freebsd-nq/lib/libpthread/thread/thr_sigaction.c
David Xu a772047bc6 o Use a daemon thread to monitor signal events in kernel, if pending
signals were changed in kernel, it will retrieve the pending set and
  try to find a thread to dispatch the signal. The dispatching process
  can be rolled back if the signal is no longer in kernel.

o Create two functions _thr_signal_init() and _thr_signal_deinit(),
  all signal action settings are retrieved from kernel when threading
  mode is turned on, after a fork(), child process will reset them to
  user settings by calling _thr_signal_deinit(). when threading mode
  is not turned on, all signal operations are direct past to kernel.

o When a thread generated a synchoronous signals and its context returned
  from completed list, UTS will retrieve the signal from its mailbox and try
  to deliver the signal to thread.

o Context signal mask is now only used when delivering signals, thread's
  current signal mask is always the one in pthread structure.

o Remove have_signals field in pthread structure, replace it with
  psf_valid in pthread_signal_frame. when psf_valid is true, in context
  switch time, thread will backout itself from some mutex/condition
  internal queues, then begin to process signals. when a thread is not
  at blocked state and running, check_pending indicates there are signals
  for the thread, after preempted and then resumed time, UTS will try to
  deliver signals to the thread.

o At signal delivering time, not only pending signals in thread will be
  scanned, process's pending signals will be scanned too.

o Change sigwait code a bit, remove field sigwait in pthread_wait_data,
  replace it with oldsigmask in pthread structure, when a thread calls
  sigwait(), its current signal mask is backuped to oldsigmask, and waitset
  is copied to its signal mask and when the thread gets a signal in the
  waitset range, its current signal mask is restored from oldsigmask,
  these are done in atomic fashion.

o Two additional POSIX APIs are implemented, sigwaitinfo() and sigtimedwait().

o Signal code locking is better than previous, there is fewer race conditions.

o Temporary disable most of code in _kse_single_thread as it is not safe
  after fork().
2003-06-28 09:55:02 +00:00

114 lines
3.8 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 <signal.h>
#include <errno.h>
#include <pthread.h>
#include "thr_private.h"
__weak_reference(_sigaction, sigaction);
int
_sigaction(int sig, const struct sigaction * act, struct sigaction * oact)
{
int ret = 0;
struct sigaction gact;
struct pthread *curthread;
kse_critical_t crit;
/* Check if the signal number is out of range: */
if (sig < 1 || sig > _SIG_MAXSIG) {
/* Return an invalid argument: */
errno = EINVAL;
ret = -1;
} else {
if (!_kse_isthreaded())
return __sys_sigaction(sig, act, oact);
crit = _kse_critical_enter();
curthread = _get_curthread();
KSE_LOCK_ACQUIRE(curthread->kse, &_thread_signal_lock);
/*
* Check if the existing signal action structure contents are
* to be returned:
*/
if (oact != NULL) {
/* Return the existing signal action contents: */
oact->sa_handler = _thread_sigact[sig - 1].sa_handler;
oact->sa_mask = _thread_sigact[sig - 1].sa_mask;
oact->sa_flags = _thread_sigact[sig - 1].sa_flags;
}
/* Check if a signal action was supplied: */
if (act != NULL) {
/* Set the new signal handler: */
_thread_sigact[sig - 1].sa_mask = act->sa_mask;
_thread_sigact[sig - 1].sa_flags = act->sa_flags;
_thread_sigact[sig - 1].sa_handler = act->sa_handler;
}
/*
* Check if the kernel needs to be advised of a change
* in signal action:
*/
if (act != NULL && sig != SIGINFO) {
gact.sa_mask = act->sa_mask;
gact.sa_flags = SA_SIGINFO | act->sa_flags;
/*
* Check if the signal handler is being set to
* the default or ignore handlers:
*/
if (act->sa_handler == SIG_DFL ||
act->sa_handler == SIG_IGN)
/* Specify the built in handler: */
gact.sa_handler = act->sa_handler;
else
/*
* Specify the thread kernel signal
* handler:
*/
gact.sa_handler = (void (*) ())_thr_sig_handler;
/* Change the signal action in the kernel: */
if (__sys_sigaction(sig, &gact, NULL) != 0)
ret = -1;
}
KSE_LOCK_RELEASE(curthread->kse, &_thread_signal_lock);
_kse_critical_leave(crit);
}
/* Return the completion status: */
return (ret);
}