rcu: Stop excluding CPU hotplug in synchronize_sched_expedited() (807226e2) · Commits · 戴 / test

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 <paulmck@linux.vnet.ibm.com>

kernel/rcu/tree.c

+1 −13

Original line number	Diff line number	Diff line
		@@ -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);

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