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!
252 lines
7.9 KiB
C
252 lines
7.9 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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/* Allocate space for global thread variables here: */
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#define GLOBAL_PTHREAD_PRIVATE
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/time.h>
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#ifdef _THREAD_SAFE
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#include <machine/reg.h>
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#include <pthread.h>
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#include "pthread_private.h"
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#ifdef GCC_2_8_MADE_THREAD_AWARE
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typedef void *** (*dynamic_handler_allocator)();
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extern void __set_dynamic_handler_allocator(dynamic_handler_allocator);
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static pthread_key_t except_head_key;
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typedef struct {
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void **__dynamic_handler_chain;
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void *top_elt[2];
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} except_struct;
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static void ***dynamic_allocator_handler_fn()
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{
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except_struct *dh = (except_struct *)pthread_getspecific(except_head_key);
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if(dh == NULL) {
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dh = (except_struct *)malloc( sizeof(except_struct) );
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memset(dh, '\0', sizeof(except_struct));
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dh->__dynamic_handler_chain= dh->top_elt;
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pthread_setspecific(except_head_key, (void *)dh);
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}
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return &dh->__dynamic_handler_chain;
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}
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#endif /* GCC_2_8_MADE_THREAD_AWARE */
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/*
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* Threaded process initialization
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*/
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void
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_thread_init(void)
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{
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int flags;
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int i;
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struct sigaction act;
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/* Check if this function has already been called: */
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if (_thread_initial)
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/* Only initialise the threaded application once. */
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return;
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/* Get the standard I/O flags before messing with them : */
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for (i = 0; i < 3; i++)
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if ((_pthread_stdio_flags[i] =
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_thread_sys_fcntl(i,F_GETFL, NULL)) == -1)
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PANIC("Cannot get stdio flags");
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/*
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* Create a pipe that is written to by the signal handler to prevent
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* signals being missed in calls to _select:
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*/
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if (_thread_sys_pipe(_thread_kern_pipe) != 0) {
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/* Cannot create pipe, so abort: */
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PANIC("Cannot create kernel pipe");
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}
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/* Get the flags for the read pipe: */
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else if ((flags = _thread_sys_fcntl(_thread_kern_pipe[0], F_GETFL, NULL)) == -1) {
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/* Abort this application: */
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PANIC("Cannot get kernel read pipe flags");
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}
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/* Make the read pipe non-blocking: */
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else if (_thread_sys_fcntl(_thread_kern_pipe[0], F_SETFL, flags | O_NONBLOCK) == -1) {
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/* Abort this application: */
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PANIC("Cannot make kernel read pipe non-blocking");
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}
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/* Get the flags for the write pipe: */
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else if ((flags = _thread_sys_fcntl(_thread_kern_pipe[1], F_GETFL, NULL)) == -1) {
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/* Abort this application: */
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PANIC("Cannot get kernel write pipe flags");
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}
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/* Make the write pipe non-blocking: */
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else if (_thread_sys_fcntl(_thread_kern_pipe[1], F_SETFL, flags | O_NONBLOCK) == -1) {
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/* Abort this application: */
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PANIC("Cannot get kernel write pipe flags");
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}
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/* Allocate memory for the thread structure of the initial thread: */
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else if ((_thread_initial = (pthread_t) malloc(sizeof(struct pthread))) == NULL) {
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/*
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* Insufficient memory to initialise this application, so
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* abort:
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*/
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PANIC("Cannot allocate memory for initial thread");
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} else {
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/* Zero the global kernel thread structure: */
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memset(&_thread_kern_thread, 0, sizeof(struct pthread));
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memset(_thread_initial, 0, sizeof(struct pthread));
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/* Default the priority of the initial thread: */
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_thread_initial->pthread_priority = PTHREAD_DEFAULT_PRIORITY;
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/* Initialise the state of the initial thread: */
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_thread_initial->state = PS_RUNNING;
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/* Initialise the queue: */
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_thread_queue_init(&(_thread_initial->join_queue));
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/* Initialise the rest of the fields: */
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_thread_initial->specific_data = NULL;
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_thread_initial->cleanup = NULL;
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_thread_initial->queue = NULL;
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_thread_initial->qnxt = NULL;
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_thread_initial->nxt = NULL;
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_thread_initial->flags = 0;
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_thread_initial->error = 0;
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_thread_link_list = _thread_initial;
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_thread_run = _thread_initial;
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/* Initialise the global signal action structure: */
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sigfillset(&act.sa_mask);
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act.sa_handler = (void (*) ()) _thread_sig_handler;
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act.sa_flags = SA_RESTART;
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/* Enter a loop to get the existing signal status: */
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for (i = 1; i < NSIG; i++) {
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/* Check for signals which cannot be trapped: */
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if (i == SIGKILL || i == SIGSTOP) {
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}
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/* Get the signal handler details: */
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else if (_thread_sys_sigaction(i, NULL,
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&_thread_sigact[i - 1]) != 0) {
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/*
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* Abort this process if signal
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* initialisation fails:
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*/
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PANIC("Cannot read signal handler info");
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}
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}
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/*
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* Install the signal handler for the most important
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* signals that the user-thread kernel needs. Actually
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* SIGINFO isn't really needed, but it is nice to have.
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*/
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if (_thread_sys_sigaction(SIGVTALRM, &act, NULL) != 0 ||
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_thread_sys_sigaction(SIGINFO , &act, NULL) != 0 ||
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_thread_sys_sigaction(SIGCHLD , &act, NULL) != 0) {
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/*
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* Abort this process if signal initialisation fails:
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*/
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PANIC("Cannot initialise signal handler");
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}
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/* Get the table size: */
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if ((_thread_dtablesize = getdtablesize()) < 0) {
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/*
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* Cannot get the system defined table size, so abort
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* this process.
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*/
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PANIC("Cannot get dtablesize");
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}
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/* Allocate memory for the file descriptor table: */
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if ((_thread_fd_table = (struct fd_table_entry **) malloc(sizeof(struct fd_table_entry *) * _thread_dtablesize)) == NULL) {
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/*
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* Cannot allocate memory for the file descriptor
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* table, so abort this process.
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*/
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PANIC("Cannot allocate memory for file descriptor table");
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} else {
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/*
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* Enter a loop to initialise the file descriptor
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* table:
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*/
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for (i = 0; i < _thread_dtablesize; i++) {
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/* Initialise the file descriptor table: */
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_thread_fd_table[i] = NULL;
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}
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}
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}
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#ifdef GCC_2_8_MADE_THREAD_AWARE
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/* Create the thread-specific data for the exception linked list. */
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if(pthread_key_create(&except_head_key, NULL) != 0)
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PANIC("Failed to create thread specific execption head");
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/* Setup the gcc exception handler per thread. */
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__set_dynamic_handler_allocator( dynamic_allocator_handler_fn );
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#endif /* GCC_2_8_MADE_THREAD_AWARE */
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return;
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}
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/*
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* Special start up code for NetBSD/Alpha
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*/
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#if defined(__NetBSD__) && defined(__alpha__)
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int
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main(int argc, char *argv[], char *env);
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int
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_thread_main(int argc, char *argv[], char *env)
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{
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_thread_init();
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return (main(argc, argv, env));
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}
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#endif
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#else
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/*
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* A stub for non-threaded programs.
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*/
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void
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_thread_init(void)
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{
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}
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#endif
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