[linux-block.git] / include / linux / notifier.h

/*
 *	Routines to manage notifier chains for passing status changes to any
 *	interested routines. We need this instead of hard coded call lists so
 *	that modules can poke their nose into the innards. The network devices
 *	needed them so here they are for the rest of you.
 *
 *				Alan Cox <Alan.Cox@linux.org>
 */
 
#ifndef _LINUX_NOTIFIER_H
#define _LINUX_NOTIFIER_H
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>

/*
 * Notifier chains are of three types:
 *
 *	Atomic notifier chains: Chain callbacks run in interrupt/atomic
 *		context. Callouts are not allowed to block.
 *	Blocking notifier chains: Chain callbacks run in process context.
 *		Callouts are allowed to block.
 *	Raw notifier chains: There are no restrictions on callbacks,
 *		registration, or unregistration.  All locking and protection
 *		must be provided by the caller.
 *
 * atomic_notifier_chain_register() may be called from an atomic context,
 * but blocking_notifier_chain_register() must be called from a process
 * context.  Ditto for the corresponding _unregister() routines.
 *
 * atomic_notifier_chain_unregister() and blocking_notifier_chain_unregister()
 * _must not_ be called from within the call chain.
 */

struct notifier_block {
	int (*notifier_call)(struct notifier_block *, unsigned long, void *);
	struct notifier_block *next;
	int priority;
};

struct atomic_notifier_head {
	spinlock_t lock;
	struct notifier_block *head;
};

struct blocking_notifier_head {
	struct rw_semaphore rwsem;
	struct notifier_block *head;
};

struct raw_notifier_head {
	struct notifier_block *head;
};

#define ATOMIC_INIT_NOTIFIER_HEAD(name) do {	\
		spin_lock_init(&(name)->lock);	\
		(name)->head = NULL;		\
	} while (0)
#define BLOCKING_INIT_NOTIFIER_HEAD(name) do {	\
		init_rwsem(&(name)->rwsem);	\
		(name)->head = NULL;		\
	} while (0)
#define RAW_INIT_NOTIFIER_HEAD(name) do {	\
		(name)->head = NULL;		\
	} while (0)

#define ATOMIC_NOTIFIER_INIT(name) {				\
		.lock = SPIN_LOCK_UNLOCKED,			\
		.head = NULL }
#define BLOCKING_NOTIFIER_INIT(name) {				\
		.rwsem = __RWSEM_INITIALIZER((name).rwsem),	\
		.head = NULL }
#define RAW_NOTIFIER_INIT(name)	{				\
		.head = NULL }

#define ATOMIC_NOTIFIER_HEAD(name)				\
	struct atomic_notifier_head name =			\
		ATOMIC_NOTIFIER_INIT(name)
#define BLOCKING_NOTIFIER_HEAD(name)				\
	struct blocking_notifier_head name =			\
		BLOCKING_NOTIFIER_INIT(name)
#define RAW_NOTIFIER_HEAD(name)					\
	struct raw_notifier_head name =				\
		RAW_NOTIFIER_INIT(name)

#ifdef __KERNEL__

extern int atomic_notifier_chain_register(struct atomic_notifier_head *,
		struct notifier_block *);
extern int blocking_notifier_chain_register(struct blocking_notifier_head *,
		struct notifier_block *);
extern int raw_notifier_chain_register(struct raw_notifier_head *,
		struct notifier_block *);

extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *,
		struct notifier_block *);
extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *,
		struct notifier_block *);
extern int raw_notifier_chain_unregister(struct raw_notifier_head *,
		struct notifier_block *);

extern int atomic_notifier_call_chain(struct atomic_notifier_head *,
		unsigned long val, void *v);
extern int blocking_notifier_call_chain(struct blocking_notifier_head *,
		unsigned long val, void *v);
extern int raw_notifier_call_chain(struct raw_notifier_head *,
		unsigned long val, void *v);

#define NOTIFY_DONE		0x0000		/* Don't care */
#define NOTIFY_OK		0x0001		/* Suits me */
#define NOTIFY_STOP_MASK	0x8000		/* Don't call further */
#define NOTIFY_BAD		(NOTIFY_STOP_MASK|0x0002)
						/* Bad/Veto action */
/*
 * Clean way to return from the notifier and stop further calls.
 */
#define NOTIFY_STOP		(NOTIFY_OK|NOTIFY_STOP_MASK)

/*
 *	Declared notifiers so far. I can imagine quite a few more chains
 *	over time (eg laptop power reset chains, reboot chain (to clean 
 *	device units up), device [un]mount chain, module load/unload chain,
 *	low memory chain, screenblank chain (for plug in modular screenblankers) 
 *	VC switch chains (for loadable kernel svgalib VC switch helpers) etc...
 */
 
/* netdevice notifier chain */
#define NETDEV_UP	0x0001	/* For now you can't veto a device up/down */
#define NETDEV_DOWN	0x0002
#define NETDEV_REBOOT	0x0003	/* Tell a protocol stack a network interface
				   detected a hardware crash and restarted
				   - we can use this eg to kick tcp sessions
				   once done */
#define NETDEV_CHANGE	0x0004	/* Notify device state change */
#define NETDEV_REGISTER 0x0005
#define NETDEV_UNREGISTER	0x0006
#define NETDEV_CHANGEMTU	0x0007
#define NETDEV_CHANGEADDR	0x0008
#define NETDEV_GOING_DOWN	0x0009
#define NETDEV_CHANGENAME	0x000A
#define NETDEV_FEAT_CHANGE	0x000B

#define SYS_DOWN	0x0001	/* Notify of system down */
#define SYS_RESTART	SYS_DOWN
#define SYS_HALT	0x0002	/* Notify of system halt */
#define SYS_POWER_OFF	0x0003	/* Notify of system power off */

#define NETLINK_URELEASE	0x0001	/* Unicast netlink socket released */

#define CPU_ONLINE		0x0002 /* CPU (unsigned)v is up */
#define CPU_UP_PREPARE		0x0003 /* CPU (unsigned)v coming up */
#define CPU_UP_CANCELED		0x0004 /* CPU (unsigned)v NOT coming up */
#define CPU_DOWN_PREPARE	0x0005 /* CPU (unsigned)v going down */
#define CPU_DOWN_FAILED		0x0006 /* CPU (unsigned)v NOT going down */
#define CPU_DEAD		0x0007 /* CPU (unsigned)v dead */

#endif /* __KERNEL__ */
#endif /* _LINUX_NOTIFIER_H */
Commit	Line	Data
1da177e4 LT	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>
e041c683 AS	13	#include <linux/mutex.h>
e041c683 AS	14	#include <linux/rwsem.h>
1da177e4	15
e041c683 AS	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 *);
1da177e4 LT	37	struct notifier_block *next;
	38	int priority;
	39	};
	40
e041c683 AS	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, \
	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)
1da177e4 LT	85
	86	#ifdef __KERNEL__
	87
e041c683 AS	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);
1da177e4 LT	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 */
e041c683 AS	112	#define NOTIFY_BAD (NOTIFY_STOP_MASK\|0x0002)
e041c683 AS	113	/* Bad/Veto action */
1da177e4 LT	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
d8a33ac4	141	#define NETDEV_FEAT_CHANGE 0x000B
1da177e4 LT	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 */