rcu: Remove event tracing from rcu_cpu_notify(), used by offline CPUs

Offline CPUs cannot safely invoke trace events, but such CPUs do execute
within rcu_cpu_notify().  Therefore, this commit removes the trace events
from rcu_cpu_notify().  These trace events are for utilization, against
which rcu_cpu_notify() execution time should be negligible.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b42001fd55fbe0020d09590848f44ca2a3a94127..a7151d26b940cd8be156527aaf2146e891b5cd5c 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3629,7 +3629,6 @@ static int rcu_cpu_notify(struct notifier_block *self,
        struct rcu_node *rnp = rdp->mynode;
        struct rcu_state *rsp;
 
-       trace_rcu_utilization(TPS("Start CPU hotplug"));
        switch (action) {
        case CPU_UP_PREPARE:
        case CPU_UP_PREPARE_FROZEN:
@@ -3661,7 +3660,6 @@ static int rcu_cpu_notify(struct notifier_block *self,
        default:
                break;
        }
-       trace_rcu_utilization(TPS("End CPU hotplug"));
        return NOTIFY_OK;
 }