280 lines
8.8 KiB
Diff
280 lines
8.8 KiB
Diff
commit 3abf3bd4edc86fb28c099cc85203cb46a811e0b8
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Mon Sep 13 11:06:08 2021 +0200
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nptl: pthread_kill, pthread_cancel should not fail after exit (bug 19193)
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This closes one remaining race condition related to bug 12889: if
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the thread already exited on the kernel side, returning ESRCH
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is not correct because that error is reserved for the thread IDs
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(pthread_t values) whose lifetime has ended. In case of a
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kernel-side exit and a valid thread ID, no signal needs to be sent
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and cancellation does not have an effect, so just return 0.
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sysdeps/pthread/tst-kill4.c triggers undefined behavior and is
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removed with this commit.
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Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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(cherry picked from commit 8af8456004edbab71f8903a60a3cae442cf6fe69)
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diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
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index cc25ff21f364e8a4..9bac6e3b76a20312 100644
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--- a/nptl/pthread_cancel.c
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+++ b/nptl/pthread_cancel.c
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@@ -62,10 +62,11 @@ __pthread_cancel (pthread_t th)
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{
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volatile struct pthread *pd = (volatile struct pthread *) th;
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- /* Make sure the descriptor is valid. */
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- if (INVALID_TD_P (pd))
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- /* Not a valid thread handle. */
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- return ESRCH;
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+ if (pd->tid == 0)
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+ /* The thread has already exited on the kernel side. Its outcome
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+ (regular exit, other cancelation) has already been
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+ determined. */
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+ return 0;
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static int init_sigcancel = 0;
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if (atomic_load_relaxed (&init_sigcancel) == 0)
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diff --git a/nptl/pthread_kill.c b/nptl/pthread_kill.c
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index f79a2b26fc7f72e5..5d4c86f9205a6fb5 100644
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--- a/nptl/pthread_kill.c
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+++ b/nptl/pthread_kill.c
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@@ -46,7 +46,12 @@ __pthread_kill_internal (pthread_t threadid, int signo)
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? INTERNAL_SYSCALL_ERRNO (val) : 0);
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}
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else
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- val = ESRCH;
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+ /* The kernel reports that the thread has exited. POSIX specifies
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+ the ESRCH error only for the case when the lifetime of a thread
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+ ID has ended, but calling pthread_kill on such a thread ID is
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+ undefined in glibc. Therefore, do not treat kernel thread exit
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+ as an error. */
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+ val = 0;
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return val;
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}
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diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile
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index 42f9fc507263657d..dedfa0d290da4949 100644
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--- a/sysdeps/pthread/Makefile
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+++ b/sysdeps/pthread/Makefile
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@@ -89,7 +89,7 @@ tests += tst-cnd-basic tst-mtx-trylock tst-cnd-broadcast \
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tst-join8 tst-join9 tst-join10 tst-join11 tst-join12 tst-join13 \
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tst-join14 tst-join15 \
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tst-key1 tst-key2 tst-key3 tst-key4 \
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- tst-kill1 tst-kill2 tst-kill3 tst-kill4 tst-kill5 tst-kill6 \
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+ tst-kill1 tst-kill2 tst-kill3 tst-kill5 tst-kill6 \
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tst-locale1 tst-locale2 \
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tst-memstream \
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tst-mutex-errorcheck tst-mutex1 tst-mutex2 tst-mutex3 tst-mutex4 \
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@@ -118,6 +118,9 @@ tests += tst-cnd-basic tst-mtx-trylock tst-cnd-broadcast \
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tst-unload \
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tst-unwind-thread \
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tst-pt-vfork1 tst-pt-vfork2 tst-vfork1x tst-vfork2x \
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+ tst-pthread_cancel-exited \
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+ tst-pthread_kill-exited \
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+ # tests
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tests-time64 := \
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tst-abstime-time64 \
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diff --git a/sysdeps/pthread/tst-kill4.c b/sysdeps/pthread/tst-kill4.c
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deleted file mode 100644
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index 9563939792b96ebd..0000000000000000
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--- a/sysdeps/pthread/tst-kill4.c
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+++ /dev/null
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@@ -1,90 +0,0 @@
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-/* Copyright (C) 2003-2021 Free Software Foundation, Inc.
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- This file is part of the GNU C Library.
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- Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
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-
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- The GNU C Library is free software; you can redistribute it and/or
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- modify it under the terms of the GNU Lesser General Public
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- License as published by the Free Software Foundation; either
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- version 2.1 of the License, or (at your option) any later version.
