executor.c revision 1.3 
1/*	$NetBSD: executor.c,v 1.3 2024/07/06 09:53:19 andvar Exp $	*/
2
3/*-
4 * Copyright (c) 2018 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD: executor.c,v 1.3 2024/07/06 09:53:19 andvar Exp $");
31
32#include <sys/param.h>
33#include <sys/module.h>
34#include <sys/callout.h>
35#include <sys/once.h>
36
37/*
38 * Check if dmesg prints
39 * "executor <no-of-seconds-after-loading>" every second
40 * and "executor once" exactly once in the beginning
41 * to test this module
42 */
43
44MODULE(MODULE_CLASS_MISC, executor, NULL);
45
46static void callout_example(void *);
47static int runonce_example(void);
48
49static int executor_count = 0; //To hold the count of seconds
50
51static callout_t sc;
52
53/* Creating a variable that marks whether the function has executed or not */
54static once_t ctl;
55static ONCE_DECL(ctl);
56
57/*
58 * runonce_example : This function should execute only once
59 * It should return 0 as RUN_ONCE calls the function until it returns 0.
60 */
61
62static int
63runonce_example(void) {
64	printf("executor once\n");
65	return 0;
66}
67
68/*
69 * callout_example : This function should get executed every second.
70 * It calls runonce_example each time.
71 * It prints the seconds elapsed after the module was loaded.
72 * It reschedules the callout to the next second using callout_schedule
73 */
74
75static void
76callout_example(void *arg) {
77	RUN_ONCE(&ctl, runonce_example);
78	executor_count++;
79	printf("Callout %d\n", executor_count);
80	callout_schedule(&sc, mstohz(1000));
81}
82
83/*
84 * executor_modcmd : has two tasks
85 * On loading the module it needs to initialize a callout handle and schedule
86 * the first callout.
87 * On unloading the module it needs to stop and destroy the callout handle
88 */
89
90static int
91executor_modcmd(modcmd_t cmd, void *arg)
92{
93	switch(cmd) {
94	case MODULE_CMD_INIT:
95		printf("executor module inserted\n");
96		callout_init(&sc, CALLOUT_MPSAFE);
97		callout_reset(&sc, mstohz(1000), callout_example, NULL);
98		break;
99	case MODULE_CMD_FINI:
100		printf("executor module unloaded\n");
101		callout_halt(&sc, NULL);
102		callout_destroy(&sc);
103		break;
104	default:
105		return ENOTTY;
106	}
107	return 0;
108}
109