include/linux/notifier.h

/* */
This source file includes following definitions.
notifier_chain_register
notifier_chain_unregister
notifier_call_chain
   1 /*
   2  *      Routines to manage notifier chains for passing status changes to any
   3  *      interested routines. We need this instead of hard coded call lists so
   4  *      that modules can poke their nose into the innards. The network devices
   5  *      needed them so here they are for the rest of you.
   6  *
   7  *                              Alan Cox <Alan.Cox@linux.org>
   8  */
   9  
  10 #ifndef _LINUX_NOTIFIER_H
  11 #define _LINUX_NOTIFIER_H
  12 #include <linux/errno.h>
  13 
  14 struct notifier_block
  15 {
  16         int (*notifier_call)(unsigned long, void *);
  17         struct notifier_block *next;
  18         int priority;
  19 };
  20 
  21 
  22 #ifdef __KERNEL__
  23 
  24 #define NOTIFY_DONE             0x0000          /* Don't care */
  25 #define NOTIFY_OK               0x0001          /* Suits me */
  26 #define NOTIFY_STOP_MASK        0x8000          /* Don't call further */
  27 #define NOTIFY_BAD              (NOTIFY_STOP_MASK|0x0002)       /* Bad/Veto action      */
  28 
  29 extern __inline__ int notifier_chain_register(struct notifier_block **list, struct notifier_block *n)
     /*  */
  30 {
  31         while(*list)
  32         {
  33                 if(n->priority > (*list)->priority)
  34                         break;
  35                 list= &((*list)->next);
  36         }
  37         n->next = *list;
  38         *list=n;
  39         return 0;
  40 }
  41 
  42 /*
  43  *      Warning to any non GPL module writers out there.. these functions are
  44  *      GPL'd
  45  */
  46  
  47 extern __inline__ int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n)
     /*  */
  48 {
  49         while((*nl)!=NULL)
  50         {
  51                 if((*nl)==n)
  52                 {
  53                         *nl=n->next;
  54                         return 0;
  55                 }
  56                 nl=&((*nl)->next);
  57         }
  58         return -ENOENT;
  59 }
  60 
  61 /*
  62  *      This is one of these things that is generally shorter inline
  63  */
  64  
  65 extern __inline__ int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v)
     /*  */
  66 {
  67         int ret=NOTIFY_DONE;
  68         struct notifier_block *nb = *n;
  69         while(nb)
  70         {
  71                 ret=nb->notifier_call(val,v);
  72                 if(ret&NOTIFY_STOP_MASK)
  73                         return ret;
  74                 nb=nb->next;
  75         }
  76         return ret;
  77 }
  78 
  79 
  80 /*
  81  *      Declared notifiers so far. I can imagine quite a few more chains
  82  *      over time (eg laptop power reset chains, reboot chain (to clean 
  83  *      device units up), device [un]mount chain, module load/unload chain,
  84  *      low memory chain, screenblank chain (for plug in modular screenblankers) 
  85  *      VC switch chains (for loadable kernel svgalib VC switch helpers) etc...
  86  */
  87  
  88 /* netdevice notifier chain */
  89 #define NETDEV_UP       0x0001  /* For now you can't veto a device up/down */
  90 #define NETDEV_DOWN     0x0002
  91 #define NETDEV_REBOOT   0x0003  /* Tell a protocol stack a network interface
  92                                    detected a hardware crash and restarted
  93                                    - we can use this eg to kick tcp sessions
  94                                    once done */
  95 #endif
  96 #endif
/* */
root/include/linux/notifier.h

INCLUDED FROM

DEFINITIONS
