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rcu: Stop excluding CPU hotplug in synchronize_sched_expedited()

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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>
This commit is contained in:
Paul E. McKenney 2015-08-07 12:03:45 -07:00
parent 83c2c735e7
commit 807226e2fb
1 changed files with 1 additions and 13 deletions
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14
kernel/rcu/tree.c
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@ -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);