Allow a single-threaded program to cancel itself
There is nothing in the POSIX specification to disallow a single-threaded program from cancelling itself, so we forcibly enable multiple_threads to allow the next available cancellation point in the thread to run. Also added additional tests to cover various cancellation scenarios.
This commit is contained in:
Siddhesh Poyarekar
parent
2949684c16
commit
439bf404b8
19
NEWS
19
NEWS
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@ -17,15 +17,16 @@ Version 2.16
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10153, 10210, 10254, 10346, 10545, 10716, 11174, 11322, 11365, 11451,
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11494, 11521, 11837, 11959, 12047, 12340, 13058, 13525, 13526, 13527,
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13528, 13529, 13530, 13531, 13532, 13533, 13547, 13551, 13552, 13553,
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13555, 13559, 13563, 13566, 13583, 13592, 13618, 13637, 13656, 13658,
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13673, 13691, 13695, 13704, 13705, 13706, 13726, 13738, 13739, 13750,
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13758, 13760, 13761, 13775, 13786, 13787, 13792, 13806, 13824, 13840,
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13841, 13844, 13846, 13851, 13852, 13854, 13871, 13872, 13873, 13879,
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13883, 13884, 13885, 13886, 13892, 13895, 13908, 13910, 13911, 13912,
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13913, 13914, 13915, 13916, 13917, 13918, 13919, 13920, 13921, 13922,
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13923, 13924, 13926, 13927, 13928, 13938, 13941, 13942, 13954, 13955,
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13956, 13963, 13967, 13970, 13973, 13979, 13983, 14012, 14027, 14033,
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14034, 14040, 14049, 14053, 14055, 14064, 14080, 14083, 14103, 14104
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13555, 13559, 13563, 13566, 13583, 13592, 13613, 13618, 13637, 13656,
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13658, 13673, 13691, 13695, 13704, 13705, 13706, 13726, 13738, 13739,
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13750, 13758, 13760, 13761, 13775, 13786, 13787, 13792, 13806, 13824,
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13840, 13841, 13844, 13846, 13851, 13852, 13854, 13871, 13872, 13873,
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13879, 13883, 13884, 13885, 13886, 13892, 13895, 13908, 13910, 13911,
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13912, 13913, 13914, 13915, 13916, 13917, 13918, 13919, 13920, 13921,
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13922, 13923, 13924, 13926, 13927, 13928, 13938, 13941, 13942, 13954,
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13955, 13956, 13963, 13967, 13970, 13973, 13979, 13983, 14012, 14027,
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14033, 14034, 14040, 14049, 14053, 14055, 14064, 14080, 14083, 14103,
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14104
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* ISO C11 support:
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@ -1,3 +1,22 @@
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2012-05-15 Siddhesh Poyarekar <siddhesh@redhat.com>
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Jakub Jelinek <jakub@redhat.com>
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[BZ #13613]
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* Makefile (tests): Add test cases.
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* descr.h (struct pthread): Add a comment describing multiple_threads.
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* pthreadP.h (__pthread_multiple_threads): Expand comment to include
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single-process case.
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* pthread_cancel.c (pthread_cancel): Enable multiple_threads
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before setting cancelstate of the thread.
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* sysdeps/unix/sysv/linux/libc_multiple_threads.c
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(__libc_multiple_threads): Add explanatory comment.
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* tst-cancel-self-cancelstate.c: New test case.
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* tst-cancel-self-canceltype.c: Likewise.
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* tst-cancel-self-cleanup.c: Supporting file for test cases.
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* tst-cancel-self-testcancel.c: New test case.
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* tst-cancel-self.c: Likewise.
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* vars.c: Expand comment to include single-process case.
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2012-05-14 H.J. Lu <hongjiu.lu@intel.com>
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* sysdeps/x86_64/tls.h: Don't include <bits/wordsize.h>.
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@ -236,6 +236,8 @@ tests = tst-typesizes \
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tst-cancel11 tst-cancel12 tst-cancel13 tst-cancel14 tst-cancel15 \
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tst-cancel16 tst-cancel17 tst-cancel18 tst-cancel19 tst-cancel20 \
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tst-cancel21 tst-cancel22 tst-cancel23 tst-cancel24 tst-cancel25 \
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tst-cancel-self tst-cancel-self-cancelstate \
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tst-cancel-self-canceltype tst-cancel-self-testcancel \
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tst-cleanup0 tst-cleanup1 tst-cleanup2 tst-cleanup3 tst-cleanup4 \
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tst-flock1 tst-flock2 \
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tst-signal1 tst-signal2 tst-signal3 tst-signal4 tst-signal5 \
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15
nptl/descr.h
15
nptl/descr.h
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@ -131,6 +131,21 @@ struct pthread
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#else
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struct
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{
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/* multiple_threads is enabled either when the process has spawned at
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least one thread or when a single-threaded process cancels itself.
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This enables additional code to introduce locking before doing some
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compare_and_exchange operations and also enable cancellation points.
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The concepts of multiple threads and cancellation points ideally
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should be separate, since it is not necessary for multiple threads to
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have been created for cancellation points to be enabled, as is the
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case is when single-threaded process cancels itself.
