x86, ds: fix bounds check in ds selftest

Fix a bad bounds check in the debug store selftest.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Cc: roland@redhat.com
Cc: eranian@googlemail.com
Cc: oleg@redhat.com
Cc: juan.villacis@intel.com
Cc: ak@linux.jf.intel.com
LKML-Reference: <20090403144558.450027000@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/ds_selftest.c

@@ -47,8 +47,13 @@ static int ds_selftest_bts_consistency(const struct bts_trace *trace)
 		printk(KERN_CONT "bad bts buffer setup...");
 		error = -1;
 	}
+	/*
+	 * We allow top in [begin; end], since its not clear when the
+	 * overflow adjustment happens: after the increment or before the
+	 * write.
+	 */
 	if ((trace->ds.top < trace->ds.begin) ||
-	    (trace->ds.end <= trace->ds.top)) {
+	    (trace->ds.end < trace->ds.top)) {
 		printk(KERN_CONT "bts top out of bounds...");
 		error = -1;
 	}