zfs_debug.c revision 268650 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2013 by Delphix. All rights reserved.
24 */
25
26#include <sys/zfs_context.h>
27
28list_t zfs_dbgmsgs;
29int zfs_dbgmsg_size;
30kmutex_t zfs_dbgmsgs_lock;
31int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
32
33void
34zfs_dbgmsg_init(void)
35{
36	list_create(&zfs_dbgmsgs, sizeof (zfs_dbgmsg_t),
37	    offsetof(zfs_dbgmsg_t, zdm_node));
38	mutex_init(&zfs_dbgmsgs_lock, NULL, MUTEX_DEFAULT, NULL);
39}
40
41void
42zfs_dbgmsg_fini(void)
43{
44	zfs_dbgmsg_t *zdm;
45
46	while ((zdm = list_remove_head(&zfs_dbgmsgs)) != NULL) {
47		int size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
48		kmem_free(zdm, size);
49		zfs_dbgmsg_size -= size;
50	}
51	mutex_destroy(&zfs_dbgmsgs_lock);
52	ASSERT0(zfs_dbgmsg_size);
53}
54
55/*
56 * Print these messages by running:
57 * echo ::zfs_dbgmsg | mdb -k
58 *
59 * Monitor these messages by running:
60 * 	dtrace -q -n 'zfs-dbgmsg{printf("%s\n", stringof(arg0))}'
61 */
62void
63zfs_dbgmsg(const char *fmt, ...)
64{
65	int size;
66	va_list adx;
67	zfs_dbgmsg_t *zdm;
68
69	va_start(adx, fmt);
70	size = vsnprintf(NULL, 0, fmt, adx);
71	va_end(adx);
72
73	/*
74	 * There is one byte of string in sizeof (zfs_dbgmsg_t), used
75	 * for the terminating null.
76	 */
77	zdm = kmem_alloc(sizeof (zfs_dbgmsg_t) + size, KM_SLEEP);
78	zdm->zdm_timestamp = gethrestime_sec();
79
80	va_start(adx, fmt);
81	(void) vsnprintf(zdm->zdm_msg, size + 1, fmt, adx);
82	va_end(adx);
83
84	DTRACE_PROBE1(zfs__dbgmsg, char *, zdm->zdm_msg);
85
86	mutex_enter(&zfs_dbgmsgs_lock);
87	list_insert_tail(&zfs_dbgmsgs, zdm);
88	zfs_dbgmsg_size += sizeof (zfs_dbgmsg_t) + size;
89	while (zfs_dbgmsg_size > zfs_dbgmsg_maxsize) {
90		zdm = list_remove_head(&zfs_dbgmsgs);
91		size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
92		kmem_free(zdm, size);
93		zfs_dbgmsg_size -= size;
94	}
95	mutex_exit(&zfs_dbgmsgs_lock);
96}
97
98void
99zfs_dbgmsg_print(const char *tag)
100{
101	zfs_dbgmsg_t *zdm;
102
103	(void) printf("ZFS_DBGMSG(%s):\n", tag);
104	mutex_enter(&zfs_dbgmsgs_lock);
105	for (zdm = list_head(&zfs_dbgmsgs); zdm;
106	    zdm = list_next(&zfs_dbgmsgs, zdm))
107		(void) printf("%s\n", zdm->zdm_msg);
108	mutex_exit(&zfs_dbgmsgs_lock);
109}
110