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Fix race between SMOB marking and finalization

* libguile/smob.c (clear_smobnum): New helper.
  (finalize_smob): Re-set the smobnum to the "finalized smob" type
  before finalizing.  Fixes #19883.
  (scm_smob_prehistory): Pre-register a "finalized smob" type, which has
  no mark procedure.
* test-suite/standalone/test-smob-mark-race.c: New file.
* test-suite/standalone/Makefile.am: Arrange to build and run the new
  test.
This commit is contained in:
Andy Wingo 2016-06-23 11:47:42 +02:00
parent 08df681976
commit 8dff3af087
3 changed files with 101 additions and 3 deletions

View file

@ -275,4 +275,10 @@ test_smob_mark_LDADD = $(LIBGUILE_LDADD)
check_PROGRAMS += test-smob-mark
TESTS += test-smob-mark
test_smob_mark_race_SOURCES = test-smob-mark-race.c
test_smob_mark_race_CFLAGS = ${test_cflags}
test_smob_mark_race_LDADD = $(LIBGUILE_LDADD)
check_PROGRAMS += test-smob-mark-race
TESTS += test-smob-mark-race
EXTRA_DIST += ${check_SCRIPTS}

View file

@ -0,0 +1,65 @@
/* Copyright (C) 2016 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#if HAVE_CONFIG_H
#include <config.h>
#endif
#undef NDEBUG
#include <libguile.h>
#include <assert.h>
static SCM
mark_smob (SCM smob)
{
assert (SCM_SMOB_DATA (smob) == 1);
return SCM_BOOL_F;
}
static size_t
finalize_smob (SCM smob)
{
assert (SCM_SMOB_DATA (smob) == 1);
SCM_SET_SMOB_DATA (smob, 0);
/* Allocate a bit in the hopes of triggering a new GC, making the
marker race with the finalizer. */
scm_cons (SCM_BOOL_F, SCM_BOOL_F);
return 0;
}
static void
tests (void *data, int argc, char **argv)
{
scm_t_bits tc16;
int i;
tc16 = scm_make_smob_type ("smob with finalizer", 0);
scm_set_smob_mark (tc16, mark_smob);
scm_set_smob_free (tc16, finalize_smob);
for (i = 0; i < 1000 * 1000; i++)
scm_new_smob (tc16, 1);
}
int
main (int argc, char *argv[])
{
scm_boot_guile (argc, argv, tests, NULL);
return 0;
}