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-rw-r--r--lib/libkse/thread/thr_sig.c584
1 files changed, 584 insertions, 0 deletions
diff --git a/lib/libkse/thread/thr_sig.c b/lib/libkse/thread/thr_sig.c
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+++ b/lib/libkse/thread/thr_sig.c
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+/*
+ * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by John Birrell.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/signalvar.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#ifdef _THREAD_SAFE
+#include <pthread.h>
+#include "pthread_private.h"
+
+/* Prototypes: */
+static void _thread_sig_check_state(pthread_t pthread, int sig);
+
+/* Static variables: */
+static spinlock_t signal_lock = _SPINLOCK_INITIALIZER;
+static unsigned int pending_sigs[NSIG];
+static unsigned int handled_sigs[NSIG];
+static int volatile check_pending = 0;
+
+/* Initialize signal handling facility: */
+void
+_thread_sig_init(void)
+{
+ int i;
+
+ /* Clear pending and handled signal counts: */
+ for (i = 1; i < NSIG; i++) {
+ pending_sigs[i - 1] = 0;
+ handled_sigs[i - 1] = 0;
+ }
+
+ /* Clear the lock: */
+ signal_lock.access_lock = 0;
+
+ /* Clear the process pending signals: */
+ sigemptyset(&_process_sigpending);
+}
+
+void
+_thread_sig_handler(int sig, int code, ucontext_t * scp)
+{
+ pthread_t pthread;
+ int i;
+ char c;
+
+ /* Check if an interval timer signal: */
+ if (sig == _SCHED_SIGNAL) {
+ if (_thread_kern_in_sched != 0) {
+ /*
+ * The scheduler is already running; ignore this
+ * signal.
+ */
+ }
+ /*
+ * Check if the scheduler interrupt has come when
+ * the currently running thread has deferred thread
+ * signals.
+ */
+ else if (_thread_run->sig_defer_count > 0)
+ _thread_run->yield_on_sig_undefer = 1;
+
+ else {
+ /*
+ * Schedule the next thread. This function is not
+ * expected to return because it will do a longjmp
+ * instead.
+ */
+ _thread_kern_sched(scp);
+
+ /*
+ * This point should not be reached, so abort the
+ * process:
+ */
+ PANIC("Returned to signal function from scheduler");
+ }
+ }
+ /*
+ * Check if the kernel has been interrupted while the scheduler
+ * is accessing the scheduling queues or if there is a currently
+ * running thread that has deferred signals.
+ */
+ else if ((_queue_signals != 0) || ((_thread_kern_in_sched == 0) &&
+ (_thread_run->sig_defer_count > 0))) {
+ /* Cast the signal number to a character variable: */
+ c = sig;
+
+ /*
+ * Write the signal number to the kernel pipe so that it will
+ * be ready to read when this signal handler returns.
+ */
+ _thread_sys_write(_thread_kern_pipe[1], &c, 1);
+
+ /* Indicate that there are queued signals in the pipe. */
+ _sigq_check_reqd = 1;
+ }
+ else {
+ if (_atomic_lock(&signal_lock.access_lock)) {
+ /* There is another signal handler running: */
+ pending_sigs[sig - 1]++;
+ check_pending = 1;
+ }
+ else {
+ /* It's safe to handle the signal now. */
+ pthread = _thread_sig_handle(sig, scp);
+
+ /* Reset the pending and handled count back to 0: */
+ pending_sigs[sig - 1] = 0;
+ handled_sigs[sig - 1] = 0;
+
+ if (pthread == NULL)
+ signal_lock.access_lock = 0;
+ else {
+ sigaddset(&pthread->sigmask, sig);
+ signal_lock.access_lock = 0;
+ _thread_sig_deliver(pthread, sig);
+ sigdelset(&pthread->sigmask, sig);
+ }
+ }
+
+ /* Enter a loop to process pending signals: */
+ while ((check_pending != 0) &&
+ (_atomic_lock(&signal_lock.access_lock) == 0)) {
+ check_pending = 0;
+ for (i = 1; i < NSIG; i++) {
+ if (pending_sigs[i - 1] > handled_sigs[i - 1]) {
+ pending_sigs[i - 1] = handled_sigs[i - 1];
+ pthread = _thread_sig_handle(i, scp);
+ if (pthread != NULL) {
+ sigaddset(&pthread->sigmask, i);
+ signal_lock.access_lock = 0;
+ _thread_sig_deliver(pthread, i);
+ sigdelset(&pthread->sigmask, i);
+ if (_atomic_lock(&signal_lock.access_lock)) {
+ check_pending = 1;
+ return;
+ }
+ }
+ }
+ }
+ signal_lock.access_lock = 0;
+ }
+ }
+}
+
+pthread_t
+_thread_sig_handle(int sig, ucontext_t * scp)
+{
+ int i;
+ pthread_t pthread, pthread_next;
+ pthread_t suspended_thread, signaled_thread;
+
+ /* Check if the signal requires a dump of thread information: */
+ if (sig == SIGINFO)
+ /* Dump thread information to file: */
+ _thread_dump_info();
+
+ /* Check if an interval timer signal: */
+ else if (sig == _SCHED_SIGNAL) {
+ /*
+ * This shouldn't ever occur (should this panic?).
