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zdb/ztest: improve and harmonise crash output #16181

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zdb/ztest: improve and harmonise crash output #16181

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c328a51
zdb: bring crash handling over from ztest
robn May 9, 2024
43ba4a2
zdb/ztest: use libspl backtrace for crashes
robn May 10, 2024
a32b895
libspl: lift backtrace into a separate file
robn May 10, 2024
eb505e4
backtrace: rework for signal safety
robn May 10, 2024
b77206f
zfs_dbgmsg_print: make FreeBSD and Linux consistent
robn May 10, 2024
96b60cb
zdb/ztest: send dbgmsg output to stderr
robn May 10, 2024
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52 changes: 47 additions & 5 deletions cmd/zdb/zdb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,7 @@
#include <sys/brt_impl.h>
#include <zfs_comutil.h>
#include <sys/zstd/zstd.h>
#include <sys/backtrace.h>

#include <libnvpair.h>
#include <libzutil.h>
Expand Down Expand Up @@ -828,11 +829,34 @@ usage(void)
static void
dump_debug_buffer(void)
{
if (dump_opt['G']) {
(void) printf("\n");
(void) fflush(stdout);
zfs_dbgmsg_print("zdb");
}
ssize_t ret __attribute__((unused));

if (!dump_opt['G'])
return;
/*
* We use write() instead of printf() so that this function
* is safe to call from a signal handler.
*/
ret = write(STDERR_FILENO, "\n", 1);
zfs_dbgmsg_print(STDERR_FILENO, "zdb");
}

static void sig_handler(int signo)
{
struct sigaction action;

libspl_backtrace(STDERR_FILENO);
dump_debug_buffer();

/*
* Restore default action and re-raise signal so SIGSEGV and
* SIGABRT can trigger a core dump.
*/
action.sa_handler = SIG_DFL;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
(void) sigaction(signo, &action, NULL);
raise(signo);
}

/*
Expand Down Expand Up @@ -8899,9 +8923,27 @@ main(int argc, char **argv)
char *spa_config_path_env, *objset_str;
boolean_t target_is_spa = B_TRUE, dataset_lookup = B_FALSE;
nvlist_t *cfg = NULL;
struct sigaction action;

dprintf_setup(&argc, argv);

/*
* Set up signal handlers, so if we crash due to bad on-disk data we
* can get more info. Unlike ztest, we don't bail out if we can't set
* up signal handlers, because zdb is very useful without them.
*/
action.sa_handler = sig_handler;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
if (sigaction(SIGSEGV, &action, NULL) < 0) {
(void) fprintf(stderr, "zdb: cannot catch SIGSEGV: %s\n",
strerror(errno));
}
if (sigaction(SIGABRT, &action, NULL) < 0) {
(void) fprintf(stderr, "zdb: cannot catch SIGABRT: %s\n",
strerror(errno));
}

/*
* If there is an environment variable SPA_CONFIG_PATH it overrides
* default spa_config_path setting. If -U flag is specified it will
Expand Down
17 changes: 4 additions & 13 deletions cmd/ztest.c
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Original file line number Diff line number Diff line change
Expand Up @@ -136,9 +136,7 @@
#include <libzutil.h>
#include <sys/crypto/icp.h>
#include <sys/zfs_impl.h>
#if (__GLIBC__ && !__UCLIBC__)
#include <execinfo.h> /* for backtrace() */
#endif
#include <sys/backtrace.h>

static int ztest_fd_data = -1;
static int ztest_fd_rand = -1;
Expand Down Expand Up @@ -617,22 +615,15 @@ dump_debug_buffer(void)
* 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");
ret = write(STDERR_FILENO, "\n", 1);
zfs_dbgmsg_print(STDERR_FILENO, "ztest");
}

#define BACKTRACE_SZ 100

static void sig_handler(int signo)
{
struct sigaction action;
#if (__GLIBC__ && !__UCLIBC__) /* backtrace() is a GNU extension */
int nptrs;
void *buffer[BACKTRACE_SZ];

nptrs = backtrace(buffer, BACKTRACE_SZ);
backtrace_symbols_fd(buffer, nptrs, STDERR_FILENO);
#endif
libspl_backtrace(STDERR_FILENO);
dump_debug_buffer();

/*
Expand Down
2 changes: 1 addition & 1 deletion include/sys/zfs_debug.h
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Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,7 @@ extern void zfs_dbgmsg_fini(void);

#ifndef _KERNEL
extern int dprintf_find_string(const char *string);
extern void zfs_dbgmsg_print(const char *tag);
extern void zfs_dbgmsg_print(int fd, const char *tag);
#endif

