rcu: Separate accounting of callbacks from callback-free CPUs

Currently, callback invocations from callback-free CPUs are accounted to
the CPU that registered the callback, but using the same field that is
used for normal callbacks.  This makes it impossible to determine from
debugfs output whether callbacks are in fact being diverted.  This commit
therefore adds a separate ->n_nocbs_invoked field in the rcu_data structure
in which diverted callback invocations are counted.  RCU's debugfs tracing
still displays normal callback invocations using ci=, but displayed
diverted callbacks with nci=.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 3189f9aa3e8..0d095dcaa67 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -148,8 +148,9 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
 #endif /* #ifdef CONFIG_RCU_BOOST */
         seq_printf(m, " b=%ld", rdp->blimit);
-        seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
-                   rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
+        seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
+                   rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
+                   rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 }
 
 static int show_rcudata(struct seq_file *m, void *v)