4fc937ef8f
Before this change, a signal was delivered to each thread that
didn't have the signal masked. Signals also improperly woke up
threads waiting on I/O. With this change, signals are now
handled in the following way:
o If a thread is waiting in a sigwait for the signal,
then the thread is woken up.
o If no threads are sigwait'ing on the signal and a
thread is in a sigsuspend waiting for the signal,
then the thread is woken up.
o In the case that no threads are waiting or suspended
on the signal, then the signal is delivered to the
first thread we find that has the signal unmasked.
o If no threads are waiting or suspended on the signal,
and no threads have the signal unmasked, then the signal
is added to the process wide pending signal set. The
signal will be delivered to the first thread that unmasks
the signal.
If there is an installed signal handler, it is only invoked
if the chosen thread was not in a sigwait.
In the case that multiple threads are waiting or suspended
on a signal, or multiple threads have the signal unmasked,
we wake up/deliver the signal to the first thread we find.
The above rules still apply.
Reported by: Scott Hess <scott@avantgo.com>
Reviewed by: jb, jasone
439 lines
11 KiB
C
439 lines
11 KiB
C
/*
|
|
* 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_signal(pthread_t pthread, int sig);
|
|
|
|
/* 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;
|
|
|
|
/* Clear the process pending signals: */
|
|
sigemptyset(&_process_sigpending);
|
|
}
|
|
|
|
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;
|
|
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);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
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;
|
|
}
|
|
}
|
|
|
|
/* 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 {
|
|
pthread_t pthread_saved = _thread_run;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/* 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: */
|
|
static 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_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_SIGWAIT:
|
|
case PS_SPINBLOCK:
|
|
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 ((_thread_sigact[sig - 1].sa_flags & SA_RESTART) == 0 &&
|
|
(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 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;
|
|
}
|
|
}
|
|
|
|
/* 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 or process that aren't blocked:
|
|
*/
|
|
sigset = _thread_run->sigpend;
|
|
SIGSETOR(sigset, _process_sigpending);
|
|
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(&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);
|
|
|
|
/*
|
|
* Dispatch the signal via the custom signal
|
|
* handler:
|
|
*/
|
|
(*(_thread_sigact[i - 1].sa_handler))(i);
|
|
}
|
|
}
|
|
#endif
|