+ */
+ } else {
+ /* Check if a child has terminated: */
+ if (sig == SIGCHLD) {
+ /*
+ * Go through the file list and set all files
+ * to non-blocking again in case the child
+ * set some of them to block. Sigh.
+ */
+ for (i = 0; i < _thread_dtablesize; i++) {
+ /* Check if this file is used: */
+ if (_thread_fd_table[i] != NULL) {
+ /*
+ * Set the file descriptor to
+ * non-blocking:
+ */
+ _thread_sys_fcntl(i, F_SETFL,
+ _thread_fd_table[i]->flags |
+ O_NONBLOCK);
+ }
+ }
+ /*
+ * Enter a loop to wake up all threads waiting
+ * for a process to complete:
+ */
+ for (pthread = TAILQ_FIRST(&_waitingq);
+ pthread != NULL; pthread = pthread_next) {
+ /*
+ * Grab the next thread before possibly
+ * destroying the link entry:
+ */
+ pthread_next = TAILQ_NEXT(pthread, pqe);
+
+ /*
+ * If this thread is waiting for a child
+ * process to complete, wake it up:
+ */
+ if (pthread->state == PS_WAIT_WAIT) {
+ /* Make the thread runnable: */
+ PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+ /* Return the signal number: */
+ pthread->signo = sig;
+ }
+ }
+ }
+
+ /*
+ * POSIX says that pending SIGCONT signals are
+ * discarded when one of these signals occurs.
+ */
+ if (sig == SIGTSTP || sig == SIGTTIN || sig == SIGTTOU) {
+ /*
+ * Enter a loop to discard pending SIGCONT
+ * signals:
+ */
+ TAILQ_FOREACH(pthread, &_thread_list, tle) {
+ sigdelset(&pthread->sigpend,SIGCONT);
+ }
+ }
+
+ /*
+ * Enter a loop to look for threads that have the
+ * signal unmasked. POSIX specifies that a thread
+ * in a sigwait will get the signal over any other
+ * threads. Second preference will be threads in
+ * in a sigsuspend. If none of the above, then the
+ * signal is delivered to the first thread we find.
+ */
+ suspended_thread = NULL;
+ signaled_thread = NULL;
+ for (pthread = TAILQ_FIRST(&_waitingq);
+ pthread != NULL; pthread = pthread_next) {
+ /*
+ * Grab the next thread before possibly destroying
+ * the link entry.
+ */
+ pthread_next = TAILQ_NEXT(pthread, pqe);
+
+ if ((pthread->state == PS_SIGWAIT) &&
+ sigismember(pthread->data.sigwait, sig)) {
+ /* Change the state of the thread to run: */
+ PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+ /* Return the signal number: */
+ pthread->signo = sig;
+
+ /*
+ * POSIX doesn't doesn't specify which thread
+ * will get the signal if there are multiple
+ * waiters, so we give it to the first thread
+ * we find.
+ *
+ * Do not attempt to deliver this signal
+ * to other threads.
