mirror of
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Take lock in pthread_cond_wait cleanup handler only when needed
[BZ #14652] When a thread waiting in pthread_cond_wait with a PI mutex is cancelled after it has returned successfully from the futex syscall but just before async cancellation is disabled, it enters its cancellation handler with the mutex held and simply calling a mutex_lock again will result in a deadlock. Hence, it is necessary to see if the thread owns the lock and try to lock it only if it doesn't.
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NEWS
2
NEWS
@ -16,7 +16,7 @@ Version 2.17
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14336, 14337, 14347, 14349, 14376, 14417, 14459, 14476, 14477, 14505,
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14510, 14516, 14518, 14519, 14530, 14532, 14538, 14543, 14544, 14545,
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14557, 14562, 14568, 14576, 14579, 14583, 14587, 14602, 14621, 14638,
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14645, 14648, 14660, 14661.
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14645, 14648, 14652, 14660, 14661.
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* Support for STT_GNU_IFUNC symbols added for s390 and s390x.
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Optimized versions of memcpy, memset, and memcmp added for System z10 and
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@ -1,3 +1,21 @@
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2012-10-10 Siddhesh Poyarekar <siddhesh@redhat.com>
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[BZ #14652]
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* Makefile (tests): New test case tst-cond25.
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(LDFLAGS-tst-cond25): Link tst-cond25 against librt.
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* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S
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(__condvar_tw_cleanup): Lock mutex only if we don't already
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own it.
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* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S
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(__condvar_w_cleanup): Likewise.
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* sysdeps/unix/sysv/linux/pthread-pi-defines.sym: Add TID_MASK.
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* sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S
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(__condvar_cleanup2): Lock mutex only if we don't already
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own it.
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* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
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(__condvar_cleanup1): Likewise.
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* tst-cond25.c: New test case.
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2012-10-09 Roland McGrath <roland@hack.frob.com>
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* sysdeps/pthread/configure: Regenerated.
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@ -206,7 +206,7 @@ tests = tst-typesizes \
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tst-cond1 tst-cond2 tst-cond3 tst-cond4 tst-cond5 tst-cond6 tst-cond7 \
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tst-cond8 tst-cond9 tst-cond10 tst-cond11 tst-cond12 tst-cond13 \
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tst-cond14 tst-cond15 tst-cond16 tst-cond17 tst-cond18 tst-cond19 \
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tst-cond20 tst-cond21 tst-cond22 tst-cond23 tst-cond24 \
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tst-cond20 tst-cond21 tst-cond22 tst-cond23 tst-cond24 tst-cond25 \
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tst-cond-except \
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tst-robust1 tst-robust2 tst-robust3 tst-robust4 tst-robust5 \
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tst-robust6 tst-robust7 tst-robust8 tst-robust9 \
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@ -276,6 +276,7 @@ gen-as-const-headers = pthread-errnos.sym
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LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst
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LDFLAGS-tst-cond24 = -lrt
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LDFLAGS-tst-cond25 = -lrt
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include ../Makeconfig
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@ -649,10 +649,24 @@ __condvar_tw_cleanup:
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movl $0x7fffffff, %edx
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ENTER_KERNEL
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/* Lock the mutex only if we don't own it already. This only happens
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in case of PI mutexes, if we got cancelled after a successful
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return of the futex syscall and before disabling async
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cancellation. */
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5: movl 24+FRAME_SIZE(%esp), %eax
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call __pthread_mutex_cond_lock
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movl MUTEX_KIND(%eax), %ebx
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andl $(ROBUST_BIT|PI_BIT), %ebx
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cmpl $PI_BIT, %ebx
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jne 8f
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movl %esi, (%esp)
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movl (%eax), %ebx
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andl $TID_MASK, %ebx
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cmpl %ebx, %gs:TID
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je 9f
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8: call __pthread_mutex_cond_lock
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9: movl %esi, (%esp)
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.LcallUR:
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call _Unwind_Resume
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hlt
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@ -566,10 +566,24 @@ __condvar_w_cleanup:
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movl $0x7fffffff, %edx
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ENTER_KERNEL
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/* Lock the mutex only if we don't own it already. This only happens
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in case of PI mutexes, if we got cancelled after a successful
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return of the futex syscall and before disabling async
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cancellation. */
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5: movl 24+FRAME_SIZE(%esp), %eax
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call __pthread_mutex_cond_lock
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movl MUTEX_KIND(%eax), %ebx
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andl $(ROBUST_BIT|PI_BIT), %ebx
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cmpl $PI_BIT, %ebx
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jne 8f
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movl %esi, (%esp)
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movl (%eax), %ebx
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andl $TID_MASK, %ebx
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cmpl %ebx, %gs:TID
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je 9f
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8: call __pthread_mutex_cond_lock
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9: movl %esi, (%esp)
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.LcallUR:
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call _Unwind_Resume
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hlt
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@ -6,3 +6,4 @@ MUTEX_KIND offsetof (pthread_mutex_t, __data.__kind)
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ROBUST_BIT PTHREAD_MUTEX_ROBUST_NORMAL_NP
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PI_BIT PTHREAD_MUTEX_PRIO_INHERIT_NP
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PS_BIT PTHREAD_MUTEX_PSHARED_BIT
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TID_MASK FUTEX_TID_MASK
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@ -771,10 +771,24 @@ __condvar_cleanup2:
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movl $SYS_futex, %eax
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syscall
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/* Lock the mutex only if we don't own it already. This only happens
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in case of PI mutexes, if we got cancelled after a successful
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return of the futex syscall and before disabling async
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cancellation. */
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5: movq 16(%rsp), %rdi
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callq __pthread_mutex_cond_lock
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movl MUTEX_KIND(%rdi), %eax
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andl $(ROBUST_BIT|PI_BIT), %eax
