srcu.h

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/*
 * Sleepable Read-Copy Update mechanism for mutual exclusion
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2006
 *
 * Author: Paul McKenney <[email protected]>
 *
 * For detailed explanation of Read-Copy Update mechanism see -
 *      Documentation/RCU/ *.txt
 *
 */

#ifndef _LINUX_SRCU_H
#define _LINUX_SRCU_H

#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/workqueue.h>

struct srcu_struct_array {
    unsigned long c[2];
    unsigned long seq[2];
};

struct rcu_batch {
    struct rcu_head *head, **tail;
};

struct srcu_struct {
    unsigned completed;
    struct srcu_struct_array __percpu *per_cpu_ref;
    spinlock_t queue_lock; /* protect ->batch_queue, ->running */
    bool running;
    /* callbacks just queued */
    struct rcu_batch batch_queue;
    /* callbacks try to do the first check_zero */
    struct rcu_batch batch_check0;
    /* callbacks done with the first check_zero and the flip */
    struct rcu_batch batch_check1;
    struct rcu_batch batch_done;
    struct delayed_work work;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
    struct lockdep_map dep_map;
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
};

#ifdef CONFIG_DEBUG_LOCK_ALLOC

int __init_srcu_struct(struct srcu_struct *sp, const char *name,
               struct lock_class_key *key);

#define init_srcu_struct(sp) \
({ \
    static struct lock_class_key __srcu_key; \
    \
    __init_srcu_struct((sp), #sp, &__srcu_key); \
})

#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

int init_srcu_struct(struct srcu_struct *sp);

#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */

void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
        void (*func)(struct rcu_head *head));

void cleanup_srcu_struct(struct srcu_struct *sp);
int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
void synchronize_srcu(struct srcu_struct *sp);
void synchronize_srcu_expedited(struct srcu_struct *sp);
long srcu_batches_completed(struct srcu_struct *sp);
void srcu_barrier(struct srcu_struct *sp);

#ifdef CONFIG_DEBUG_LOCK_ALLOC

static inline int srcu_read_lock_held(struct srcu_struct *sp)
{
    if (!debug_lockdep_rcu_enabled())
        return 1;
    if (rcu_is_cpu_idle())
        return 0;
    if (!rcu_lockdep_current_cpu_online())
        return 0;
    return lock_is_held(&sp->dep_map);
}

#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

static inline int srcu_read_lock_held(struct srcu_struct *sp)
{
    return 1;
}

#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */

#define srcu_dereference_check(p, sp, c) \
    __rcu_dereference_check((p), srcu_read_lock_held(sp) || (c), __rcu)

#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)

static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
{
    int retval = __srcu_read_lock(sp);

    rcu_lock_acquire(&(sp)->dep_map);
    rcu_lockdep_assert(!rcu_is_cpu_idle(),
               "srcu_read_lock() used illegally while idle");
    return retval;
}

static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
    __releases(sp)
{
    rcu_lockdep_assert(!rcu_is_cpu_idle(),
               "srcu_read_unlock() used illegally while idle");
    rcu_lock_release(&(sp)->dep_map);
    __srcu_read_unlock(sp, idx);
}

static inline int srcu_read_lock_raw(struct srcu_struct *sp)
{
    unsigned long flags;
    int ret;

    local_irq_save(flags);
    ret =  __srcu_read_lock(sp);
    local_irq_restore(flags);
    return ret;
}

static inline void srcu_read_unlock_raw(struct srcu_struct *sp, int idx)
{
    unsigned long flags;

    local_irq_save(flags);
    __srcu_read_unlock(sp, idx);
    local_irq_restore(flags);
}

#endif