freebsd-nq/lib/libkse/thread/thr_sig.c

783 lines
20 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 <setjmp.h>
#include <errno.h>
#include <pthread.h>
#include "thr_private.h"
/* Prototypes: */
static void thread_sig_handle_special(int sig);
static void thread_sig_add(struct pthread *pthread, int sig, int has_args);
static void thread_sig_check_state(struct pthread *pthread, int sig);
static struct pthread *thread_sig_find(int sig);
static void thread_sigframe_add(struct pthread *thread, int sig,
int has_args);
static void thread_sigframe_save(struct pthread *thread,
struct pthread_state_data *psd);
static void thread_sigframe_restore(struct pthread *thread,
struct pthread_state_data *psd);
/* #define DEBUG_SIGNAL */
#ifdef DEBUG_SIGNAL
#define DBG_MSG stdout_debug
#else
#define DBG_MSG(x...)
#endif
/*
* Dispatch a signal to a thread, if appropriate.
*/
void
_thread_sig_dispatch(int sig)
{
struct pthread *pthread;
DBG_MSG(">>> _thread_sig_dispatch(%d)\n", sig);
thread_sig_handle_special(sig);
if (sigismember(&_thread_sigmask, sig))
/* Don't deliver the signal if it's masked. */
return;
/* Mask the signal until it's handled. */
sigaddset(&_thread_sigmask, sig);
/* This signal will be handled; clear the pending flag. */
sigdelset(&_thread_sigpending, sig);
/*
* Deliver the signal to a thread.
*/
if ((pthread = thread_sig_find(sig)) == NULL) {
DBG_MSG("No thread to handle signal %d\n", sig);
return;
}
DBG_MSG("Got signal %d, selecting thread %p\n", sig, pthread);
thread_sig_add(pthread, sig, /*has_args*/ 1);
}
/*
* Find a thread that can handle the signal.
*/
static struct pthread *
thread_sig_find(int sig)
{
struct pthread *curthread = _get_curthread();
struct pthread *pthread, *pthread_next;
struct pthread *suspended_thread, *signaled_thread;
DBG_MSG("Looking for thread to handle signal %d\n", sig);
/* Check if the signal requires a dump of thread information: */
if (sig == SIGINFO) {
/* Dump thread information to file: */
_thread_dump_info();
/* Unblock this signal to allow further dumps: */
sigdelset(&_thread_sigmask, sig);
}
/*
* 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. Third
* preference will be the current thread. If none of the
* above, then the signal is delivered to the first thread
* that is found. Note that if a custom handler is not
* installed, the signal only affects threads in sigwait.
*/
suspended_thread = NULL;
if ((curthread != &_thread_kern_thread) &&
!sigismember(&curthread->mailbox.tm_context.uc_sigmask, sig))
signaled_thread = curthread;
else
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);
/*
* A signal handler is not invoked for threads
* in sigwait. Clear the blocked and pending
* flags.
*/
sigdelset(&_thread_sigmask, sig);
sigdelset(&_thread_sigpending, sig);
/* 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 and do not add the signal
* to the process pending set.
*/
return (NULL);
}
if (!sigismember(
&pthread->mailbox.tm_context.uc_sigmask, sig) &&
((pthread->flags & PTHREAD_FLAGS_SUSPENDED) == 0)) {
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->mailbox.tm_context.uc_sigmask, sig)) {
signaled_thread = pthread;
break;
}
}
}
if (suspended_thread == NULL &&
signaled_thread == NULL)
/*
* Add it to the set of signals pending
* on the process:
*/
sigaddset(&_thread_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;
return (pthread);
}
/* Returns nothing. */
return (NULL);
}
#if __XXX_NOT_YET__
void
_thread_sig_check_pending(struct pthread *pthread)
{
sigset_t sigset;
int i;
/*
* Check if there are pending signals for the running
* thread or process that aren't blocked:
*/
sigset = pthread->sigpend;
SIGSETOR(sigset, _thread_sigpending);
SIGSETNAND(sigset, pthread->sigmask);
SIGSETNAND(sigset, _thread_sigmask);
if (SIGNOTEMPTY(sigset)) {
for (i = 1; i < NSIG; i++) {
if (sigismember(&sigset, i) != 0) {
if (sigismember(&pthread->sigpend, i) != 0)
thread_sig_add(pthread, i,
/*has_args*/ 0);
else {
thread_sig_add(pthread, i,
/*has_args*/ 1);
sigdelset(&_thread_sigpending, i);
}
}
}
}
}
#endif
#if __XXX_NOT_YET__
/*
* This can only be called from the kernel scheduler. It assumes that
* all thread contexts are saved and that a signal frame can safely be
* added to any user thread.
