Fix #32087: Crash while changing values in comp editor (bt and blender included)

Issue was caused by threading conflict between compositor output node which
is freeing buffers used by render result image and image draw code which
could use buffers at the same time as compositor frees this buffers.

Solved by adding adding  lock around viewer image invalidation and image
drawing.

Use renamed LOCK_PREVIEW mutex for this, which si not called LOCK_DRAW_IMAGE.
With new compositor locking for preview is not needed so it could be removed.

Added the same lock around viewer operation which also frees buffers used
by viewer image. It's actually quite difficult to check whether this is
indeed needed. This code seems to be using acquire/release technique, but
somehow acquiring ImBuf before invalidating it in compositor operation
doesn't resolve the issue, so probably it's not actually locking acquire
and things should be checked deeper.

7 files changed, 31 insertions, 17 deletions

diff --git a/source/blender/blenlib/BLI_threads.h b/source/blender/blenlib/BLI_threads.h
index 3b75797a3a9..902373bcd6b 100644
--- a/source/blender/blenlib/BLI_threads.h
+++ b/source/blender/blenlib/BLI_threads.h
@@ -70,7 +70,7 @@ int     BLI_system_thread_count(void); /* gets the number of threads the system
  * One custom lock available now. can be extended. */
 
 #define LOCK_IMAGE      0
-#define LOCK_PREVIEW    1
+#define LOCK_DRAW_IMAGE 1
 #define LOCK_VIEWER     2
 #define LOCK_CUSTOM1    3
 #define LOCK_RCACHE     4
diff --git a/source/blender/blenlib/intern/threads.c b/source/blender/blenlib/intern/threads.c
index 348fa29eae7..9994f89acd5 100644
--- a/source/blender/blenlib/intern/threads.c
+++ b/source/blender/blenlib/intern/threads.c
@@ -106,7 +106,7 @@ static void *thread_tls_data;
  ************************************************ */
 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 _image_draw_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t _viewer_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t _custom1_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t _rcache_lock = PTHREAD_MUTEX_INITIALIZER;
@@ -337,8 +337,8 @@ void BLI_lock_thread(int type)
 {
 	if (type == LOCK_IMAGE)
 		pthread_mutex_lock(&_image_lock);
-	else if (type == LOCK_PREVIEW)
-		pthread_mutex_lock(&_preview_lock);
+	else if (type == LOCK_DRAW_IMAGE)
+		pthread_mutex_lock(&_image_draw_lock);
 	else if (type == LOCK_VIEWER)
 		pthread_mutex_lock(&_viewer_lock);
 	else if (type == LOCK_CUSTOM1)
@@ -357,8 +357,8 @@ void BLI_unlock_thread(int type)
 {
 	if (type == LOCK_IMAGE)
 		pthread_mutex_unlock(&_image_lock);
-	else if (type == LOCK_PREVIEW)
-		pthread_mutex_unlock(&_preview_lock);
+	else if (type == LOCK_DRAW_IMAGE)
+		pthread_mutex_unlock(&_image_draw_lock);
 	else if (type == LOCK_VIEWER)
 		pthread_mutex_unlock(&_viewer_lock);
 	else if (type == LOCK_CUSTOM1)
diff --git a/source/blender/compositor/operations/COM_CompositorOperation.cpp b/source/blender/compositor/operations/COM_CompositorOperation.cpp
index 445b0634ced..43aad4f19d9 100644
--- a/source/blender/compositor/operations/COM_CompositorOperation.cpp
+++ b/source/blender/compositor/operations/COM_CompositorOperation.cpp
@@ -27,6 +27,7 @@
 #include "BKE_image.h"
 
 extern "C" {
+	#include "BLI_threads.h"
 	#include "RE_pipeline.h"
 	#include "RE_shader_ext.h"
 	#include "RE_render_ext.h"
@@ -63,6 +64,7 @@ void CompositorOperation::deinitExecution()
 		const RenderData *rd = this->m_rd;
 		Render *re = RE_GetRender_FromData(rd);
 		RenderResult *rr = RE_AcquireResultWrite(re);
+
 		if (rr) {
 			if (rr->rectf != NULL) {
 				MEM_freeN(rr->rectf);
@@ -75,7 +77,9 @@ void CompositorOperation::deinitExecution()
 			}
 		}
 