+ */
+ return (NULL);
+ }
+ else if (!sigismember(&pthread->sigmask, sig)) {
+ if (pthread->state == PS_SIGSUSPEND) {
+ if (suspended_thread == NULL)
+ suspended_thread = pthread;
+ } else if (signaled_thread == NULL)
+ signaled_thread = pthread;
+ }
+ }
+
+ /*
+ * If we didn't find a thread in the waiting queue,
+ * check the all threads queue:
+ */
+ if (suspended_thread == NULL && signaled_thread == NULL) {
+ /*
+ * Enter a loop to look for other threads capable
+ * of receiving the signal:
+ */
+ TAILQ_FOREACH(pthread, &_thread_list, tle) {
+ if (!sigismember(&pthread->sigmask, sig)) {
+ signaled_thread = pthread;
+ break;
+ }
+ }
+ }
+
+ /* Check if the signal is not being ignored: */
+ if (_thread_sigact[sig - 1].sa_handler != SIG_IGN) {
+ if (suspended_thread == NULL &&
+ signaled_thread == NULL)
+ /*
+ * Add it to the set of signals pending
+ * on the process:
+ */
+ sigaddset(&_process_sigpending, sig);
+ else {
+ /*
+ * We only deliver the signal to one thread;
+ * give preference to the suspended thread:
+ */
+ if (suspended_thread != NULL)
+ pthread = suspended_thread;
+ else
+ pthread = signaled_thread;
+
+ /*
+ * Perform any state changes due to signal
+ * arrival:
+ */
+ _thread_sig_check_state(pthread, sig);
+ return (pthread);
+ }
+ }
+ }
+
+ /* Returns nothing. */
+ return (NULL);
+}
+
+/* Perform thread specific actions in response to a signal: */
+static void
+_thread_sig_check_state(pthread_t pthread, int sig)
+{
+ /*
+ * Process according to thread state:
+ */
+ switch (pthread->state) {
+ /*
+ * States which do not change when a signal is trapped:
+ */
+ case PS_COND_WAIT:
+ case PS_DEAD:
+ case PS_DEADLOCK:
+ case PS_FDLR_WAIT:
+ case PS_FDLW_WAIT:
+ case PS_FILE_WAIT:
+ case PS_JOIN:
+ case PS_MUTEX_WAIT:
+ case PS_RUNNING:
+ case PS_STATE_MAX:
+ case PS_SIGTHREAD:
+ case PS_SPINBLOCK:
+ case PS_SUSPENDED:
+ /* Increment the pending signal count. */
+ sigaddset(&pthread->sigpend,sig);
+ break;
+
+ case PS_SIGWAIT:
+ /* Wake up the thread if the signal is blocked. */
+ if (sigismember(pthread->data.sigwait, sig)) {
+ /* Change the state of the thread to run: */
+ PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+ /* Return the signal number: */
+ pthread->signo = sig;
+ } else
+ /* Increment the pending signal count. */
+ sigaddset(&pthread->sigpend,sig);
+ break;
+
+
+ /*
+ * The wait state is a special case due to the handling of
+ * SIGCHLD signals.
+ */
+ case PS_WAIT_WAIT:
+ /*
+ * Check for signals other than the death of a child
+ * process:
+ */
+ if (sig != SIGCHLD)
+ /* Flag the operation as interrupted: */
+ pthread->interrupted = 1;
+
+ /* Change the state of the thread to run: */
+ PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+ /* Return the signal number: */
+ pthread->signo = sig;
+ break;
+
+ /*
+ * States that are interrupted by the occurrence of a signal
+ * other than the scheduling alarm:
+ */
+ case PS_FDR_WAIT:
+ case PS_FDW_WAIT:
+ case PS_POLL_WAIT:
+ case PS_SLEEP_WAIT:
+ case PS_SELECT_WAIT:
+ if ((_thread_sigact[sig - 1].sa_flags & SA_RESTART) == 0) {
+ /* Flag the operation as interrupted: */
+ pthread->interrupted = 1;
+
+ if (pthread->flags & PTHREAD_FLAGS_IN_WORKQ)
+ PTHREAD_WORKQ_REMOVE(pthread);
+
+ /* Change the state of the thread to run: */
+ PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+ /* Return the signal number: */
+ pthread->signo = sig;
+ }
+ break;
+
+ case PS_SIGSUSPEND:
+ /*
+ * Only wake up the thread if there is a handler installed
+ * for the signal.
