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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2022 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#ifndef XFS_HOOKS_H_
#define XFS_HOOKS_H_
#if defined(CONFIG_XFS_LIVE_HOOKS_SRCU)
struct xfs_hooks {
struct srcu_notifier_head head;
};
#elif defined(CONFIG_XFS_LIVE_HOOKS_BLOCKING)
struct xfs_hooks {
struct blocking_notifier_head head;
};
#else
struct xfs_hooks { /* empty */ };
#endif
/*
* If hooks and jump labels are enabled, we use jump labels (aka patching of
* the code segment) to avoid the minute overhead of calling an empty notifier
* chain when we know there are no callers. If hooks are enabled without jump
* labels, hardwire the predicate to true because calling an empty srcu
* notifier chain isn't so expensive.
*/
#if defined(CONFIG_JUMP_LABEL) && defined(CONFIG_XFS_LIVE_HOOKS)
# define DEFINE_STATIC_XFS_HOOK_SWITCH(name) \
static DEFINE_STATIC_KEY_FALSE(name)
# define xfs_hooks_switch_on(name) static_branch_inc(name)
# define xfs_hooks_switch_off(name) static_branch_dec(name)
# define xfs_hooks_switched_on(name) static_branch_unlikely(name)
#elif defined(CONFIG_XFS_LIVE_HOOKS)
# define DEFINE_STATIC_XFS_HOOK_SWITCH(name)
# define xfs_hooks_switch_on(name) ((void)0)
# define xfs_hooks_switch_off(name) ((void)0)
# define xfs_hooks_switched_on(name) (true)
#else
# define DEFINE_STATIC_XFS_HOOK_SWITCH(name)
# define xfs_hooks_switch_on(name) ((void)0)
# define xfs_hooks_switch_off(name) ((void)0)
# define xfs_hooks_switched_on(name) (false)
#endif /* JUMP_LABEL && XFS_LIVE_HOOKS */
#ifdef CONFIG_XFS_LIVE_HOOKS
struct xfs_hook {
/* This must come at the start of the structure. */
struct notifier_block nb;
};
typedef int (*xfs_hook_fn_t)(struct xfs_hook *hook, unsigned long action,
void *data);
void xfs_hooks_init(struct xfs_hooks *chain);
int xfs_hooks_add(struct xfs_hooks *chain, struct xfs_hook *hook);
void xfs_hooks_del(struct xfs_hooks *chain, struct xfs_hook *hook);
int xfs_hooks_call(struct xfs_hooks *chain, unsigned long action,
void *priv);
static inline void xfs_hook_setup(struct xfs_hook *hook, xfs_hook_fn_t fn)
{
hook->nb.notifier_call = (notifier_fn_t)fn;
hook->nb.priority = 0;
}
#else
# define xfs_hooks_init(chain) ((void)0)
# define xfs_hooks_call(chain, val, priv) (NOTIFY_DONE)
#endif
#endif /* XFS_HOOKS_H_ */
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