[PATCH v2] Test case for BZ 19329

[Szabolcs Nagy <szabolcs dot nagy at arm dot com>]

Test concurrent dlopen and pthread_create when the loaded
modules have TLS.  This triggers dl-tls assertion failures
more reliably than the tst-stack4 test.

The dlopened module has 100 DT_NEEDED dependencies and
the number of concurrent threads created during dlopen
can wildly depend on filesystem speed and hardware.

v2:
- undef NDEBUG.
- join nop threads so at most 3 threads exist at a time.
- remove stack size setting (resource usage is no longer a concern).
- stop creating threads after dlopen observably finished.
- print the number of threads created for debugging.

Doing the test in a fork loop can make it more reliable,
but not any faster.

2016-11-25  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* nptl/Makefile (tests): Add tst-tls7.
	(modules-names): Add tst-tls7mod, tst-tls7mod-dep.
	* nptl/tst-tls7.c: New file.
	* nptl/tst-tls7mod-dep.c: New file.
	* nptl/tst-tls7mod.c: New file.

diff --git a/nptl/Makefile b/nptl/Makefile
index 11588fe..90152d2 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -327,7 +327,7 @@ tests += tst-cancelx2 tst-cancelx3 tst-cancelx4 tst-cancelx5 \
 	 tst-oncex3 tst-oncex4
 ifeq ($(build-shared),yes)
 tests += tst-atfork2 tst-tls3 tst-tls3-malloc tst-tls4 tst-tls5 tst-_res1 \
-	 tst-fini1 tst-stackguard1
+	 tst-fini1 tst-stackguard1 tst-tls7
 tests-nolibpthread += tst-fini1
 ifeq ($(have-z-execstack),yes)
 tests += tst-execstack
@@ -338,7 +338,7 @@ modules-names = tst-atfork2mod tst-tls3mod tst-tls4moda tst-tls4modb \
 		tst-tls5mod tst-tls5moda tst-tls5modb tst-tls5modc \
 		tst-tls5modd tst-tls5mode tst-tls5modf tst-stack4mod \
 		tst-_res1mod1 tst-_res1mod2 tst-execstack-mod tst-fini1mod \
-		tst-join7mod
+		tst-join7mod tst-tls7mod tst-tls7mod-dep
 extra-test-objs += $(addsuffix .os,$(strip $(modules-names))) \
 		   tst-cleanup4aux.o tst-cleanupx4aux.o
 test-extras += $(modules-names) tst-cleanup4aux tst-cleanupx4aux
@@ -545,6 +545,18 @@ $(objpfx)tst-tls5: $(objpfx)tst-tls5mod.so $(shared-thread-library)
 LDFLAGS-tst-tls5 = $(no-as-needed)
 LDFLAGS-tst-tls5mod.so = -Wl,-soname,tst-tls5mod.so
 
+$(objpfx)tst-tls7: $(libdl) $(shared-thread-library)
+tst-tls7mod-deps = $(shell for i in 0 1 2 3 4 5 6 7 8 9; do \
+			    for j in 0 1 2 3 4 5 6 7 8 9; do \
+			      echo $(objpfx)tst-tls7mod-dep-$$i-$$j.so; \
+			    done; done)
+$(objpfx)tst-tls7.out: $(objpfx)tst-tls7mod.so
+$(objpfx)tst-tls7mod.so: $(tst-tls7mod-deps)
+$(tst-tls7mod-deps): $(objpfx)tst-tls7mod-dep.so
+	cp -f $< $@
+clean:
+	rm -f $(tst-tls7mod-deps)
+
 ifeq ($(build-shared),yes)
 $(objpfx)tst-tls6.out: tst-tls6.sh $(objpfx)tst-tls5 \
 		       $(objpfx)tst-tls5moda.so $(objpfx)tst-tls5modb.so \
diff --git a/nptl/tst-tls7.c b/nptl/tst-tls7.c
new file mode 100644
index 0000000..73d3f3d
--- /dev/null
+++ b/nptl/tst-tls7.c
@@ -0,0 +1,68 @@
+/* Test concurrent dlopen and pthread_create: BZ 19329.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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 2.1 of the License, or (at your option) any later version.
+
+   The GNU C 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 the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <dlfcn.h>
+#include <pthread.h>
+#include <limits.h>
+#include <stdio.h>
+#include <atomic.h>
+
+#undef NDEBUG
+#include <assert.h>
+
+#define THREADS 10000
+
+static volatile int done;
+
+static void *
+start (void *a)
+{
+  assert (dlopen ("tst-tls7mod.so", RTLD_LAZY) != NULL);
+  atomic_store_relaxed (&done, 1);
+  return 0;
+}
+
+static void *
+nop (void *a)
+{
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  pthread_t t1, t2;
+  int i;
+
+  /* Load a module with lots of dependencies and TLS.  */
+  assert (pthread_create (&t1, 0, start, 0) == 0);
+
+  /* Concurrently create lots of threads until dlopen is observably done.  */
+  for (i = 0; i < THREADS && !atomic_load_relaxed (&done); i++)
+    {
+      assert (pthread_create (&t2, 0, nop, 0) == 0);
+      assert (pthread_join (t2, 0) == 0);
+    }
+
+  assert (pthread_join (t1, 0) == 0);
+  printf ("threads created during dlopen: %d\n", i);
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/nptl/tst-tls7mod-dep.c b/nptl/tst-tls7mod-dep.c
new file mode 100644
index 0000000..206ece4
--- /dev/null
+++ b/nptl/tst-tls7mod-dep.c
@@ -0,0 +1 @@
+int __thread x;
diff --git a/nptl/tst-tls7mod.c b/nptl/tst-tls7mod.c
new file mode 100644
index 0000000..206ece4
--- /dev/null
+++ b/nptl/tst-tls7mod.c
@@ -0,0 +1 @@
+int __thread x;