#ifdef __cplusplus
Expand Down
111 changes: 106 additions & 5 deletions lib/libnvpair/libnvpair.abi
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,7 @@
<elf-symbol name='fnvpair_value_uint64' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
<elf-symbol name='fnvpair_value_uint8' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
<elf-symbol name='libspl_assertf' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
<elf-symbol name='libspl_backtrace' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
<elf-symbol name='libspl_set_assert_ok' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
<elf-symbol name='nv_alloc_fini' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
<elf-symbol name='nv_alloc_init' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
Expand Down Expand Up @@ -1156,6 +1157,11 @@
<parameter type-id='80f4b756'/>
<return type-id='95e97e5e'/>
</function-decl>
<function-decl name='strchr' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='80f4b756'/>
<parameter type-id='95e97e5e'/>
<return type-id='26a90f95'/>
</function-decl>
<function-decl name='strcspn' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='80f4b756'/>
<parameter type-id='80f4b756'/>
Expand Down Expand Up @@ -2041,21 +2047,121 @@
</function-type>
</abi-instr>
<abi-instr address-size='64' path='lib/libspl/assert.c' language='LANG_C99'>
<array-type-def dimensions='1' type-id='a84c031d' size-in-bits='320' id='36c46961'>
<subrange length='40' type-id='7359adad' id='8f80b239'/>
</array-type-def>
<union-decl name='pthread_mutex_t' size-in-bits='320' naming-typedef-id='7a6844eb' visibility='default' id='70681f9b'>
<data-member access='public'>
<var-decl name='__data' type-id='4c734837' visibility='default'/>
</data-member>
<data-member access='public'>
<var-decl name='__size' type-id='36c46961' visibility='default'/>
</data-member>
<data-member access='public'>
<var-decl name='__align' type-id='bd54fe1a' visibility='default'/>
</data-member>
</union-decl>
<typedef-decl name='pthread_mutex_t' type-id='70681f9b' id='7a6844eb'/>
<class-decl name='__pthread_mutex_s' size-in-bits='320' is-struct='yes' visibility='default' id='4c734837'>
<data-member access='public' layout-offset-in-bits='0'>
<var-decl name='__lock' type-id='95e97e5e' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='32'>
<var-decl name='__count' type-id='f0981eeb' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='64'>
<var-decl name='__owner' type-id='95e97e5e' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='96'>
<var-decl name='__nusers' type-id='f0981eeb' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='128'>
<var-decl name='__kind' type-id='95e97e5e' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='160'>
<var-decl name='__spins' type-id='a2185560' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='176'>
<var-decl name='__elision' type-id='a2185560' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='192'>
<var-decl name='__list' type-id='518fb49c' visibility='default'/>
</data-member>
</class-decl>
<class-decl name='__pthread_internal_list' size-in-bits='128' is-struct='yes' visibility='default' id='0e01899c'>
<data-member access='public' layout-offset-in-bits='0'>
<var-decl name='__prev' type-id='4d98cd5a' visibility='default'/>
</data-member>
<data-member access='public' layout-offset-in-bits='64'>
<var-decl name='__next' type-id='4d98cd5a' visibility='default'/>
</data-member>
</class-decl>
<typedef-decl name='__pthread_list_t' type-id='0e01899c' id='518fb49c'/>
<typedef-decl name='__pid_t' type-id='95e97e5e' id='3629bad8'/>
<pointer-type-def type-id='0e01899c' size-in-bits='64' id='4d98cd5a'/>
<pointer-type-def type-id='7a6844eb' size-in-bits='64' id='18c91f9e'/>
<function-decl name='libspl_backtrace' mangled-name='libspl_backtrace' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='libspl_backtrace'>
<parameter type-id='95e97e5e'/>
<return type-id='48b5725f'/>
</function-decl>
<function-decl name='pthread_mutex_lock' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='18c91f9e'/>
<return type-id='95e97e5e'/>
</function-decl>
<function-decl name='pthread_mutex_unlock' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='18c91f9e'/>
<return type-id='95e97e5e'/>
</function-decl>
<function-decl name='abort' visibility='default' binding='global' size-in-bits='64'>
<return type-id='48b5725f'/>
</function-decl>
<function-decl name='getpid' visibility='default' binding='global' size-in-bits='64'>
<return type-id='3629bad8'/>
</function-decl>
<function-decl name='__vfprintf_chk' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='e75a27e9'/>
<parameter type-id='95e97e5e'/>
<parameter type-id='9d26089a'/>
<parameter type-id='b7f2d5e6'/>
<return type-id='95e97e5e'/>
</function-decl>
<function-decl name='gettid' visibility='default' binding='global' size-in-bits='64'>
<return type-id='3629bad8'/>
</function-decl>
<function-decl name='prctl' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='95e97e5e'/>
<parameter is-variadic='yes'/>
<return type-id='95e97e5e'/>
</function-decl>
<function-decl name='libspl_set_assert_ok' mangled-name='libspl_set_assert_ok' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='libspl_set_assert_ok'>
<parameter type-id='c19b74c3' name='val'/>
<return type-id='48b5725f'/>
</function-decl>
</abi-instr>
<abi-instr address-size='64' path='lib/libspl/backtrace.c' language='LANG_C99'>
<typedef-decl name='__ssize_t' type-id='bd54fe1a' id='41060289'/>
<typedef-decl name='ssize_t' type-id='41060289' id='79a0948f'/>
<qualified-type-def type-id='eaa32e2f' const='yes' id='83be723c'/>
<pointer-type-def type-id='83be723c' size-in-bits='64' id='7acd98a2'/>
<pointer-type-def type-id='eaa32e2f' size-in-bits='64' id='63e171df'/>
<function-decl name='backtrace' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='63e171df'/>
<parameter type-id='95e97e5e'/>
<return type-id='95e97e5e'/>
</function-decl>
<function-decl name='backtrace_symbols_fd' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='7acd98a2'/>
<parameter type-id='95e97e5e'/>
<parameter type-id='95e97e5e'/>
<return type-id='48b5725f'/>
</function-decl>
<function-decl name='write' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='95e97e5e'/>
<parameter type-id='eaa32e2f'/>
<parameter type-id='b59d7dce'/>
<return type-id='79a0948f'/>
</function-decl>
</abi-instr>
<abi-instr address-size='64' path='module/nvpair/fnvpair.c' language='LANG_C99'>
<function-decl name='fnvlist_alloc' mangled-name='fnvlist_alloc' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='fnvlist_alloc'>
<return type-id='5ce45b60'/>
Expand Down Expand Up @@ -2536,11 +2642,6 @@
<parameter type-id='b59d7dce'/>
<return type-id='95e97e5e'/>
</function-decl>
<function-decl name='strchr' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='80f4b756'/>
<parameter type-id='95e97e5e'/>
<return type-id='26a90f95'/>
</function-decl>
<function-decl name='strlen' visibility='default' binding='global' size-in-bits='64'>
<parameter type-id='80f4b756'/>
<return type-id='b59d7dce'/>
Expand Down
3 changes: 2 additions & 1 deletion lib/libspl/Makefile.am
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,8 @@ noinst_LTLIBRARIES += libspl_assert.la libspl.la
CPPCHECKTARGETS += libspl_assert.la libspl.la

