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weston: remove SEGV and ABRT handlers

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Catching an ABRT is kind of ok, catching a SEGV is russian roulette. We
have been quite lucky with it, but I've started hitting crashes inside
malloc() which causes a deadlock when our SEGV handler needs to malloc()
as well (weston_log_timestamp()).

One reason to catch SEGV and ABRT was to attempt to restore the VT on
the DRM-backend. Nowadays that job is done by logind or weston-launch.

The signal handler also printed a backtrace, which for me personally has
been extremely helpful. Arguably it's not necessary though, when we have
core files and services that catch cores. For instance, if using
systemd, 'coredumpctl gdb' is delightfully easy for getting into the
saved core.

Therefore, this code does more harm than it is useful, so remove it. We
also drop an optional dependency to libunwind.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniels@collabora.com>
dev
Pekka Paalanen 7 years ago committed by Daniel Stone
parent c34a9f5ca6
commit bb707dc0fe
4 changed files with 4 additions and 157 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 8
      Makefile.am
  2. 119
      compositor/main.c
  3. 20
      configure.ac
  4. 14
      man/weston.man

8
Makefile.am
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@ -71,8 +71,8 @@ install-libweston_moduleLTLIBRARIES install-moduleLTLIBRARIES: install-libLTLIBR
lib_LTLIBRARIES = libweston-@LIBWESTON_MAJOR@.la
libweston_@LIBWESTON_MAJOR@_la_CPPFLAGS = $(AM_CPPFLAGS) -DIN_WESTON
libweston_@LIBWESTON_MAJOR@_la_CFLAGS = $(AM_CFLAGS) \
$(COMPOSITOR_CFLAGS) $(EGL_CFLAGS) $(LIBUNWIND_CFLAGS) $(LIBDRM_CFLAGS)
libweston_@LIBWESTON_MAJOR@_la_LIBADD = $(COMPOSITOR_LIBS) $(LIBUNWIND_LIBS) \
$(COMPOSITOR_CFLAGS) $(EGL_CFLAGS) $(LIBDRM_CFLAGS)
libweston_@LIBWESTON_MAJOR@_la_LIBADD = $(COMPOSITOR_LIBS) \
$(DL_LIBS) -lm $(CLOCK_GETTIME_LIBS) \
$(LIBINPUT_BACKEND_LIBS) libshared.la
libweston_@LIBWESTON_MAJOR@_la_LDFLAGS = -version-info $(LT_VERSION_INFO)
@ -190,9 +190,9 @@ weston_LDFLAGS = -export-dynamic
weston_CPPFLAGS = $(AM_CPPFLAGS) -DIN_WESTON \
-DMODULEDIR='"$(moduledir)"' \
-DXSERVER_PATH='"@XSERVER_PATH@"'
weston_CFLAGS = $(AM_CFLAGS) $(COMPOSITOR_CFLAGS) $(LIBUNWIND_CFLAGS)
weston_CFLAGS = $(AM_CFLAGS) $(COMPOSITOR_CFLAGS)
weston_LDADD = libshared.la libweston-@LIBWESTON_MAJOR@.la \
$(COMPOSITOR_LIBS) $(LIBUNWIND_LIBS) \
$(COMPOSITOR_LIBS) \
$(DL_LIBS) $(LIBINPUT_BACKEND_LIBS) \
$(CLOCK_GETRES_LIBS) \
-lm

