module/zfs/zfs_debug.c

   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) 2012, 2014 by Delphix. All rights reserved.
  24  */
  25
  26 #include <sys/zfs_context.h>
  27
  28 typedef struct zfs_dbgmsg {
  29         procfs_list_node_t      zdm_node;
  30         time_t                  zdm_timestamp;
  31         int                     zdm_size;
  32         char                    zdm_msg[1]; /* variable length allocation */
  33 } zfs_dbgmsg_t;
  34
  35 procfs_list_t zfs_dbgmsgs;
  36 int zfs_dbgmsg_size = 0;
  37 int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
  38
  39 /*
  40  * Internal ZFS debug messages are enabled by default.
  41  *
  42  * # Print debug messages
  43  * cat /proc/spl/kstat/zfs/dbgmsg
  44  *
  45  * # Disable the kernel debug message log.
  46  * echo 0 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
  47  *
  48  * # Clear the kernel debug message log.
  49  * echo 0 >/proc/spl/kstat/zfs/dbgmsg
  50  */
  51 int zfs_dbgmsg_enable = 1;
  52
  53 static int
  54 zfs_dbgmsg_show_header(struct seq_file *f)
  55 {
  56         seq_printf(f, "%-12s %-8s\n", "timestamp", "message");
  57         return (0);
  58 }
  59
  60 static int
  61 zfs_dbgmsg_show(struct seq_file *f, void *p)
  62 {
  63         zfs_dbgmsg_t *zdm = (zfs_dbgmsg_t *)p;
  64         seq_printf(f, "%-12llu %-s\n",
  65             (u_longlong_t)zdm->zdm_timestamp, zdm->zdm_msg);
  66         return (0);
  67 }
  68
  69 static void
  70 zfs_dbgmsg_purge(int max_size)
  71 {
  72         while (zfs_dbgmsg_size > max_size) {
  73                 zfs_dbgmsg_t *zdm = list_remove_head(&zfs_dbgmsgs.pl_list);
  74                 if (zdm == NULL)
  75                         return;
  76
  77                 int size = zdm->zdm_size;
  78                 kmem_free(zdm, size);
  79                 zfs_dbgmsg_size -= size;
  80         }
  81 }
  82
  83 static int
  84 zfs_dbgmsg_clear(procfs_list_t *procfs_list)
  85 {
  86         mutex_enter(&zfs_dbgmsgs.pl_lock);
  87         zfs_dbgmsg_purge(0);
  88         mutex_exit(&zfs_dbgmsgs.pl_lock);
  89         return (0);
  90 }
  91
  92 void
  93 zfs_dbgmsg_init(void)
  94 {
  95         procfs_list_install("zfs",
  96             "dbgmsg",
  97             &zfs_dbgmsgs,
  98             zfs_dbgmsg_show,
  99             zfs_dbgmsg_show_header,
 100             zfs_dbgmsg_clear,
 101             offsetof(zfs_dbgmsg_t, zdm_node));
 102 }
 103
 104 void
 105 zfs_dbgmsg_fini(void)
 106 {
 107         procfs_list_uninstall(&zfs_dbgmsgs);
 108         zfs_dbgmsg_purge(0);
 109
 110         /*
 111          * TODO - decide how to make this permanent
 112          */
 113 #ifdef _KERNEL
 114         procfs_list_destroy(&zfs_dbgmsgs);
 115 #endif
 116 }
 117
 118 void
 119 __set_error(const char *file, const char *func, int line, int err)
 120 {
 121         /*
 122          * To enable this:
 123          *
 124          * $ echo 512 >/sys/module/zfs/parameters/zfs_flags
 125          */
 126         if (zfs_flags & ZFS_DEBUG_SET_ERROR)
 127                 __dprintf(file, func, line, "error %lu", err);
 128 }
 129
 130 #ifdef _KERNEL
 131 static void
 132 __zfs_dbgmsg(char *buf)
 133 {
 134         int size = sizeof (zfs_dbgmsg_t) + strlen(buf);
 135         zfs_dbgmsg_t *zdm = kmem_zalloc(size, KM_SLEEP);
 136         zdm->zdm_size = size;
 137         zdm->zdm_timestamp = gethrestime_sec();
 138         strcpy(zdm->zdm_msg, buf);
 139
 140         mutex_enter(&zfs_dbgmsgs.pl_lock);
 141         procfs_list_add(&zfs_dbgmsgs, zdm);
 142         zfs_dbgmsg_size += size;
 143         zfs_dbgmsg_purge(MAX(zfs_dbgmsg_maxsize, 0));
 144         mutex_exit(&zfs_dbgmsgs.pl_lock);
 145 }
 146
 147 void
 148 __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 149 {
 150         const char *newfile;
 151         va_list adx;
 152         size_t size;
 153         char *buf;
 154         char *nl;
 155         int i;
 156
 157         size = 1024;
 158         buf = kmem_alloc(size, KM_SLEEP);
 159
 160         /*
 161          * Get rid of annoying prefix to filename.
 162          */
 163         newfile = strrchr(file, '/');
 164         if (newfile != NULL) {
 165                 newfile = newfile + 1; /* Get rid of leading / */
 166         } else {
 167                 newfile = file;
 168         }
 169
 170         i = snprintf(buf, size, "%s:%d:%s(): ", newfile, line, func);
 171
 172         if (i < size) {
 173                 va_start(adx, fmt);
 174                 (void) vsnprintf(buf + i, size - i, fmt, adx);
 175                 va_end(adx);
 176         }
 177
 178         /*
 179          * Get rid of trailing newline.
 180          */
 181         nl = strrchr(buf, '\n');
 182         if (nl != NULL)
 183                 *nl = '\0';
 184
 185         /*
 186          * To get this data enable the zfs__dprintf trace point as shown:
 187          *
 188          * # Enable zfs__dprintf tracepoint, clear the tracepoint ring buffer
 189          * $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
 190          * $ echo 0 > /sys/kernel/debug/tracing/trace
 191          *
 192          * # Dump the ring buffer.
 193          * $ cat /sys/kernel/debug/tracing/trace
 194          */
 195         DTRACE_PROBE1(zfs__dprintf, char *, buf);
 196
 197         /*
 198          * To get this data:
 199          *
 200          * $ cat /proc/spl/kstat/zfs/dbgmsg
 201          *
 202          * To clear the buffer:
 203          * $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
 204          */
 205         __zfs_dbgmsg(buf);
 206
 207         kmem_free(buf, size);
 208 }
 209
 210 #else
 211
 212 void
 213 zfs_dbgmsg_print(const char *tag)
 214 {
 215         (void) printf("ZFS_DBGMSG(%s):\n", tag);
 216         mutex_enter(&zfs_dbgmsgs.pl_lock);
 217         for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs.pl_list); zdm != NULL;
 218             zdm = list_next(&zfs_dbgmsgs.pl_list, zdm))
 219                 (void) printf("%s\n", zdm->zdm_msg);
 220         mutex_exit(&zfs_dbgmsgs.pl_lock);
 221 }
 222 #endif /* _KERNEL */
 223
 224 #ifdef _KERNEL
 225 module_param(zfs_dbgmsg_enable, int, 0644);
 226 MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
 227
 228 module_param(zfs_dbgmsg_maxsize, int, 0644);
 229 MODULE_PARM_DESC(zfs_dbgmsg_maxsize, "Maximum ZFS debug log size");
 230 #endif