*/
void
_thread_sig_handle_pending(void)
{
struct pthread *pthread;
int sig;
/*
* Check the array of pending signals:
*/
for (sig = 1; sig <= NSIG; sig++) {
if (sigismember(&_thread_sigpending, sig)) {
/* This signal is no longer pending. */
sigdelset(&_thread_sigpending, sig);
/* Some signals need special handling. */
thread_sig_handle_special(sig);
/* Deliver the signal. */
if (sigismember(&_thread_sigmask, sig)) {
sigaddset(&_thread_sigmask, sig);
if ((pthread = thread_sig_find(sig)) != NULL) {
/*
* Setup the target thread to receive
* the signal:
*/
thread_sig_add(pthread, sig,
/*has_args*/ 1);
}
}
}
}
}
#endif
/*
* Do special processing to the thread states before we deliver
* a signal to the application.
*/
static void
thread_sig_handle_special(int sig)
{
struct pthread *pthread, *pthread_next;
int i;
switch (sig) {
case SIGCHLD:
/*
* 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;
}
}
break;
/*
* POSIX says that pending SIGCONT signals are
* discarded when one of these signals occurs.
*/
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
/*
* Enter a loop to discard pending SIGCONT
* signals:
*/
TAILQ_FOREACH(pthread, &_thread_list, tle) {
sigdelset(&pthread->sigpend, SIGCONT);
}
break;
default:
break;
}
}
/*
* Perform thread specific actions in response to a signal.
* This function is only called if there is a handler installed
* for the signal, and if the target thread has the signal
* unmasked.
*/
static void
thread_sig_add(struct pthread *pthread, int sig, int has_args)
{
int suppress_handler = 0;
/* Make sure this signal isn't still in the pending set: */
sigdelset(&pthread->sigpend, sig);
/*
* Process according to thread state:
*/
switch (pthread->state) {
/*
* States which do not change when a signal is trapped:
*/
case PS_DEAD:
case PS_DEADLOCK:
case PS_STATE_MAX:
/*
* You can't call a signal handler for threads in these
* states.
*/
suppress_handler = 1;
break;
/*
* States which do not need any cleanup handling when signals
* occur:
*/
case PS_RUNNING:
/*
* Remove the thread from the queue before changing its
* priority:
*/
if ((pthread->flags & PTHREAD_FLAGS_IN_PRIOQ) != 0)
PTHREAD_PRIOQ_REMOVE(pthread);
break;
case PS_SUSPENDED:
break;
case PS_SPINBLOCK:
/* Remove the thread from the workq and waitq: */
PTHREAD_WORKQ_REMOVE(pthread);
PTHREAD_WAITQ_REMOVE(pthread);
/* Make the thread runnable: */
PTHREAD_SET_STATE(pthread, PS_RUNNING);
break;
case PS_SIGWAIT:
/* The signal handler is not called for threads in SIGWAIT. */
suppress_handler = 1;
/* 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:
if (sig == SIGCHLD) {
/* Change the state of the thread to run: */
PTHREAD_WAITQ_REMOVE(pthread);
PTHREAD_SET_STATE(pthread, PS_RUNNING);
/* Return the signal number: */
pthread->signo = sig;
}
else {
/*
* Mark the thread as interrupted only if the
* restart flag is not set on the signal action:
*/
PTHREAD_WAITQ_REMOVE(pthread);
PTHREAD_SET_STATE(pthread, PS_RUNNING);
}
break;
/*
* States which cannot be interrupted but still require the
* signal handler to run:
*/
case PS_COND_WAIT:
case PS_MUTEX_WAIT:
/*
* Remove the thread from the wait queue. It will
* be added back to the wait queue once all signal
* handlers have been invoked.
