From 347126a2e2be1aeb6763dd6ae9ea38cb901eb942 Mon Sep 17 00:00:00 2001
From: David Xu <davidxu@FreeBSD.org>
Date: Tue, 12 Dec 2006 03:08:49 +0000
Subject: [PATCH] Move checking for c_has_waiters into low level
 _thr_ucond_signal and _thr_ucond_broadcast, clear condition variable pointer
 in cancellation info after returing from _thr_ucond_wait, since kernel has
 already dropped the internal lock, so we don't need to unlock it in
 cancellation handler again.

---
 lib/libthr/thread/thr_cond.c | 24 ++++++++----------------
 lib/libthr/thread/thr_umtx.c |  4 ++++
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/lib/libthr/thread/thr_cond.c b/lib/libthr/thread/thr_cond.c
index 3ea053475095..85eecaaf1ee5 100644
--- a/lib/libthr/thread/thr_cond.c
+++ b/lib/libthr/thread/thr_cond.c
@@ -124,13 +124,6 @@ _pthread_cond_destroy(pthread_cond_t *cond)
 	else {
 		cv = *cond;
 		THR_UMUTEX_LOCK(curthread, &cv->c_lock);
-#if 0
-		/* Lock the condition variable structure: */
-		if (cv->c_kerncv.c_has_waiters) {
-			THR_UMUTEX_UNLOCK(curthread, &cv->c_lock);
-			return (EBUSY);
-		}
-#endif
 		/*
 		 * NULL the caller's pointer now that the condition
 		 * variable has been destroyed:
@@ -143,7 +136,6 @@ _pthread_cond_destroy(pthread_cond_t *cond)
 		 * variable structure:
 		 */
 		free(cv);
-
 	}
 	/* Return the completion status: */
 	return (rval);
@@ -163,9 +155,10 @@ cond_cancel_handler(void *arg)
 	struct cond_cancel_info *info = (struct cond_cancel_info *)arg;
 	pthread_cond_t  cv;
 
-	cv = *(info->cond);
-	if ((cv->c_lock.m_owner & ~UMUTEX_CONTESTED) == TID(curthread))
+	if (info->cond != NULL) {
+		cv = *(info->cond);
 		THR_UMUTEX_UNLOCK(curthread, &cv->c_lock);
+	}
 	_mutex_cv_lock(info->mutex, info->count);
 }
 
@@ -209,6 +202,7 @@ cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
 		THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &info);
 		_thr_cancel_enter_defer(curthread);
 		ret = _thr_ucond_wait(&cv->c_kerncv, &cv->c_lock, tsp, 1);
+		info.cond = NULL;
 		_thr_cancel_leave_defer(curthread, ret);
 		THR_CLEANUP_POP(curthread, 0);
 	} else {
@@ -275,12 +269,10 @@ cond_signal_common(pthread_cond_t *cond, int broadcast)
 
 	cv = *cond;
 	THR_UMUTEX_LOCK(curthread, &cv->c_lock);
-	if (cv->c_kerncv.c_has_waiters) {
-		if (!broadcast)
-			ret = _thr_ucond_signal(&cv->c_kerncv);
-		else
-			ret = _thr_ucond_broadcast(&cv->c_kerncv);
-	}
+	if (!broadcast)
+		ret = _thr_ucond_signal(&cv->c_kerncv);
+	else
+		ret = _thr_ucond_broadcast(&cv->c_kerncv);
 	THR_UMUTEX_UNLOCK(curthread, &cv->c_lock);
 	return (ret);
 }
diff --git a/lib/libthr/thread/thr_umtx.c b/lib/libthr/thread/thr_umtx.c
index 8a8c908a91d5..9de346e216a1 100644
--- a/lib/libthr/thread/thr_umtx.c
+++ b/lib/libthr/thread/thr_umtx.c
@@ -131,6 +131,8 @@ _thr_ucond_wait(struct ucond *cv, struct umutex *m,
 int
 _thr_ucond_signal(struct ucond *cv)
 {
+	if (!cv->c_has_waiters)
+		return (0);
 	if (_umtx_op(cv, UMTX_OP_CV_SIGNAL, 0, NULL, NULL) == 0)
 		return (0);
 	return (errno);
@@ -139,6 +141,8 @@ _thr_ucond_signal(struct ucond *cv)
 int
 _thr_ucond_broadcast(struct ucond *cv)
 {
+	if (!cv->c_has_waiters)
+		return (0);
 	if (_umtx_op(cv, UMTX_OP_CV_BROADCAST, 0, NULL, NULL) == 0)
 		return (0);
 	return (errno);