0,0 → 1,69 |
/* |
* 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 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; |
|
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; |
}; |
|
/* 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 */ |
|
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#endif /* _LINUX_NOTIFIER_H */ |