If we are at cancellation point, always work as deferred mode despite
whether asynchronous mode is turned on or not, this always gives us a chance to decide whether thread should be canceled or not in cancellation points.
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parent
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=212952
@ -270,46 +270,44 @@ static void
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check_cancel(struct pthread *curthread, ucontext_t *ucp)
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{
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if (__predict_true(!curthread->cancel_pending || !curthread->cancel_enable ||
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curthread->no_cancel))
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if (__predict_true(!curthread->cancel_pending ||
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!curthread->cancel_enable || curthread->no_cancel))
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return;
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if (curthread->cancel_async) {
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/*
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* Otherwise, we are in defer mode, and we are at
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* cancel point, tell kernel to not block the current
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* thread on next cancelable system call.
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*
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* There are three cases we should call thr_wake() to
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* turn on TDP_WAKEUP or send SIGCANCEL in kernel:
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* 1) we are going to call a cancelable system call,
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* non-zero cancel_point means we are already in
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* cancelable state, next system call is cancelable.
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* 2) because _thr_ast() may be called by
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* THR_CRITICAL_LEAVE() which is used by rtld rwlock
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* and any libthr internal locks, when rtld rwlock
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* is used, it is mostly caused my an unresolved PLT.
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* those routines may clear the TDP_WAKEUP flag by
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* invoking some system calls, in those cases, we
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* also should reenable the flag.
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* 3) thread is in sigsuspend(), and the syscall insists
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* on getting a signal before it agrees to return.
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*/
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if (curthread->cancel_point) {
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if (curthread->in_sigsuspend && ucp) {
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SIGADDSET(ucp->uc_sigmask, SIGCANCEL);
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curthread->unblock_sigcancel = 1;
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_thr_send_sig(curthread, SIGCANCEL);
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} else
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thr_wake(curthread->tid);
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} else if (curthread->cancel_async) {
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/*
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* asynchronous cancellation mode, act upon
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* asynchronous cancellation mode, act upon
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* immediately.
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*/
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*/
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_pthread_exit_mask(PTHREAD_CANCELED,
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ucp? &ucp->uc_sigmask : NULL);
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} else {
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/*
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* Otherwise, we are in defer mode, and we are at
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* cancel point, tell kernel to not block the current
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* thread on next cancelable system call.
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*
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* There are three cases we should call thr_wake() to
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* turn on TDP_WAKEUP or send SIGCANCEL in kernel:
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* 1) we are going to call a cancelable system call,
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* non-zero cancel_point means we are already in
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* cancelable state, next system call is cancelable.
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* 2) because _thr_ast() may be called by
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* THR_CRITICAL_LEAVE() which is used by rtld rwlock
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* and any libthr internal locks, when rtld rwlock
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* is used, it is mostly caused my an unresolved PLT.
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* those routines may clear the TDP_WAKEUP flag by
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* invoking some system calls, in those cases, we
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* also should reenable the flag.
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* 3) thread is in sigsuspend(), and the syscall insists
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* on getting a signal before it agrees to return.
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*/
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if (curthread->cancel_point) {
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if (curthread->in_sigsuspend && ucp) {
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SIGADDSET(ucp->uc_sigmask, SIGCANCEL);
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curthread->unblock_sigcancel = 1;
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_thr_send_sig(curthread, SIGCANCEL);
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} else
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thr_wake(curthread->tid);
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}
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}
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}
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