include/linux/notifier.h - kernel/msm-4.19 - Gitiles

 /*
  *	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>
 #include <linux/srcu.h>

 /*
  * Notifier chains are of four 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.
  *	SRCU notifier chains: A variant of blocking notifier chains, with
  *		the same restrictions.
  *
  * atomic_notifier_chain_register() may be called from an atomic context,
  * but blocking_notifier_chain_register() and srcu_notifier_chain_register()
  * must be called from a process context.  Ditto for the corresponding
  * _unregister() routines.
  *
  * atomic_notifier_chain_unregister(), blocking_notifier_chain_unregister(),
  * and srcu_notifier_chain_unregister() _must not_ be called from within
  * the call chain.
  *
  * SRCU notifier chains are an alternative form of blocking notifier chains.
  * They use SRCU (Sleepable Read-Copy Update) instead of rw-semaphores for
  * protection of the chain links.  This means there is _very_ low overhead
  * in srcu_notifier_call_chain(): no cache bounces and no memory barriers.
  * As compensation, srcu_notifier_chain_unregister() is rather expensive.
  * SRCU notifier chains should be used when the chain will be called very
  * often but notifier_blocks will seldom be removed.  Also, SRCU notifier
  * chains are slightly more difficult to use because they require special
  * runtime initialization.
  */

 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;
 };

 struct srcu_notifier_head {
 	struct mutex mutex;
 	struct srcu_struct srcu;
 	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)

 /* srcu_notifier_heads must be initialized and cleaned up dynamically */
 extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
 #define srcu_cleanup_notifier_head(name)	\
 		cleanup_srcu_struct(&(name)->srcu);

 #define ATOMIC_NOTIFIER_INIT(name) {				\
 		.lock = __SPIN_LOCK_UNLOCKED(name.lock),	\
 		.head = NULL }
 #define BLOCKING_NOTIFIER_INIT(name) {				\
 		.rwsem = __RWSEM_INITIALIZER((name).rwsem),	\
 		.head = NULL }
 #define RAW_NOTIFIER_INIT(name)	{				\
 		.head = NULL }
 /* srcu_notifier_heads cannot be initialized statically */

 #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 *nh,
 		struct notifier_block *nb);
 extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
 		struct notifier_block *nb);
 extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
 		struct notifier_block *nb);
 extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
 		struct notifier_block *nb);

 extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
 		struct notifier_block *nb);
 extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
 		struct notifier_block *nb);
 extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
 		struct notifier_block *nb);
 extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
 		struct notifier_block *nb);

 extern int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
 		unsigned long val, void *v);
 extern int __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
 	unsigned long val, void *v, int nr_to_call, int *nr_calls);
 extern int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
 		unsigned long val, void *v);
 extern int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
 	unsigned long val, void *v, int nr_to_call, int *nr_calls);
 extern int raw_notifier_call_chain(struct raw_notifier_head *nh,
 		unsigned long val, void *v);
 extern int __raw_notifier_call_chain(struct raw_notifier_head *nh,
 	unsigned long val, void *v, int nr_to_call, int *nr_calls);
 extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
 		unsigned long val, void *v);
 extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
 	unsigned long val, void *v, int nr_to_call, int *nr_calls);

 #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)

 /* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */
 static inline int notifier_from_errno(int err)
 {
 	return NOTIFY_STOP_MASK | (NOTIFY_OK - err);
 }

 /* Restore (negative) errno value from notify return value. */
 static inline int notifier_to_errno(int ret)
 {
 	ret &= ~NOTIFY_STOP_MASK;
 	return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0;
 }

 /*
  *	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 */
 #define CPU_LOCK_ACQUIRE	0x0008 /* Acquire all hotcpu locks */
 #define CPU_LOCK_RELEASE	0x0009 /* Release all hotcpu locks */
 #define CPU_DYING		0x000A /* CPU (unsigned)v not running any task,
 				        * not handling interrupts, soon dead */

 /* Used for CPU hotplug events occuring while tasks are frozen due to a suspend
  * operation in progress
  */
 #define CPU_TASKS_FROZEN	0x0010

