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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242/* SPDX-License-Identifier: GPL-2.0 *//* * 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. */
struct notifier_block;
typedef int (*notifier_fn_t)(struct notifier_block *nb, unsigned long action, void *data);
struct notifier_block { notifier_fn_t notifier_call; struct notifier_block __rcu *next; int priority;};
struct atomic_notifier_head { spinlock_t lock; struct notifier_block __rcu *head;};
struct blocking_notifier_head { struct rw_semaphore rwsem; struct notifier_block __rcu *head;};
struct raw_notifier_head { struct notifier_block __rcu *head;};
struct srcu_notifier_head { struct mutex mutex; struct srcu_usage srcuu; struct srcu_struct srcu; struct notifier_block __rcu *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 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 }
#define SRCU_NOTIFIER_INIT(name, pcpu) \ { \ .mutex = __MUTEX_INITIALIZER(name.mutex), \ .head = NULL, \ .srcuu = __SRCU_USAGE_INIT(name.srcuu), \ .srcu = __SRCU_STRUCT_INIT(name.srcu, name.srcuu, pcpu, 0), \ }
#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 CONFIG_TREE_SRCU#define _SRCU_NOTIFIER_HEAD(name, mod) \ static DEFINE_PER_CPU(struct srcu_data, name##_head_srcu_data); \ mod struct srcu_notifier_head name = \ SRCU_NOTIFIER_INIT(name, name##_head_srcu_data)
#else#define _SRCU_NOTIFIER_HEAD(name, mod) \ mod struct srcu_notifier_head name = \ SRCU_NOTIFIER_INIT(name, name)
#endif
#define SRCU_NOTIFIER_HEAD(name) \ _SRCU_NOTIFIER_HEAD(name, /* not static */)
#define SRCU_NOTIFIER_HEAD_STATIC(name) \ _SRCU_NOTIFIER_HEAD(name, static)
#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_register_unique_prio( struct atomic_notifier_head *nh, struct notifier_block *nb);extern int blocking_notifier_chain_register_unique_prio( struct blocking_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 blocking_notifier_call_chain(struct blocking_notifier_head *nh, unsigned long val, void *v);extern int raw_notifier_call_chain(struct raw_notifier_head *nh, unsigned long val, void *v);extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh, unsigned long val, void *v);
extern int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh, unsigned long val_up, unsigned long val_down, void *v);extern int raw_notifier_call_chain_robust(struct raw_notifier_head *nh, unsigned long val_up, unsigned long val_down, void *v);
extern bool atomic_notifier_call_chain_is_empty(struct atomic_notifier_head *nh);
#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){ if (err) return NOTIFY_STOP_MASK | (NOTIFY_OK - err);
return NOTIFY_OK;}
/* 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... */ /* CPU notfiers are defined in include/linux/cpu.h. */
/* netdevice notifiers are defined in include/linux/netdevice.h */
/* reboot notifiers are defined in include/linux/reboot.h. */
/* Hibernation and suspend events are defined in include/linux/suspend.h. */
/* Virtual Terminal events are defined in include/linux/vt.h. */
#define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */
/* 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 */
#endif /* __KERNEL__ */#endif /* _LINUX_NOTIFIER_H */