mirror of
https://github.com/openvswitch/ovs
synced 2025-08-22 09:58:01 +00:00
57cccb0763
Some systems may provide backtrace() in libc but for some reason
not provide any frames when attempting to use it.
On those systems the fatal_signal_init() function currently logs
this debug message: "Capturing of dummy backtrace has failed."
A consequence of this logging may be false negative test results.
Logging the fact that backtrace() does not work has limited value
on a production system and I propose we drop it.
Fixes: 759a29dc2d97 ("backtrace: Extend the backtrace functionality.")
Reported-at: https://launchpad.net/bugs/2032623
Acked-by: Ales Musil <amusil@redhat.com>
Signed-off-by: Frode Nordahl <frode.nordahl@canonical.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
576 lines
15 KiB
C
576 lines
15 KiB
C
/*
|
||
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
|
||
*
|
||
* Licensed under the Apache License, Version 2.0 (the "License");
|
||
* you may not use this file except in compliance with the License.
|
||
* You may obtain a copy of the License at:
|
||
*
|
||
* http://www.apache.org/licenses/LICENSE-2.0
|
||
*
|
||
* Unless required by applicable law or agreed to in writing, software
|
||
* distributed under the License is distributed on an "AS IS" BASIS,
|
||
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
* See the License for the specific language governing permissions and
|
||
* limitations under the License.
|
||
*/
|
||
#include <config.h>
|
||
#include "backtrace.h"
|
||
#include "fatal-signal.h"
|
||
#include <errno.h>
|
||
#include <signal.h>
|
||
#include <stdbool.h>
|
||
#include <stdio.h>
|
||
#include <stdint.h>
|
||
#include <stdlib.h>
|
||
#include <string.h>
|
||
#include <unistd.h>
|
||
#include "ovs-thread.h"
|
||
#include "openvswitch/poll-loop.h"
|
||
#include "openvswitch/shash.h"
|
||
#include "sset.h"
|
||
#include "signals.h"
|
||
#include "socket-util.h"
|
||
#include "util.h"
|
||
#include "openvswitch/vlog.h"
|
||
|
||
#include "openvswitch/type-props.h"
|
||
|
||
#if defined(HAVE_UNWIND) || defined(HAVE_BACKTRACE)
|
||
#include "daemon-private.h"
|
||
#endif
|
||
|
||
#ifdef HAVE_BACKTRACE
|
||
#include <execinfo.h>
|
||
#endif
|
||
|
||
#ifndef SIG_ATOMIC_MAX
|
||
#define SIG_ATOMIC_MAX TYPE_MAXIMUM(sig_atomic_t)
|
||
#endif
|
||
|
||
VLOG_DEFINE_THIS_MODULE(fatal_signal);
|
||
|
||
/* Signals to catch. */
|
||
#ifndef _WIN32
|
||
static const int fatal_signals[] = { SIGTERM, SIGINT, SIGHUP, SIGALRM,
|
||
SIGSEGV };
|
||
#else
|
||
static const int fatal_signals[] = { SIGTERM };
|
||
#endif
|
||
|
||
/* Hooks to call upon catching a signal */
|
||
struct hook {
|
||
void (*hook_cb)(void *aux);
|
||
void (*cancel_cb)(void *aux);
|
||
void *aux;
|
||
bool run_at_exit;
|
||
};
|
||
#define MAX_HOOKS 32
|
||
static struct hook hooks[MAX_HOOKS];
|
||
static size_t n_hooks;
|
||
|
||
static int signal_fds[2];
|
||
static volatile sig_atomic_t stored_sig_nr = SIG_ATOMIC_MAX;
|
||
|
||
#ifdef _WIN32
|
||
static HANDLE wevent;
|
||
#endif
|
||
|
||
static struct ovs_mutex mutex;
|
||
|
||
static void call_hooks(int sig_nr);
|
||
#ifdef _WIN32
|
||
static BOOL WINAPI ConsoleHandlerRoutine(DWORD dwCtrlType);
|
||
#endif
|
||
|
||
/* Sets up a pipe or event handle that will be used to wake up the current
|
||
* process after signal is received, so it can be processed outside of the
|
||
* signal handler context in fatal_signal_run(). */
|
||
static void
|
||
fatal_signal_create_wakeup_events(void)
|
||
{
|
||
#ifndef _WIN32
|
||
xpipe_nonblocking(signal_fds);
|
||
#else
|
||
wevent = CreateEvent(NULL, TRUE, FALSE, NULL);
|
||
if (!wevent) {
|
||
char *msg_buf = ovs_lasterror_to_string();
|
||
VLOG_FATAL("Failed to create a event (%s).", msg_buf);
|
||
}
|
||
#endif
|
||
}
|
||
|
||
static void
|
||
fatal_signal_destroy_wakeup_events(void)
|
||
{
|
||
#ifndef _WIN32
|
||
close(signal_fds[0]);
|
||
signal_fds[0] = -1;
|
||
close(signal_fds[1]);
|
||
signal_fds[1] = -1;
|
||
#else
|
||
ResetEvent(wevent);
|
||
CloseHandle(wevent);
|
||
wevent = NULL;
|
||
#endif
|
||
}
|
||
|
||
|
||
/* Initializes the fatal signal handling module. Calling this function is
|
||
* optional, because calling any other function in the module will also
|
||
* initialize it. However, in a multithreaded program, the module must be
|
||
* initialized while the process is still single-threaded. */
|
||
void
|
||
fatal_signal_init(void)
|
||
{
|
||
static bool inited = false;
|
||
|
||
if (!inited) {
|
||
size_t i;
|
||
|
||
assert_single_threaded();
|
||
inited = true;
|
||
|
||
ovs_mutex_init_recursive(&mutex);
|
||
|
||
/* The dummy backtrace is needed.