+		BLI_lock_thread(LOCK_DRAW_IMAGE);
 		BKE_image_signal(BKE_image_verify_viewer(IMA_TYPE_R_RESULT, "Render Result"), NULL, IMA_SIGNAL_FREE);
+		BLI_unlock_thread(LOCK_DRAW_IMAGE);
 
 		if (re) {
 			RE_ReleaseResult(re);
diff --git a/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp b/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp
index 446b169763c..2470b239987 100644
--- a/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp
+++ b/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp
@@ -62,6 +62,8 @@ void ViewerBaseOperation::initImage()
 	
 	if (!ibuf) return;
 	if (ibuf->x != (int)getWidth() || ibuf->y != (int)getHeight()) {
+		BLI_lock_thread(LOCK_DRAW_IMAGE);
+
 		imb_freerectImBuf(ibuf);
 		imb_freerectfloatImBuf(ibuf);
 		IMB_freezbuffloatImBuf(ibuf);
@@ -70,6 +72,8 @@ void ViewerBaseOperation::initImage()
 		imb_addrectImBuf(ibuf);
 		imb_addrectfloatImBuf(ibuf);
 		anImage->ok = IMA_OK_LOADED;
+
+		BLI_unlock_thread(LOCK_DRAW_IMAGE);
 	}
 	
 	/* now we combine the input with ibuf */
diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index ac71eb972f6..88eb280ea6b 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -728,11 +728,21 @@ void draw_image_main(SpaceImage *sima, ARegion *ar, Scene *scene)
 	/* retrieve the image and information about it */
 	ima = ED_space_image(sima);
 	ED_space_image_zoom(sima, ar, &zoomx, &zoomy);
-	ibuf = ED_space_image_acquire_buffer(sima, &lock);
 
 	show_viewer = (ima && ima->source == IMA_SRC_VIEWER);
 	show_render = (show_viewer && ima->type == IMA_TYPE_R_RESULT);
 
+	if (show_viewer) {
+		/* use locked draw for drawing viewer image buffer since the conpositor
+		 * is running in separated thread and compositor could free this buffers.
+		 * other images are not modifying in such a way so they does not require
+		 * lock (sergey)
+		 */
+		BLI_lock_thread(LOCK_DRAW_IMAGE);
+	}
+
+	ibuf = ED_space_image_acquire_buffer(sima, &lock);
+
 	/* draw the image or grid */
 	if (ibuf == NULL)
 		ED_region_grid_draw(ar, zoomx, zoomy);
@@ -770,5 +780,8 @@ void draw_image_main(SpaceImage *sima, ARegion *ar, Scene *scene)
 	/* render info */
 	if (ima && show_render)
 		draw_render_info(scene, ima, ar);
-}
 
+	if (show_viewer) {
+		BLI_unlock_thread(LOCK_DRAW_IMAGE);
+	}
+}
diff --git a/source/blender/editors/space_node/node_draw.c b/source/blender/editors/space_node/node_draw.c
index 17545ddc4de..adf52313307 100644
--- a/source/blender/editors/space_node/node_draw.c
+++ b/source/blender/editors/space_node/node_draw.c
@@ -335,9 +335,6 @@ static void node_update_basis(const bContext *C, bNodeTree *ntree, bNode *node)
 
 	/* preview rect? */
 	if (node->flag & NODE_PREVIEW) {
-		/* only recalculate size when there's a preview actually, otherwise we use stored result */
-		BLI_lock_thread(LOCK_PREVIEW);
-
 		if (node->preview && node->preview->rect) {
 			float aspect = 1.0f;
 			
@@ -374,8 +371,6 @@ static void node_update_basis(const bContext *C, bNodeTree *ntree, bNode *node)
 			node->prvr.ymin = dy - oldh;
 			dy = node->prvr.ymin - NODE_DYS / 2;
 		}
-
-		BLI_unlock_thread(LOCK_PREVIEW);
 	}
 
 	/* buttons rect? */
@@ -861,10 +856,8 @@ static void node_draw_basis(const bContext *C, ARegion *ar, SpaceNode *snode, bN
 	
 	/* preview */
 	if (node->flag & NODE_PREVIEW) {
-		BLI_lock_thread(LOCK_PREVIEW);
 		if (node->preview && node->preview->rect && !BLI_rctf_is_empty(&node->prvr))
 			node_draw_preview(node->preview, &node->prvr);
-		BLI_unlock_thread(LOCK_PREVIEW);
 	}
 	
 	UI_ThemeClearColor(color_id);
diff --git a/source/blender/nodes/composite/node_composite_util.c b/source/blender/nodes/composite/node_composite_util.c
index 98ded3ea3b3..1b9ff610e4c 100644
--- a/source/blender/nodes/composite/node_composite_util.c
+++ b/source/blender/nodes/composite/node_composite_util.c
@@ -647,7 +647,7 @@ void generate_preview(void *data, bNode *node, CompBuf *stackbuf)
 		if (stackbuf_use!=stackbuf)
 			free_compbuf(stackbuf_use);
 
-		BLI_lock_thread(LOCK_PREVIEW);
+		// BLI_lock_thread(LOCK_PREVIEW);
 
 		if (preview->rect)
 			MEM_freeN(preview->rect);
@@ -655,7 +655,7 @@ void generate_preview(void *data, bNode *node, CompBuf *stackbuf)
 		preview->ysize= ysize;
 		preview->rect= rect;
 
-		BLI_unlock_thread(LOCK_PREVIEW);
+		// BLI_unlock_thread(LOCK_PREVIEW);
 	}
 }