119
compositor/main.c
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@ -43,11 +43,6 @@
#include <sys/time.h>
#include <linux/limits.h>
#ifdef HAVE_LIBUNWIND
#define UNW_LOCAL_ONLY
#include <libunwind.h>
#endif
#include "weston.h"
#include "compositor.h"
#include "../shared/os-compatibility.h"
@ -190,85 +185,6 @@ sigchld_handler(int signal_number, void *data)
return 1;
}
#ifdef HAVE_LIBUNWIND
static void
print_backtrace(void)
{
unw_cursor_t cursor;
unw_context_t context;
unw_word_t off;
unw_proc_info_t pip;
int ret, i = 0;
char procname[256];
const char *filename;
Dl_info dlinfo;
pip.unwind_info = NULL;
ret = unw_getcontext(&context);
if (ret) {
weston_log("unw_getcontext: %d\n", ret);
return;
}
ret = unw_init_local(&cursor, &context);
if (ret) {
weston_log("unw_init_local: %d\n", ret);
return;
}
ret = unw_step(&cursor);
while (ret > 0) {
ret = unw_get_proc_info(&cursor, &pip);
if (ret) {
weston_log("unw_get_proc_info: %d\n", ret);
break;
}
ret = unw_get_proc_name(&cursor, procname, 256, &off);
if (ret && ret != -UNW_ENOMEM) {
if (ret != -UNW_EUNSPEC)
weston_log("unw_get_proc_name: %d\n", ret);
procname[0] = '?';
procname[1] = 0;
}
if (dladdr((void *)(pip.start_ip + off), &dlinfo) && dlinfo.dli_fname &&
*dlinfo.dli_fname)
filename = dlinfo.dli_fname;
else
filename = "?";
weston_log("%u: %s (%s%s+0x%x) [%p]\n", i++, filename, procname,
ret == -UNW_ENOMEM ? "..." : "", (int)off, (void *)(pip.start_ip + off));
ret = unw_step(&cursor);
if (ret < 0)
weston_log("unw_step: %d\n", ret);
}
}
#else
static void
print_backtrace(void)
{
void *buffer[32];
int i, count;
Dl_info info;
count = backtrace(buffer, ARRAY_LENGTH(buffer));
for (i = 0; i < count; i++) {
dladdr(buffer[i], &info);
weston_log(" [%016lx] %s (%s)\n",
(long) buffer[i],
info.dli_sname ? info.dli_sname : "--",
info.dli_fname);
}
}
#endif
static void
child_client_exec(int sockfd, const char *path)
{
@ -643,39 +559,6 @@ static int on_term_signal(int signal_number, void *data)
return 1;
}
static void
on_caught_signal(int s, siginfo_t *siginfo, void *context)
{
/* This signal handler will do a best-effort backtrace, and
* then call the backend restore function, which will switch
* back to the vt we launched from or ungrab X etc and then
* raise SIGTRAP. If we run weston under gdb from X or a
* different vt, and tell gdb "handle *s* nostop", this
* will allow weston to switch back to gdb on crash and then
* gdb will catch the crash with SIGTRAP.*/
weston_log("caught signal: %d\n", s);
print_backtrace();
if (segv_compositor && segv_compositor->backend)
segv_compositor->backend->restore(segv_compositor);
raise(SIGTRAP);
}
static void
catch_signals(void)
{
struct sigaction action;
action.sa_flags = SA_SIGINFO | SA_RESETHAND;
action.sa_sigaction = on_caught_signal;
sigemptyset(&action.sa_mask);
sigaction(SIGSEGV, &action, NULL);
sigaction(SIGABRT, &action, NULL);
}
static const char *
clock_name(clockid_t clk_id)
{
@ -1830,8 +1713,6 @@ int main(int argc, char *argv[])
weston_log_set_handler(vlog, vlog_continue);
weston_log_file_open(log);
catch_signals();
weston_log("%s\n"
STAMP_SPACE "%s\n"
STAMP_SPACE "Bug reports to: %s\n"

20
configure.ac
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@ -603,26 +603,6 @@ if test "x$GCC" = "xyes"; then
fi
AC_SUBST(GCC_CFLAGS)
AC_ARG_ENABLE(libunwind,
AS_HELP_STRING([--disable-libunwind],
[Disable libunwind usage for backtraces]),,
enable_libunwind=auto)
AM_CONDITIONAL(HAVE_LIBUNWIND, [test "x$enable_libunwind" = xyes])
have_libunwind=no
if test "x$enable_libunwind" != "xno"; then
PKG_CHECK_MODULES(LIBUNWIND,
libunwind,
have_libunwind=yes,
have_libunwind=no)
if test "x$have_libunwind" = "xno" -a "x$enable_libunwind" = "xyes"; then
AC_MSG_ERROR([libunwind support explicitly requested, but libunwind couldn't be found])
fi
if test "x$have_libunwind" = "xyes"; then
enable_libunwind=yes
AC_DEFINE(HAVE_LIBUNWIND, 1, [Have libunwind support])
fi
fi
if test "x$WESTON_NATIVE_BACKEND" = "x"; then
WESTON_NATIVE_BACKEND="drm-backend.so"

14
man/weston.man
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@ -324,20 +324,6 @@ The directory for Weston's socket and lock files.
Wayland clients will automatically use this.
.
.\" ***************************************************************
.SH DIAGNOSTICS
Weston has a segmentation fault handler, that attempts to restore
the virtual console or ungrab X before raising
.BR SIGTRAP .
If you run
.BR weston " under " gdb (1)
from an X11 terminal or a different virtual terminal, and tell gdb
.IP
handle SIGSEGV nostop
.PP
This will allow weston to switch back to gdb on crash and then
gdb will catch the crash with SIGTRAP.
.
.\" ***************************************************************
.SH BUGS
Bugs should be reported to the freedesktop.org bugzilla at
https://bugs.freedesktop.org with product "Wayland" and

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