it has not.  For existing data, remove it from the
  75  * inter_module_entry list.
  76  */
  77 void inter_module_unregister(const char *im_name)
  78 {
  79         struct list_head *tmp;
  80         struct inter_module_entry *ime;
  81
  82         spin_lock(&ime_lock);
  83         list_for_each(tmp, &ime_list) {
  84                 ime = list_entry(tmp, struct inter_module_entry, list);
  85                 if (strcmp(ime->im_name, im_name) == 0) {
  86                         list_del(&(ime->list));
  87                         spin_unlock(&ime_lock);
  88                         kfree(ime);
  89                         return;
  90                 }
  91         }
  92         spin_unlock(&ime_lock);
  93         if (kmalloc_failed) {
  94                 printk(KERN_ERR
  95                         "inter_module_unregister: no entry for '%s', "
  96                         "probably caused by previous kmalloc failure\n",
  97                         im_name);
  98                 return;
  99         }
 100         else {
 101                 /* Program logic error, fatal */
 102                 printk(KERN_ERR "inter_module_unregister: no entry for '%s'", im_name);
 103                 BUG();
 104         }
 105 }
 106
 107 /**
 108  * inter_module_get - return arbitrary userdata from another module.
 109  * @im_name: an arbitrary string to identify the data, must be unique
 110  *
 111  * Description: If the im_name has not been registered, return NULL.
 112  * Try to increment the use count on the owning module, if that fails
 113  * then return NULL.  Otherwise return the userdata.
 114  */
 115 static const void *inter_module_get(const char *im_name)
 116 {
 117         struct list_head *tmp;
 118         struct inter_module_entry *ime;
 119         const void *result = NULL;
 120
 121         spin_lock(&ime_lock);
 122         list_for_each(tmp, &ime_list) {
 123                 ime = list_entry(tmp, struct inter_module_entry, list);
 124                 if (strcmp(ime->im_name, im_name) == 0) {
 125                         if (try_module_get(ime->owner))
 126                                 result = ime->userdata;
 127                         break;
 128                 }
 129         }
 130         spin_unlock(&ime_lock);
 131         return(result);
 132 }
 133
 134 /**
 135  * inter_module_get_request - im get with automatic request_module.
 136  * @im_name: an arbitrary string to identify the data, must be unique
 137  * @modname: module that is expected to register im_name
 138  *
 139  * Description: If inter_module_get fails, do request_module then retry.
 140  */
 141 const void *inter_module_get_request(const char *im_name, const char *modname)
 142 {
 143         const void *result = inter_module_get(im_name);
 144         if (!result) {
 145                 request_module("%s", modname);
 146                 result = inter_module_get(im_name);
 147         }
 148         return(result);
 149 }
 150
 151 /**
 152  * inter_module_put - release use of data from another module.
 153  * @im_name: an arbitrary string to identify the data, must be unique
 154  *
 155  * Description: If the im_name has not been registered, complain,
 156  * otherwise decrement the use count on the owning module.
 157  */
 158 void inter_module_put(const char *im_name)
 159 {
 160         struct list_head *tmp;
 161         struct inter_module_entry *ime;
 162
 163         spin_lock(&ime_lock);
 164         list_for_each(tmp, &ime_list) {
 165                 ime = list_entry(tmp, struct inter_module_entry, list);
 166                 if (strcmp(ime->im_name, im_name) == 0) {
 167                         if (ime->owner)
 168                                 module_put(ime->owner);
 169                         spin_unlock(&ime_lock);
 170                         return;
 171                 }
 172         }
 173         spin_unlock(&ime_lock);
 174         printk(KERN_ERR "inter_module_put: no entry for '%s'", im_name);
 175         BUG();
 176 }
 177
 178 EXPORT_SYMBOL(inter_module_register);
 179 EXPORT_SYMBOL(inter_module_unregister);
 180 EXPORT_SYMBOL(inter_module_get_request);
 181 EXPORT_SYMBOL(inter_module_put);
 182
 183 MODULE_LICENSE("GPL");
 184