+ */
+ if (_thread_sigact[sig - 1].sa_handler != SIG_DFL) {
+ /* Change the state of the thread to run: */
+ PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+ /* Return the signal number: */
+ pthread->signo = sig;
+ }
+ break;
+ }
+}
+
+/* Send a signal to a specific thread (ala pthread_kill): */
+void
+_thread_sig_send(pthread_t pthread, int sig)
+{
+ /*
+ * Check that the signal is not being ignored:
+ */
+ if (_thread_sigact[sig - 1].sa_handler != SIG_IGN) {
+ if (pthread->state == PS_SIGWAIT &&
+ sigismember(pthread->data.sigwait, sig)) {
+ /* Change the state of the thread to run: */
+ PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+ /* Return the signal number: */
+ pthread->signo = sig;
+ } else if (pthread->state != PS_SIGWAIT &&
+ !sigismember(&pthread->sigmask, sig)) {
+ /* Perform any state changes due to signal arrival: */
+ _thread_sig_check_state(pthread, sig);
+
+ /* Call the installed signal handler: */
+ _thread_sig_deliver(pthread, sig);
+ }
+ else {
+ /* Increment the pending signal count. */
+ sigaddset(&pthread->sigpend,sig);
+ }
+ }
+}
+
+/* Dispatch pending signals to the running thread: */
+void
+_dispatch_signals()
+{
+ sigset_t sigset, mask;
+ int i;
+
+ /*
+ * Check if there are pending signals for the running
+ * thread or process that aren't blocked:
+ */
+ sigset = _thread_run->sigpend;
+ SIGSETOR(sigset, _process_sigpending);
+ SIGSETNAND(sigset, _thread_run->sigmask);
+ if (SIGNOTEMPTY(sigset)) {
+ /*
+ * Enter a loop to calculate deliverable pending signals
+ * before actually delivering them. The pending signals
+ * must be removed from the pending signal sets before
+ * calling the signal handler because the handler may
+ * call library routines that again check for and deliver
+ * pending signals.
+ */
+ for (i = 1; i < NSIG; i++) {
+ /*
+ * Check that a custom handler is installed
+ * and if the signal is not blocked:
+ */
+ if (_thread_sigact[i - 1].sa_handler != SIG_DFL &&
+ _thread_sigact[i - 1].sa_handler != SIG_IGN &&
+ sigismember(&sigset, i)) {
+ if (sigismember(&_thread_run->sigpend,i))
+ /* Clear the thread pending signal: */
+ sigdelset(&_thread_run->sigpend,i);
+ else
+ /* Clear the process pending signal: */
+ sigdelset(&_process_sigpending,i);
+ }
+ else
+ /* Remove the signal if it can't be handled: */
+ sigdelset(&sigset, i);
+ }
+
+ /* Now deliver the signals: */
+ for (i = 1; i < NSIG; i++) {
+ if (sigismember(&sigset, i))
+ /* Deliver the signal to the running thread: */
+ _thread_sig_deliver(_thread_run, i);
+ }
+ }
+}
+
+/* Deliver a signal to a thread: */
+void
+_thread_sig_deliver(pthread_t pthread, int sig)
+{
+ sigset_t mask;
+ pthread_t pthread_saved;
+
+ /*
+ * Check that a custom handler is installed
+ * and if the signal is not blocked:
+ */
+ if (_thread_sigact[sig - 1].sa_handler != SIG_DFL &&
+ _thread_sigact[sig - 1].sa_handler != SIG_IGN) {
+ /* Save the current thread: */
+ pthread_saved = _thread_run;
+
+ /* Save the threads signal mask: */
+ mask = pthread->sigmask;
+
+ /*
+ * Add the current signal and signal handler
+ * mask to the threads current signal mask:
+ */
+ SIGSETOR(pthread->sigmask, _thread_sigact[sig - 1].sa_mask);
+ sigaddset(&pthread->sigmask, sig);
+
+ /* Current thread inside critical region? */
+ if (_thread_run->sig_defer_count > 0)
+ pthread->sig_defer_count++;
+
+ _thread_run = pthread;
+
+ /*
+ * Dispatch the signal via the custom signal
+ * handler:
+ */
+ (*(_thread_sigact[sig - 1].sa_handler))(sig);
+
+ _thread_run = pthread_saved;
+
+ /* Current thread inside critical region? */
+ if (_thread_run->sig_defer_count > 0)
+ pthread->sig_defer_count--;
+
+ /* Restore the threads signal mask: */
+ pthread->sigmask = mask;
+ }
+}
+#endif
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