 #define CPU_ONLINE_FROZEN	(CPU_ONLINE | CPU_TASKS_FROZEN)
 #define CPU_UP_PREPARE_FROZEN	(CPU_UP_PREPARE | CPU_TASKS_FROZEN)
 #define CPU_UP_CANCELED_FROZEN	(CPU_UP_CANCELED | CPU_TASKS_FROZEN)
 #define CPU_DOWN_PREPARE_FROZEN	(CPU_DOWN_PREPARE | CPU_TASKS_FROZEN)
 #define CPU_DOWN_FAILED_FROZEN	(CPU_DOWN_FAILED | CPU_TASKS_FROZEN)
 #define CPU_DEAD_FROZEN		(CPU_DEAD | CPU_TASKS_FROZEN)
 #define CPU_DYING_FROZEN	(CPU_DYING | CPU_TASKS_FROZEN)

 /* Hibernation and suspend events */
 #define PM_HIBERNATION_PREPARE	0x0001 /* Going to hibernate */
 #define PM_POST_HIBERNATION	0x0002 /* Hibernation finished */
 #define PM_SUSPEND_PREPARE	0x0003 /* Going to suspend the system */
 #define PM_POST_SUSPEND		0x0004 /* Suspend finished */

 /* Console keyboard events.
  * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
  * KBD_KEYSYM. */
 #define KBD_KEYCODE		0x0001 /* Keyboard keycode, called before any other */
 #define KBD_UNBOUND_KEYCODE	0x0002 /* Keyboard keycode which is not bound to any other */
 #define KBD_UNICODE		0x0003 /* Keyboard unicode */
 #define KBD_KEYSYM		0x0004 /* Keyboard keysym */
 #define KBD_POST_KEYSYM		0x0005 /* Called after keyboard keysym interpretation */

 extern struct blocking_notifier_head reboot_notifier_list;

 /* Virtual Terminal events. */
 #define VT_ALLOCATE		0x0001 /* Console got allocated */
 #define VT_DEALLOCATE		0x0002 /* Console will be deallocated */
 #define VT_WRITE		0x0003 /* A char got output */
 #define VT_UPDATE		0x0004 /* A bigger update occurred */

 #endif /* __KERNEL__ */
 #endif /* _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>
	#include <linux/srcu.h>

	/*
	* Notifier chains are of four 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.
	* SRCU notifier chains: A variant of blocking notifier chains, with
	* the same restrictions.
	*
	* atomic_notifier_chain_register() may be called from an atomic context,
	* but blocking_notifier_chain_register() and srcu_notifier_chain_register()
	* must be called from a process context. Ditto for the corresponding
	* _unregister() routines.
	*
	* atomic_notifier_chain_unregister(), blocking_notifier_chain_unregister(),
	* and srcu_notifier_chain_unregister() _must not_ be called from within
	* the call chain.
	*
	* SRCU notifier chains are an alternative form of blocking notifier chains.
	* They use SRCU (Sleepable Read-Copy Update) instead of rw-semaphores for
	* protection of the chain links. This means there is _very_ low overhead
	* in srcu_notifier_call_chain(): no cache bounces and no memory barriers.
	* As compensation, srcu_notifier_chain_unregister() is rather expensive.
	* SRCU notifier chains should be used when the chain will be called very
	* often but notifier_blocks will seldom be removed. Also, SRCU notifier
	* chains are slightly more difficult to use because they require special
	* runtime initialization.
	*/

	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;
	};

	struct srcu_notifier_head {
	struct mutex mutex;
	struct srcu_struct srcu;
	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)

	/* srcu_notifier_heads must be initialized and cleaned up dynamically */
	extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
	#define srcu_cleanup_notifier_head(name) \
	cleanup_srcu_struct(&(name)->srcu);

	#define ATOMIC_NOTIFIER_INIT(name) { \
	.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
	.head = NULL }
	#define BLOCKING_NOTIFIER_INIT(name) { \
	.rwsem = __RWSEM_INITIALIZER((name).rwsem), \
	.head = NULL }
	#define RAW_NOTIFIER_INIT(name) { \
	.head = NULL }
	/* srcu_notifier_heads cannot be initialized statically */