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cmpl $PI_BIT, %eax
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jne 7f
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movq 24(%rsp), %rdi
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movl (%rdi), %eax
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andl $TID_MASK, %eax
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cmpl %eax, %fs:TID
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je 8f
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7: callq __pthread_mutex_cond_lock
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8: movq 24(%rsp), %rdi
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movq FRAME_SIZE(%rsp), %r15
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movq FRAME_SIZE+8(%rsp), %r14
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movq FRAME_SIZE+16(%rsp), %r13
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@ -495,10 +495,24 @@ __condvar_cleanup1:
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movl $SYS_futex, %eax
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syscall
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/* Lock the mutex only if we don't own it already. This only happens
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in case of PI mutexes, if we got cancelled after a successful
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return of the futex syscall and before disabling async
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cancellation. */
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5: movq 16(%rsp), %rdi
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callq __pthread_mutex_cond_lock
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movl MUTEX_KIND(%rdi), %eax
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andl $(ROBUST_BIT|PI_BIT), %eax
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cmpl $PI_BIT, %eax
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jne 7f
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movq 24(%rsp), %rdi
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movl (%rdi), %eax
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andl $TID_MASK, %eax
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cmpl %eax, %fs:TID
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je 8f
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7: callq __pthread_mutex_cond_lock
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8: movq 24(%rsp), %rdi
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.LcallUR:
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call _Unwind_Resume@PLT
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hlt
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282
nptl/tst-cond25.c
Normal file
282
nptl/tst-cond25.c
Normal file
@ -0,0 +1,282 @@
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/* Verify that condition variables synchronized by PI mutexes don't hang on
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on cancellation.
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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 <errno.h>
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#include <sys/types.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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#include <sys/time.h>
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#include <time.h>
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#define NUM 5
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#define ITERS 10000
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#define COUNT 100
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typedef void *(*thr_func) (void *);
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pthread_mutex_t mutex;
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pthread_cond_t cond;
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void cleanup (void *u)
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{
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/* pthread_cond_wait should always return with the mutex locked. */
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if (pthread_mutex_unlock (&mutex))
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abort ();
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}
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void *
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signaller (void *u)
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{
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int i, ret = 0;
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void *tret = NULL;
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for (i = 0; i < ITERS; i++)
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{
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if ((ret = pthread_mutex_lock (&mutex)) != 0)
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{
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tret = (void *)1;
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printf ("signaller:mutex_lock failed: %s\n", strerror (ret));
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goto out;
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}
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if ((ret = pthread_cond_signal (&cond)) != 0)
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{
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tret = (void *)1;
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printf ("signaller:signal failed: %s\n", strerror (ret));
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goto unlock_out;
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}
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if ((ret = pthread_mutex_unlock (&mutex)) != 0)
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{
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tret = (void *)1;
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printf ("signaller:mutex_unlock failed: %s\n", strerror (ret));
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goto out;
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}
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pthread_testcancel ();
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}
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out:
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return tret;
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unlock_out:
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if ((ret = pthread_mutex_unlock (&mutex)) != 0)
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printf ("signaller:mutex_unlock[2] failed: %s\n", strerror (ret));
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goto out;
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}
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void *
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waiter (void *u)
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{
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int i, ret = 0;
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void *tret = NULL;
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int seq = (int)u;
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for (i = 0; i < ITERS / NUM; i++)
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{
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if ((ret = pthread_mutex_lock (&mutex)) != 0)
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{
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tret = (void *)1;
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printf ("waiter[%u]:mutex_lock failed: %s\n", seq, strerror (ret));
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goto out;
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}
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pthread_cleanup_push (cleanup, NULL);
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if ((ret = pthread_cond_wait (&cond, &mutex)) != 0)
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{
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tret = (void *)1;
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printf ("waiter[%u]:wait failed: %s\n", seq, strerror (ret));
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goto unlock_out;
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}
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if ((ret = pthread_mutex_unlock (&mutex)) != 0)
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{
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tret = (void *)1;
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printf ("waiter[%u]:mutex_unlock failed: %s\n", seq, strerror (ret));
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goto out;
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}
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pthread_cleanup_pop (0);
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}
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out:
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puts ("waiter tests done");
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return tret;
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unlock_out:
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if ((ret = pthread_mutex_unlock (&mutex)) != 0)
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printf ("waiter:mutex_unlock[2] failed: %s\n", strerror (ret));
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goto out;
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}
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void *
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timed_waiter (void *u)
