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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
This commit is contained in:
Tom Caputi 2018-10-15 15:14:22 -04:00 committed by Brian Behlendorf
parent c04812f964
commit ab4c009e3d
5 changed files with 82 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
cmd/zdb/zdb.c
View File

@ -225,6 +225,7 @@ dump_debug_buffer(void)
{
if (dump_opt['G']) {
(void) printf("\n");
(void) fflush(stdout);
zfs_dbgmsg_print("zdb");
}
}

19
cmd/ztest/ztest.c
View File

@ -178,6 +178,7 @@ typedef struct ztest_shared_opts {
uint64_t zo_metaslab_force_ganging;
int zo_mmp_test;
int zo_special_vdevs;
int zo_dump_dbgmsg;
} ztest_shared_opts_t;
static const ztest_shared_opts_t ztest_opts_defaults = {
@ -484,7 +485,6 @@ static kmutex_t ztest_checkpoint_lock;
static pthread_rwlock_t ztest_name_lock;
static boolean_t ztest_dump_core = B_TRUE;
static boolean_t ztest_dump_debug_buffer = B_FALSE;
static boolean_t ztest_exiting;
/* Global commit callback list */
@ -533,10 +533,16 @@ _umem_logging_init(void)
static void
dump_debug_buffer(void)
{
if (!ztest_dump_debug_buffer)
ssize_t ret __attribute__((unused));
if (!ztest_opts.zo_dump_dbgmsg)
return;
(void) printf("\n");
/*
* We use write() instead of printf() so that this function
* is safe to call from a signal handler.
*/
ret = write(STDOUT_FILENO, "\n", 1);
zfs_dbgmsg_print("ztest");
}
@ -591,10 +597,11 @@ fatal(int do_perror, char *message, ...)
(void) fprintf(stderr, "%s\n", buf);
fatal_msg = buf; /* to ease debugging */
dump_debug_buffer();
if (ztest_dump_core)
abort();
else
dump_debug_buffer();
exit(3);
}
@ -866,7 +873,7 @@ process_options(int argc, char **argv)
usage(B_FALSE);
break;
case 'G':
ztest_dump_debug_buffer = B_TRUE;
zo->zo_dump_dbgmsg = 1;
break;
case 'h':
usage(B_TRUE);

7
include/sys/zfs_debug.h
View File

@ -55,11 +55,12 @@ extern int zfs_dbgmsg_enable;
#define ZFS_DEBUG_SET_ERROR (1 << 9)
#define ZFS_DEBUG_INDIRECT_REMAP (1 << 10)
extern void __dprintf(const char *file, const char *func,
extern void __zfs_dbgmsg(char *buf);
extern void __dprintf(boolean_t dprint, const char *file, const char *func,
int line, const char *fmt, ...);
#define zfs_dbgmsg(...) \
if (zfs_dbgmsg_enable) \
__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
__dprintf(B_FALSE, __FILE__, __func__, __LINE__, __VA_ARGS__)
#ifdef ZFS_DEBUG
/*
@ -69,7 +70,7 @@ extern void __dprintf(const char *file, const char *func,
*/
#define dprintf(...) \
if (zfs_flags & ZFS_DEBUG_DPRINTF) \
__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
__dprintf(B_TRUE, __FILE__, __func__, __LINE__, __VA_ARGS__)
#else
#define dprintf(...) ((void)0)
#endif /* ZFS_DEBUG */

35
lib/libzpool/kernel.c
View File

@ -783,7 +783,8 @@ dprintf_setup(int *argc, char **argv)
* =========================================================================
*/
void
__dprintf(const char *file, const char *func, int line, const char *fmt, ...)
__dprintf(boolean_t dprint, const char *file, const char *func,
int line, const char *fmt, ...)
{
const char *newfile;
va_list adx;
@ -798,9 +799,14 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
newfile = file;
}
if (dprintf_print_all ||
dprintf_find_string(newfile) ||
dprintf_find_string(func)) {
if (dprint) {
/* dprintf messages are printed immediately */
if (!dprintf_print_all &&
!dprintf_find_string(newfile) &&
!dprintf_find_string(func))
return;
/* Print out just the function name if requested */
flockfile(stdout);
if (dprintf_find_string("pid"))
@ -813,11 +819,30 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
(void) printf("%llu ", gethrtime());
if (dprintf_find_string("long"))
(void) printf("%s, line %d: ", newfile, line);
(void) printf("%s: ", func);
(void) printf("dprintf: %s: ", func);
va_start(adx, fmt);
(void) vprintf(fmt, adx);
va_end(adx);
funlockfile(stdout);
} else {
/* zfs_dbgmsg is logged for dumping later */
size_t size;
char *buf;
int i;
size = 1024;
buf = umem_alloc(size, UMEM_NOFAIL);
i = snprintf(buf, size, "%s:%d:%s(): ", newfile, line, func);
if (i < size) {
va_start(adx, fmt);
(void) vsnprintf(buf + i, size - i, fmt, adx);
va_end(adx);
}
__zfs_dbgmsg(buf);
umem_free(buf, size);
}
}

46
module/zfs/zfs_debug.c
View File

@ -124,11 +124,10 @@ __set_error(const char *file, const char *func, int line, int err)
* $ echo 512 >/sys/module/zfs/parameters/zfs_flags
*/
if (zfs_flags & ZFS_DEBUG_SET_ERROR)
__dprintf(file, func, line, "error %lu", err);
__dprintf(B_FALSE, file, func, line, "error %lu", err);
}
#ifdef _KERNEL
static void
void
__zfs_dbgmsg(char *buf)
{
int size = sizeof (zfs_dbgmsg_t) + strlen(buf);
@ -144,8 +143,11 @@ __zfs_dbgmsg(char *buf)
mutex_exit(&zfs_dbgmsgs.pl_lock);
}
#ifdef _KERNEL
void
__dprintf(const char *file, const char *func, int line, const char *fmt, ...)
__dprintf(boolean_t dprint, const char *file, const char *func,
int line, const char *fmt, ...)
{
const char *newfile;
va_list adx;
@ -153,6 +155,7 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
char *buf;
char *nl;
int i;
char *prefix = (dprint) ? "dprintf: " : "";
size = 1024;
buf = kmem_alloc(size, KM_SLEEP);
@ -167,7 +170,7 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
newfile = file;
}
i = snprintf(buf, size, "%s:%d:%s(): ", newfile, line, func);
i = snprintf(buf, size, "%s%s:%d:%s(): ", prefix, newfile, line, func);
if (i < size) {
va_start(adx, fmt);
@ -176,11 +179,13 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
}
/*
* Get rid of trailing newline.
* Get rid of trailing newline for dprintf logs.
*/
nl = strrchr(buf, '\n');
if (nl != NULL)
*nl = '\0';
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:
@ -212,11 +217,28 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
void
zfs_dbgmsg_print(const char *tag)
{
(void) printf("ZFS_DBGMSG(%s):\n", 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))
(void) printf("%s\n", zdm->zdm_msg);
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 */