02c3c85869
some cases we want to improve:
1) if a thread signal got a signal while in cancellation point,
it is possible the TDP_WAKEUP may be eaten by signal handler
if the handler called some interruptibly system calls.
2) In signal handler, we want to disable cancellation.
3) When thread holding some low level locks, it is better to
disable signal, those code need not to worry reentrancy,
sigprocmask system call is avoided because it is a bit expensive.
The signal handler wrapper works in this way:
1) libthr installs its signal handler if user code invokes sigaction
to install its handler, the user handler is recorded in internal
array.
2) when a signal is delivered, libthr's signal handler is invoke,
libthr checks if thread holds some low level lock or is in critical
region, if it is true, the signal is buffered, and all signals are
masked, once the thread leaves critical region, correct signal
mask is restored and buffered signal is processed.
3) before user signal handler is invoked, cancellation is temporarily
disabled, after user signal handler is returned, cancellation state
is restored, and pending cancellation is rescheduled.
168 lines
4.1 KiB
C
168 lines
4.1 KiB
C
/*
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* Copyright (c) 2005, David Xu <davidxu@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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#include "namespace.h"
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#include <pthread.h>
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#include "un-namespace.h"
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#include "thr_private.h"
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__weak_reference(_pthread_cancel, pthread_cancel);
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__weak_reference(_pthread_setcancelstate, pthread_setcancelstate);
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__weak_reference(_pthread_setcanceltype, pthread_setcanceltype);
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__weak_reference(_pthread_testcancel, pthread_testcancel);
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static inline void
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testcancel(struct pthread *curthread)
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{
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if (__predict_false(SHOULD_CANCEL(curthread) &&
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!THR_IN_CRITICAL(curthread)))
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_pthread_exit(PTHREAD_CANCELED);
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}
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void
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_thr_testcancel(struct pthread *curthread)
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{
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testcancel(curthread);
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}
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int
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_pthread_cancel(pthread_t pthread)
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{
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struct pthread *curthread = _get_curthread();
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int ret;
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/*
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* POSIX says _pthread_cancel should be async cancellation safe.
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* _thr_ref_add and _thr_ref_delete will enter and leave critical
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* region automatically.
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*/
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if ((ret = _thr_ref_add(curthread, pthread, 0)) == 0) {
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THR_THREAD_LOCK(curthread, pthread);
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if (!pthread->cancel_pending) {
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pthread->cancel_pending = 1;
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if (pthread->cancel_enable)
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_thr_send_sig(pthread, SIGCANCEL);
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}
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THR_THREAD_UNLOCK(curthread, pthread);
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_thr_ref_delete(curthread, pthread);
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}
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return (ret);
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}
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int
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_pthread_setcancelstate(int state, int *oldstate)
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{
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struct pthread *curthread = _get_curthread();
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int oldval;
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oldval = curthread->cancel_enable;
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switch (state) {
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case PTHREAD_CANCEL_DISABLE:
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curthread->cancel_enable = 0;
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break;
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case PTHREAD_CANCEL_ENABLE:
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curthread->cancel_enable = 1;
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testcancel(curthread);
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break;
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default:
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return (EINVAL);
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}
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if (oldstate) {
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*oldstate = oldval ? PTHREAD_CANCEL_ENABLE :
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PTHREAD_CANCEL_DISABLE;
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}
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return (0);
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}
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int
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_pthread_setcanceltype(int type, int *oldtype)
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{
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struct pthread *curthread = _get_curthread();
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int oldval;
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oldval = curthread->cancel_async;
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switch (type) {
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case PTHREAD_CANCEL_ASYNCHRONOUS:
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curthread->cancel_async = 1;
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testcancel(curthread);
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break;
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case PTHREAD_CANCEL_DEFERRED:
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curthread->cancel_async = 0;
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break;
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default:
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return (EINVAL);
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}
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if (oldtype) {
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*oldtype = oldval ? PTHREAD_CANCEL_ASYNCHRONOUS :
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PTHREAD_CANCEL_DEFERRED;
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}
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return (0);
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}
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void
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_pthread_testcancel(void)
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{
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struct pthread *curthread = _get_curthread();
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curthread->cancel_point = 1;
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testcancel(curthread);
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curthread->cancel_point = 0;
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}
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void
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_thr_cancel_enter(struct pthread *curthread)
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{
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curthread->cancel_point = 1;
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testcancel(curthread);
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}
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void
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_thr_cancel_enter2(struct pthread *curthread, int maycancel)
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{
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curthread->cancel_point = 1;
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if (__predict_false(SHOULD_CANCEL(curthread) &&
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!THR_IN_CRITICAL(curthread))) {
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if (!maycancel)
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thr_wake(curthread->tid);
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else
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_pthread_exit(PTHREAD_CANCELED);
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}
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}
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void
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_thr_cancel_leave(struct pthread *curthread, int maycancel)
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{
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if (maycancel)
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testcancel(curthread);
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curthread->cancel_point = 0;
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}
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