In case we already did initialize and prepare kernel access, no need to do it

again. Especially not because it'd likely fail because we are now most probably
in the kernel.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30711 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/bus_managers/usb/Transfer.cpp

@@ -126,6 +126,10 @@ Transfer::AdvanceByFragment(size_t actualLength)
 status_t
 Transfer::InitKernelAccess()
 {
+	// nothing to do if we are already prepared
+	if (fClonedArea >= B_OK)
+		return B_OK;
+
 	// we might need to access a buffer in userspace. this will not
 	// be possible in the kernel space finisher thread unless we
 	// get the proper area id for the space we need and then clone it