freebsd-nq/module/zfs/zfs_debug.c
Tom Caputi ab4c009e3d Fix dbgmsg printing in ztest and zdb
This patch resolves a problem where the -G option in both zdb and
ztest would cause the code to call __dprintf() to print zfs_dbgmsg
output. This function was not properly wired to add messages to the
dbgmsg log as it is in userspace and so the messages were simply
dropped. This patch also tries to add some degree of distinction to
dprintf() (which now prints directly to stdout) and zfs_dbgmsg()
(which adds messages to an internal list that can be dumped with
zfs_dbgmsg_print()).

In addition, this patch corrects an issue where ztest used a global
variable to decide whether to dump the dbgmsg buffer on a crash.
This did not work because ztest spins up more instances of itself
using execv(), which did not copy the global variable to the new
process. The option has been moved to the ztest_shared_opts_t
which already exists for interprocess communication.

This patch also changes zfs_dbgmsg_print() to use write() calls
instead of printf() so that it will not fail when used in a signal
handler.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes #8010
2018-10-24 14:36:50 -07:00

253 lines
5.8 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2014 by Delphix. All rights reserved.
*/
#include <sys/zfs_context.h>
typedef struct zfs_dbgmsg {
procfs_list_node_t zdm_node;
time_t zdm_timestamp;
int zdm_size;
char zdm_msg[1]; /* variable length allocation */
} zfs_dbgmsg_t;
procfs_list_t zfs_dbgmsgs;
int zfs_dbgmsg_size = 0;
int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
/*
* Internal ZFS debug messages are enabled by default.
*
* # Print debug messages
* cat /proc/spl/kstat/zfs/dbgmsg
*
* # Disable the kernel debug message log.
* echo 0 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
*
* # Clear the kernel debug message log.
* echo 0 >/proc/spl/kstat/zfs/dbgmsg
*/
int zfs_dbgmsg_enable = 1;
static int
zfs_dbgmsg_show_header(struct seq_file *f)
{
seq_printf(f, "%-12s %-8s\n", "timestamp", "message");
return (0);
}
static int
zfs_dbgmsg_show(struct seq_file *f, void *p)
{
zfs_dbgmsg_t *zdm = (zfs_dbgmsg_t *)p;
seq_printf(f, "%-12llu %-s\n",
(u_longlong_t)zdm->zdm_timestamp, zdm->zdm_msg);
return (0);
}
static void
zfs_dbgmsg_purge(int max_size)
{
while (zfs_dbgmsg_size > max_size) {
zfs_dbgmsg_t *zdm = list_remove_head(&zfs_dbgmsgs.pl_list);
if (zdm == NULL)
return;
int size = zdm->zdm_size;
kmem_free(zdm, size);
zfs_dbgmsg_size -= size;
}
}
static int
zfs_dbgmsg_clear(procfs_list_t *procfs_list)
{
mutex_enter(&zfs_dbgmsgs.pl_lock);
zfs_dbgmsg_purge(0);
mutex_exit(&zfs_dbgmsgs.pl_lock);
return (0);
}
void
zfs_dbgmsg_init(void)
{
procfs_list_install("zfs",
"dbgmsg",
&zfs_dbgmsgs,
zfs_dbgmsg_show,
zfs_dbgmsg_show_header,
zfs_dbgmsg_clear,
offsetof(zfs_dbgmsg_t, zdm_node));
}
void
zfs_dbgmsg_fini(void)
{
procfs_list_uninstall(&zfs_dbgmsgs);
zfs_dbgmsg_purge(0);
/*
* TODO - decide how to make this permanent
*/
#ifdef _KERNEL
procfs_list_destroy(&zfs_dbgmsgs);
#endif
}
void
__set_error(const char *file, const char *func, int line, int err)
{
/*
* To enable this:
*
* $ echo 512 >/sys/module/zfs/parameters/zfs_flags
*/
if (zfs_flags & ZFS_DEBUG_SET_ERROR)
__dprintf(B_FALSE, file, func, line, "error %lu", err);
}
void
__zfs_dbgmsg(char *buf)
{
int size = sizeof (zfs_dbgmsg_t) + strlen(buf);
zfs_dbgmsg_t *zdm = kmem_zalloc(size, KM_SLEEP);
zdm->zdm_size = size;
zdm->zdm_timestamp = gethrestime_sec();
strcpy(zdm->zdm_msg, buf);
mutex_enter(&zfs_dbgmsgs.pl_lock);
procfs_list_add(&zfs_dbgmsgs, zdm);
zfs_dbgmsg_size += size;
zfs_dbgmsg_purge(MAX(zfs_dbgmsg_maxsize, 0));
mutex_exit(&zfs_dbgmsgs.pl_lock);
}
#ifdef _KERNEL
void
__dprintf(boolean_t dprint, const char *file, const char *func,
int line, const char *fmt, ...)
{
const char *newfile;
va_list adx;
size_t size;
char *buf;
char *nl;
int i;
char *prefix = (dprint) ? "dprintf: " : "";
size = 1024;
buf = kmem_alloc(size, KM_SLEEP);
/*
* Get rid of annoying prefix to filename.
*/
newfile = strrchr(file, '/');
if (newfile != NULL) {
newfile = newfile + 1; /* Get rid of leading / */
} else {
newfile = file;
}
i = snprintf(buf, size, "%s%s:%d:%s(): ", prefix, newfile, line, func);
if (i < size) {
va_start(adx, fmt);
(void) vsnprintf(buf + i, size - i, fmt, adx);
va_end(adx);
}
/*
* Get rid of trailing newline for dprintf logs.
*/
if (dprint && buf[0] != '\0') {
nl = &buf[strlen(buf) - 1];
if (*nl == '\n')
*nl = '\0';
}
/*
* To get this data enable the zfs__dprintf trace point as shown:
*
* # Enable zfs__dprintf tracepoint, clear the tracepoint ring buffer
* $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
* $ echo 0 > /sys/kernel/debug/tracing/trace
*
* # Dump the ring buffer.
* $ cat /sys/kernel/debug/tracing/trace
*/
DTRACE_PROBE1(zfs__dprintf, char *, buf);
/*
* To get this data:
*
* $ cat /proc/spl/kstat/zfs/dbgmsg
*
* To clear the buffer:
* $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
*/
__zfs_dbgmsg(buf);
kmem_free(buf, size);
}
#else
void
zfs_dbgmsg_print(const char *tag)
{
ssize_t ret __attribute__((unused));
/*
* We use write() in this function instead of printf()
* so it is safe to call from a signal handler.
*/
ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
ret = write(STDOUT_FILENO, tag, strlen(tag));
ret = write(STDOUT_FILENO, ") START:\n", 9);
mutex_enter(&zfs_dbgmsgs.pl_lock);
for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs.pl_list); zdm != NULL;
zdm = list_next(&zfs_dbgmsgs.pl_list, zdm)) {
ret = write(STDOUT_FILENO, zdm->zdm_msg,
strlen(zdm->zdm_msg));
ret = write(STDOUT_FILENO, "\n", 1);
}
ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
ret = write(STDOUT_FILENO, tag, strlen(tag));
ret = write(STDOUT_FILENO, ") END\n", 6);
mutex_exit(&zfs_dbgmsgs.pl_lock);
}
#endif /* _KERNEL */
#ifdef _KERNEL
module_param(zfs_dbgmsg_enable, int, 0644);
MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
module_param(zfs_dbgmsg_maxsize, int, 0644);
MODULE_PARM_DESC(zfs_dbgmsg_maxsize, "Maximum ZFS debug log size");
#endif