NetBSD/lib/libpthread/pthreads/signal.c

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/* ==== signal.c ============================================================
* Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu
1993-12-20 22:31:06 +03:00
* 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 Chris Provenzano.
* 4. The name of Chris Provenzano may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO 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.
*
* Description : Queue functions.
*
* 1.00 93/07/21 proven
* -Started coding this file.
*/
#ifndef lint
static const char rcsid[] = "$Id: signal.c,v 1.3 1994/02/07 22:04:29 proven Exp $ $provenid: signal.c,v 1.18 1994/02/07 02:19:28 proven Exp $";
#endif
#include <pthread.h>
#include <signal.h>
/*
* Time which select in fd_kern_wait() will sleep.
* If there are no threads to run we sleep for an hour or until
* we get an interrupt or an fd thats awakens. To make sure we
* don't miss an interrupt this variable gets reset too zero in
* sig_handler_real().
*/
struct timeval __fd_kern_wait_timeout = { 0, 0 };
/*
* Global for user-kernel lock, and blocked signals
*/
static volatile sigset_t sig_to_tryagain;
static volatile sigset_t sig_to_process;
static volatile int kernel_lock = 0;
static volatile int sig_count = 0;
static void sig_handler(int signal);
static void set_thread_timer();
void sig_prevent(void);
void sig_resume(void);
/* ==========================================================================
* context_switch()
*
* This routine saves the current state of the running thread gets
* the next thread to run and restores it's state. To allow different
* processors to work with this routine, I allow the machdep_restore_state()
* to either return or have it return from machdep_save_state with a value
* other than 0, this is for implementations which use setjmp/longjmp.
*/
static void context_switch()
{
struct pthread **current, *next, *last;
semaphore *lock;
int count;
/* save state of current thread */
if (machdep_save_state()) {
return;
}
last = pthread_run;
if (pthread_run = pthread_queue_deq(&pthread_current_queue)) {
/* restore state of new current thread */
machdep_restore_state();
return;
}
/* Poll all the kernel fds */
fd_kern_poll();
context_switch_reschedule:;
/*
* Go through the reschedule list once, this is the only place
* that goes through the queue without using the queue routines.
*
* But first delete the current queue.
*/
pthread_queue_init(&pthread_current_queue);
current = &(pthread_link_list);
count = 0;
while (*current) {
switch((*current)->state) {
case PS_RUNNING:
pthread_queue_enq(&pthread_current_queue, *current);
current = &((*current)->pll);
count++;
break;
case PS_DEAD:
/* Cleanup thread, unless we're using the stack */
if (((*current)->flags & PF_DETACHED) && (*current != last)) {
next = (*current)->pll;
lock = &((*current)->lock);
if (SEMAPHORE_TEST_AND_SET(lock)) {
/* Couldn't cleanup this time, try again later */
current = &((*current)->pll);
} else {
if (!((*current)->attr.stackaddr_attr)) {
free (machdep_pthread_cleanup(&((*current)->machdep_data)));
}
free (*current);
*current = next;
}
} else {
current = &((*current)->pll);
}
break;
default:
/* Should be on a different queue. Ignore. */
current = &((*current)->pll);
count++;
break;
}
}
/* Are there any threads to run */
if (pthread_run = pthread_queue_deq(&pthread_current_queue)) {
/* restore state of new current thread */
machdep_restore_state();
return;
}
/* Are there any threads at all */
if (count) {
/*
* Do a wait, timeout is set to a hour unless we get an interrupt
* before the select in wich case it polls and returns.
*/
fd_kern_wait();
/* Check for interrupts, but ignore SIGVTALR */
sigdelset(&sig_to_process, SIGVTALRM);
if (sig_to_process) {
/* Process interrupts */
sig_handler(0);
}
goto context_switch_reschedule;
}
exit(0);
}
/* ==========================================================================
* sig_handler_pause()
*
* Wait until a signal is sent to the process.
*/
void sig_handler_pause()
{
sigset_t sig_to_block, sig_to_pause;
sigfillset(&sig_to_block);
sigemptyset(&sig_to_pause);
sigprocmask(SIG_BLOCK, &sig_to_block, NULL);
if (!sig_to_process) {
sigsuspend(&sig_to_pause);
}
sigprocmask(SIG_UNBLOCK, &sig_to_block, NULL);
}
/* ==========================================================================
* context_switch_done()
*
* This routine does all the things that are necessary after a context_switch()
* calls the machdep_restore_state(). DO NOT put this in the context_switch()
* routine because sometimes the machdep_restore_state() doesn't return
* to context_switch() but instead ends up in machdep_thread_start() or
* some such routine, which will need to call this routine and
* sig_check_and_resume().
*/
void context_switch_done()
{
sigdelset(&sig_to_process, SIGVTALRM);
set_thread_timer();
}
/* ==========================================================================
* set_thread_timer()
*
* Assums kernel is locked.
