4a027d50c7
for the process, not a separate set for each thread). By default, the process now only has signal handlers installed for SIGVTALRM, SIGINFO and SIGCHLD. The thread kernel signal handler is installed for other signals on demand. This means that SIG_IGN and SIG_DFL processing is now left to the kernel, not the thread kernel. Change the signal dispatch to no longer use a signal thread, and call the signal handler using the stack of the thread that has the signal pending. Change the atomic lock method to use test-and-set asm code with a yield if blocked. This introduces separate locks for each type of object instead of blocking signals to prevent a context switch. It was this blocking of signals that caused the performance degradation the people have noted. This is a *big* change!
105 lines
3.6 KiB
C
105 lines
3.6 KiB
C
/*
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* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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#include <signal.h>
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#include <errno.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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int
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sigaction(int sig, const struct sigaction * act, struct sigaction * oact)
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{
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int ret = 0;
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struct sigaction gact;
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/* Check if the signal number is out of range: */
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if (sig < 1 || sig > NSIG) {
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/* Return an invalid argument: */
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errno = EINVAL;
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ret = -1;
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} else {
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/*
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* Check if the existing signal action structure contents are
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* to be returned:
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*/
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if (oact != NULL) {
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/* Return the existing signal action contents: */
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oact->sa_handler = _thread_sigact[sig - 1].sa_handler;
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oact->sa_mask = _thread_sigact[sig - 1].sa_mask;
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oact->sa_flags = _thread_sigact[sig - 1].sa_flags;
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}
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/* Check if a signal action was supplied: */
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if (act != NULL) {
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/* Set the new signal handler: */
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_thread_sigact[sig - 1].sa_mask = act->sa_mask;
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_thread_sigact[sig - 1].sa_flags = act->sa_flags;
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_thread_sigact[sig - 1].sa_handler = act->sa_handler;
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}
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/*
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* Check if the kernel needs to be advised of a change
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* in signal action:
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*/
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if (act != NULL && sig != SIGVTALRM && sig != SIGCHLD &&
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sig != SIGINFO) {
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/* Initialise the global signal action structure: */
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gact.sa_mask = act->sa_mask;
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gact.sa_flags = act->sa_flags | SA_RESTART;
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/*
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* Check if the signal handler is being set to
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* the default or ignore handlers:
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*/
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if (act->sa_handler == SIG_DFL ||
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act->sa_handler == SIG_IGN)
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/* Specify the built in handler: */
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gact.sa_handler = act->sa_handler;
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else
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/*
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* Specify the thread kernel signal
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* handler:
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*/
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gact.sa_handler = (void (*) ()) _thread_sig_handler;
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/* Change the signal action in the kernel: */
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if (_thread_sys_sigaction(sig,&gact,NULL) != 0)
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ret = -1;
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}
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}
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/* Return the completion status: */
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return (ret);
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}
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#endif
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