Fixes for thread related render / compositing crashes:

* Viewer node could free image while it is being redrawn, viewer image
  buffers now need acquire/release to be accessed as was already the
  case for render results.
* The Composite node could free the image buffers outside of a lock,
  also causing simultaneous redraw to crash.
* Especially on Windows, re-rendering could crash when drawing an image
  that was freed. When RE_RenderInProgress was true it would access the
  image buffer and simply return it while it could still contain a pointer
  to a render result buffer that was already freed. I don't understand
  why this case was there in the first place, so I've removed it.

Possibly fixes bugs #20174, #21418, #21391, #21394.

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/threads.c b/source/blender/blenlib/intern/threads.c
index 02d6ab0b7b5..be016456fc4 100644
--- a/source/blender/blenlib/intern/threads.c
+++ b/source/blender/blenlib/intern/threads.c
@@ -109,6 +109,7 @@ A sample loop can look like this (pseudo c);
 static pthread_mutex_t _malloc_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t _image_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t _preview_lock = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t _viewer_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t _custom1_lock = PTHREAD_MUTEX_INITIALIZER;
 static int thread_levels= 0;	/* threads can be invoked inside threads */
 
@@ -327,6 +328,8 @@ void BLI_lock_thread(int type)
 		pthread_mutex_lock(&_image_lock);
 	else if (type==LOCK_PREVIEW)
 		pthread_mutex_lock(&_preview_lock);
+	else if (type==LOCK_VIEWER)
+		pthread_mutex_lock(&_viewer_lock);
 	else if (type==LOCK_CUSTOM1)
 		pthread_mutex_lock(&_custom1_lock);
 }
@@ -337,6 +340,8 @@ void BLI_unlock_thread(int type)
 		pthread_mutex_unlock(&_image_lock);
 	else if (type==LOCK_PREVIEW)
 		pthread_mutex_unlock(&_preview_lock);
+	else if (type==LOCK_VIEWER)
+		pthread_mutex_unlock(&_viewer_lock);
 	else if(type==LOCK_CUSTOM1)
 		pthread_mutex_unlock(&_custom1_lock);
 }