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 <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 15b19baaade5971fc54dd717e81c6f6f2e0e8ad2..7e7df5deadf91afc46760443e4aa871a5eb8a800 100644 (file)
--- 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);