1 files changed, 17 insertions, 16 deletions

diff --git a/intern/cycles/util/util_task.cpp b/intern/cycles/util/util_task.cpp
index ea0abd6f54f..2b209c135f4 100644
--- a/intern/cycles/util/util_task.cpp
+++ b/intern/cycles/util/util_task.cpp
@@ -38,6 +38,8 @@ TaskPool::~TaskPool()
 
 void TaskPool::push(Task *task, bool front)
 {
+	thread_scoped_lock num_lock(num_mutex);
+
 	TaskScheduler::Entry entry;
 
 	entry.task = task;
@@ -102,22 +104,17 @@ void TaskPool::wait_work()
 
 void TaskPool::cancel()
 {
+	thread_scoped_lock num_lock(num_mutex);
+
 	do_cancel = true;
 
 	TaskScheduler::clear(this);
-	
-	{
-		thread_scoped_lock num_lock(num_mutex);
-
-		while(num)
-			num_cond.wait(num_lock);
-	}
-
-	do_cancel = false;
 }
 
 void TaskPool::stop()
 {
+	thread_scoped_lock num_lock(num_mutex);
+	
 	TaskScheduler::clear(this);
 
 	assert(num == 0);
@@ -130,20 +127,20 @@ bool TaskPool::cancelled()
 
 void TaskPool::num_decrease(int done)
 {
-	num_mutex.lock();
 	num -= done;
-
 	assert(num >= 0);
-	if(num == 0)
+	
+	if(num == 0) {
+		do_cancel = false;
+		
 		num_cond.notify_all();
-
-	num_mutex.unlock();
+	}
 }
 
 void TaskPool::num_increase()
 {
-	thread_scoped_lock num_lock(num_mutex);
 	num++;
+	
 	num_cond.notify_all();
 }
 
@@ -239,7 +236,11 @@ void TaskScheduler::thread_run(int thread_id)
 		delete entry.task;
 
 		/* notify pool task was done */
-		entry.pool->num_decrease(1);
+		{
+			/* not called from TaskPool, have to explicitly lock the mutex here */
+			thread_scoped_lock num_lock(entry.pool->num_mutex);
+			entry.pool->num_decrease(1);
+		}
 	}
 }