1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2019 Eric van Gyzen
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  *
27  * $FreeBSD$
28  */
29 
30 /*
31  * Free a pending callout.  This was useful for testing the
32  * "show callout_last" ddb command.
33  */
34 
35 #include <sys/param.h>
36 #include <sys/conf.h>
37 #include <sys/kernel.h>
38 #include <sys/lock.h>
39 #include <sys/module.h>
40 #include <sys/mutex.h>
41 #include <sys/systm.h>
42 
43 static struct callout callout_free;
44 static struct mtx callout_free_mutex;
45 static int callout_free_arg;
46 
47 static void
48 callout_free_func(void *arg)
49 {
50 	printf("squirrel!\n");
51 	mtx_destroy(&callout_free_mutex);
52 	memset(&callout_free, 'C', sizeof(callout_free));
53 }
54 
55 static int
56 callout_free_load(module_t mod, int cmd, void *arg)
57 {
58 	int error;
59 
60 	switch (cmd) {
61 	case MOD_LOAD:
62 		mtx_init(&callout_free_mutex, "callout_free", NULL, MTX_DEF);
63 		/*
64 		 * Do not pass CALLOUT_RETURNUNLOCKED so the callout
65 		 * subsystem will unlock the "destroyed" mutex.
66 		 */
67 		callout_init_mtx(&callout_free, &callout_free_mutex, 0);
68 		printf("callout_free_func = %p\n", callout_free_func);
69 		printf("callout_free_arg = %p\n", &callout_free_arg);
70 		callout_reset(&callout_free, hz/10, callout_free_func,
71 		    &callout_free_arg);
72 		error = 0;
73 		break;
74 
75 	case MOD_UNLOAD:
76 		error = 0;
77 		break;
78 
79 	default:
80 		error = EOPNOTSUPP;
81 		break;
82 	}
83 
84 	return (error);
85 }
86 
87 DEV_MODULE(callout_free, callout_free_load, NULL);
88