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  */
  24
  25 #include <sys/zfs_context.h>
  26
  27 list_t zfs_dbgmsgs;
  28 int zfs_dbgmsg_size;
  29 kmutex_t zfs_dbgmsgs_lock;
  30 int zfs_dbgmsg_maxsize = 1<<20; /* 1MB */
  31
  32 void
  33 zfs_dbgmsg_init(void)
  34 {
  35         list_create(&zfs_dbgmsgs, sizeof (zfs_dbgmsg_t),
  36             offsetof(zfs_dbgmsg_t, zdm_node));
  37         mutex_init(&zfs_dbgmsgs_lock, NULL, MUTEX_DEFAULT, NULL);
  38 }
  39
  40 void
  41 zfs_dbgmsg_fini(void)
  42 {
  43         zfs_dbgmsg_t *zdm;
  44
  45         while ((zdm = list_remove_head(&zfs_dbgmsgs)) != NULL) {
  46                 int size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
  47                 kmem_free(zdm, size);
  48                 zfs_dbgmsg_size -= size;
  49         }
  50         mutex_destroy(&zfs_dbgmsgs_lock);
  51         ASSERT3U(zfs_dbgmsg_size, ==, 0);
  52 }
  53
  54 /*
  55  * Print these messages by running:
  56  *      echo ::zfs_dbgmsg | mdb -k
  57  *
  58  * Monitor these messages by running:
  59  *      dtrace -q -n 'zfs-dbgmsg{printf("%s\n", stringof(arg0))}'
  60  */
  61 void
  62 zfs_dbgmsg(const char *fmt, ...)
  63 {
  64         int size;
  65         va_list adx;
  66         zfs_dbgmsg_t *zdm;
  67
  68         va_start(adx, fmt);
  69         size = vsnprintf(NULL, 0, fmt, adx);
  70         va_end(adx);
  71
  72         /*
  73          * There is one byte of string in sizeof (zfs_dbgmsg_t), used
  74          * for the terminating null.
  75          */
  76         zdm = kmem_alloc(sizeof (zfs_dbgmsg_t) + size, KM_SLEEP);
  77         zdm->zdm_timestamp = gethrestime_sec();
  78
  79         va_start(adx, fmt);
  80         (void) vsnprintf(zdm->zdm_msg, size + 1, fmt, adx);
  81         va_end(adx);
  82
  83         DTRACE_PROBE1(zfs__dbgmsg, char *, zdm->zdm_msg);
  84
  85         mutex_enter(&zfs_dbgmsgs_lock);
  86         list_insert_tail(&zfs_dbgmsgs, zdm);
  87         zfs_dbgmsg_size += sizeof (zfs_dbgmsg_t) + size;
  88         while (zfs_dbgmsg_size > zfs_dbgmsg_maxsize) {
  89                 zdm = list_remove_head(&zfs_dbgmsgs);
  90                 size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
  91                 kmem_free(zdm, size);
  92                 zfs_dbgmsg_size -= size;
  93         }
  94         mutex_exit(&zfs_dbgmsgs_lock);
  95 }