Changeset 256452 in webkit

Timestamp:

Feb 12, 2020 10:46:31 AM (4 years ago)

Author:

Simon Fraser

Message:

Pages that trigger a redirect will sometimes be left blank
​https://bugs.webkit.org/show_bug.cgi?id=207614
rdar://problem/59077740

Reviewed by Tim Horton.

TiledCoreAnimationDrawingArea::setRootCompositingGraphicsLayer() can be called when the layer tree
is frozen, in which case we stash away the layer in m_pendingRootLayer to be parented later at flush
time. However, this sequence of calls had a bug:

setRootCompositingGraphicsLayer() when frozen

-> stash in m_pendingRootLayer

setRootCompositingGraphicsLayer() when not frozen

-> set the root layer

flushLayers()

-> set the root layer to the (old) m_pendingRootLayer

So we need to clear m_pendingRootLayer at step 2.

Very timing dependent, hard to test.

• WebProcess/WebPage/mac/TiledCoreAnimationDrawingArea.mm:

(WebKit::TiledCoreAnimationDrawingArea::setRootCompositingLayer):

Location:

trunk/Source/WebKit

Files:

• ChangeLog (modified) (1 diff)
• WebProcess/WebPage/mac/TiledCoreAnimationDrawingArea.mm (modified) (1 diff)

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2020-02-12  Simon Fraser  <simon.fraser@apple.com>
+
+        Pages that trigger a redirect will sometimes be left blank
+        https://bugs.webkit.org/show_bug.cgi?id=207614
+        rdar://problem/59077740
+
+        Reviewed by Tim Horton.
+
+        TiledCoreAnimationDrawingArea::setRootCompositingGraphicsLayer() can be called when the layer tree
+        is frozen, in which case we stash away the layer in m_pendingRootLayer to be parented later at flush
+        time. However, this sequence of calls had a bug:
+
+        setRootCompositingGraphicsLayer() when frozen
+            -> stash in m_pendingRootLayer
+        setRootCompositingGraphicsLayer() when not frozen
+            -> set the root layer
+        flushLayers()
+            -> set the root layer to the (old) m_pendingRootLayer
+
+        So we need to clear m_pendingRootLayer at step 2.
+
+        Very timing dependent, hard to test.
+
+        * WebProcess/WebPage/mac/TiledCoreAnimationDrawingArea.mm:
+        (WebKit::TiledCoreAnimationDrawingArea::setRootCompositingLayer):
+
 2020-02-12  Per Arne Vollan  <pvollan@apple.com>
 

trunk/Source/WebKit/WebProcess/WebPage/mac/TiledCoreAnimationDrawingArea.mm

@@ -138 +138 @@
     }
 
+    m_pendingRootLayer = nullptr;
     setRootCompositingLayer(rootLayer);
 }