source: mainline/kernel/generic/src/time/timeout.c@ 0b5203b

/*
 * 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.
 */

/** @addtogroup kernel_time
 * @{
 */

/**
 * @file
 * @brief Timeout management functions.
 */

#include <time/timeout.h>
#include <typedefs.h>
#include <config.h>
#include <panic.h>
#include <synch/spinlock.h>
#include <halt.h>
#include <cpu.h>
#include <arch/asm.h>
#include <arch.h>

/** Initialize timeouts
 *
 * Initialize kernel timeouts.
 *
 */
void timeout_init(void)
{
        irq_spinlock_initialize(&CPU->timeoutlock, "cpu.timeoutlock");
        list_initialize(&CPU->timeout_active_list);
}

/** Reinitialize timeout
 *
 * Initialize all members except the lock.
 *
 * @param timeout Timeout to be initialized.
 *
 */
void timeout_reinitialize(timeout_t *timeout)
{
        timeout->cpu = NULL;
        timeout->ticks = 0;
        timeout->handler = NULL;
        timeout->arg = NULL;
        link_initialize(&timeout->link);
}

/** Initialize timeout
 *
 * Initialize all members including the lock.
 *
 * @param timeout Timeout to be initialized.
 *
 */
void timeout_initialize(timeout_t *timeout)
{
        irq_spinlock_initialize(&timeout->lock, "timeout_t_lock");
        timeout_reinitialize(timeout);
}

/** Register timeout
 *
 * Insert timeout handler f (with argument arg)
 * to timeout list and make it execute in
 * time microseconds (or slightly more).
 *
 * @param timeout Timeout structure.
 * @param time    Number of usec in the future to execute the handler.
 * @param handler Timeout handler function.
 * @param arg     Timeout handler argument.
 *
 */
void timeout_register(timeout_t *timeout, uint64_t time,
    timeout_handler_t handler, void *arg)
{
        irq_spinlock_lock(&CPU->timeoutlock, true);
        irq_spinlock_lock(&timeout->lock, false);

        if (timeout->cpu)
                panic("Unexpected: timeout->cpu != 0.");

        timeout->cpu = CPU;
        timeout->ticks = us2ticks(time);

        timeout->handler = handler;
        timeout->arg = arg;

        /*
         * Insert timeout into the active timeouts list according to timeout->ticks.
         */
        uint64_t sum = 0;
        timeout_t *target = NULL;
        link_t *cur;
        for (cur = CPU->timeout_active_list.head.next;
            cur != &CPU->timeout_active_list.head; cur = cur->next) {
                target = list_get_instance(cur, timeout_t, link);
                irq_spinlock_lock(&target->lock, false);

                if (timeout->ticks < sum + target->ticks) {
                        irq_spinlock_unlock(&target->lock, false);
                        break;
                }

                sum += target->ticks;
                irq_spinlock_unlock(&target->lock, false);
        }

        /* Avoid using cur->prev directly */
        link_t *prev = cur->prev;
        list_insert_after(&timeout->link, prev);

        /*
         * Adjust timeout->ticks according to ticks
         * accumulated in target's predecessors.
         */
        timeout->ticks -= sum;

        /*
         * Decrease ticks of timeout's immediate succesor by timeout->ticks.
         */
        if (cur != &CPU->timeout_active_list.head) {
                irq_spinlock_lock(&target->lock, false);
                target->ticks -= timeout->ticks;
                irq_spinlock_unlock(&target->lock, false);
        }

        irq_spinlock_unlock(&timeout->lock, false);
        irq_spinlock_unlock(&CPU->timeoutlock, true);
}

/** Unregister timeout
 *
 * Remove timeout from timeout list.
 *
 * @param timeout Timeout to unregister.
 *
 * @return True on success, false on failure.
 *
 */
bool timeout_unregister(timeout_t *timeout)
{
        DEADLOCK_PROBE_INIT(p_tolock);

grab_locks:
        irq_spinlock_lock(&timeout->lock, true);
        if (!timeout->cpu) {
                irq_spinlock_unlock(&timeout->lock, true);
                return false;
        }

        if (!irq_spinlock_trylock(&timeout->cpu->timeoutlock)) {
                irq_spinlock_unlock(&timeout->lock, true);
                DEADLOCK_PROBE(p_tolock, DEADLOCK_THRESHOLD);
                goto grab_locks;
        }

        /*
         * Now we know for sure that timeout hasn't been activated yet
         * and is lurking in timeout->cpu->timeout_active_list.
         */

        link_t *cur = timeout->link.next;
        if (cur != &timeout->cpu->timeout_active_list.head) {
                timeout_t *tmp = list_get_instance(cur, timeout_t, link);
                irq_spinlock_lock(&tmp->lock, false);
                tmp->ticks += timeout->ticks;
                irq_spinlock_unlock(&tmp->lock, false);
        }

        list_remove(&timeout->link);
        irq_spinlock_unlock(&timeout->cpu->timeoutlock, false);

        timeout_reinitialize(timeout);
        irq_spinlock_unlock(&timeout->lock, true);

        return true;
}

/** @}
 */