|
||
* See comment for send_backtrace_to_monitor(). */
|
||
struct backtrace dummy_bt;
|
||
|
||
backtrace_capture(&dummy_bt);
|
||
|
||
fatal_signal_create_wakeup_events();
|
||
|
||
#ifdef _WIN32
|
||
/* Register a function to handle Ctrl+C. */
|
||
SetConsoleCtrlHandler(ConsoleHandlerRoutine, true);
|
||
#endif
|
||
|
||
for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
|
||
int sig_nr = fatal_signals[i];
|
||
#ifndef _WIN32
|
||
struct sigaction old_sa;
|
||
|
||
xsigaction(sig_nr, NULL, &old_sa);
|
||
if (old_sa.sa_handler == SIG_DFL
|
||
&& signal(sig_nr, fatal_signal_handler) == SIG_ERR) {
|
||
VLOG_FATAL("signal failed (%s)", ovs_strerror(errno));
|
||
}
|
||
#else
|
||
if (signal(sig_nr, fatal_signal_handler) == SIG_ERR) {
|
||
VLOG_FATAL("signal failed (%s)", ovs_strerror(errno));
|
||
}
|
||
#endif
|
||
}
|
||
atexit(fatal_signal_atexit_handler);
|
||
}
|
||
}
|
||
|
||
/* Registers 'hook_cb' to be called from inside poll_block() following a fatal
|
||
* signal. 'hook_cb' does not need to be async-signal-safe. In a
|
||
* multithreaded program 'hook_cb' might be called from any thread, with
|
||
* threads other than the one running 'hook_cb' in unknown states.
|
||
*
|
||
* If 'run_at_exit' is true, 'hook_cb' is also called during normal process
|
||
* termination, e.g. when exit() is called or when main() returns.
|
||
*
|
||
* If the current process forks, fatal_signal_fork() may be called to clear the
|
||
* parent process's fatal signal hooks, so that 'hook_cb' is only called when
|
||
* the child terminates, not when the parent does. When fatal_signal_fork() is
|
||
* called, it calls the 'cancel_cb' function if it is nonnull, passing 'aux',
|
||
* to notify that the hook has been canceled. This allows the hook to free
|
||
* memory, etc. */
|
||
void
|
||
fatal_signal_add_hook(void (*hook_cb)(void *aux), void (*cancel_cb)(void *aux),
|
||
void *aux, bool run_at_exit)
|
||
{
|
||
fatal_signal_init();
|
||
|
||
ovs_mutex_lock(&mutex);
|
||
ovs_assert(n_hooks < MAX_HOOKS);
|
||
hooks[n_hooks].hook_cb = hook_cb;
|
||
hooks[n_hooks].cancel_cb = cancel_cb;
|
||
hooks[n_hooks].aux = aux;
|
||
hooks[n_hooks].run_at_exit = run_at_exit;
|
||
n_hooks++;
|
||
ovs_mutex_unlock(&mutex);
|
||
}
|
||
|
||
#ifdef HAVE_UNWIND
|
||
/* Convert unsigned long long to string. This is needed because
|
||
* using snprintf() is not async signal safe. */
|
||
static inline int
|
||
llong_to_hex_str(unsigned long long value, char *str)
|
||
{
|
||
int i = 0, res;
|
||
|
||
if (value / 16 > 0) {
|
||
i = llong_to_hex_str(value / 16, str);
|
||
}
|
||
|
||
res = value % 16;
|
||
str[i] = "0123456789abcdef"[res];
|
||
|
||
return i + 1;
|
||
}
|
||
|
||
/* Send the backtrace buffer to monitor thread.