*/
PTHREAD_WAITQ_REMOVE(pthread);
break;
case PS_JOIN:
/*
* Remove the thread from the wait queue. It will
* be added back to the wait queue once all signal
* handlers have been invoked.
*/
PTHREAD_WAITQ_REMOVE(pthread);
/* Make the thread runnable: */
PTHREAD_SET_STATE(pthread, PS_RUNNING);
break;
case PS_SLEEP_WAIT:
/*
* Unmasked signals always cause sleep to terminate early,
* regardless of SA_RESTART:
*/
pthread->interrupted = 1;
/* Remove threads in poll and select from the workq: */
if ((pthread->flags & PTHREAD_FLAGS_IN_WORKQ) != 0)
PTHREAD_WORKQ_REMOVE(pthread);
PTHREAD_WAITQ_REMOVE(pthread);
PTHREAD_SET_STATE(pthread, PS_RUNNING);
break;
case PS_SIGSUSPEND:
PTHREAD_WAITQ_REMOVE(pthread);
PTHREAD_SET_STATE(pthread, PS_RUNNING);
break;
}
DBG_MSG(">>> suppress_handler = %d\n", suppress_handler);
if (suppress_handler == 0) {
/* Setup a signal frame and save the current threads state: */
thread_sigframe_add(pthread, sig, has_args);
/*
* Signals are deferred until just before the threads
* signal handler is invoked:
*/
pthread->sig_defer_count = 1;
/* Make sure the thread is runnable: */
if (pthread->state != PS_RUNNING)
PTHREAD_SET_STATE(pthread, PS_RUNNING);
/*
* The thread should be removed from all scheduling
* queues at this point. Raise the priority and place
* the thread in the run queue. It is also possible
* for a signal to be sent to a suspended thread,
* mostly via pthread_kill(). If a thread is suspended,
* don't insert it into the priority queue; just set
* its state to suspended and it will run the signal
* handler when it is resumed.
*/
pthread->active_priority |= PTHREAD_SIGNAL_PRIORITY;
if ((pthread->flags & PTHREAD_FLAGS_SUSPENDED) != 0)
PTHREAD_SET_STATE(pthread, PS_SUSPENDED);
else
PTHREAD_PRIOQ_INSERT_TAIL(pthread);
}
}
#if __XXX_NOT_YET__
static void
thread_sig_check_state(struct pthread *pthread, int sig)
{
/*
* Process according to thread state:
*/
switch (pthread->state) {
/*
* States which do not change when a signal is trapped:
*/
case PS_DEAD:
case PS_DEADLOCK:
case PS_STATE_MAX:
case PS_RUNNING:
case PS_SUSPENDED:
case PS_SPINBLOCK:
case PS_COND_WAIT:
case PS_JOIN:
case PS_MUTEX_WAIT:
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:
if (sig == SIGCHLD) {
/*
* Remove the thread from the wait queue and
* make it runnable:
*/
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
/* Return the signal number: */
pthread->signo = sig;
}
break;
case PS_FDLR_WAIT:
case PS_FDLW_WAIT:
case PS_SIGSUSPEND:
case PS_SLEEP_WAIT:
/*
* Remove the thread from the wait queue and make it
* runnable:
*/
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
/* Flag the operation as interrupted: */
pthread->interrupted = 1;
break;
/*
* These states are additionally in the work queue:
*/
case PS_FDR_WAIT:
case PS_FDW_WAIT:
case PS_FILE_WAIT:
case PS_POLL_WAIT:
case PS_SELECT_WAIT:
/*
* Remove the thread from the wait and work queues, and
* make it runnable:
*/
PTHREAD_WORKQ_REMOVE(pthread);
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
/* Flag the operation as interrupted: */
pthread->interrupted = 1;
break;
}
}
#endif
#if __XXX_NOT_YET__
/*
* Send a signal to a specific thread (ala pthread_kill):
*/
void
_thread_sig_send(struct pthread *pthread, int sig)
{
struct pthread *curthread = _get_curthread();
/* Check for signals whose actions are SIG_DFL: */
if (_thread_sigact[sig - 1].sa_handler == SIG_DFL) {
/*
* Check to see if a temporary signal handler is
* installed for sigwaiters:
*/
if (_thread_dfl_count[sig] == 0)
/*
* Deliver the signal to the process if a handler
* is not installed:
*/
kill(getpid(), sig);
/*
* Assuming we're still running after the above kill(),
* make any necessary state changes to the thread:
*/
thread_sig_check_state(pthread, sig);
}
/*
* Check that the signal is not being ignored:
*/
else 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 (sigismember(&pthread->sigmask, sig))
/* Add the signal to the pending set: */
sigaddset(&pthread->sigpend, sig);
else if (pthread == curthread)
/* Call the signal handler for the current thread: */
thread_sig_invoke_handler(sig, NULL, NULL);
else {
/* Protect the scheduling queues: */
_thread_kern_sig_defer();
/*
* Perform any state changes due to signal
* arrival:
*/
thread_sig_add(pthread, sig, /* has args */ 0);
/* Unprotect the scheduling queues: */
_thread_kern_sig_undefer();
}
}
}
#endif
/*
* User thread signal handler wrapper.