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-
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- The GNU C Library is distributed in the hope that it will be useful,
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- but WITHOUT ANY WARRANTY; without even the implied warranty of
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- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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- Lesser General Public License for more details.
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-
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- You should have received a copy of the GNU Lesser General Public
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- License along with the GNU C Library; if not, see
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- <https://www.gnu.org/licenses/>. */
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-
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-#include <errno.h>
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-#include <pthread.h>
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-#include <signal.h>
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-#include <stdio.h>
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-#include <stdlib.h>
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-#include <unistd.h>
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-
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-
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-static void *
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-tf (void *a)
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-{
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- return NULL;
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-}
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-
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-
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-int
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-do_test (void)
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-{
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- pthread_attr_t at;
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- if (pthread_attr_init (&at) != 0)
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- {
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- puts ("attr_create failed");
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- exit (1);
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- }
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-
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- /* Limit thread stack size, because if it is too large, pthread_join
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- will free it immediately rather than put it into stack cache. */
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- if (pthread_attr_setstacksize (&at, 2 * 1024 * 1024) != 0)
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- {
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- puts ("setstacksize failed");
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- exit (1);
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- }
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-
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- pthread_t th;
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- if (pthread_create (&th, &at, tf, NULL) != 0)
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- {
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- puts ("create failed");
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- exit (1);
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- }
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-
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- pthread_attr_destroy (&at);
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-
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- if (pthread_join (th, NULL) != 0)
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- {
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- puts ("join failed");
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- exit (1);
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- }
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-
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- /* The following only works because we assume here something about
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- the implementation. Namely, that the memory allocated for the
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- thread descriptor is not going away, that the TID field is
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- cleared and therefore the signal is sent to process 0, and that
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- we can savely assume there is no other process with this ID at
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- that time. */
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- int e = pthread_kill (th, 0);
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- if (e == 0)
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- {
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- puts ("pthread_kill succeeded");
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- exit (1);
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- }
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- if (e != ESRCH)
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- {
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- puts ("pthread_kill didn't return ESRCH");
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- exit (1);
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- }
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-
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- return 0;
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-}
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-
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-
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-#define TEST_FUNCTION do_test ()
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-#include "../test-skeleton.c"
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diff --git a/sysdeps/pthread/tst-pthread_cancel-exited.c b/sysdeps/pthread/tst-pthread_cancel-exited.c
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new file mode 100644
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index 0000000000000000..811c9bee07ab2638
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--- /dev/null
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+++ b/sysdeps/pthread/tst-pthread_cancel-exited.c
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@@ -0,0 +1,45 @@
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+/* Test that pthread_kill succeeds for an exited thread.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+/* This test verifies that pthread_kill returns 0 (and not ESRCH) for
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+ a thread that has exited on the kernel side. */
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+
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+#include <stddef.h>
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+#include <support/support.h>
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+#include <support/xthread.h>
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+
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+static void *
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+noop_thread (void *closure)
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+{
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+ return NULL;
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+}
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+
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+static int
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+do_test (void)
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+{
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+ pthread_t thr = xpthread_create (NULL, noop_thread, NULL);
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+
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+ support_wait_for_thread_exit ();
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+
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+ xpthread_cancel (thr);
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+ xpthread_join (thr);
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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diff --git a/sysdeps/pthread/tst-pthread_kill-exited.c b/sysdeps/pthread/tst-pthread_kill-exited.c
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new file mode 100644
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index 0000000000000000..7575fb6d58cae99c
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--- /dev/null
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+++ b/sysdeps/pthread/tst-pthread_kill-exited.c
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@@ -0,0 +1,46 @@
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+/* Test that pthread_kill succeeds for an exited thread.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+/* This test verifies that pthread_kill returns 0 (and not ESRCH) for
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+ a thread that has exited on the kernel side. */
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+
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+#include <signal.h>
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+#include <stddef.h>
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+#include <support/support.h>
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+#include <support/xthread.h>
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+
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+static void *
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+noop_thread (void *closure)
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+{
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+ return NULL;
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+}
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+
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+static int
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+do_test (void)
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+{
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+ pthread_t thr = xpthread_create (NULL, noop_thread, NULL);
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+
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+ support_wait_for_thread_exit ();
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+
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+ xpthread_kill (thr, SIGUSR1);
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+ xpthread_join (thr);
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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