From 807226e2fbb504d82cd504b7b6114896db41ef63 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 7 Aug 2015 12:03:45 -0700 Subject: [PATCH 1/1] rcu: Stop excluding CPU hotplug in synchronize_sched_expedited() Now that synchronize_sched_expedited() uses IPIs, a hook in rcu_sched_qs(), and the ->expmask field in the rcu_node combining tree, it is no longer necessary to exclude CPU hotplug. Any races with CPU hotplug will be detected when attempting to send the IPI. This commit therefore removes the code excluding CPU hotplug operations. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 15b19baaade5..7e7df5deadf9 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3785,19 +3785,9 @@ void synchronize_sched_expedited(void) /* Take a snapshot of the sequence number. */ s = rcu_exp_gp_seq_snap(rsp); - if (!try_get_online_cpus()) { - /* CPU hotplug operation in flight, fall back to normal GP. */ - wait_rcu_gp(call_rcu_sched); - atomic_long_inc(&rsp->expedited_normal); - return; - } - WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id())); - rnp = exp_funnel_lock(rsp, s); - if (rnp == NULL) { - put_online_cpus(); + if (rnp == NULL) return; /* Someone else did our work for us. */ - } rcu_exp_gp_seq_start(rsp); sync_sched_exp_select_cpus(rsp); @@ -3805,8 +3795,6 @@ void synchronize_sched_expedited(void) rcu_exp_gp_seq_end(rsp); mutex_unlock(&rnp->exp_funnel_mutex); - - put_online_cpus(); } EXPORT_SYMBOL_GPL(synchronize_sched_expedited); -- 2.34.1