From cba712beebf32b27fea71241aa3cdd2ab0fc31a3 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 19 May 2021 02:09:29 +0200 Subject: [PATCH] rcu/nocb: Remove NOCB deferred wakeup from rcutree_dead_cpu() At CPU offline time, we must handle any pending wakeup for the nocb_gp kthread linked to the outgoing CPU. Now we are making sure of that twice: 1) From rcu_report_dead() when the outgoing CPU makes the very last local cleanups by itself before switching offline. 2) From rcutree_dead_cpu(). Here the offlining CPU has gone and is truly now offline. Another CPU takes care of post-portem cleaning up and check if the offline CPU had pending wakeup. Both ways are fine but we have to choose one or the other because we don't need to repeat that action. Simply benefit from cache locality and keep only the first solution. Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index b6eb480402e0..0fda98a0d12e 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2471,9 +2471,6 @@ int rcutree_dead_cpu(unsigned int cpu) WRITE_ONCE(rcu_state.n_online_cpus, rcu_state.n_online_cpus - 1); /* Adjust any no-longer-needed kthreads. */ rcu_boost_kthread_setaffinity(rnp, -1); - /* Do any needed no-CB deferred wakeups from this CPU. */ - do_nocb_deferred_wakeup(per_cpu_ptr(&rcu_data, cpu)); - // Stop-machine done, so allow nohz_full to disable tick. tick_dep_clear(TICK_DEP_BIT_RCU); return 0;