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(B_FALSE, file, func, line, "error %lu", err);
 128 }
 129
 130 void
 131 __zfs_dbgmsg(char *buf)
 132 {
 133         int size = sizeof (zfs_dbgmsg_t) + strlen(buf);
 134         zfs_dbgmsg_t *zdm = kmem_zalloc(size, KM_SLEEP);
 135         zdm->zdm_size = size;
 136         zdm->zdm_timestamp = gethrestime_sec();
 137         strcpy(zdm->zdm_msg, buf);
 138
 139         mutex_enter(&zfs_dbgmsgs.pl_lock);
 140         procfs_list_add(&zfs_dbgmsgs, zdm);
 141         zfs_dbgmsg_size += size;
 142         zfs_dbgmsg_purge(MAX(zfs_dbgmsg_maxsize, 0));
 143         mutex_exit(&zfs_dbgmsgs.pl_lock);
 144 }
 145
 146 #ifdef _KERNEL
 147
 148 void
 149 __dprintf(boolean_t dprint, const char *file, const char *func,
 150     int line, const char *fmt, ...)
 151 {
 152         const char *newfile;
 153         va_list adx;
 154         size_t size;
 155         char *buf;
 156         char *nl;
 157         int i;
 158         char *prefix = (dprint) ? "dprintf: " : "";
 159
 160         size = 1024;
 161         buf = kmem_alloc(size, KM_SLEEP);
 162
 163         /*
 164          * Get rid of annoying prefix to filename.
 165          */
 166         newfile = strrchr(file, '/');
 167         if (newfile != NULL) {
 168                 newfile = newfile + 1; /* Get rid of leading / */
 169         } else {
 170                 newfile = file;
 171         }
 172
 173         i = snprintf(buf, size, "%s%s:%d:%s(): ", prefix, newfile, line, func);
 174
 175         if (i < size) {
 176                 va_start(adx, fmt);
 177                 (void) vsnprintf(buf + i, size - i, fmt, adx);
 178                 va_end(adx);
 179         }
 180
 181         /*
 182          * Get rid of trailing newline for dprintf logs.
 183          */
 184         if (dprint && buf[0] != '\0') {
 185                 nl = &buf[strlen(buf) - 1];
 186                 if (*nl == '\n')
 187                         *nl = '\0';
 188         }
 189
 190         /*
 191          * To get this data enable the zfs__dprintf trace point as shown:
 192          *
 193          * # Enable zfs__dprintf tracepoint, clear the tracepoint ring buffer
 194          * $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
 195          * $ echo 0 > /sys/kernel/debug/tracing/trace
 196          *
 197          * # Dump the ring buffer.
 198          * $ cat /sys/kernel/debug/tracing/trace
 199          */
 200         DTRACE_PROBE1(zfs__dprintf, char *, buf);
 201
 202         /*
 203          * To get this data:
 204          *
 205          * $ cat /proc/spl/kstat/zfs/dbgmsg
 206          *
 207          * To clear the buffer:
 208          * $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
 209          */
 210         __zfs_dbgmsg(buf);
 211
 212         kmem_free(buf, size);
 213 }
 214
 215 #else
 216
 217 void
 218 zfs_dbgmsg_print(const char *tag)
 219 {
 220         ssize_t ret __attribute__((unused));
 221
 222         /*
 223          * We use write() in this function instead of printf()
 224          * so it is safe to call from a signal handler.
 225          */
 226         ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
 227         ret = write(STDOUT_FILENO, tag, strlen(tag));
 228         ret = write(STDOUT_FILENO, ") START:\n", 9);
 229
 230         mutex_enter(&zfs_dbgmsgs.pl_lock);
 231         for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs.pl_list); zdm != NULL;
 232             zdm = list_next(&zfs_dbgmsgs.pl_list, zdm)) {
 233                 ret = write(STDOUT_FILENO, zdm->zdm_msg,
 234                     strlen(zdm->zdm_msg));
 235                 ret = write(STDOUT_FILENO, "\n", 1);
 236         }
 237
 238         ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
 239         ret = write(STDOUT_FILENO, tag, strlen(tag));
 240         ret = write(STDOUT_FILENO, ") END\n", 6);
 241
 242         mutex_exit(&zfs_dbgmsgs.pl_lock);
 243 }
 244 #endif /* _KERNEL */
 245
 246 #ifdef _KERNEL
 247 module_param(zfs_dbgmsg_enable, int, 0644);
 248 MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
 249
 250 module_param(zfs_dbgmsg_maxsize, int, 0644);
 251 MODULE_PARM_DESC(zfs_dbgmsg_maxsize, "Maximum ZFS debug log size");
 252 #endif