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Subject[take26-resend1 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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