source: mainline/kernel/generic/src/time/timeout.c

/*
 * Copyright (c) 2001-2004 Jakub Jermar
 * Copyright (c) 2022 Jiří Zárevúcky
 * 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);
}

/** Initialize timeout
 *
 * Initialize all members including the lock.
 *
 * @param timeout Timeout to be initialized.
 *
 */
void timeout_initialize(timeout_t *timeout)
{
        link_initialize(&timeout->link);
        timeout->cpu = NULL;
}

/* Only call when interrupts are disabled. */
deadline_t timeout_deadline_in_usec(uint32_t usec)
{
        if (usec == 0)
                return 0;

        return CPU_LOCAL->current_clock_tick + us2ticks(usec);
}

static void timeout_register_deadline_locked(timeout_t *timeout, deadline_t deadline,
    timeout_handler_t handler, void *arg)
{
        assert(!link_in_use(&timeout->link));

        *timeout = (timeout_t) {
                .cpu = CPU,
                .deadline = deadline,
                .handler = handler,
                .arg = arg,
                .finished = ATOMIC_VAR_INIT(false),
        };

        /* Insert timeout into the active timeouts list according to timeout->deadline. */

        link_t *last = list_last(&CPU->timeout_active_list);
        if (last == NULL || timeout->deadline >= list_get_instance(last, timeout_t, link)->deadline) {
                list_append(&timeout->link, &CPU->timeout_active_list);
        } else {
                for (link_t *cur = list_first(&CPU->timeout_active_list); cur != NULL;
                    cur = list_next(cur, &CPU->timeout_active_list)) {

                        if (timeout->deadline < list_get_instance(cur, timeout_t, link)->deadline) {
                                list_insert_before(&timeout->link, cur);
                                break;
                        }
                }
        }
}

/** 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);
        timeout_register_deadline_locked(timeout, timeout_deadline_in_usec(time), handler, arg);
        irq_spinlock_unlock(&CPU->timeoutlock, true);
}

void timeout_register_deadline(timeout_t *timeout, deadline_t deadline,
    timeout_handler_t handler, void *arg)
{
        irq_spinlock_lock(&CPU->timeoutlock, true);
        timeout_register_deadline_locked(timeout, deadline, handler, arg);
        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)
{
        if (atomic_load_explicit(&timeout->finished, memory_order_acquire))
                /* The timeout fired and finished already, no need to check the list. */
                return false;

        assert(timeout->cpu);

        irq_spinlock_lock(&timeout->cpu->timeoutlock, true);

        bool success = link_in_use(&timeout->link);
        if (success) {
                list_remove(&timeout->link);
        }

        irq_spinlock_unlock(&timeout->cpu->timeoutlock, true);

        if (!success) {
                /* Timeout was fired, we need to wait for the callback to finish. */
                while (!atomic_load_explicit(&timeout->finished, memory_order_acquire))
                        cpu_spin_hint();
        }

        return success;
}

/** @}
 */