Re: [PATCH 03/15] Add test case for [BZ #19329]

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 15/02/2021 08:57, Szabolcs Nagy via Libc-alpha wrote:
> From: 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, 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.

I can easily reproduce it on x86_64 (8 cpus), powerpc64 (128
cpus), and aarch64 (160 cpus); however this tests does pass
on a more limited armhf box (2 cpus).  In any case, this
should be ok.

Also, this patch should be move after the BZ #19329 fix in
this set (otherwise it will generate make check failures).

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

The glibc build with -std=gnu11, so I think it should be ok
to use stdatomic and move out tests-internal.

> 
> 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.

There is no need to add ChangeLog entries anymore.

> ---
>  nptl/Makefile          | 17 +++++++++--
>  nptl/tst-tls7.c        | 69 ++++++++++++++++++++++++++++++++++++++++++
>  nptl/tst-tls7mod-dep.c |  1 +
>  nptl/tst-tls7mod.c     |  1 +
>  4 files changed, 85 insertions(+), 3 deletions(-)
>  create mode 100644 nptl/tst-tls7.c
>  create mode 100644 nptl/tst-tls7mod-dep.c
>  create mode 100644 nptl/tst-tls7mod.c
> 
> 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

Ok, although I think we can make is non internal test.

>  
> +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

Ok.

> @@ -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))

Ok.

> 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;

I think there is no need to define it volatile once it always
accessed through atomic functions.

> +
> +static void *
> +start (void *a)
> +{
> +  if (dlopen ("tst-tls7mod.so", RTLD_LAZY) == NULL)

Use xdlopen.

> +    {
> +      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>

Ok.

> 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;
> 

Ok.