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timeval: Avoid backtrace() from signal handler on x86-64.

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backtrace() is really useful, but it is not signal safe everywhere.  We
need to reassess whether it is reasonable to use it anywhere, but
immediately we need to disable it on x86-64 (with glibc) because it is
causing segfaults in testing.

Bug #15497.
Reported-by: Ram Jothikumar <rjothikumar@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
This commit is contained in:
Ben Pfaff
2013-03-07 17:13:49 -08:00
parent be80bc65c1
commit 4906f197e9
1 changed files with 16 additions and 12 deletions
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28
lib/timeval.c
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@@ -17,9 +17,6 @@
#include <config.h>
#include "timeval.h"
#include <errno.h>
#if HAVE_EXECINFO_H
#include <execinfo.h>
#endif
#include <poll.h>
#include <signal.h>
#include <stdlib.h>
@@ -38,6 +35,15 @@
#include "util.h"
#include "vlog.h"
/* backtrace() from <execinfo.h> is really useful, but it is not signal safe
* everywhere, such as on x86-64. */
#if HAVE_EXECINFO_H && !defined __x86_64__
# define USE_BACKTRACE 1
# include <execinfo.h>
#else
# define USE_BACKTRACE 0
#endif
VLOG_DEFINE_THIS_MODULE(timeval);
/* The clock to use for measuring time intervals. This is CLOCK_MONOTONIC by
@@ -93,9 +99,7 @@ static void timespec_add(struct timespec *sum,
const struct timespec *a, const struct timespec *b);
static unixctl_cb_func backtrace_cb;
#ifndef HAVE_EXECINFO_H
#define HAVE_EXECINFO_H 0
#if !USE_BACKTRACE
static int
backtrace(void **buffer OVS_UNUSED, int size OVS_UNUSED)
{
@@ -107,7 +111,7 @@ backtrace_symbols(void *const *buffer OVS_UNUSED, int size OVS_UNUSED)
{
NOT_REACHED();
}
#endif
#endif /* !USE_BACKTRACE */
/* Initializes the timetracking module, if not already initialized. */
static void
@@ -124,7 +128,7 @@ time_init(void)
* initialization which is not signal safe. This can cause deadlocks if
* run from the signal handler. As a workaround, force the initialization
* to happen here. */
if (HAVE_EXECINFO_H) {
if (USE_BACKTRACE) {
void *bt[1];
backtrace(bt, ARRAY_SIZE(bt));
@@ -132,7 +136,7 @@ time_init(void)
memset(traces, 0, sizeof traces);
if (HAVE_EXECINFO_H && CACHE_TIME) {
if (USE_BACKTRACE && CACHE_TIME) {
unixctl_command_register("backtrace", "", 0, 0, backtrace_cb, NULL);
}
@@ -419,7 +423,7 @@ sigalrm_handler(int sig_nr OVS_UNUSED)
wall_tick = true;
monotonic_tick = true;
if (HAVE_EXECINFO_H && CACHE_TIME) {
if (USE_BACKTRACE && CACHE_TIME) {
struct trace *trace = &traces[trace_head];
trace->n_frames = backtrace(trace->backtrace,
@@ -633,7 +637,7 @@ format_backtraces(struct ds *ds, size_t min_count)
{
time_init();
if (HAVE_EXECINFO_H && CACHE_TIME) {
if (USE_BACKTRACE && CACHE_TIME) {
struct hmap trace_map = HMAP_INITIALIZER(&trace_map);
struct trace *trace, *next;
sigset_t oldsigs;
@@ -730,7 +734,7 @@ backtrace_cb(struct unixctl_conn *conn,
{
struct ds ds = DS_EMPTY_INITIALIZER;
ovs_assert(HAVE_EXECINFO_H && CACHE_TIME);
ovs_assert(USE_BACKTRACE && CACHE_TIME);
format_backtraces(&ds, 0);
unixctl_command_reply(conn, ds_cstr(&ds));
ds_destroy(&ds);