rcu: Make RCU CPU stall warnings use ->gp_seq

This commit makes the RCU CPU stall-warning code in print_other_cpu_stall(),
print_cpu_stall(), and check_cpu_stall() use ->gp_seq instead of ->gpnum
and ->completed.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 2036dc7..f4a88e3 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1755,12 +1755,12 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
 	 */
 	touch_nmi_watchdog();
 
-	if (rsp->gpnum == rdp->gpnum) {
+	ticks_value = rcu_seq_ctr(rsp->gp_seq - rdp->gp_seq);
+	if (ticks_value) {
+		ticks_title = "GPs behind";
+	} else {
 		ticks_title = "ticks this GP";
 		ticks_value = rdp->ticks_this_gp;
-	} else {
-		ticks_title = "GPs behind";
-		ticks_value = rsp->gpnum - rdp->gpnum;
 	}
 	print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
 	delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);