From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Szabolcs Nagy <szabolcs.nagy@arm.com>
Subject: Re: [PATCH v2 07/14] elf: Add test case for [BZ #19329]
Date: Thu, 15 Apr 2021 16:21:33 -0300 [thread overview]
Message-ID: <c354eef3-db2a-51dd-1098-eaa96d2a6b57@linaro.org> (raw)
In-Reply-To: <8df69dbc6cc31456a99ef4165fd0eeffc4de4678.1618301209.git.szabolcs.nagy@arm.com>
On 13/04/2021 05:19, Szabolcs Nagy via Libc-alpha wrote:
> Test concurrent dlopen and pthread_create when the loaded modules have
> TLS. This triggers dl-tls assertion failures more reliably than the
> nptl/tst-stack4 test.
>
> The dlopened module has 100 DT_NEEDED dependencies with TLS, they were
> reused from an existing TLS test. The number of created threads during
> dlopen depends on filesystem speed and hardware, but at most 3 threads
> are alive at a time to limit resource usage.
>
> ---
> v5:
> - moved from nptl/ to elf/
> - use many tls modules from another test (affects the timing a bit as
> these need more relocation processing, but still detects the race)
> - use xdlopen
> - use stdatomic.h
> - moved from tests-internal back to tests
> - use acq/rel atomics instead of relaxed, this works too and cleaner.
> - moved after bug fix patch.
>
> 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.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> elf/Makefile | 9 ++++--
> elf/tst-tls21.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++
> elf/tst-tls21mod.c | 1 +
> 3 files changed, 76 insertions(+), 2 deletions(-)
> create mode 100644 elf/tst-tls21.c
> create mode 100644 elf/tst-tls21mod.c
>
> diff --git a/elf/Makefile b/elf/Makefile
> index b1344f1133..e9377608eb 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -223,7 +223,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
> tst-single_threaded tst-single_threaded-pthread \
> tst-tls-ie tst-tls-ie-dlmopen argv0test \
> tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \
> - tst-tls20
> + tst-tls20 tst-tls21
> # reldep9
> tests-internal += loadtest unload unload2 circleload1 \
> neededtest neededtest2 neededtest3 neededtest4 \
Ok.
> @@ -345,7 +345,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
> libmarkermod2-1 libmarkermod2-2 \
> libmarkermod3-1 libmarkermod3-2 libmarkermod3-3 \
> libmarkermod4-1 libmarkermod4-2 libmarkermod4-3 libmarkermod4-4 \
> - tst-tls20mod-bad
> + tst-tls20mod-bad tst-tls21mod
>
> # Most modules build with _ISOMAC defined, but those filtered out
> # depend on internal headers.
Ok.
> @@ -1932,3 +1932,8 @@ tst-tls20mod-bad.so-no-z-defs = yes
> $(objpfx)tst-tls20: $(libdl) $(shared-thread-library)
> $(objpfx)tst-tls20.out: $(objpfx)tst-tls20mod-bad.so \
> $(tst-tls-many-dynamic-modules:%=$(objpfx)%.so)
> +
> +# Reuses tst-tls-many-dynamic-modules
> +$(objpfx)tst-tls21: $(libdl) $(shared-thread-library)
> +$(objpfx)tst-tls21.out: $(objpfx)tst-tls21mod.so
> +$(objpfx)tst-tls21mod.so: $(tst-tls-many-dynamic-modules:%=$(objpfx)%.so)
Ok.
> diff --git a/elf/tst-tls21.c b/elf/tst-tls21.c
> new file mode 100644
> index 0000000000..560bf5813a
> --- /dev/null
> +++ b/elf/tst-tls21.c
> @@ -0,0 +1,68 @@
> +/* 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 <stdatomic.h>
> +#include <support/xdlfcn.h>
> +#include <support/xthread.h>
> +
> +#define THREADS 10000
> +
> +static atomic_int done;
> +
> +static void *
> +start (void *a)
> +{
> + /* Load a module with many dependencies that each have TLS. */
> + xdlopen ("tst-tls21mod.so", RTLD_LAZY);
> + atomic_store_explicit (&done, 1, memory_order_release);
> + 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; i++)
> + {
> + if (atomic_load_explicit (&done, memory_order_acquire) != 0)
> + break;
> + 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/elf/tst-tls21mod.c b/elf/tst-tls21mod.c
> new file mode 100644
> index 0000000000..206ece4fb3
> --- /dev/null
> +++ b/elf/tst-tls21mod.c
> @@ -0,0 +1 @@
> +int __thread x;
>
Ok.
