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
44 MODULE(MODULE_CLASS_MISC, executor, NULL);
45
46 static void callout_example(void *);
47 static int runonce_example(void);
48
49 static int executor_count = 0; //To hold the count of seconds
50
51 static callout_t sc;
52
53 /* Creating a variable that marks whether the function has executed or not */
54 static once_t ctl;
55 static 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
62 static int
runonce_example(void)63 runonce_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
75 static void
callout_example(void * arg)76 callout_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
90 static int
executor_modcmd(modcmd_t cmd,void * arg)91 executor_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