diff -r d45b74d3fb20 -r d57b86b1867a kernel/eka/drivers/usbcc/ps_usbc.cpp
--- a/kernel/eka/drivers/usbcc/ps_usbc.cpp	Tue Aug 31 11:40:45 2010 +0100
+++ b/kernel/eka/drivers/usbcc/ps_usbc.cpp	Mon Sep 13 15:16:07 2010 +0100
@@ -1078,9 +1078,11 @@
 			{
 	        OstTraceDef0(OST_TRACE_CATEGORY_RND, TRACE_NORMAL, DUSBCLIENTCONTROLLER_SETUPREADBUFFER_DUP11, "  iEp0_RxExtraData: trying again...");
 			const TBool rx_data = iEp0DataReceiving;
-		    const TInt irq = __SPIN_LOCK_IRQSAVE(iUsbLock);
+			
+			//Note:  Currently, ProcessEp0ReceiveDone() is only called in the thread context, 
+			//       but in the future, if this ProcessEp0ReceiveDone() is called in IRQ context, 
+			//       we have to notice that ProcessEp0ReceiveDone() has hold a fast mutex already.
 			err = ProcessEp0ReceiveDone(iEp0_RxExtraCount);
-	        __SPIN_UNLOCK_IRQRESTORE(iUsbLock, irq);
 			if (err == KErrNone)
 				{
 				iEp0_RxExtraData = EFalse;