*
* thread - current running thread
*/
void
_thread_sig_wrapper(int sig, siginfo_t *info, ucontext_t *context)
{
struct pthread_state_data psd;
struct pthread *thread = _get_curthread();
__siginfohandler_t *handler;
/* Save the thread's previous state. */
thread_sigframe_save(thread, &psd);
/* Check the threads previous state: */
if (psd.psd_state != PS_RUNNING) {
/*
* Do a little cleanup handling for those threads in
* queues before calling the signal handler. Signals
* for these threads are temporarily blocked until
* after cleanup handling.
*/
switch (psd.psd_state) {
case PS_COND_WAIT:
_cond_wait_backout(thread);
psd.psd_state = PS_RUNNING;
break;
case PS_MUTEX_WAIT:
_mutex_lock_backout(thread);
psd.psd_state = PS_RUNNING;
break;
default:
break;
}
}
/* Unblock the signal in case we don't return from the handler. */
/*
* XXX - This is totally bogus. We need to lock the signal mask
* somehow.
*/
sigdelset(&_thread_sigmask, sig);
/*
* Lower the priority before calling the handler in case
* it never returns (longjmps back):
*/
thread->active_priority &= ~PTHREAD_SIGNAL_PRIORITY;
/*
* Reenable interruptions without checking for the need to
* context switch.
*/
thread->sig_defer_count = 0;
if (_thread_sigact[sig -1].sa_handler != NULL) {
handler = (__siginfohandler_t *)
_thread_sigact[sig - 1].sa_handler;
handler(sig, info, context);
}
/* Restore the signal frame. */
thread_sigframe_restore(thread, &psd);
/* The signal mask was restored; check for any pending signals. */
/* XXX - thread->check_pending = 1; */
}
static void
thread_sigframe_add(struct pthread *thread, int sig, int has_args)
{
struct pthread_signal_frame *psf = NULL;
unsigned long stackp;
/* Add a signal frame to the stack, pointing to our signal wrapper. */
signalcontext(&thread->mailbox.tm_context, sig,
(__sighandler_t *)_thread_sig_wrapper);
/* Setup the new signal mask. */
SIGSETOR(thread->mailbox.tm_context.uc_sigmask,
_thread_sigact[sig - 1].sa_mask);
sigaddset(&thread->mailbox.tm_context.uc_sigmask, sig);
}
static void
thread_sigframe_restore(struct pthread *thread, struct pthread_state_data *psd)
{
thread->wakeup_time = psd->psd_wakeup_time;
thread->data = psd->psd_wait_data;
thread->state = psd->psd_state;
thread->flags = psd->psd_flags;
thread->interrupted = psd->psd_interrupted;
thread->sig_defer_count = psd->psd_sig_defer_count;
}
static void
thread_sigframe_save(struct pthread *thread, struct pthread_state_data *psd)
{
psd->psd_wakeup_time = thread->wakeup_time;
psd->psd_wait_data = thread->data;
psd->psd_state = thread->state;
psd->psd_flags = thread->flags &
(PTHREAD_FLAGS_PRIVATE | PTHREAD_FLAGS_TRACE);
psd->psd_interrupted = thread->interrupted;
psd->psd_sig_defer_count = thread->sig_defer_count;
}
void
_thread_sig_handler(int sig, siginfo_t *info, ucontext_t *context)
{
/* Nothing. */
}