	#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 *nh,
	struct notifier_block *nb);
	extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
	struct notifier_block *nb);
	extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
	struct notifier_block *nb);
	extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
	struct notifier_block *nb);

	extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
	struct notifier_block *nb);
	extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
	struct notifier_block *nb);
	extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
	struct notifier_block *nb);
	extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
	struct notifier_block *nb);

	extern int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
	unsigned long val, void *v);
	extern int __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
	unsigned long val, void v, int nr_to_call, int nr_calls);
	extern int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
	unsigned long val, void *v);
	extern int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
	unsigned long val, void v, int nr_to_call, int nr_calls);
	extern int raw_notifier_call_chain(struct raw_notifier_head *nh,
	unsigned long val, void *v);
	extern int __raw_notifier_call_chain(struct raw_notifier_head *nh,
	unsigned long val, void v, int nr_to_call, int nr_calls);
	extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
	unsigned long val, void *v);
	extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
	unsigned long val, void v, int nr_to_call, int nr_calls);

	#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)

	/* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */
	static inline int notifier_from_errno(int err)
	{
	return NOTIFY_STOP_MASK \| (NOTIFY_OK - err);
	}

	/* Restore (negative) errno value from notify return value. */
	static inline int notifier_to_errno(int ret)
	{
	ret &= ~NOTIFY_STOP_MASK;
	return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0;
	}

	/*
	* 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 */
	#define CPU_LOCK_ACQUIRE 0x0008 /* Acquire all hotcpu locks */
	#define CPU_LOCK_RELEASE 0x0009 /* Release all hotcpu locks */
	#define CPU_DYING 0x000A /* CPU (unsigned)v not running any task,
	* not handling interrupts, soon dead */

	/* Used for CPU hotplug events occuring while tasks are frozen due to a suspend
	* operation in progress
	*/
	#define CPU_TASKS_FROZEN 0x0010

	#define CPU_ONLINE_FROZEN (CPU_ONLINE \| CPU_TASKS_FROZEN)
	#define CPU_UP_PREPARE_FROZEN (CPU_UP_PREPARE \| CPU_TASKS_FROZEN)
	#define CPU_UP_CANCELED_FROZEN (CPU_UP_CANCELED \| CPU_TASKS_FROZEN)
	#define CPU_DOWN_PREPARE_FROZEN (CPU_DOWN_PREPARE \| CPU_TASKS_FROZEN)
	#define CPU_DOWN_FAILED_FROZEN (CPU_DOWN_FAILED \| CPU_TASKS_FROZEN)
	#define CPU_DEAD_FROZEN (CPU_DEAD \| CPU_TASKS_FROZEN)
	#define CPU_DYING_FROZEN (CPU_DYING \| CPU_TASKS_FROZEN)

	/* Hibernation and suspend events */
	#define PM_HIBERNATION_PREPARE 0x0001 /* Going to hibernate */
	#define PM_POST_HIBERNATION 0x0002 /* Hibernation finished */
	#define PM_SUSPEND_PREPARE 0x0003 /* Going to suspend the system */
	#define PM_POST_SUSPEND 0x0004 /* Suspend finished */

	/* Console keyboard events.
	* Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
	* KBD_KEYSYM. */
	#define KBD_KEYCODE 0x0001 /* Keyboard keycode, called before any other */
	#define KBD_UNBOUND_KEYCODE 0x0002 /* Keyboard keycode which is not bound to any other */
	#define KBD_UNICODE 0x0003 /* Keyboard unicode */
	#define KBD_KEYSYM 0x0004 /* Keyboard keysym */
	#define KBD_POST_KEYSYM 0x0005 /* Called after keyboard keysym interpretation */

	extern struct blocking_notifier_head reboot_notifier_list;

	/* Virtual Terminal events. */
	#define VT_ALLOCATE 0x0001 /* Console got allocated */
	#define VT_DEALLOCATE 0x0002 /* Console will be deallocated */
	#define VT_WRITE 0x0003 /* A char got output */
	#define VT_UPDATE 0x0004 /* A bigger update occurred */

	#endif /* __KERNEL__ */
	#endif /* _LINUX_NOTIFIER_H */