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 list_t zfs_dbgmsgs;
  29 int zfs_dbgmsg_size;
  30 kmutex_t zfs_dbgmsgs_lock;
  31 int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
  32
  33 void
  34 zfs_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
  41 void
  42 zfs_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  * To get this data enable the zfs__dbgmsg tracepoint as shown:
  57  *
  58  * # Enable zfs__dbgmsg tracepoint, clear the tracepoint ring buffer
  59  * $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
  60  * $ echo 0 > /sys/kernel/debug/tracing/trace
  61  *
  62  * # Dump the ring buffer.
  63  * $ cat /sys/kernel/debug/tracing/trace
  64  */
  65 void
  66 zfs_dbgmsg(const char *fmt, ...)
  67 {
  68         int size;
  69         va_list adx;
  70         char *nl;
  71         zfs_dbgmsg_t *zdm;
  72
  73         va_start(adx, fmt);
  74         size = vsnprintf(NULL, 0, fmt, adx);
  75         va_end(adx);
  76
  77         /*
  78          * There is one byte of string in sizeof (zfs_dbgmsg_t), used
  79          * for the terminating null.
  80          */
  81         zdm = kmem_alloc(sizeof (zfs_dbgmsg_t) + size, KM_PUSHPAGE);
  82         zdm->zdm_timestamp = gethrestime_sec();
  83
  84         va_start(adx, fmt);
  85         (void) vsnprintf(zdm->zdm_msg, size + 1, fmt, adx);
  86         va_end(adx);
  87
  88         /*
  89          * Get rid of trailing newline.
  90          */
  91         nl = strrchr(zdm->zdm_msg, '\n');
  92         if (nl != NULL)
  93                 *nl = '\0';
  94
  95         DTRACE_PROBE1(zfs__dbgmsg, char *, zdm->zdm_msg);
  96
  97         mutex_enter(&zfs_dbgmsgs_lock);
  98         list_insert_tail(&zfs_dbgmsgs, zdm);
  99         zfs_dbgmsg_size += sizeof (zfs_dbgmsg_t) + size;
 100         while (zfs_dbgmsg_size > zfs_dbgmsg_maxsize) {
 101                 zdm = list_remove_head(&zfs_dbgmsgs);
 102                 size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
 103                 kmem_free(zdm, size);
 104                 zfs_dbgmsg_size -= size;
 105         }
 106         mutex_exit(&zfs_dbgmsgs_lock);
 107 }
 108
 109 void
 110 zfs_dbgmsg_print(const char *tag)
 111 {
 112 #if !defined(_KERNEL)
 113         zfs_dbgmsg_t *zdm;
 114
 115         (void) printf("ZFS_DBGMSG(%s):\n", tag);
 116         mutex_enter(&zfs_dbgmsgs_lock);
 117         for (zdm = list_head(&zfs_dbgmsgs); zdm;
 118             zdm = list_next(&zfs_dbgmsgs, zdm))
 119                 (void) printf("%s\n", zdm->zdm_msg);
 120         mutex_exit(&zfs_dbgmsgs_lock);
 121 #endif /* !_KERNEL */
 122 }