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/*

 * Copyright (C) 2001-2004 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <time/timeout.h>

#include <typedefs.h>

#include <arch/types.h>

#include <config.h>

#include <panic.h>

#include <synch/spinlock.h>

#include <func.h>

#include <cpu.h>

#include <arch/asm.h>

#include <arch.h>

/** Initialize timeouts

 *

 * Initialize kernel timeouts.

 *

 */

void timeout_init(void)

{

    spinlock_initialize(&CPU->timeoutlock, "timeout_lock");

    list_initialize(&CPU->timeout_active_head);

}

/** Reinitialize timeout

 *

 * Initialize all members except the lock.

 *

 * @param t Timeout to be initialized.

 *

 */

void timeout_reinitialize(timeout_t *t)

{

    t->cpu = NULL;

    t->ticks = 0;

    t->handler = NULL;

    t->arg = NULL;

    link_initialize(&t->link);

}

/** Initialize timeout

 *

 * Initialize all members including the lock.

 *

 * @param t Timeout to be initialized.

 *

 */

void timeout_initialize(timeout_t *t)

{

    spinlock_initialize(&t->lock, "timeout_t_lock");

    timeout_reinitialize(t);

}

/** Register timeout

 *

 * Insert timeout handler f (with argument arg)

 * to timeout list and make it execute in

 * time microseconds (or slightly more).

 *

 * @param t    Timeout structure.

 * @param time Number of usec in the future to execute

 *             the handler.

 * @param f    Timeout handler function.

 * @param arg  Timeout handler argument.

 *

 */

void timeout_register(timeout_t *t, __u64 time, timeout_handler_t f, void *arg)

{

    timeout_t *hlp = NULL;

    link_t *l, *m;

    ipl_t ipl;

    __u64 sum;

    ipl = interrupts_disable();

    spinlock_lock(&CPU->timeoutlock);

    spinlock_lock(&t->lock);

    if (t->cpu)

        panic("t->cpu != 0");

    t->cpu = CPU;

    t->ticks = us2ticks(time);

    t->handler = f;

    t->arg = arg;

    /*

     * Insert t into the active timeouts list according to t->ticks.

     */

    sum = 0;

    l = CPU->timeout_active_head.next;

    while (l != &CPU->timeout_active_head) {

        hlp = list_get_instance(l, timeout_t, link);

        spinlock_lock(&hlp->lock);

        if (t->ticks < sum + hlp->ticks) {

            spinlock_unlock(&hlp->lock);

            break;

        }

        sum += hlp->ticks;

        spinlock_unlock(&hlp->lock);

        l = l->next;

    }

    m = l->prev;

    list_prepend(&t->link, m); /* avoid using l->prev */

    /*

     * Adjust t->ticks according to ticks accumulated in h's predecessors.

     */

    t->ticks -= sum;

    /*

     * Decrease ticks of t's immediate succesor by t->ticks.

     */

    if (l != &CPU->timeout_active_head) {

        spinlock_lock(&hlp->lock);

        hlp->ticks -= t->ticks;

        spinlock_unlock(&hlp->lock);

    }

    spinlock_unlock(&t->lock);

    spinlock_unlock(&CPU->timeoutlock);

    interrupts_restore(ipl);

}

/** Unregister timeout

 *

 * Remove timeout from timeout list.

 *

 * @param t Timeout to unregister.

 *

 * @return true on success, false on failure.

 */

bool timeout_unregister(timeout_t *t)

{

    timeout_t *hlp;

    link_t *l;

    ipl_t ipl;

grab_locks:

    ipl = interrupts_disable();

    spinlock_lock(&t->lock);

    if (!t->cpu) {

        spinlock_unlock(&t->lock);

        interrupts_restore(ipl);

        return false;

    }

    if (!spinlock_trylock(&t->cpu->timeoutlock)) {

        spinlock_unlock(&t->lock);

        interrupts_restore(ipl);       

        goto grab_locks;

    }

    /*

     * Now we know for sure that t hasn't been activated yet

     * and is lurking in t->cpu->timeout_active_head queue.

     */

    l = t->link.next;

    if (l != &t->cpu->timeout_active_head) {

        hlp = list_get_instance(l, timeout_t, link);

        spinlock_lock(&hlp->lock);

        hlp->ticks += t->ticks;

        spinlock_unlock(&hlp->lock);

    }

    list_remove(&t->link);

    spinlock_unlock(&t->cpu->timeoutlock);

    timeout_reinitialize(t);

    spinlock_unlock(&t->lock);

    interrupts_restore(ipl);

    return true;

}