Green shading in the line number column means the source is part of the translation unit, red means it is conditionally excluded. Highlighted line numbers link to the translation unit page. Highlighted macros link to the macro page.
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: #include <linux/srcu.h> 16: 17: /* 18: * Notifier chains are of four types: 19: * 20: * Atomic notifier chains: Chain callbacks run in interrupt/atomic 21: * context. Callouts are not allowed to block. 22: * Blocking notifier chains: Chain callbacks run in process context. 23: * Callouts are allowed to block. 24: * Raw notifier chains: There are no restrictions on callbacks, 25: * registration, or unregistration. All locking and protection 26: * must be provided by the caller. 27: * SRCU notifier chains: A variant of blocking notifier chains, with 28: * the same restrictions. 29: * 30: * atomic_notifier_chain_register() may be called from an atomic context, 31: * but blocking_notifier_chain_register() and srcu_notifier_chain_register() 32: * must be called from a process context. Ditto for the corresponding 33: * _unregister() routines. 34: * 35: * atomic_notifier_chain_unregister(), blocking_notifier_chain_unregister(), 36: * and srcu_notifier_chain_unregister() _must not_ be called from within 37: * the call chain. 38: * 39: * SRCU notifier chains are an alternative form of blocking notifier chains. 40: * They use SRCU (Sleepable Read-Copy Update) instead of rw-semaphores for 41: * protection of the chain links. This means there is _very_ low overhead 42: * in srcu_notifier_call_chain(): no cache bounces and no memory barriers. 43: * As compensation, srcu_notifier_chain_unregister() is rather expensive. 44: * SRCU notifier chains should be used when the chain will be called very 45: * often but notifier_blocks will seldom be removed. Also, SRCU notifier 46: * chains are slightly more difficult to use because they require special 47: * runtime initialization. 48: */ 49: 50: typedef int (*notifier_fn_t)(struct notifier_block *nb, 51: unsigned long action, void *data); 52: 53: struct notifier_block { 54: notifier_fn_t notifier_call; 55: struct notifier_block __rcu *next; 56: int priority; 57: }; 58: 59: struct atomic_notifier_head { 60: spinlock_t lock; 61: struct notifier_block __rcu *head; 62: }; 63: 64: struct blocking_notifier_head { 65: struct rw_semaphore rwsem; 66: struct notifier_block __rcu *head; 67: }; 68: 69: struct raw_notifier_head { 70: struct notifier_block __rcu *head; 71: }; 72: 73: struct srcu_notifier_head { 74: struct mutex mutex; 75: struct srcu_struct srcu; 76: struct notifier_block __rcu *head; 77: }; 78: 79: #define ATOMIC_INIT_NOTIFIER_HEAD(name) do { \ 80: spin_lock_init(&(name)->lock); \ 81: (name)->head = NULL; \ 82: } while (0) 83: #define BLOCKING_INIT_NOTIFIER_HEAD(name) do { \ 84: init_rwsem(&(name)->rwsem); \ 85: (name)->head = NULL; \ 86: } while (0) 87: #define RAW_INIT_NOTIFIER_HEAD(name) do { \ 88: (name)->head = NULL; \ 89: } while (0) 90: 91: /* srcu_notifier_heads must be initialized and cleaned up dynamically */ 92: extern void srcu_init_notifier_head(struct srcu_notifier_head *nh); 93: #define srcu_cleanup_notifier_head(name) \ 94: cleanup_srcu_struct(&(name)->srcu); 95: 96: #define ATOMIC_NOTIFIER_INIT(name) { \ 97: .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ 98: .head = NULL } 99: #define BLOCKING_NOTIFIER_INIT(name) { \ 100: .rwsem = __RWSEM_INITIALIZER((name).rwsem), \ 101: .head = NULL } 102: #define RAW_NOTIFIER_INIT(name) { \ 103: .head = NULL } 104: /* srcu_notifier_heads cannot be initialized statically */ 105: 106: #define ATOMIC_NOTIFIER_HEAD(name) \ 107: struct atomic_notifier_head name = \ 108: ATOMIC_NOTIFIER_INIT(name) 109: #define BLOCKING_NOTIFIER_HEAD(name) \ 110: struct blocking_notifier_head name = \ 111: BLOCKING_NOTIFIER_INIT(name) 112: #define RAW_NOTIFIER_HEAD(name) \ 113: struct raw_notifier_head name = \ 114: RAW_NOTIFIER_INIT(name) 115: 116: #ifdef __KERNEL__ 117: 118: extern int atomic_notifier_chain_register(struct atomic_notifier_head *nh, 119: struct notifier_block *nb); 120: extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh, 121: struct notifier_block *nb); 122: extern int raw_notifier_chain_register(struct raw_notifier_head *nh, 123: struct notifier_block *nb); 124: extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh, 125: struct notifier_block *nb); 126: 127: extern int blocking_notifier_chain_cond_register( 128: struct blocking_notifier_head *nh, 129: struct notifier_block *nb); 130: 131: extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh, 132: struct notifier_block *nb); 133: extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh, 134: struct notifier_block *nb); 135: extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh, 136: struct notifier_block *nb); 137: extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh, 138: struct notifier_block *nb); 139: 140: extern int atomic_notifier_call_chain(struct atomic_notifier_head *nh, 141: unsigned long val, void *v); 142: extern int __atomic_notifier_call_chain(struct atomic_notifier_head *nh, 143: unsigned long val, void *v, int nr_to_call, int *nr_calls); 144: extern int blocking_notifier_call_chain(struct blocking_notifier_head *nh, 145: unsigned long val, void *v); 146: extern int __blocking_notifier_call_chain(struct blocking_notifier_head *nh, 147: unsigned long val, void *v, int nr_to_call, int *nr_calls); 148: extern int raw_notifier_call_chain(struct raw_notifier_head *nh, 149: unsigned long val, void *v); 150: extern int __raw_notifier_call_chain(struct raw_notifier_head *nh, 151: unsigned long val, void *v, int nr_to_call, int *nr_calls); 152: extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh, 153: unsigned long val, void *v); 154: extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh, 155: unsigned long val, void *v, int nr_to_call, int *nr_calls); 156: 157: #define NOTIFY_DONE 0x0000 /* Don't care */ 158: #define NOTIFY_OK 0x0001 /* Suits me */ 159: #define NOTIFY_STOP_MASK 0x8000 /* Don't call further */ 160: #define NOTIFY_BAD (NOTIFY_STOP_MASK|0x0002) 161: /* Bad/Veto action */ 162: /* 163: * Clean way to return from the notifier and stop further calls. 164: */ 165: #define NOTIFY_STOP (NOTIFY_OK|NOTIFY_STOP_MASK) 166: 167: /* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */ 168: static inline int notifier_from_errno(int err) 169: { 170: if (err) 171: return NOTIFY_STOP_MASK | (NOTIFY_OK - err); 172: 173: return NOTIFY_OK; 174: } 175: 176: /* Restore (negative) errno value from notify return value. */ 177: static inline int notifier_to_errno(int ret) 178: { 179: ret &= ~NOTIFY_STOP_MASK; 180: return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0; 181: } 182: 183: /* 184: * Declared notifiers so far. I can imagine quite a few more chains 185: * over time (eg laptop power reset chains, reboot chain (to clean 186: * device units up), device [un]mount chain, module load/unload chain, 187: * low memory chain, screenblank chain (for plug in modular screenblankers) 188: * VC switch chains (for loadable kernel svgalib VC switch helpers) etc... 189: */ 190: 191: /* CPU notfiers are defined in include/linux/cpu.h. */ 192: 193: /* netdevice notifiers are defined in include/linux/netdevice.h */ 194: 195: /* reboot notifiers are defined in include/linux/reboot.h. */ 196: 197: /* Hibernation and suspend events are defined in include/linux/suspend.h. */ 198: 199: /* Virtual Terminal events are defined in include/linux/vt.h. */ 200: 201: #define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */ 202: 203: /* Console keyboard events. 204: * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and 205: * KBD_KEYSYM. */ 206: #define KBD_KEYCODE 0x0001 /* Keyboard keycode, called before any other */ 207: #define KBD_UNBOUND_KEYCODE 0x0002 /* Keyboard keycode which is not bound to any other */ 208: #define KBD_UNICODE 0x0003 /* Keyboard unicode */ 209: #define KBD_KEYSYM 0x0004 /* Keyboard keysym */ 210: #define KBD_POST_KEYSYM 0x0005 /* Called after keyboard keysym interpretation */ 211: 212: extern struct blocking_notifier_head reboot_notifier_list; 213: 214: #endif /* __KERNEL__ */ 215: #endif /* _LINUX_NOTIFIER_H */ 216: