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freebsd/lib/libc_r/uthread/uthread_spinlock.c
Daniel Eischen e5106342c6 Add weak definitions for wrapped system calls. In general:
_foo - wrapped system call
	foo - weak definition to _foo

and for cancellation points:

	_foo - wrapped system call
	__foo - enter cancellation point, call _foo(), leave
	        cancellation point
	foo - weak definition to __foo

Change use of global _thread_run to call a function to get the
currently running thread.

Make all pthread_foo functions weak definitions to _pthread_foo,
where _pthread_foo is the implementation.  This allows an application
to provide its own pthread functions.

Provide slightly different versions of pthread_mutex_lock and
pthread_mutex_init so that we can tell the difference between
a libc mutex and an application mutex.  Threads holding mutexes
internal to libc should never be allowed to exit, call signal
handlers, or cancel.

Approved by:	-arch
2001-01-24 13:03:38 +00:00

110 lines
3.8 KiB
C

/*
* 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 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 <stdio.h>
#include <sched.h>
#include <unistd.h>
#include <pthread.h>
#include <string.h>
#include "pthread_private.h"
extern char *__progname;
/*
* 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
_spinlock(spinlock_t *lck)
{
struct pthread *curthread = _get_curthread();
/*
* Try to grab the lock and loop if another thread grabs
* it before we do.
*/
while(_atomic_lock(&lck->access_lock)) {
/* Block the thread until the lock. */
curthread->data.spinlock = lck;
_thread_kern_sched_state(PS_SPINBLOCK, __FILE__, __LINE__);
}
/* The running thread now owns the lock: */
lck->lock_owner = (long) curthread;
}
/*
* 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)
{
struct pthread *curthread = _get_curthread();
int cnt = 0;
/*
* Try to grab the lock and loop if another thread grabs
* it before we do.
*/
while(_atomic_lock(&lck->access_lock)) {
cnt++;
if (cnt > 100) {
char str[256];
snprintf(str, sizeof(str), "%s - Warning: Thread %p attempted to lock %p from %s (%d) was left locked from %s (%d)\n", __progname, curthread, lck, fname, lineno, lck->fname, lck->lineno);
__sys_write(2,str,strlen(str));
__sleep(1);
cnt = 0;
}
/* Block the thread until the lock. */
curthread->data.spinlock = lck;
_thread_kern_sched_state(PS_SPINBLOCK, fname, lineno);
}
/* The running thread now owns the lock: */
lck->lock_owner = (long) curthread;
lck->fname = fname;
lck->lineno = lineno;
}