Commit 756cbf6b authored Aug 15, 2013 by Paul E. McKenney

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. ]

parent 9261dd0d

kernel/rcutree_plugin.h

+4 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}