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    Subject[take27 5/8] kevent: Timer notifications.
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    Timer notifications.

    Timer notifications can be used for fine grained per-process time
    management, since interval timers are very inconvenient to use,
    and they are limited.

    This subsystem uses high-resolution timers.
    id.raw[0] is used as number of seconds
    id.raw[1] is used as number of nanoseconds

    Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>

    diff --git a/kernel/kevent/kevent_timer.c b/kernel/kevent/kevent_timer.c
    new file mode 100644
    index 0000000..df93049
    --- /dev/null
    +++ b/kernel/kevent/kevent_timer.c
    @@ -0,0 +1,112 @@
    +/*
    + * 2006 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru>
    + * All rights reserved.
    + *
    + * 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
    + */
    +
    +#include <linux/kernel.h>
    +#include <linux/types.h>
    +#include <linux/list.h>
    +#include <linux/slab.h>
    +#include <linux/spinlock.h>
    +#include <linux/hrtimer.h>
    +#include <linux/jiffies.h>
    +#include <linux/kevent.h>
    +
    +struct kevent_timer
    +{
    + struct hrtimer ktimer;
    + struct kevent_storage ktimer_storage;
    + struct kevent *ktimer_event;
    +};
    +
    +static int kevent_timer_func(struct hrtimer *timer)
    +{
    + struct kevent_timer *t = container_of(timer, struct kevent_timer, ktimer);
    + struct kevent *k = t->ktimer_event;
    +
    + kevent_storage_ready(&t->ktimer_storage, NULL, KEVENT_MASK_ALL);
    + hrtimer_forward(timer, timer->base->softirq_time,
    + ktime_set(k->event.id.raw[0], k->event.id.raw[1]));
    + return HRTIMER_RESTART;
    +}
    +
    +static struct lock_class_key kevent_timer_key;
    +
    +static int kevent_timer_enqueue(struct kevent *k)
    +{
    + int err;
    + struct kevent_timer *t;
    +
    + t = kmalloc(sizeof(struct kevent_timer), GFP_KERNEL);
    + if (!t)
    + return -ENOMEM;
    +
    + hrtimer_init(&t->ktimer, CLOCK_MONOTONIC, HRTIMER_REL);
    + t->ktimer.expires = ktime_set(k->event.id.raw[0], k->event.id.raw[1]);
    + t->ktimer.function = kevent_timer_func;
    + t->ktimer_event = k;
    +
    + err = kevent_storage_init(&t->ktimer, &t->ktimer_storage);
    + if (err)
    + goto err_out_free;
    + lockdep_set_class(&t->ktimer_storage.lock, &kevent_timer_key);
    +
    + err = kevent_storage_enqueue(&t->ktimer_storage, k);
    + if (err)
    + goto err_out_st_fini;
    +
    + hrtimer_start(&t->ktimer, t->ktimer.expires, HRTIMER_REL);
    +
    + return 0;
    +
    +err_out_st_fini:
    + kevent_storage_fini(&t->ktimer_storage);
    +err_out_free:
    + kfree(t);
    +
    + return err;
    +}
    +
    +static int kevent_timer_dequeue(struct kevent *k)
    +{
    + struct kevent_storage *st = k->st;
    + struct kevent_timer *t = container_of(st, struct kevent_timer, ktimer_storage);
    +
    + hrtimer_cancel(&t->ktimer);
    + kevent_storage_dequeue(st, k);
    + kfree(t);
    +
    + return 0;
    +}
    +
    +static int kevent_timer_callback(struct kevent *k)
    +{
    + k->event.ret_data[0] = jiffies_to_msecs(jiffies);
    + return 1;
    +}
    +
    +static int __init kevent_init_timer(void)
    +{
    + struct kevent_callbacks tc = {
    + .callback = &kevent_timer_callback,
    + .enqueue = &kevent_timer_enqueue,
    + .dequeue = &kevent_timer_dequeue};
    +
    + return kevent_add_callbacks(&tc, KEVENT_TIMER);
    +}
    +module_init(kevent_init_timer);
    +
    -
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