Fix a race condition where we might get updates thrown at us right after a

framebuffer switch, but before we've been given the pointer to the new
framebuffer.


git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@4839 3789f03b-4d11-0410-bbf8-ca57d06f2519

3 files changed, 19 insertions, 0 deletions

diff --git a/unix/xserver/hw/vnc/XserverDesktop.cc b/unix/xserver/hw/vnc/XserverDesktop.cc
index 23dbee0c..5fc32c3a 100644
--- a/unix/xserver/hw/vnc/XserverDesktop.cc
+++ b/unix/xserver/hw/vnc/XserverDesktop.cc
@@ -188,6 +188,16 @@ void XserverDesktop::serverReset(ScreenPtr pScreen_)
   cmap = (ColormapPtr) retval;
 }
 
+void XserverDesktop::blockUpdates()
+{
+  server->blockUpdates();
+}
+
+void XserverDesktop::unblockUpdates()
+{
+  server->unblockUpdates();
+}
+
 void XserverDesktop::setFramebuffer(int w, int h, void* fbptr, int stride)
 {
   width_ = w;
diff --git a/unix/xserver/hw/vnc/XserverDesktop.h b/unix/xserver/hw/vnc/XserverDesktop.h
index 39045835..0aba4ef6 100644
--- a/unix/xserver/hw/vnc/XserverDesktop.h
+++ b/unix/xserver/hw/vnc/XserverDesktop.h
@@ -61,6 +61,8 @@ public:
 
   // methods called from X server code
   void serverReset(ScreenPtr pScreen);
+  void blockUpdates();
+  void unblockUpdates();
   void setFramebuffer(int w, int h, void* fbptr, int stride);
   void setColormap(ColormapPtr cmap);
   void setColourMapEntries(ColormapPtr pColormap, int ndef, xColorItem* pdef);
diff --git a/unix/xserver/hw/vnc/vncHooks.cc b/unix/xserver/hw/vnc/vncHooks.cc
index 611ebcf5..b03b6aa0 100644
--- a/unix/xserver/hw/vnc/vncHooks.cc
+++ b/unix/xserver/hw/vnc/vncHooks.cc
@@ -605,6 +605,11 @@ static Bool vncHooksRandRSetConfig(ScreenPtr pScreen, Rotation rotation,
   RegionRec reg;
   BoxRec box;
 
+  // We need to prevent the RFB core from accessing the framebuffer
+  // for a while as there might be updates thrown our way inside
+  // rrSetConfig (i.e. before we have a pointer to the new framebuffer).
+  vncHooksScreen->desktop->blockUpdates();
+
   rp->rrSetConfig = vncHooksScreen->RandRSetConfig;
   ret = (*rp->rrSetConfig)(pScreen, rotation, rate, pSize);
   rp->rrSetConfig = vncHooksRandRSetConfig;
@@ -617,6 +622,8 @@ static Bool vncHooksRandRSetConfig(ScreenPtr pScreen, Rotation rotation,
                                           vncFbptr[pScreen->myNum],
                                           vncFbstride[pScreen->myNum]);
 
+  vncHooksScreen->desktop->unblockUpdates();
+
   // Mark entire screen as changed
   box.x1 = 0;
   box.y1 = 0;