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Since enabling multiple_threads enables additional code in
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cancellation points and compare_and_exchange operations, there is a
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potential for an unneeded performance hit when it is enabled in a
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single-threaded, self-canceling process. This is OK though, since a
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single-threaded process will enable async cancellation only when it
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looks to cancel itself and is hence going to end anyway. */
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int multiple_threads;
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int gscope_flag;
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# ifndef __ASSUME_PRIVATE_FUTEX
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@ -378,7 +378,9 @@ extern int *__libc_pthread_init (unsigned long int *ptr,
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const struct pthread_functions *functions)
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internal_function;
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/* Variable set to a nonzero value if more than one thread runs or ran. */
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/* Variable set to a nonzero value either if more than one thread runs or ran,
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or if a single-threaded process is trying to cancel itself. See
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nptl/descr.h for more context on the single-threaded process case. */
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extern int __pthread_multiple_threads attribute_hidden;
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/* Pointer to the corresponding variable in libc. */
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extern int *__libc_multiple_threads_ptr attribute_hidden;
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@ -95,6 +95,14 @@ pthread_cancel (th)
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break;
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}
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/* A single-threaded process should be able to kill itself, since there is
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nothing in the POSIX specification that says that it cannot. So we set
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multiple_threads to true so that cancellation points get executed. */
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THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
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#ifndef TLS_MULTIPLE_THREADS_IN_TCB
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__pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
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#endif
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}
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/* Mark the thread as canceled. This has to be done
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atomically since other bits could be modified as well. */
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@ -20,6 +20,9 @@
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#ifndef NOT_IN_libc
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# ifndef TLS_MULTIPLE_THREADS_IN_TCB
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/* Variable set to a nonzero value either if more than one thread runs or ran,
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or if a single-threaded process is trying to cancel itself. See
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nptl/descr.h for more context on the single-threaded process case. */
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int __libc_multiple_threads attribute_hidden;
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# endif
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#endif
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@ -0,0 +1,65 @@
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/* Copyright (C) 2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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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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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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<http://www.gnu.org/licenses/>. */
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "tst-cancel-self-cleanup.c"
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static int
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do_test (void)
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{
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int ret = 0;
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volatile int should_fail = 1;
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pthread_cleanup_push (cleanup, &should_fail);
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if ((ret = pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL)) != 0)
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{
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printf ("setcancelstate(disable) failed: %s\n", strerror (ret));
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exit (1);
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}
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if ((ret = pthread_cancel (pthread_self ())) != 0)
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{
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printf ("cancel failed: %s\n", strerror (ret));
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exit (1);
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}
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usleep (100);
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should_fail = 0;
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if ((ret = pthread_setcancelstate (PTHREAD_CANCEL_ENABLE, NULL)) != 0)
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{
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printf ("setcancelstate(enable) failed: %s\n", strerror (ret));
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exit (1);
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}
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/* The write syscall within this printf should give us our cancellation
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point. */
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printf ("Could not cancel self.\n");
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pthread_cleanup_pop (0);
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return 1;
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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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@ -0,0 +1,53 @@
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/* Copyright (C) 2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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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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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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<http://www.gnu.org/licenses/>. */
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "tst-cancel-self-cleanup.c"
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static int
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do_test (void)
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{
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int ret = 0, should_fail = 0;
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pthread_cleanup_push (cleanup, &should_fail);
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if ((ret = pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, NULL)) != 0)
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{
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printf ("setcanceltype failed: %s\n", strerror (ret));
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exit (1);
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}
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if ((ret = pthread_cancel (pthread_self ())) != 0)
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{
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printf ("cancel failed: %s\n", strerror (ret));
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exit (1);
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}
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/* Wait to be canceled. Don't give any cancellation points to play with. */
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while (1);
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pthread_cleanup_pop (0);
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return 1;
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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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@ -0,0 +1,23 @@
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/* Copyright (C) 2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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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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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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<http://www.gnu.org/licenses/>. */
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static void
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cleanup (void *cleanup_should_fail)
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{
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printf ("Main thread got cancelled and is being cleaned up now\n");
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exit (*(int *)cleanup_should_fail);
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}
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@ -0,0 +1,48 @@
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/* Copyright (C) 2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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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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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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<http://www.gnu.org/licenses/>. */
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "tst-cancel-self-cleanup.c"
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static int
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do_test (void)
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{
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int ret = 0, should_fail = 0;
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pthread_cleanup_push (cleanup, &should_fail);
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if ((ret = pthread_cancel (pthread_self ())) != 0)
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{
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printf ("cancel failed: %s\n", strerror (ret));
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exit (1);
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}
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pthread_testcancel ();
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printf ("Could not cancel self.\n");
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pthread_cleanup_pop (0);
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return 1;
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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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@ -0,0 +1,48 @@
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/* Copyright (C) 2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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
|
||||
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
|
||||
Lesser General Public License for more details.
|
||||
|
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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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||||
<http://www.gnu.org/licenses/>. */
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "tst-cancel-self-cleanup.c"
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static int
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do_test (void)
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{
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int ret = 0, should_fail = 0;
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pthread_cleanup_push (cleanup, &should_fail);
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if ((ret = pthread_cancel (pthread_self ())) != 0)
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{
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printf ("cancel failed: %s\n", strerror (ret));
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exit (1);
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}
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/* The write syscall within this printf should give us our cancellation
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point. */
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printf ("Could not cancel self.\n");
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pthread_cleanup_pop (0);
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return 1;
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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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@ -32,7 +32,9 @@ size_t __default_stacksize attribute_hidden
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int __is_smp attribute_hidden;
|
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|
||||
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
|
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/* Variable set to a nonzero value if more than one thread runs or ran. */
|
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/* Variable set to a nonzero value either if more than one thread runs or ran,
|
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or if a single-threaded process is trying to cancel itself. See
|
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nptl/descr.h for more context on the single-threaded process case. */
|
||||
int __pthread_multiple_threads attribute_hidden;
|
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#endif
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|
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Loading…
Reference in New Issue