libspl_assert_la_SOURCES = \
%D%/assert.c
%D%/assert.c \
%D%/backtrace.c

libspl_la_SOURCES = \
%D%/libspl_impl.h \
Expand Down
52 changes: 2 additions & 50 deletions lib/libspl/assert.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@

#include <assert.h>
#include <pthread.h>
#include <sys/backtrace.h>

#if defined(__linux__)
#include <errno.h>
Expand All @@ -51,55 +52,6 @@
pthread_getname_np(pthread_self(), buf, len);
#endif

#if defined(HAVE_LIBUNWIND)
#define UNW_LOCAL_ONLY
#include <libunwind.h>

static inline void
libspl_dump_backtrace(void)
{
unw_context_t uc;
unw_cursor_t cp;
unw_word_t ip, off;
char funcname[128];
#ifdef HAVE_LIBUNWIND_ELF
char objname[128];
unw_word_t objoff;
#endif

fprintf(stderr, "Call trace:\n");
unw_getcontext(&uc);
unw_init_local(&cp, &uc);
while (unw_step(&cp) > 0) {
unw_get_reg(&cp, UNW_REG_IP, &ip);
unw_get_proc_name(&cp, funcname, sizeof (funcname), &off);
#ifdef HAVE_LIBUNWIND_ELF
unw_get_elf_filename(&cp, objname, sizeof (objname), &objoff);
fprintf(stderr, " [0x%08lx] %s+0x%2lx (in %s +0x%2lx)\n",
ip, funcname, off, objname, objoff);
#else
fprintf(stderr, " [0x%08lx] %s+0x%2lx\n", ip, funcname, off);
#endif
}
}
#elif defined(HAVE_BACKTRACE)
#include <execinfo.h>

static inline void
libspl_dump_backtrace(void)
{
void *btptrs[100];
size_t nptrs = backtrace(btptrs, 100);
char **bt = backtrace_symbols(btptrs, nptrs);
fprintf(stderr, "Call trace:\n");
for (size_t i = 0; i < nptrs; i++)
fprintf(stderr, " %s\n", bt[i]);
free(bt);
}
#else
#define libspl_dump_backtrace()
#endif

#if defined(__APPLE__)
static inline uint64_t
libspl_gettid(void)
Expand Down Expand Up @@ -151,7 +103,7 @@ libspl_assertf(const char *file, const char *func, int line,
getpid(), libspl_getprogname(),
libspl_gettid(), tname);

libspl_dump_backtrace();
libspl_backtrace(STDERR_FILENO);

#if !__has_feature(attribute_analyzer_noreturn) && !defined(__COVERITY__)
if (libspl_assert_ok) {
Expand Down
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