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/******************************************************************************
* include/xen/notifier.h
*
* Routines to manage notifier chains for passing status changes to any
* interested routines.
*
* Original code from Linux kernel 2.6.27 (Alan Cox <Alan.Cox@linux.org>)
*/
#ifndef __XEN_NOTIFIER_H__
#define __XEN_NOTIFIER_H__
#include <xen/types.h>
#include <xen/errno.h>
#include <xen/kernel.h>
#include <xen/list.h>
/*
* Xen includes only one type of notifier chains inherited from Linux:
* Raw notifier chains: There are no restrictions on callbacks,
* registration, or unregistration. All locking and protection
* must be provided by the caller.
*/
struct notifier_block {
int (*notifier_call)(struct notifier_block *, unsigned long, void *);
struct list_head chain;
int priority;
};
struct notifier_head {
struct notifier_block head;
};
#define NOTIFIER_INIT(name) { .head.chain = LIST_HEAD_INIT(name.head.chain) }
#define NOTIFIER_HEAD(name) \
struct notifier_head name = NOTIFIER_INIT(name)
void notifier_chain_register(
struct notifier_head *nh, struct notifier_block *nb);
void notifier_chain_unregister(
struct notifier_head *nh, struct notifier_block *nb);
int notifier_call_chain(
struct notifier_head *nh, unsigned long val, void *v,
struct notifier_block **pcursor);
/* Notifier flag values: OR into @val passed to notifier_call_chain(). */
#define NOTIFY_FORWARD 0x0000 /* Call chain highest-priority-first */
#define NOTIFY_REVERSE 0x8000 /* Call chain lowest-priority-first */
/* Handler completion values */
#define NOTIFY_DONE 0x0000
#define NOTIFY_STOP_MASK 0x8000
#define NOTIFY_STOP (NOTIFY_STOP_MASK|NOTIFY_DONE)
#define NOTIFY_BAD (NOTIFY_STOP_MASK|EINVAL)
/* Encapsulate (negative) errno value. */
static inline int notifier_from_errno(int err)
{
return NOTIFY_STOP_MASK | -err;
}
/* Restore (negative) errno value from notify return value. */
static inline int notifier_to_errno(int ret)
{
return -(ret & ~NOTIFY_STOP_MASK);
}
#endif /* __XEN_NOTIFIER_H__ */
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