module/os/linux/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 https://opensource.org/licenses/CDDL-1.0.
  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 #include <sys/trace_zfs.h>
  28
  29 typedef struct zfs_dbgmsg {
  30         procfs_list_node_t      zdm_node;
  31         uint64_t                zdm_timestamp;
  32         uint_t                  zdm_size;
  33         char                    zdm_msg[]; /* variable length allocation */
  34 } zfs_dbgmsg_t;
  35
  36 static procfs_list_t zfs_dbgmsgs;
  37 static uint_t zfs_dbgmsg_size = 0;
  38 static uint_t zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
  39
  40 /*
  41  * Internal ZFS debug messages are enabled by default.
  42  *
  43  * # Print debug messages
  44  * cat /proc/spl/kstat/zfs/dbgmsg
  45  *
  46  * # Disable the kernel debug message log.
  47  * echo 0 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
  48  *
  49  * # Clear the kernel debug message log.
  50  * echo 0 >/proc/spl/kstat/zfs/dbgmsg
  51  */
  52 int zfs_dbgmsg_enable = B_TRUE;
  53
  54 static int
  55 zfs_dbgmsg_show_header(struct seq_file *f)
  56 {
  57         seq_printf(f, "%-12s %-8s\n", "timestamp", "message");
  58         return (0);
  59 }
  60
  61 static int
  62 zfs_dbgmsg_show(struct seq_file *f, void *p)
  63 {
  64         zfs_dbgmsg_t *zdm = (zfs_dbgmsg_t *)p;
  65         seq_printf(f, "%-12llu %-s\n",
  66             (u_longlong_t)zdm->zdm_timestamp, zdm->zdm_msg);
  67         return (0);
  68 }
  69
  70 static void
  71 zfs_dbgmsg_purge(uint_t max_size)
  72 {
  73         while (zfs_dbgmsg_size > max_size) {
  74                 zfs_dbgmsg_t *zdm = list_remove_head(&zfs_dbgmsgs.pl_list);
  75                 if (zdm == NULL)
  76                         return;
  77
  78                 uint_t size = zdm->zdm_size;
  79                 kmem_free(zdm, size);
  80                 zfs_dbgmsg_size -= size;
  81         }
  82 }
  83
  84 static int
  85 zfs_dbgmsg_clear(procfs_list_t *procfs_list)
  86 {
  87         (void) procfs_list;
  88         mutex_enter(&zfs_dbgmsgs.pl_lock);
  89         zfs_dbgmsg_purge(0);
  90         mutex_exit(&zfs_dbgmsgs.pl_lock);
  91         return (0);
  92 }
  93
  94 void
  95 zfs_dbgmsg_init(void)
  96 {
  97         procfs_list_install("zfs",
  98             NULL,
  99             "dbgmsg",
 100             0600,
 101             &zfs_dbgmsgs,
 102             zfs_dbgmsg_show,
 103             zfs_dbgmsg_show_header,
 104             zfs_dbgmsg_clear,
 105             offsetof(zfs_dbgmsg_t, zdm_node));
 106 }
 107
 108 void
 109 zfs_dbgmsg_fini(void)
 110 {
 111         procfs_list_uninstall(&zfs_dbgmsgs);
 112         zfs_dbgmsg_purge(0);
 113
 114         procfs_list_destroy(&zfs_dbgmsgs);
 115 }
 116
 117 void
 118 __set_error(const char *file, const char *func, int line, int err)
 119 {
 120         /*
 121          * To enable this:
 122          *
 123          * $ echo 512 >/sys/module/zfs/parameters/zfs_flags
 124          */
 125         if (zfs_flags & ZFS_DEBUG_SET_ERROR)
 126                 __dprintf(B_FALSE, file, func, line, "error %lu",
 127                     (ulong_t)err);
 128 }
 129
 130 void
 131 __zfs_dbgmsg(char *buf)
 132 {
 133         uint_t size = sizeof (zfs_dbgmsg_t) + strlen(buf) + 1;
 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(zfs_dbgmsg_maxsize);
 143         mutex_exit(&zfs_dbgmsgs.pl_lock);
 144 }
 145
 146 void
 147 __dprintf(boolean_t dprint, const char *file, const char *func,
 148     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         char *prefix = (dprint) ? "dprintf: " : "";
 157
 158         size = 1024;
 159         buf = kmem_alloc(size, KM_SLEEP);
 160
 161         /*
 162          * Get rid of annoying prefix to filename.
 163          */
 164         newfile = strrchr(file, '/');
 165         if (newfile != NULL) {
 166                 newfile = newfile + 1; /* Get rid of leading / */
 167         } else {
 168                 newfile = file;
 169         }
 170
 171         i = snprintf(buf, size, "%px %s%s:%d:%s(): ",
 172             curthread, prefix, newfile, line, func);
 173
 174         if (i < size) {
 175                 va_start(adx, fmt);
 176                 (void) vsnprintf(buf + i, size - i, fmt, adx);
 177                 va_end(adx);
 178         }
 179
 180         /*
 181          * Get rid of trailing newline for dprintf logs.
 182          */
 183         if (dprint && buf[0] != '\0') {
 184                 nl = &buf[strlen(buf) - 1];
 185                 if (*nl == '\n')
 186                         *nl = '\0';
 187         }
 188
 189         /*
 190          * To get this data enable the zfs__dprintf trace point as shown:
 191          *
 192          * # Enable zfs__dprintf tracepoint, clear the tracepoint ring buffer
 193          * $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
 194          * $ echo 0 > /sys/kernel/debug/tracing/trace
 195          *
 196          * # Dump the ring buffer.
 197          * $ cat /sys/kernel/debug/tracing/trace
 198          */
 199         DTRACE_PROBE1(zfs__dprintf, char *, buf);
 200
 201         /*
 202          * To get this data:
 203          *
 204          * $ cat /proc/spl/kstat/zfs/dbgmsg
 205          *
 206          * To clear the buffer:
 207          * $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
 208          */
 209         __zfs_dbgmsg(buf);
 210
 211         kmem_free(buf, size);
 212 }
 213
 214 module_param(zfs_dbgmsg_enable, int, 0644);
 215 MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
 216
 217 /* BEGIN CSTYLED */
 218 module_param(zfs_dbgmsg_maxsize, uint, 0644);
 219 /* END CSTYLED */
 220 MODULE_PARM_DESC(zfs_dbgmsg_maxsize, "Maximum ZFS debug log size");