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authorad <ad@NetBSD.org>2007-09-13 23:51:47 +0000
committerad <ad@NetBSD.org>2007-09-13 23:51:47 +0000
commit20e3392edc8d116aa42fc6fb3daa1456c090dd49 (patch)
treea83f6a4f3f9a0f3a1f2e158f023ee09c9404c1b6 /lib/libpthread
parentaff14ee9c85d5f7ef3c66280a8dbf7056dd34b67 (diff)
Add a per-mutex deferred wakeup flag so that threads doing something like
the following do not wake other threads early: pthread_mutex_lock(&mutex); pthread_cond_broadcast(&cond); foo = malloc(100); /* takes libc mutexes */ pthread_mutex_unlock(&mutex);
Diffstat (limited to 'lib/libpthread')
-rw-r--r--lib/libpthread/pthread_cond.c10
-rw-r--r--lib/libpthread/pthread_int.h4
-rw-r--r--lib/libpthread/pthread_mutex.c6
-rw-r--r--lib/libpthread/pthread_mutex2.c37
4 files changed, 35 insertions, 22 deletions
diff --git a/lib/libpthread/pthread_cond.c b/lib/libpthread/pthread_cond.c
index 2f8879c1dee..4266250ed72 100644
--- a/lib/libpthread/pthread_cond.c
+++ b/lib/libpthread/pthread_cond.c
@@ -1,4 +1,4 @@
-/* $NetBSD: pthread_cond.c,v 1.36 2007/09/08 22:49:50 ad Exp $ */
+/* $NetBSD: pthread_cond.c,v 1.37 2007/09/13 23:51:47 ad Exp $ */
/*-
* Copyright (c) 2001, 2006, 2007 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__RCSID("$NetBSD: pthread_cond.c,v 1.36 2007/09/08 22:49:50 ad Exp $");
+__RCSID("$NetBSD: pthread_cond.c,v 1.37 2007/09/13 23:51:47 ad Exp $");
#include <errno.h>
#include <sys/time.h>
@@ -324,8 +324,8 @@ pthread_cond_signal(pthread_cond_t *cond)
* deferred wakeup list. The waiter will be set running when the
* caller (this thread) releases the mutex.
*/
- if (mutex != NULL && pthread__mutex_owned(self, mutex) &&
- self->pt_nwaiters < pthread__unpark_max) {
+ if (mutex != NULL && self->pt_nwaiters < pthread__unpark_max &&
+ pthread__mutex_deferwake(self, mutex)) {
signaled->pt_sleepobj = NULL;
signaled->pt_sleeponq = 0;
pthread_spinunlock(&cond->ptc_lock);
@@ -363,7 +363,7 @@ pthread_cond_broadcast(pthread_cond_t *cond)
* Try to defer waking threads (see pthread_cond_signal()).
* Only transfer waiters for which there is no pending wakeup.
*/
- if (mutex != NULL && pthread__mutex_owned(self, mutex)) {
+ if (mutex != NULL && pthread__mutex_deferwake(self, mutex)) {
for (signaled = PTQ_FIRST(&cond->ptc_waiters);
signaled != NULL;
signaled = next) {
diff --git a/lib/libpthread/pthread_int.h b/lib/libpthread/pthread_int.h
index 5ff010de00a..e0c91df8564 100644
--- a/lib/libpthread/pthread_int.h
+++ b/lib/libpthread/pthread_int.h
@@ -1,4 +1,4 @@
-/* $NetBSD: pthread_int.h,v 1.54 2007/09/11 18:11:29 ad Exp $ */
+/* $NetBSD: pthread_int.h,v 1.55 2007/09/13 23:51:47 ad Exp $ */
/*-
* Copyright (c) 2001, 2002, 2003, 2006, 2007 The NetBSD Foundation, Inc.
