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freebsd-dev/lib/libpthread/thread/thr_spinlock.c

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Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
/*
* Copyright (c) 1997 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 REGENTS 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.
*
Add support for compile time debug. This is enabled if libc_r is built with -D_LOCK_DEBUG. This adds the file name and line number to each lock call and these are stored in the spinlock structure. When using debug mode, the lock function will check if the thread is trying to lock something it has already locked. This is not supposed to happen because the lock will be freed too early. Without lock debug, libc_r should be smaller and slightly faster.
1998-06-09 23:13:10 +00:00
* $Id: uthread_spinlock.c,v 1.3 1998/06/06 07:27:06 jb Exp $
Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
*
*/
#include <stdio.h>
#include <sched.h>
#include <unistd.h>
#include <pthread.h>
Add a warning message for a thread locking against itself. This is not supposed to happen, but I have seen bogus g++ code that causes it.
1998-06-06 07:27:06 +00:00
#include <string.h>
Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
#include "pthread_private.h"
Add support for compile time debug. This is enabled if libc_r is built with -D_LOCK_DEBUG. This adds the file name and line number to each lock call and these are stored in the spinlock structure. When using debug mode, the lock function will check if the thread is trying to lock something it has already locked. This is not supposed to happen because the lock will be freed too early. Without lock debug, libc_r should be smaller and slightly faster.
1998-06-09 23:13:10 +00:00
extern char *__progname;
Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
/*
* Lock a location for the running thread. Yield to allow other
* threads to run if this thread is blocked because the lock is
* not available. Note that this function does not sleep. It
* assumes that the lock will be available very soon.
*/
void
Add support for compile time debug. This is enabled if libc_r is built with -D_LOCK_DEBUG. This adds the file name and line number to each lock call and these are stored in the spinlock structure. When using debug mode, the lock function will check if the thread is trying to lock something it has already locked. This is not supposed to happen because the lock will be freed too early. Without lock debug, libc_r should be smaller and slightly faster.
1998-06-09 23:13:10 +00:00
_spinlock(spinlock_t *lck)
Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
{
Add support for compile time debug. This is enabled if libc_r is built with -D_LOCK_DEBUG. This adds the file name and line number to each lock call and these are stored in the spinlock structure. When using debug mode, the lock function will check if the thread is trying to lock something it has already locked. This is not supposed to happen because the lock will be freed too early. Without lock debug, libc_r should be smaller and slightly faster.
1998-06-09 23:13:10 +00:00
/*
* Try to grab the lock and loop if another thread grabs
* it before we do.
*/
while(_atomic_lock(&lck->access_lock)) {
/* Give up the time slice: */
sched_yield();
Add a warning message for a thread locking against itself. This is not supposed to happen, but I have seen bogus g++ code that causes it.
1998-06-06 07:27:06 +00:00
Add support for compile time debug. This is enabled if libc_r is built with -D_LOCK_DEBUG. This adds the file name and line number to each lock call and these are stored in the spinlock structure. When using debug mode, the lock function will check if the thread is trying to lock something it has already locked. This is not supposed to happen because the lock will be freed too early. Without lock debug, libc_r should be smaller and slightly faster.
1998-06-09 23:13:10 +00:00
/* Check if already locked by the running thread: */
if (lck->lock_owner == (long) _thread_run)
return;
}
Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
Add support for compile time debug. This is enabled if libc_r is built with -D_LOCK_DEBUG. This adds the file name and line number to each lock call and these are stored in the spinlock structure. When using debug mode, the lock function will check if the thread is trying to lock something it has already locked. This is not supposed to happen because the lock will be freed too early. Without lock debug, libc_r should be smaller and slightly faster.
1998-06-09 23:13:10 +00:00
/* The running thread now owns the lock: */
lck->lock_owner = (long) _thread_run;
}
/*
* Lock a location for the running thread. Yield to allow other
* threads to run if this thread is blocked because the lock is
* not available. Note that this function does not sleep. It
* assumes that the lock will be available very soon.
*
* This function checks if the running thread has already locked the
* location, warns if this occurs and creates a thread dump before
* returning.
*/
void
_spinlock_debug(spinlock_t *lck, char *fname, int lineno)
{
Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
/*
* Try to grab the lock and loop if another thread grabs
* it before we do.
*/
Add support for compile time debug. This is enabled if libc_r is built with -D_LOCK_DEBUG. This adds the file name and line number to each lock call and these are stored in the spinlock structure. When using debug mode, the lock function will check if the thread is trying to lock something it has already locked. This is not supposed to happen because the lock will be freed too early. Without lock debug, libc_r should be smaller and slightly faster.
1998-06-09 23:13:10 +00:00
while(_atomic_lock(&lck->access_lock)) {
/* Give up the time slice: */
sched_yield();
/* Check if already locked by the running thread: */
if (lck->lock_owner == (long) _thread_run) {
char str[256];
snprintf(str, sizeof(str), "%s - Warning: Thread %p attempted to lock %p from %s (%d) which it had already locked in %s (%d)\n", __progname, _thread_run, lck, fname, lineno, lck->fname, lck->lineno);
_thread_sys_write(2,str,strlen(str));
/* Create a thread dump to help debug this problem: */
_thread_dump_info();
return;
}
}
/* The running thread now owns the lock: */
lck->lock_owner = (long) _thread_run;
lck->fname = fname;
lck->lineno = lineno;
Change signal model to match POSIX (i.e. one set of signal handlers 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!
1998-04-29 09:59:34 +00:00
}
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