Add test case for [BZ #19329]

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, the
number of concurrent threads created during dlopen depends
on filesystem speed and hardware. At most 3 threads exist
at a time to limit resource usage.

Doing the test in a fork loop can make it more reliable.

---
v4:
- rebased, updated copyright year.
- moved to tests-internal because of <atomic.h>

v3:
- use the new test support code.
- better Makefile usage so modules are cleaned properly.

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.

2016-12-13  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.

4 files changed, 85 insertions, 3 deletions

diff --git a/nptl/Makefile b/nptl/Makefile
index 8fb7fee6db..208629876d 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -355,20 +355,25 @@ tests += tst-cancelx7 tst-cancelx17 tst-cleanupx4
 
 ifeq ($(build-shared),yes)
 tests += tst-compat-forwarder tst-audit-threads
-tests-internal += tst-tls3 tst-tls3-malloc tst-tls5 tst-stackguard1
+tests-internal += tst-tls3 tst-tls3-malloc tst-tls5 tst-stackguard1 tst-tls7
 ifeq ($(have-z-execstack),yes)
 tests += tst-execstack
 endif
 endif
 
+one-hundred = $(foreach x,0 1 2 3 4 5 6 7 8 9, \
+  0$x 1$x 2$x 3$x 4$x 5$x 6$x 7$x 8$x 9$x)
+tst-tls7mod-deps = $(one-hundred:%=tst-tls7mod-dep-%.so)
+
 modules-names = tst-tls3mod \
 		tst-tls5mod tst-tls5moda tst-tls5modb tst-tls5modc \
 		tst-tls5modd tst-tls5mode tst-tls5modf tst-stack4mod \
 		tst-execstack-mod \
 		tst-compat-forwarder-mod tst-audit-threads-mod1 \
-		tst-audit-threads-mod2
+		tst-audit-threads-mod2 \
+		tst-tls7mod tst-tls7mod-dep
 extra-test-objs += $(addsuffix .os,$(strip $(modules-names))) \
-		   tst-cleanup4aux.o tst-cleanupx4aux.o
+		   tst-cleanup4aux.o tst-cleanupx4aux.o $(tst-tls7mod-deps)
 test-extras += tst-cleanup4aux tst-cleanupx4aux
 
 tst-tls3mod.so-no-z-defs = yes
@@ -517,6 +522,12 @@ $(objpfx)tst-tls6.out: tst-tls6.sh $(objpfx)tst-tls5 \
 	$(evaluate-test)
 endif
 
+$(objpfx)tst-tls7: $(libdl) $(shared-thread-library)
+$(objpfx)tst-tls7.out: $(objpfx)tst-tls7mod.so
+$(objpfx)tst-tls7mod.so: $(tst-tls7mod-deps:%=$(objpfx)%)
+$(tst-tls7mod-deps:%=$(objpfx)%): $(objpfx)tst-tls7mod-dep.so
+	cp -f $< $@
+
 $(objpfx)tst-dlsym1: $(libdl) $(shared-thread-library)
 
 ifeq (yes,$(build-shared))
diff --git a/nptl/tst-tls7.c b/nptl/tst-tls7.c
new file mode 100644
index 0000000000..4b3f9005fe
--- /dev/null
+++ b/nptl/tst-tls7.c
@@ -0,0 +1,69 @@
+/* Test concurrent dlopen and pthread_create: BZ 19329.
+   Copyright (C) 2021 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 <stdio.h>
+#include <atomic.h>
+
+#include <support/xthread.h>
+
+#define THREADS 10000
+
+static volatile int done;
+
+static void *
+start (void *a)
+{
+  if (dlopen ("tst-tls7mod.so", RTLD_LAZY) == NULL)
+    {
+      printf ("dlopen failed: %s\n", dlerror ());
+      exit (1);
+    }
+  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.  */
+  t1 = xpthread_create (0, start, 0);
+
+  /* Concurrently create lots of threads until dlopen is observably done.  */
+  for (i = 0; i < THREADS && !atomic_load_relaxed (&done); i++)
+    {
+      t2 = xpthread_create (0, nop, 0);
+      xpthread_join (t2);
+    }
+
+  xpthread_join (t1);
+  printf ("threads created during dlopen: %d\n", i);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/nptl/tst-tls7mod-dep.c b/nptl/tst-tls7mod-dep.c
new file mode 100644
index 0000000000..206ece4fb3
--- /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 0000000000..206ece4fb3
--- /dev/null
+++ b/nptl/tst-tls7mod.c
@@ -0,0 +1 @@
+int __thread x;