Revision: 4839
http://tigervnc.svn.sourceforge.net/tigervnc/?rev=4839&view=rev
Author: ossman_
Date: 2012-01-23 15:54:11 +0000 (Mon, 23 Jan 2012)
Log Message:
-----------
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.
Modified Paths:
--------------
trunk/common/rfb/VNCServer.h
trunk/common/rfb/VNCServerST.cxx
trunk/common/rfb/VNCServerST.h
trunk/unix/xserver/hw/vnc/XserverDesktop.cc
trunk/unix/xserver/hw/vnc/XserverDesktop.h
trunk/unix/xserver/hw/vnc/vncHooks.cc
Modified: trunk/common/rfb/VNCServer.h
===================================================================
--- trunk/common/rfb/VNCServer.h 2012-01-23 15:43:42 UTC (rev 4838)
+++ trunk/common/rfb/VNCServer.h 2012-01-23 15:54:11 UTC (rev 4839)
@@ -30,6 +30,13 @@
class VNCServer : public UpdateTracker {
public:
+ // blockUpdates()/unblockUpdates() tells the server that the pixel buffer
+ // is currently in flux and may not be accessed. The attributes of the
+ // pixel buffer may still be accessed, but not the frame buffer itself.
+ // Note that access must be unblocked the exact same number of times it
+ // was blocked.
+ virtual void blockUpdates() = 0;
+ virtual void unblockUpdates() = 0;
// setPixelBuffer() tells the server to use the given pixel buffer (and
// optionally a modified screen layout). If this differs in size from
Modified: trunk/common/rfb/VNCServerST.cxx
===================================================================
--- trunk/common/rfb/VNCServerST.cxx 2012-01-23 15:43:42 UTC (rev 4838)
+++ trunk/common/rfb/VNCServerST.cxx 2012-01-23 15:54:11 UTC (rev 4839)
@@ -47,6 +47,7 @@
// otherwise blacklisted connections might be "forgotten".
+#include <assert.h>
#include <stdlib.h>
#include <rfb/ServerCore.h>
@@ -77,7 +78,8 @@
// -=- Constructors/Destructor
VNCServerST::VNCServerST(const char* name_, SDesktop* desktop_)
- : blHosts(&blacklist), desktop(desktop_), desktopStarted(false), pb(0),
+ : blHosts(&blacklist), desktop(desktop_), desktopStarted(false),
+ blockCounter(0), pb(0),
name(strDup(name_)), pointerClient(0), comparer(0),
renderedCursorInvalid(false),
queryConnectionHandler(0), keyRemapper(&KeyRemapper::defInstance),
@@ -259,6 +261,22 @@
// VNCServer methods
+void VNCServerST::blockUpdates()
+{
+ blockCounter++;
+}
+
+void VNCServerST::unblockUpdates()
+{
+ assert(blockCounter > 0);
+
+ blockCounter--;
+
+ // Flush out any updates we might have blocked
+ if (blockCounter == 0)
+ tryUpdate();
+}
+
void VNCServerST::setPixelBuffer(PixelBuffer* pb_, const ScreenSet& layout)
{
pb = pb_;
@@ -545,6 +563,9 @@
{
std::list<VNCSConnectionST*>::iterator ci, ci_next;
+ if (blockCounter > 0)
+ return;
+
if (!checkDefer())
return;
@@ -571,6 +592,10 @@
if (ui.is_empty() && !(renderCursor && renderedCursorInvalid))
return true;
+ // Block clients as the frame buffer cannot be safely accessed
+ if (blockCounter > 0)
+ return false;
+
// Block client from updating if we are currently deferring updates
if (!checkDefer())
return false;
Modified: trunk/common/rfb/VNCServerST.h
===================================================================
--- trunk/common/rfb/VNCServerST.h 2012-01-23 15:43:42 UTC (rev 4838)
+++ trunk/common/rfb/VNCServerST.h 2012-01-23 15:54:11 UTC (rev 4839)
@@ -82,6 +82,8 @@
// Methods overridden from VNCServer
+ virtual void blockUpdates();
+ virtual void unblockUpdates();
virtual void setPixelBuffer(PixelBuffer* pb, const ScreenSet& layout);
virtual void setPixelBuffer(PixelBuffer* pb);
virtual void setScreenLayout(const ScreenSet& layout);
@@ -209,6 +211,7 @@
SDesktop* desktop;
bool desktopStarted;
+ int blockCounter;
PixelBuffer* pb;
ScreenSet screenLayout;
Modified: trunk/unix/xserver/hw/vnc/XserverDesktop.cc
===================================================================
--- trunk/unix/xserver/hw/vnc/XserverDesktop.cc 2012-01-23 15:43:42 UTC (rev
4838)
+++ trunk/unix/xserver/hw/vnc/XserverDesktop.cc 2012-01-23 15:54:11 UTC (rev
4839)
@@ -188,6 +188,16 @@
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;
Modified: trunk/unix/xserver/hw/vnc/XserverDesktop.h
===================================================================
--- trunk/unix/xserver/hw/vnc/XserverDesktop.h 2012-01-23 15:43:42 UTC (rev
4838)
+++ trunk/unix/xserver/hw/vnc/XserverDesktop.h 2012-01-23 15:54:11 UTC (rev
4839)
@@ -61,6 +61,8 @@
// 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);
Modified: trunk/unix/xserver/hw/vnc/vncHooks.cc
===================================================================
--- trunk/unix/xserver/hw/vnc/vncHooks.cc 2012-01-23 15:43:42 UTC (rev
4838)
+++ trunk/unix/xserver/hw/vnc/vncHooks.cc 2012-01-23 15:54:11 UTC (rev
4839)
@@ -605,6 +605,11 @@
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 @@
vncFbptr[pScreen->myNum],
vncFbstride[pScreen->myNum]);
+ vncHooksScreen->desktop->unblockUpdates();
+
// Mark entire screen as changed
box.x1 = 0;
box.y1 = 0;
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