next prev parent reply other threads:[~2021-04-15 19:21 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-13 8:17 [PATCH v2 00/14] Dynamic TLS related data race fixes Szabolcs Nagy
2021-04-13 8:18 ` [PATCH v2 01/14] elf: Fix a DTV setup issue [BZ #27136] Szabolcs Nagy
2021-04-13 8:36 ` Andreas Schwab
2021-04-13 9:35 ` Szabolcs Nagy
2021-04-13 10:22 ` Andreas Schwab
2021-04-13 10:34 ` Szabolcs Nagy
2021-04-13 10:51 ` Andreas Schwab
2021-04-13 8:18 ` [PATCH v2 02/14] elf: Add a DTV setup test " Szabolcs Nagy
2021-04-14 18:06 ` Adhemerval Zanella
2021-04-15 9:53 ` Szabolcs Nagy
2021-04-13 8:18 ` [PATCH v2 03/14] elf: Fix comments and logic in _dl_add_to_slotinfo Szabolcs Nagy
2021-04-14 18:12 ` Adhemerval Zanella
2021-04-13 8:18 ` [PATCH v2 04/14] elf: Refactor _dl_update_slotinfo to avoid use after free Szabolcs Nagy
2021-04-14 18:20 ` Adhemerval Zanella
2021-04-13 8:19 ` [PATCH v2 05/14] elf: Fix data races in pthread_create and TLS access [BZ #19329] Szabolcs Nagy
2021-04-15 17:44 ` Adhemerval Zanella
2021-04-13 8:19 ` [PATCH v2 06/14] elf: Use relaxed atomics for racy accesses " Szabolcs Nagy
2021-04-15 18:21 ` Adhemerval Zanella
2021-04-16 9:12 ` Szabolcs Nagy
2021-05-11 2:56 ` Carlos O'Donell
2021-05-11 9:31 ` Szabolcs Nagy
2021-05-11 16:19 ` Szabolcs Nagy
2021-05-12 20:33 ` Carlos O'Donell
2021-04-13 8:19 ` [PATCH v2 07/14] elf: Add test case for " Szabolcs Nagy
2021-04-15 19:21 ` Adhemerval Zanella [this message]
2021-04-13 8:20 ` [PATCH v2 08/14] elf: Fix DTV gap reuse logic [BZ #27135] Szabolcs Nagy
2021-04-15 19:45 ` Adhemerval Zanella
2021-06-24 9:48 ` Florian Weimer
2021-06-24 12:27 ` Florian Weimer
2021-06-24 12:57 ` Adhemerval Zanella
2021-06-24 14:20 ` Florian Weimer
2021-06-24 18:58 ` Szabolcs Nagy
2021-04-13 8:20 ` [PATCH v2 09/14] x86_64: Avoid lazy relocation of tlsdesc [BZ #27137] Szabolcs Nagy
2021-04-13 14:02 ` H.J. Lu
2021-04-13 8:20 ` [PATCH v2 10/14] i386: " Szabolcs Nagy
2021-04-13 14:02 ` H.J. Lu
2021-04-13 8:21 ` [PATCH v2 11/14] x86_64: Remove lazy tlsdesc relocation related code Szabolcs Nagy
2021-04-13 14:03 ` H.J. Lu
2021-04-13 8:21 ` [PATCH v2 12/14] i386: " Szabolcs Nagy
2021-04-13 14:04 ` H.J. Lu
2021-04-13 8:21 ` [PATCH v2 13/14] elf: " Szabolcs Nagy
2021-04-15 19:52 ` Adhemerval Zanella
2021-04-13 8:21 ` [PATCH v2 14/14] RFC elf: Fix slow tls access after dlopen [BZ #19924] Szabolcs Nagy
2022-09-16 9:54 ` Carlos O'Donell
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