@@ -256,7 +256,7 @@ void pthread__membar_full(void);
void pthread__membar_producer(void);
void pthread__membar_consumer(void);
-int pthread__mutex_owned(pthread_t, pthread_mutex_t *);
+int pthread__mutex_deferwake(pthread_t, pthread_mutex_t *);
int pthread__mutex_catchup(pthread_mutex_t *);
#ifndef pthread__smt_pause
diff --git a/lib/libpthread/pthread_mutex.c b/lib/libpthread/pthread_mutex.c
index 9b306169de9..bb746da1c02 100644
--- a/lib/libpthread/pthread_mutex.c
+++ b/lib/libpthread/pthread_mutex.c
@@ -1,4 +1,4 @@
-/* $NetBSD: pthread_mutex.c,v 1.35 2007/09/11 10:27:44 ad Exp $ */
+/* $NetBSD: pthread_mutex.c,v 1.36 2007/09/13 23:51:47 ad Exp $ */
/*-
* Copyright (c) 2001, 2003, 2006, 2007 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__RCSID("$NetBSD: pthread_mutex.c,v 1.35 2007/09/11 10:27:44 ad Exp $");
+__RCSID("$NetBSD: pthread_mutex.c,v 1.36 2007/09/13 23:51:47 ad Exp $");
#include <errno.h>
#include <limits.h>
@@ -469,7 +469,7 @@ pthread_once(pthread_once_t *once_control, void (*routine)(void))
}
int
-pthread__mutex_owned(pthread_t thread, pthread_mutex_t *mutex)
+pthread__mutex_deferwake(pthread_t thread, pthread_mutex_t *mutex)
{
return mutex->ptm_owner == thread;
diff --git a/lib/libpthread/pthread_mutex2.c b/lib/libpthread/pthread_mutex2.c
index eed06934648..2a0b6d2d91d 100644
--- a/lib/libpthread/pthread_mutex2.c
+++ b/lib/libpthread/pthread_mutex2.c
@@ -1,4 +1,4 @@
-/* $NetBSD: pthread_mutex2.c,v 1.6 2007/09/11 18:11:29 ad Exp $ */
+/* $NetBSD: pthread_mutex2.c,v 1.7 2007/09/13 23:51:47 ad Exp $ */
/*-
* Copyright (c) 2001, 2003, 2006, 2007 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__RCSID("$NetBSD: pthread_mutex2.c,v 1.6 2007/09/11 18:11:29 ad Exp $");
+__RCSID("$NetBSD: pthread_mutex2.c,v 1.7 2007/09/13 23:51:47 ad Exp $");
#include <errno.h>
#include <limits.h>
@@ -63,6 +63,8 @@ __RCSID("$NetBSD: pthread_mutex2.c,v 1.6 2007/09/11 18:11:29 ad Exp $");
#define MUTEX_RECURSIVE_BIT (0x02UL)
#define MUTEX_THREAD (-16L)
+#define MUTEX_DEFERRED(x) (*(char *)&(x)->ptm_lock)
+
#define MUTEX_HAS_WAITERS(x) ((uintptr_t)(x) & MUTEX_WAITERS_BIT)
#define MUTEX_RECURSIVE(x) ((uintptr_t)(x) & MUTEX_RECURSIVE_BIT)
#define MUTEX_OWNER(x) ((uintptr_t)(x) & MUTEX_THREAD)
@@ -128,6 +130,7 @@ pthread_mutex_init(pthread_mutex_t *ptm, const pthread_mutexattr_t *attr)
ptm->ptm_magic = _PT_MUTEX_MAGIC;
ptm->ptm_waiters = NULL;
ptm->ptm_private = NULL;
+ MUTEX_DEFERRED(ptm) = 0;
return 0;
}
@@ -332,9 +335,12 @@ pthread_mutex_unlock(pthread_mutex_t *ptm)
{
void *owner;
pthread_t self;
+ char deferred;
self = pthread__self();
owner = self;
+ deferred = MUTEX_DEFERRED(ptm);
+ MUTEX_DEFERRED(ptm) = 0;
if (__predict_false(!mutex_cas(&ptm->ptm_owner, &owner, NULL)))
return pthread__mutex_unlock_slow(ptm);
@@ -343,7 +349,7 @@ pthread_mutex_unlock(pthread_mutex_t *ptm)
* There were no waiters, but we may have deferred waking
* other threads until mutex unlock - we must wake them now.
*/
- if (self->pt_nwaiters != 0)
+ if (deferred)
return pthread__mutex_catchup(ptm);
return 0;
@@ -353,6 +359,7 @@ NOINLINE static int
pthread__mutex_unlock_slow(pthread_mutex_t *ptm)
{
pthread_t self, owner, new;
+ char deferred;
int weown;
pthread__error(EINVAL, "Invalid mutex",
@@ -386,19 +393,22 @@ pthread__mutex_unlock_slow(pthread_mutex_t *ptm)
* Release the mutex. If there appear to be waiters, then
* wake them up.
*/
- if (new != owner) {
- owner = pthread__atomic_swap_ptr(&ptm->ptm_owner, new);
- if (MUTEX_HAS_WAITERS(owner) != 0) {
- pthread__mutex_wakeup(self, ptm);
- return 0;
- }
+ if (new == owner)
+ return 0;
+
+ deferred = MUTEX_DEFERRED(ptm);
+ MUTEX_DEFERRED(ptm) = 0;
+ owner = pthread__atomic_swap_ptr(&ptm->ptm_owner, new);
+ if (MUTEX_HAS_WAITERS(owner) != 0) {
+ pthread__mutex_wakeup(self, ptm);
+ return 0;
}
/*
* There were no waiters, but we may have deferred waking
* other threads until mutex unlock - we must wake them now.
*/
- if (self->pt_nwaiters != 0)
+ if (deferred)
return pthread__mutex_catchup(ptm);
return 0;
@@ -543,10 +553,13 @@ pthread_once(pthread_once_t *once_control, void (*routine)(void))
}
int
-pthread__mutex_owned(pthread_t thread, pthread_mutex_t *ptm)
+pthread__mutex_deferwake(pthread_t thread, pthread_mutex_t *ptm)
{
- return MUTEX_OWNER(ptm->ptm_owner) == (uintptr_t)thread;
+ if (MUTEX_OWNER(ptm->ptm_owner) != (uintptr_t)thread)
+ return 0;
+ MUTEX_DEFERRED(ptm) = 1;
+ return 1;
}
#endif /* PTHREAD__HAVE_ATOMIC */