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{
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int i, ret;
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void *tret = NULL;
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int seq = (int)u;
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for (i = 0; i < ITERS / NUM; i++)
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{
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struct timespec ts;
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if ((ret = clock_gettime(CLOCK_REALTIME, &ts)) != 0)
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{
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tret = (void *)1;
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printf ("%u:clock_gettime failed: %s\n", seq, strerror (errno));
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goto out;
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}
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ts.tv_sec += 20;
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if ((ret = pthread_mutex_lock (&mutex)) != 0)
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{
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tret = (void *)1;
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printf ("waiter[%u]:mutex_lock failed: %s\n", seq, strerror (ret));
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goto out;
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}
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pthread_cleanup_push (cleanup, NULL);
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/* We should not time out either. */
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if ((ret = pthread_cond_timedwait (&cond, &mutex, &ts)) != 0)
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{
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tret = (void *)1;
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printf ("waiter[%u]:timedwait failed: %s\n", seq, strerror (ret));
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goto unlock_out;
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}
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if ((ret = pthread_mutex_unlock (&mutex)) != 0)
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{
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tret = (void *)1;
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printf ("waiter[%u]:mutex_unlock failed: %s\n", seq, strerror (ret));
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goto out;
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}
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pthread_cleanup_pop (0);
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}
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out:
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puts ("timed_waiter tests done");
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return tret;
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unlock_out:
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if ((ret = pthread_mutex_unlock (&mutex)) != 0)
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printf ("waiter[%u]:mutex_unlock[2] failed: %s\n", seq, strerror (ret));
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goto out;
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}
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int
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do_test_wait (thr_func f)
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{
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pthread_t w[NUM];
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pthread_t s;
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pthread_mutexattr_t attr;
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int i, j, ret = 0;
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void *thr_ret;
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for (i = 0; i < COUNT; i++)
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{
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if ((ret = pthread_mutexattr_init (&attr)) != 0)
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{
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printf ("mutexattr_init failed: %s\n", strerror (ret));
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goto out;
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}
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if ((ret = pthread_mutexattr_setprotocol (&attr, PTHREAD_PRIO_INHERIT)) != 0)
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{
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printf ("mutexattr_setprotocol failed: %s\n", strerror (ret));
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goto out;
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}
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if ((ret = pthread_cond_init (&cond, NULL)) != 0)
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{
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printf ("cond_init failed: %s\n", strerror (ret));
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goto out;
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}
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if ((ret = pthread_mutex_init (&mutex, &attr)) != 0)
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{
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printf ("mutex_init failed: %s\n", strerror (ret));
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goto out;
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}
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for (j = 0; j < NUM; j++)
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if ((ret = pthread_create (&w[j], NULL, f, (void *)j)) != 0)
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{
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printf ("waiter[%d]: create failed: %s\n", j, strerror (ret));
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goto out;
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}
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if ((ret = pthread_create (&s, NULL, signaller, NULL)) != 0)
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{
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printf ("signaller: create failed: %s\n", strerror (ret));
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goto out;
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}
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for (j = 0; j < NUM; j++)
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{
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if ((ret = pthread_cancel (w[j])) != 0)
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{
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printf ("waiter[%d]: cancel failed: %s\n", j, strerror (ret));
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goto out;
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}
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if ((ret = pthread_join (w[j], &thr_ret)) != 0)
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{
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printf ("waiter[%d]: join failed: %s\n", j, strerror (ret));
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goto out;
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}
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if (thr_ret != NULL && thr_ret != PTHREAD_CANCELED)
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{
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ret = 1;
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goto out;
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}
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}
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/* The signalling thread could have ended before it was cancelled. */
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pthread_cancel (s);
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if ((ret = pthread_join (s, &thr_ret)) != 0)
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{
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printf ("signaller: join failed: %s\n", strerror (ret));
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goto out;
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}
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if (thr_ret != NULL && thr_ret != PTHREAD_CANCELED)
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{
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ret = 1;
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goto out;
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}
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}
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out:
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return ret;
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}
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int
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do_test (int argc, char **argv)
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{
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int ret = do_test_wait (waiter);
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if (ret)
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return ret;
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return do_test_wait (timed_waiter);
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}
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#define TIMEOUT 5
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#include "../test-skeleton.c"
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