1 /* $NetBSD: executor.c,v 1.1 2018/04/13 20:30:09 kamil 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 1.1 2018/04/13 20:30:09 kamil 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 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 elasped after the module was loaded. 72 * It reschedules the callout to the next second using callout_schedule 73 */ 74 75 static void 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 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, 0); 97 callout_reset(&sc, mstohz(1000), callout_example, NULL); 98 break; 99 case MODULE_CMD_FINI: 100 printf("executor module unloaded\n"); 101 callout_stop(&sc); 102 callout_destroy(&sc); 103 break; 104 default: 105 return ENOTTY; 106 } 107 return 0; 108 } 109