|
||
*
|
||
* Note that this runs in the signal handling context, any system
|
||
* library functions used here must be async-signal-safe.
|
||
*/
|
||
static inline void
|
||
send_backtrace_to_monitor(void)
|
||
{
|
||
/* volatile added to prevent a "clobbered" error on ppc64le with gcc */
|
||
volatile int dep;
|
||
struct unw_backtrace unw_bt[UNW_MAX_DEPTH];
|
||
unw_cursor_t cursor;
|
||
unw_context_t uc;
|
||
|
||
if (daemonize_fd == -1) {
|
||
return;
|
||
}
|
||
|
||
dep = 0;
|
||
unw_getcontext(&uc);
|
||
unw_init_local(&cursor, &uc);
|
||
|
||
while (dep < UNW_MAX_DEPTH && unw_step(&cursor)) {
|
||
memset(unw_bt[dep].func, 0, UNW_MAX_FUNCN);
|
||
unw_get_reg(&cursor, UNW_REG_IP, &unw_bt[dep].ip);
|
||
unw_get_proc_name(&cursor, unw_bt[dep].func, UNW_MAX_FUNCN,
|
||
&unw_bt[dep].offset);
|
||
dep++;
|
||
}
|
||
|
||
if (monitor) {
|
||
ignore(write(daemonize_fd, unw_bt,
|
||
dep * sizeof(struct unw_backtrace)));
|
||
} else {
|
||
/* Since there is no monitor daemon running, write backtrace
|
||
* in current process.
|
||
*/
|
||
char ip_str[16], offset_str[6];
|
||
char line[64], fn_name[UNW_MAX_FUNCN];
|
||
|
||
vlog_direct_write_to_log_file_unsafe(BACKTRACE_DUMP_MSG);
|
||
|
||
for (int i = 0; i < dep; i++) {
|
||
memset(line, 0, sizeof line);
|
||
memset(fn_name, 0, sizeof fn_name);
|
||
memset(offset_str, 0, sizeof offset_str);
|
||
memset(ip_str, ' ', sizeof ip_str);
|
||
ip_str[sizeof(ip_str) - 1] = 0;
|
||
|
||
llong_to_hex_str(unw_bt[i].ip, ip_str);
|
||
llong_to_hex_str(unw_bt[i].offset, offset_str);
|
||
|
||
strcat(line, "0x");
|
||
strcat(line, ip_str);
|
||
strcat(line, "<");
|
||
memcpy(fn_name, unw_bt[i].func, UNW_MAX_FUNCN - 1);
|
||
strcat(line, fn_name);
|
||
strcat(line, "+0x");
|
||
strcat(line, offset_str);
|
||
strcat(line, ">\n");
|
||
vlog_direct_write_to_log_file_unsafe(line);
|
||
}
|
||
}
|
||
}
|
||
#elif HAVE_BACKTRACE
|
||
/* Send the backtrace to monitor thread.
|
||
*
|
||
* Note that this runs in the signal handling context, any system
|
||
* library functions used here must be async-signal-safe.
|
||
* backtrace() is only signal safe if the "libgcc" or equivalent was loaded
|
||
* before the signal handler. In order to keep it safe the fatal_signal_init()
|
||
* should always call backtrace_capture which will ensure that "libgcc" or
|
||
* equivlent is loaded.
|
||
*/
|
||
static inline void
|
||
send_backtrace_to_monitor(void)
|
||
{
|
||
struct backtrace bt;
|
||
|
||
backtrace_capture(&bt);
|
||
|
||
if (monitor && daemonize_fd > -1) {
|
||
ignore(write(daemonize_fd, &bt, sizeof bt));
|
||
} else {
|
||
int log_fd = vlog_get_log_file_fd_unsafe();
|
||
|
||
if (log_fd < 0) {
|
||
return;
|
||
}
|
||
|
||
vlog_direct_write_to_log_file_unsafe(BACKTRACE_DUMP_MSG);
|
||
backtrace_symbols_fd(bt.frames, bt.n_frames, log_fd);
|
||
}
|
||
}
|
||
#else
|
||
static inline void
|
||
send_backtrace_to_monitor(void) {
|
||
/* Nothing. */
|
||
}
|
||
#endif
|
||
|
||
/* Handles fatal signal number 'sig_nr'.
