lib/libzpool/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  * Copyright (c) 2024, Rob Norris <robn@despairlabs.com>
  25  */
  26
  27 #include <sys/zfs_context.h>
  28
  29 typedef struct zfs_dbgmsg {
  30         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 list_t zfs_dbgmsgs;
  37 static kmutex_t zfs_dbgmsgs_lock;
  38 static uint_t zfs_dbgmsg_size = 0;
  39 static uint_t zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
  40
  41 int zfs_dbgmsg_enable = B_TRUE;
  42
  43 static void
  44 zfs_dbgmsg_purge(uint_t max_size)
  45 {
  46         while (zfs_dbgmsg_size > max_size) {
  47                 zfs_dbgmsg_t *zdm = list_remove_head(&zfs_dbgmsgs);
  48                 if (zdm == NULL)
  49                         return;
  50
  51                 uint_t size = zdm->zdm_size;
  52                 kmem_free(zdm, size);
  53                 zfs_dbgmsg_size -= size;
  54         }
  55 }
  56
  57 void
  58 zfs_dbgmsg_init(void)
  59 {
  60         list_create(&zfs_dbgmsgs, sizeof (zfs_dbgmsg_t),
  61             offsetof(zfs_dbgmsg_t, zdm_node));
  62         mutex_init(&zfs_dbgmsgs_lock, NULL, MUTEX_DEFAULT, NULL);
  63 }
  64
  65 void
  66 zfs_dbgmsg_fini(void)
  67 {
  68         zfs_dbgmsg_t *zdm;
  69         while ((zdm = list_remove_head(&zfs_dbgmsgs)))
  70                 umem_free(zdm, zdm->zdm_size);
  71         mutex_destroy(&zfs_dbgmsgs_lock);
  72 }
  73
  74 void
  75 __set_error(const char *file, const char *func, int line, int err)
  76 {
  77         if (zfs_flags & ZFS_DEBUG_SET_ERROR)
  78                 __dprintf(B_FALSE, file, func, line, "error %lu",
  79                     (ulong_t)err);
  80 }
  81
  82 void
  83 __zfs_dbgmsg(char *buf)
  84 {
  85         uint_t size = sizeof (zfs_dbgmsg_t) + strlen(buf) + 1;
  86         zfs_dbgmsg_t *zdm = umem_zalloc(size, KM_SLEEP);
  87         zdm->zdm_size = size;
  88         zdm->zdm_timestamp = gethrestime_sec();
  89         strcpy(zdm->zdm_msg, buf);
  90
  91         mutex_enter(&zfs_dbgmsgs_lock);
  92         list_insert_tail(&zfs_dbgmsgs, zdm);
  93         zfs_dbgmsg_size += size;
  94         zfs_dbgmsg_purge(zfs_dbgmsg_maxsize);
  95         mutex_exit(&zfs_dbgmsgs_lock);
  96 }
  97
  98 void
  99 zfs_dbgmsg_print(int fd, const char *tag)
 100 {
 101         ssize_t ret __attribute__((unused));
 102
 103         mutex_enter(&zfs_dbgmsgs_lock);
 104
 105         /*
 106          * We use write() in this function instead of printf()
 107          * so it is safe to call from a signal handler.
 108          */
 109         ret = write(fd, "ZFS_DBGMSG(", 11);
 110         ret = write(fd, tag, strlen(tag));
 111         ret = write(fd, ") START:\n", 9);
 112
 113         for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs); zdm != NULL;
 114             zdm = list_next(&zfs_dbgmsgs, zdm)) {
 115                 ret = write(fd, zdm->zdm_msg, strlen(zdm->zdm_msg));
 116                 ret = write(fd, "\n", 1);
 117         }
 118
 119         ret = write(fd, "ZFS_DBGMSG(", 11);
 120         ret = write(fd, tag, strlen(tag));
 121         ret = write(fd, ") END\n", 6);
 122
 123         mutex_exit(&zfs_dbgmsgs_lock);
 124 }