rcu: Distinguish between NOCB and non-NOCB rcu_callback trace events

One way to distinguish between NOCB and non-NOCB rcu_callback trace
events is that the former always print zero for the lazy and non-lazy
queue lengths.  Unfortunately, this also means that we cannot see the NOCB
queue lengths.  This commit therefore accesses the NOCB queue lengths,
but negates them.  NOCB rcu_callback trace events should therefore have
negative queue lengths.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Match operand size per kbuild test robot's advice. ]

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index f4ed24b..24b01b6 100644 (file)
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2147,10 +2147,12 @@ static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
        if (__is_kfree_rcu_offset((unsigned long)rhp->func))
                trace_rcu_kfree_callback(rdp->rsp->name, rhp,
                                         (unsigned long)rhp->func,
-                                        rdp->qlen_lazy, rdp->qlen);
+                                        -atomic_long_read(&rdp->nocb_q_count_lazy),
+                                        -atomic_long_read(&rdp->nocb_q_count));
        else
                trace_rcu_callback(rdp->rsp->name, rhp,
-                                  rdp->qlen_lazy, rdp->qlen);
+                                  -atomic_long_read(&rdp->nocb_q_count_lazy),
+                                  -atomic_long_read(&rdp->nocb_q_count));
        return 1;
 }