fbeb36e4bf
thread switches should be on par with that under scheduler
activations.
o Timing is achieved through the use of a fixed interval
timer (ITIMER_PROF) to count scheduling ticks instead
of retrieving the time-of-day upon every thread switch
and calculating elapsed real time.
o Polling for I/O readiness is performed once for each
scheduling tick instead of every thread switch.
o The non-signal saving/restoring versions of setjmp/longjmp
are used to save and restore thread contexts. This may
allow the removal of _THREAD_SAFE macros from setjmp()
and longjmp() - needs more investigation.
Change signal handling so that signals are handled in the
context of the thread that is receiving the signal. When
signals are dispatched to a thread, a special signal handling
frame is created on top of the target threads stack. The
frame contains the threads saved state information and a new
context in which the thread can run. The applications signal
handler is invoked through a wrapper routine that knows how
to restore the threads saved state and unwind to previous
frames.
Fix interruption of threads due to signals. Some states
were being improperly interrupted while other states were
not being interrupted. This should fix several PRs.
Signal handlers, which are invoked as a result of a process
signal (not by pthread_kill()), are now called with the
code (or siginfo_t if SA_SIGINFO was set in sa_flags) and
sigcontext_t as received from the process signal handler.
Modify the search for a thread to which a signal is delivered.
The search algorithm is now:
o First thread found in sigwait() with signal in wait mask.
o First thread found sigsuspend()'d on the signal.
o Current thread if signal is unmasked.
o First thread found with signal unmasked.
Collapse machine dependent support into macros defined in
pthread_private.h. These should probably eventually be moved
into separate MD files.
Change the range of settable priorities to be compliant with
POSIX (0-31). The threads library uses higher priorities
internally for real-time threads (not yet implemented) and
threads executing signal handlers. Real-time threads and
threads running signal handlers add 64 and 32, respectively,
to a threads base priority.
Some other small changes and cleanups.
PR: 17757 18559 21943
Reviewed by: jasone
172 lines
5.2 KiB
C
172 lines
5.2 KiB
C
/*
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* Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
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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, this list of conditions and the following 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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <signal.h>
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#include <sys/param.h>
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#include <sys/signalvar.h>
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#include <errno.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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int
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sigwait(const sigset_t *set, int *sig)
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{
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int ret = 0;
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int i;
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sigset_t tempset, waitset;
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struct sigaction act;
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_thread_enter_cancellation_point();
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/*
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* Specify the thread kernel signal handler.
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*/
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act.sa_handler = (void (*) ()) _thread_sig_handler;
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act.sa_flags = SA_RESTART | SA_SIGINFO;
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/* Ensure the signal handler cannot be interrupted by other signals: */
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sigfillset(&act.sa_mask);
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/*
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* Initialize the set of signals that will be waited on:
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*/
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waitset = *set;
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/* These signals can't be waited on. */
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sigdelset(&waitset, SIGKILL);
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sigdelset(&waitset, SIGSTOP);
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sigdelset(&waitset, _SCHED_SIGNAL);
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sigdelset(&waitset, SIGCHLD);
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sigdelset(&waitset, SIGINFO);
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/* Check to see if a pending signal is in the wait mask. */
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tempset = _thread_run->sigpend;
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SIGSETOR(tempset, _process_sigpending);
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SIGSETAND(tempset, waitset);
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if (SIGNOTEMPTY(tempset)) {
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/* Enter a loop to find a pending signal: */
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for (i = 1; i < NSIG; i++) {
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if (sigismember (&tempset, i))
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break;
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}
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/* Clear the pending signal: */
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if (sigismember(&_thread_run->sigpend,i))
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sigdelset(&_thread_run->sigpend,i);
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else
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sigdelset(&_process_sigpending,i);
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/* Return the signal number to the caller: */
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*sig = i;
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_thread_leave_cancellation_point();
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return (0);
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}
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/*
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* Access the _thread_dfl_count array under the protection of signal
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* deferral.
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*/
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_thread_kern_sig_defer();
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/*
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* Enter a loop to find the signals that are SIG_DFL. For
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* these signals we must install a dummy signal handler in
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* order for the kernel to pass them in to us. POSIX says
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* that the _application_ must explicitly install a dummy
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* handler for signals that are SIG_IGN in order to sigwait
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* on them. Note that SIG_IGN signals are left in the
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* mask because a subsequent sigaction could enable an
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* ignored signal.
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*/
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for (i = 1; i < NSIG; i++) {
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if (sigismember(&waitset, i) &&
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(_thread_sigact[i - 1].sa_handler == SIG_DFL)) {
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_thread_dfl_count[i]++;
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if (_thread_dfl_count[i] == 1) {
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if (_thread_sys_sigaction(i,&act,NULL) != 0)
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ret = -1;
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}
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}
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}
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/* Done accessing _thread_dfl_count for now. */
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_thread_kern_sig_undefer();
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if (ret == 0) {
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/*
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* Save the wait signal mask. The wait signal
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* mask is independent of the threads signal mask
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* and requires separate storage.
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*/
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_thread_run->data.sigwait = &waitset;
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/* Wait for a signal: */
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_thread_kern_sched_state(PS_SIGWAIT, __FILE__, __LINE__);
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/* Return the signal number to the caller: */
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*sig = _thread_run->signo;
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/*
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* Probably unnecessary, but since it's in a union struct
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* we don't know how it could be used in the future.
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*/
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_thread_run->data.sigwait = NULL;
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}
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/*
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* Access the _thread_dfl_count array under the protection of signal
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* deferral.
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*/
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_thread_kern_sig_defer();
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/* Restore the sigactions: */
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act.sa_handler = SIG_DFL;
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for (i = 1; i < NSIG; i++) {
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if (sigismember(&waitset, i) &&
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(_thread_sigact[i - 1].sa_handler == SIG_DFL)) {
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_thread_dfl_count[i]--;
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if (_thread_dfl_count == 0) {
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if (_thread_sys_sigaction(i,&act,NULL) != 0)
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ret = -1;
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}
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}
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}
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/* Done accessing _thread_dfl_count. */
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_thread_kern_sig_undefer();
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_thread_leave_cancellation_point();
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/* Return the completion status: */
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return (ret);
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}
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#endif
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