|
||
*
|
||
* Ordinarily this is the actual signal handler. When other code needs to
|
||
* handle one of our signals, however, it can register for that signal and, if
|
||
* and when necessary, call this function to do fatal signal processing for it
|
||
* and terminate the process. Currently only timeval.c does this, for SIGALRM.
|
||
* (It is not important whether the other code sets up its signal handler
|
||
* before or after this file, because this file will only set up a signal
|
||
* handler in the case where the signal has its default handling.) */
|
||
void
|
||
fatal_signal_handler(int sig_nr)
|
||
{
|
||
#ifndef _WIN32
|
||
if (sig_nr == SIGSEGV) {
|
||
signal(sig_nr, SIG_DFL); /* Set it back immediately. */
|
||
send_backtrace_to_monitor();
|
||
raise(sig_nr);
|
||
}
|
||
ignore(write(signal_fds[1], "", 1));
|
||
#else
|
||
SetEvent(wevent);
|
||
#endif
|
||
stored_sig_nr = sig_nr;
|
||
}
|
||
|
||
/* Check whether a fatal signal has occurred and, if so, call the fatal signal
|
||
* hooks and exit.
|
||
*
|
||
* This function is called automatically by poll_block(), but specialized
|
||
* programs that may not always call poll_block() on a regular basis should
|
||
* also call it periodically. (Therefore, any function with "block" in its
|
||
* name should call fatal_signal_run() each time it is called, either directly
|
||
* or through poll_block(), because such functions can only used by specialized
|
||
* programs that can afford to block outside their main loop around
|
||
* poll_block().)
|
||
*/
|
||
void
|
||
fatal_signal_run(void)
|
||
{
|
||
sig_atomic_t sig_nr;
|
||
|
||
fatal_signal_init();
|
||
|
||
sig_nr = stored_sig_nr;
|
||
if (sig_nr != SIG_ATOMIC_MAX) {
|
||
char namebuf[SIGNAL_NAME_BUFSIZE];
|
||
|
||
ovs_mutex_lock(&mutex);
|
||
|
||
#ifndef _WIN32
|
||
VLOG_WARN("terminating with signal %d (%s)",
|
||
(int)sig_nr, signal_name(sig_nr, namebuf, sizeof namebuf));
|
||
#else
|
||
VLOG_WARN("terminating with signal %d", (int)sig_nr);
|
||
#endif
|
||
call_hooks(sig_nr);
|
||
fflush(stderr);
|
||
|
||
/* Re-raise the signal with the default handling so that the program
|
||
* termination status reflects that we were killed by this signal */
|
||
signal(sig_nr, SIG_DFL);
|
||
raise(sig_nr);
|
||
|
||
ovs_mutex_unlock(&mutex);
|
||
OVS_NOT_REACHED();
|
||
}
|
||
}
|
||
|
||
void
|
||
fatal_signal_wait(void)
|
||
{
|
||
fatal_signal_init();
|
||
#ifdef _WIN32
|
||
poll_wevent_wait(wevent);
|
||
#else
|
||
poll_fd_wait(signal_fds[0], POLLIN);
|
||
#endif
|
||
}
|
||
|
||
void
|
||
fatal_ignore_sigpipe(void)
|
||
{
|
||
#ifndef _WIN32
|
||
signal(SIGPIPE, SIG_IGN);
|
||
#endif
|
||
}
|
||
|
||
void
|
||
fatal_signal_atexit_handler(void)
|
||
{
|
||
call_hooks(0);
|
||
}
|
||
|
||
static void
|
||
call_hooks(int sig_nr)
|
||
{
|
||
static volatile sig_atomic_t recurse = 0;
|
||
if (!recurse) {
|
||
size_t i;
|
||
|
||
recurse = 1;
|
||
|
||
for (i = 0; i < n_hooks; i++) {
|
||
struct hook *h = &hooks[i];
|
||
if (sig_nr || h->run_at_exit) {
|
||
h->hook_cb(h->aux);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#ifdef _WIN32
|
||
BOOL WINAPI ConsoleHandlerRoutine(DWORD dwCtrlType)
|
||
{
|
||
stored_sig_nr = SIGINT;
|
||
SetEvent(wevent);
|
||
return true;
|
||
}
|
||
#endif
|
||
|
||
/* Files to delete on exit. */
|
||
static struct sset files = SSET_INITIALIZER(&files);
|
||
|
||
/* Has a hook function been registered with fatal_signal_add_hook() (and not
|
||
* cleared by fatal_signal_fork())? */
|
||
static bool added_hook;
|
||
|
||
static void unlink_files(void *aux);
|
||
static void cancel_files(void *aux);
|
||
static void do_unlink_files(void);
|
||
|
||
/* Registers 'file' to be unlinked when the program terminates via exit() or a
|
||
* fatal signal. */
|
||
void
|
||
fatal_signal_add_file_to_unlink(const char *file)
|
||
{
|
||
fatal_signal_init();
|
||
|
||
ovs_mutex_lock(&mutex);
|
||
if (!added_hook) {
|
||
added_hook = true;
|
||
fatal_signal_add_hook(unlink_files, cancel_files, NULL, true);
|
||
}
|
||
|
||
sset_add(&files, file);
|
||
ovs_mutex_unlock(&mutex);
|
||
}
|
||
|
||
/* Unregisters 'file' from being unlinked when the program terminates via
|
||
* exit() or a fatal signal. */
|
||
void
|
||
fatal_signal_remove_file_to_unlink(const char *file)
|
||
{
|
||
fatal_signal_init();
|
||
|
||
ovs_mutex_lock(&mutex);
|
||
sset_find_and_delete(&files, file);
|
||
ovs_mutex_unlock(&mutex);
|
||
}
|
||
|
||
/* Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'.
