rcu: Distinguish "rcuo" kthreads by RCU flavor

Currently, the per-no-CBs-CPU kthreads are named "rcuo" followed by
the CPU number, for example, "rcuo".  This is problematic given that
there are either two or three RCU flavors, each of which gets a per-CPU
kthread with exactly the same name.  This commit therefore introduces
a one-letter abbreviation for each RCU flavor, namely 'b' for RCU-bh,
'p' for RCU-preempt, and 's' for RCU-sched.  This abbreviation is used
to distinguish the "rcuo" kthreads, for example, for CPU 0 we would have
"rcuob/0", "rcuop/0", and "rcuos/0".

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index e32236e83dda..c0164441ab92 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -111,7 +111,7 @@ static void __init rcu_bootup_announce_oddness(void)
 #ifdef CONFIG_TREE_PREEMPT_RCU
 
 struct rcu_state rcu_preempt_state =
-        RCU_STATE_INITIALIZER(rcu_preempt, call_rcu);
+        RCU_STATE_INITIALIZER(rcu_preempt, 'p', call_rcu);
 DEFINE_PER_CPU(struct rcu_data, rcu_preempt_data);
 static struct rcu_state *rcu_state = &rcu_preempt_state;
 
@@ -2517,7 +2517,8 @@ static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp)
                 return;
         for_each_cpu(cpu, rcu_nocb_mask) {
                 rdp = per_cpu_ptr(rsp->rda, cpu);
-                t = kthread_run(rcu_nocb_kthread, rdp, "rcuo%d", cpu);
+                t = kthread_run(rcu_nocb_kthread, rdp,
+                                "rcuo%c/%d", rsp->abbr, cpu);
                 BUG_ON(IS_ERR(t));
                 ACCESS_ONCE(rdp->nocb_kthread) = t;
         }