LXR linux/include/linux/notifier.h

   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#include <linux/mutex.h>
  14#include <linux/rwsem.h>
  15
  16/*
  17 * Notifier chains are of three types:
  18 *
  19 *      Atomic notifier chains: Chain callbacks run in interrupt/atomic
  20 *              context. Callouts are not allowed to block.
  21 *      Blocking notifier chains: Chain callbacks run in process context.
  22 *              Callouts are allowed to block.
  23 *      Raw notifier chains: There are no restrictions on callbacks,
  24 *              registration, or unregistration.  All locking and protection
  25 *              must be provided by the caller.
  26 *
  27 * atomic_notifier_chain_register() may be called from an atomic context,
  28 * but blocking_notifier_chain_register() must be called from a process
  29 * context.  Ditto for the corresponding _unregister() routines.
  30 *
  31 * atomic_notifier_chain_unregister() and blocking_notifier_chain_unregister()
  32 * _must not_ be called from within the call chain.
  33 */
  34
  35struct notifier_block {
  36        int (*notifier_call)(struct notifier_block *, unsigned long, void *);
  37        struct notifier_block *next;
  38        int priority;
  39};
  40
  41struct atomic_notifier_head {
  42        spinlock_t lock;
  43        struct notifier_block *head;
  44};
  45
  46struct blocking_notifier_head {
  47        struct rw_semaphore rwsem;
  48        struct notifier_block *head;
  49};
  50
  51struct raw_notifier_head {
  52        struct notifier_block *head;
  53};
  54
  55#define ATOMIC_INIT_NOTIFIER_HEAD(name) do {    \
  56                spin_lock_init(&(name)->lock);  \
  57                (name)->head = NULL;            \
  58        } while (0)
  59#define BLOCKING_INIT_NOTIFIER_HEAD(name) do {  \
  60                init_rwsem(&(name)->rwsem);     \
  61                (name)->head = NULL;            \
  62        } while (0)
  63#define RAW_INIT_NOTIFIER_HEAD(name) do {       \
  64                (name)->head = NULL;            \
  65        } while (0)
  66
  67#define ATOMIC_NOTIFIER_INIT(name) {                            \
  68                .lock = __SPIN_LOCK_UNLOCKED(name.lock),        \
  69                .head = NULL }
  70#define BLOCKING_NOTIFIER_INIT(name) {                          \
  71                .rwsem = __RWSEM_INITIALIZER((name).rwsem),     \
  72                .head = NULL }
  73#define RAW_NOTIFIER_INIT(name) {                               \
  74                .head = NULL }
  75
  76#define ATOMIC_NOTIFIER_HEAD(name)                              \
  77        struct atomic_notifier_head name =                      \
  78                ATOMIC_NOTIFIER_INIT(name)
  79#define BLOCKING_NOTIFIER_HEAD(name)                            \
  80        struct blocking_notifier_head name =                    \
  81                BLOCKING_NOTIFIER_INIT(name)
  82#define RAW_NOTIFIER_HEAD(name)                                 \
  83        struct raw_notifier_head name =                         \
  84                RAW_NOTIFIER_INIT(name)
  85
  86#ifdef __KERNEL__
  87
  88extern int atomic_notifier_chain_register(struct atomic_notifier_head *,
  89                struct notifier_block *);
  90extern int blocking_notifier_chain_register(struct blocking_notifier_head *,
  91                struct notifier_block *);
  92extern int raw_notifier_chain_register(struct raw_notifier_head *,
  93                struct notifier_block *);
  94
  95extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *,
  96                struct notifier_block *);
  97extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *,
  98                struct notifier_block *);
  99extern int raw_notifier_chain_unregister(struct raw_notifier_head *,
 100                struct notifier_block *);
 101
 102extern int atomic_notifier_call_chain(struct atomic_notifier_head *,
 103                unsigned long val, void *v);
 104extern int blocking_notifier_call_chain(struct blocking_notifier_head *,
 105                unsigned long val, void *v);
 106extern int raw_notifier_call_chain(struct raw_notifier_head *,
 107                unsigned long val, void *v);
 108
 109#define NOTIFY_DONE             0x0000          /* Don't care */
 110#define NOTIFY_OK               0x0001          /* Suits me */
 111#define NOTIFY_STOP_MASK        0x8000          /* Don't call further */
 112#define NOTIFY_BAD              (NOTIFY_STOP_MASK|0x0002)
 113                                                /* Bad/Veto action */
 114/*
 115 * Clean way to return from the notifier and stop further calls.
 116 */
 117#define NOTIFY_STOP             (NOTIFY_OK|NOTIFY_STOP_MASK)
 118
 119/*
 120 *      Declared notifiers so far. I can imagine quite a few more chains
 121 *      over time (eg laptop power reset chains, reboot chain (to clean 
 122 *      device units up), device [un]mount chain, module load/unload chain,
 123 *      low memory chain, screenblank chain (for plug in modular screenblankers) 
 124 *      VC switch chains (for loadable kernel svgalib VC switch helpers) etc...
 125 */
 126 
 127/* netdevice notifier chain */
 128#define NETDEV_UP       0x0001  /* For now you can't veto a device up/down */
 129#define NETDEV_DOWN     0x0002
 130#define NETDEV_REBOOT   0x0003  /* Tell a protocol stack a network interface
 131                                   detected a hardware crash and restarted
 132                                   - we can use this eg to kick tcp sessions
 133                                   once done */
 134#define NETDEV_CHANGE   0x0004  /* Notify device state change */
 135#define NETDEV_REGISTER 0x0005
 136#define NETDEV_UNREGISTER       0x0006
 137#define NETDEV_CHANGEMTU        0x0007
 138#define NETDEV_CHANGEADDR       0x0008
 139#define NETDEV_GOING_DOWN       0x0009
 140#define NETDEV_CHANGENAME       0x000A
 141#define NETDEV_FEAT_CHANGE      0x000B
 142
 143#define SYS_DOWN        0x0001  /* Notify of system down */
 144#define SYS_RESTART     SYS_DOWN
 145#define SYS_HALT        0x0002  /* Notify of system halt */
 146#define SYS_POWER_OFF   0x0003  /* Notify of system power off */
 147
 148#define NETLINK_URELEASE        0x0001  /* Unicast netlink socket released */
 149
 150#define CPU_ONLINE              0x0002 /* CPU (unsigned)v is up */
 151#define CPU_UP_PREPARE          0x0003 /* CPU (unsigned)v coming up */
 152#define CPU_UP_CANCELED         0x0004 /* CPU (unsigned)v NOT coming up */
 153#define CPU_DOWN_PREPARE        0x0005 /* CPU (unsigned)v going down */
 154#define CPU_DOWN_FAILED         0x0006 /* CPU (unsigned)v NOT going down */
 155#define CPU_DEAD                0x0007 /* CPU (unsigned)v dead */
 156
 157#endif /* __KERNEL__ */
 158#endif /* _LINUX_NOTIFIER_H */
 159