|
||
* Returns 0 if successful, otherwise a positive errno value. */
|
||
int
|
||
fatal_signal_unlink_file_now(const char *file)
|
||
{
|
||
int error;
|
||
|
||
fatal_signal_init();
|
||
|
||
ovs_mutex_lock(&mutex);
|
||
|
||
error = unlink(file) ? errno : 0;
|
||
if (error) {
|
||
VLOG_WARN("could not unlink \"%s\" (%s)", file, ovs_strerror(error));
|
||
}
|
||
|
||
fatal_signal_remove_file_to_unlink(file);
|
||
|
||
ovs_mutex_unlock(&mutex);
|
||
|
||
return error;
|
||
}
|
||
|
||
static void
|
||
unlink_files(void *aux OVS_UNUSED)
|
||
{
|
||
do_unlink_files();
|
||
}
|
||
|
||
static void
|
||
cancel_files(void *aux OVS_UNUSED)
|
||
{
|
||
sset_clear(&files);
|
||
added_hook = false;
|
||
}
|
||
|
||
static void
|
||
do_unlink_files(void)
|
||
{
|
||
const char *file;
|
||
|
||
SSET_FOR_EACH (file, &files) {
|
||
unlink(file);
|
||
}
|
||
}
|
||
|
||
/* Clears all of the fatal signal hooks without executing them. If any of the
|
||
* hooks passed a 'cancel_cb' function to fatal_signal_add_hook(), then those
|
||
* functions will be called, allowing them to free resources, etc.
|
||
*
|
||
* Also re-creates wake-up events, so signals in one of the processes do not
|
||
* wake up the other one.
|
||
*
|
||
* Following a fork, one of the resulting processes can call this function to
|
||
* allow it to terminate without calling the hooks registered before calling
|
||
* this function. New hooks registered after calling this function will take
|
||
* effect normally. */
|
||
void
|
||
fatal_signal_fork(void)
|
||
{
|
||
size_t i;
|
||
|
||
assert_single_threaded();
|
||
|
||
fatal_signal_destroy_wakeup_events();
|
||
fatal_signal_create_wakeup_events();
|
||
|
||
for (i = 0; i < n_hooks; i++) {
|
||
struct hook *h = &hooks[i];
|
||
if (h->cancel_cb) {
|
||
h->cancel_cb(h->aux);
|
||
}
|
||
}
|
||
n_hooks = 0;
|
||
|
||
/* Raise any signals that we have already received with the default
|
||
* handler. */
|
||
if (stored_sig_nr != SIG_ATOMIC_MAX) {
|
||
raise(stored_sig_nr);
|
||
}
|
||
}
|
||
|
||
#ifndef _WIN32
|
||
/* Blocks all fatal signals and returns previous signal mask into
|
||
* 'prev_mask'. */
|
||
void
|
||
fatal_signal_block(sigset_t *prev_mask)
|
||
{
|
||
int i;
|
||
sigset_t block_mask;
|
||
|
||
sigemptyset(&block_mask);
|
||
for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
|
||
int sig_nr = fatal_signals[i];
|
||
sigaddset(&block_mask, sig_nr);
|
||
}
|
||
xpthread_sigmask(SIG_BLOCK, &block_mask, prev_mask);
|
||
}
|
||
#endif
|