[LINUX] Kexec: Don't try to load an NULL image. This can occur when unloading.

Signed-off-by: Ian Campbell <ian.campbell@xensource.com>

linux-2.6-xen-sparse/kernel/kexec.c

@@ -1012,9 +1012,11 @@ asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
 			goto out;
 	}
 #ifdef CONFIG_XEN
-	result = xen_machine_kexec_load(image);
-	if (result)
-		goto out;
+	if (image) {
+		result = xen_machine_kexec_load(image);
+		if (result)
+			goto out;
+	}
 #endif
 	/* Install the new kernel, and  Uninstall the old */
 	image = xchg(dest_image, image);