freebsd-dev/lib/libpthread/thread/thr_concurrency.c
Daniel Eischen 1cb570c531 Change low-level locking a bit so that we can tell if
a lock is being waitied on.

Fix a races in join and cancellation.

When trying to wait on a CV and the library is not yet
threaded, make it threaded so that waiting actually works.

When trying to nanosleep() and we're not threaded, just
call the system call nanosleep instead of adding the thread
to the wait queue.

Clean up adding/removing new threads to the "all threads queue",
assigning them unique ids, and tracking how many active threads
there are.  Do it all when the thread is added to the scheduling
queue instead of making pthread_create() know how to do it.

Fix a race where a thread could be marked for signal delivery
but it could be exited before we actually add the signal to it.

Other minor cleanups and bug fixes.

Submitted by:	davidxu
Approved by:	re@ (blanket for libpthread)
2003-05-24 02:29:25 +00:00

140 lines
3.7 KiB
C

/*
* Copyright (c) 2003 Daniel M. Eischen <deischen@freebsd.org>
* Copyright (c) 2003 Sergey Osokin <osa@freebsd.org.ru>.
* 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. 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 THE AUTHORS 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 <errno.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/sysctl.h>
#include "thr_private.h"
/*#define DEBUG_CONCURRENCY */
#ifdef DEBUG_CONCURRENCY
#define DBG_MSG stdout_debug
#else
#define DBG_MSG(x...)
#endif
static int level = 0;
__weak_reference(_pthread_getconcurrency, pthread_getconcurrency);
__weak_reference(_pthread_setconcurrency, pthread_setconcurrency);
int
_pthread_getconcurrency(void)
{
return (level);
}
int
_pthread_setconcurrency(int new_level)
{
int ret;
if (new_level < 0)
ret = EINVAL;
else if (new_level == level)
ret = 0;
else if (new_level == 0) {
level = 0;
ret = 0;
} else if ((_kse_isthreaded() == 0) && (_kse_setthreaded(1) != 0)) {
DBG_MSG("Can't enable threading.\n");
ret = EAGAIN;
} else {
ret = _thr_setconcurrency(new_level);
if (ret == 0)
level = new_level;
}
return (ret);
}
int
_thr_setconcurrency(int new_level)
{
struct pthread *curthread;
struct kse *newkse;
kse_critical_t crit;
int kse_count;
int i;
int ret;
ret = 0;
curthread = _get_curthread();
/* Race condition, but so what. */
kse_count = _kse_initial->k_kseg->kg_ksecount;
for (i = kse_count; i < new_level; i++) {
newkse = _kse_alloc(curthread);
if (newkse == NULL) {
DBG_MSG("Can't alloc new KSE.\n");
ret = EAGAIN;
break;
}
newkse->k_kseg = _kse_initial->k_kseg;
newkse->k_schedq = _kse_initial->k_schedq;
newkse->k_curthread = NULL;
crit = _kse_critical_enter();
KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
TAILQ_INSERT_TAIL(&newkse->k_kseg->kg_kseq,
newkse, k_kgqe);
newkse->k_kseg->kg_ksecount++;
newkse->k_flags |= KF_STARTED;
KSE_SCHED_UNLOCK(curthread->kse, newkse->k_kseg);
if (kse_create(&newkse->k_mbx, 0) != 0) {
KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
TAILQ_REMOVE(&newkse->k_kseg->kg_kseq,
newkse, k_kgqe);
newkse->k_kseg->kg_ksecount--;
KSE_SCHED_UNLOCK(curthread->kse, newkse->k_kseg);
_kse_critical_leave(crit);
_kse_free(curthread, newkse);
DBG_MSG("kse_create syscall failed.\n");
ret = EAGAIN;
break;
} else {
_kse_critical_leave(crit);
}
}
return (ret);
}
int
_thr_setmaxconcurrency(void)
{
int vcpu;
int len;
int ret;
len = sizeof(vcpu);
ret = sysctlbyname("kern.threads.virtual_cpu", &vcpu, &len, NULL, NULL);
if (ret == 0 && vcpu > 0)
ret = _thr_setconcurrency(vcpu);
return (ret);
}