*/
static void set_thread_timer()
{
static int last_sched_attr = SCHED_RR;
switch (pthread_run->attr.sched_attr) {
case SCHED_RR:
machdep_set_thread_timer(&(pthread_run->machdep_data));
break;
case SCHED_FIFO:
if (last_sched_attr != SCHED_FIFO) {
machdep_unset_thread_timer();
}
break;
case SCHED_IO:
if ((last_sched_attr != SCHED_IO) && (!sig_count)) {
machdep_set_thread_timer(&(pthread_run->machdep_data));
}
break;
default:
machdep_set_thread_timer(&(pthread_run->machdep_data));
break;
}
last_sched_attr = pthread_run->attr.sched_attr;
}
/* ==========================================================================
* sig_handler()
*
* Assumes the kernel is locked.
*/
static void sig_handler(int sig)
{
/*
* First check for old signals, do one pass through and don't
* check any twice.
*/
if (sig_to_tryagain) {
if (sigismember(&sig_to_tryagain, SIGALRM)) {
switch (sleep_wakeup()) {
case 1:
/* Do the default action, no threads were sleeping */
case OK:
/* Woke up a sleeping thread */
sigdelset(&sig_to_tryagain, SIGALRM);
break;
case NOTOK:
/* Couldn't get appropriate locks, try again later */
break;
}
} else {
PANIC();
}
}
/*
* NOW, process signal that just came in, plus any pending on the
* signal mask. All of these must be resolved.
*/
sig_handler_top:;
switch(sig) {
case 0:
break;
case SIGVTALRM:
if (sig_count) {
sigset_t sigall;
sig_count = 0;
/* Unblock all signals */
sigemptyset(&sigall);
sigprocmask(SIG_SETMASK, &sigall, NULL);
}
context_switch();
context_switch_done();
break;
case SIGALRM:
sigdelset(&sig_to_process, SIGALRM);
switch (sleep_wakeup()) {
case 1:
/* Do the default action, no threads were sleeping */
case OK:
/* Woke up a sleeping thread */
break;
case NOTOK:
/* Couldn't get appropriate locks, try again later */
sigaddset(&sig_to_tryagain, SIGALRM);
break;
}
break;
default:
PANIC();
}
/* Determine if there are any other signals */
if (sig_to_process) {
for (sig = 1; sig <= SIGMAX; sig++) {
if (sigismember(&sig_to_process, sig)) {
/* goto sig_handler_top */
goto sig_handler_top;
}
}
}
}
/* ==========================================================================
* sig_handler_real()
*
* On a multi-processor this would need to use the test and set instruction
* otherwise the following will work.
*/
void sig_handler_real(int sig)
{
if (kernel_lock) {
__fd_kern_wait_timeout.tv_sec = 0;
sigaddset(&sig_to_process, sig);
return;
}
sig_prevent();
sig_count++;
sig_handler(sig);
sig_resume();
}
/* ==========================================================================
* sig_handler_fake()
*/
void sig_handler_fake(int sig)
{
if (kernel_lock) {
/* Currently this should be impossible */
PANIC();
}
sig_prevent();
sig_handler(sig);
sig_resume();
}
/* ==========================================================================
* reschedule()
*
* This routine assumes that the caller is the current pthread, pthread_run
* and that it has a lock on itself and that it wants to reschedule itself.
*/
void reschedule(enum pthread_state state)
{
semaphore *plock;
if (kernel_lock) {
/* Currently this should be impossible */
PANIC();
}
sig_prevent();
pthread_run->state = state;
SEMAPHORE_RESET((plock = &(pthread_run->lock)));
sig_handler(SIGVTALRM);
sig_resume();
}
/* ==========================================================================
* sig_prevent()
*/
void sig_prevent(void)
{
kernel_lock++;
}
/* ==========================================================================
* sig_resume()
*/
void sig_resume()
{
kernel_lock--;
}
/* ==========================================================================
* sig_check_and_resume()
*/
void sig_check_and_resume()
{
/* Some routine name that is yet to be determined. */
/* Only bother if we are truely unlocking the kernel */
while (!(--kernel_lock)) {
/* Assume sigset_t is not a struct or union */
if (sig_to_process) {
kernel_lock++;
sig_handler(0);
} else {
break;
}
}
}
/* ==========================================================================
* sig_init()
*
* SIGVTALRM (NOT POSIX) needed for thread timeslice timeouts.
* Since it's not POSIX I will replace it with a
* virtual timer for threads.
* SIGALRM (IS POSIX) so some special handling will be
* necessary to fake SIGALRM signals
*/
void sig_init(void)
{
int sig_to_init[] = { SIGVTALRM, SIGALRM, 0 };
#if defined(SA_RESTART)
struct sigaction act;
#endif
int i;
#if defined(SA_RESTART)
act.sa_handler = sig_handler_real;
sigemptyset(&(act.sa_mask));
act.sa_flags = SA_RESTART;
#endif
/* Initialize only the necessary signals */
for (i = 0; sig_to_init[i]; i++) {
#if defined(SA_RESTART)
if (sigaction(sig_to_init[i], &act, NULL)) {
#else
if (signal(sig_to_init[i], sig_handler_real)) {
#endif
PANIC();
}
}
}