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 (at) 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 35 struct notifier_block { 36 int (*notifier_call)(struct notifier_block *, unsigned long, void *); 37 struct notifier_block *next; 38 int priority; 39 }; 40 41 struct atomic_notifier_head { 42 spinlock_t lock; 43 struct notifier_block *head; 44 }; 45 46 struct blocking_notifier_head { 47 struct rw_semaphore rwsem; 48 struct notifier_block *head; 49 }; 50 51 struct 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 88 extern int atomic_notifier_chain_register(struct atomic_notifier_head *, 89 struct notifier_block *); 90 extern int blocking_notifier_chain_register(struct blocking_notifier_head *, 91 struct notifier_block *); 92 extern int raw_notifier_chain_register(struct raw_notifier_head *, 93 struct notifier_block *); 94 95 extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *, 96 struct notifier_block *); 97 extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *, 98 struct notifier_block *); 99 extern int raw_notifier_chain_unregister(struct raw_notifier_head *, 100 struct notifier_block *); 101 102 extern int atomic_notifier_call_chain(struct atomic_notifier_head *, 103 unsigned long val, void *v); 104 extern int blocking_notifier_call_chain(struct blocking_notifier_head *, 105 unsigned long val, void *v); 106 extern 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
