/*
* 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"
/* Static variables: */
static spinlock_t signal_lock = _SPINLOCK_INITIALIZER;
unsigned int pending_sigs[NSIG];
unsigned int handled_sigs[NSIG];
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;
}
void
_thread_sig_handler(int sig, int code, ucontext_t * scp)
{
char c;
int i;
/* 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. */
_thread_sig_handle(sig, scp);
/* Reset the pending and handled count back to 0: */
pending_sigs[sig - 1] = 0;
handled_sigs[sig - 1] = 0;
signal_lock.access_lock = 0;
}
/* 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])
_thread_sig_handle(i, scp);
}
signal_lock.access_lock = 0;
}
}
}
void
_thread_sig_handle(int sig, ucontext_t * scp)
{
int i;
pthread_t pthread, pthread_next;
/* 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);
}
}
}
/*
* 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 process each thread in the waiting
* list that is sigwait-ing on a signal. Since POSIX
* doesn't specify which thread will get the signal
* if there are multiple waiters, we'll give it to the
* first one we find.
*/
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;
/*
* Do not attempt to deliver this signal
* to other threads.
*/
return;
}
}
/* Check if the signal is not being ignored: */
if (_thread_sigact[sig - 1].sa_handler != SIG_IGN)
/*
* Enter a loop to process each thread in the linked
* list:
*/
TAILQ_FOREACH(pthread, &_thread_list, tle) {
pthread_t pthread_saved = _thread_run;
/* Current thread inside critical region? */
if (_thread_run->sig_defer_count > 0)
pthread->sig_defer_count++;
_thread_run = pthread;
_thread_signal(pthread,sig);
/*
* Dispatch pending signals to the
* running thread:
*/
_dispatch_signals();
_thread_run = pthread_saved;
/* Current thread inside critical region? */
if (_thread_run->sig_defer_count > 0)
pthread->sig_defer_count--;
}
}
/* Returns nothing. */
return;
}
/* Perform thread specific actions in response to a signal: */
void
_thread_signal(pthread_t pthread, int sig)
{
/*
* Flag the signal as pending. It will be dispatched later.
*/
sigaddset(&pthread->sigpend,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_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_SIGWAIT:
case PS_SUSPENDED:
/* Nothing to do here. */
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 (sig != SIGCHLD ||
_thread_sigact[sig - 1].sa_handler != SIG_DFL) {
/* 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 the signal is unblocked
* and there is a handler installed for the signal.
*/
if (!sigismember(&pthread->sigmask, sig) &&
_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;
}
}
/* Dispatch pending signals to the running thread: */
void
_dispatch_signals()
{
sigset_t sigset;
int i;
/*
* Check if there are pending signals for the running
* thread that aren't blocked:
*/
sigset = _thread_run->sigpend;
SIGSETNAND(sigset, _thread_run->sigmask);
if (SIGNOTEMPTY(sigset))
/* Look for all possible 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(&_thread_run->sigpend,i) &&
!sigismember(&_thread_run->sigmask,i)) {
/* Clear the pending signal: */
sigdelset(&_thread_run->sigpend,i);
/*
* Dispatch the signal via the custom signal
* handler:
*/
(*(_thread_sigact[i - 1].sa_handler))(i);
}
}
#endif
