rcu: Switch synchronize_sched_expedited() to IPI

This commit switches synchronize_sched_expedited() from stop_one_cpu_nowait()
to smp_call_function_single(), thus moving from an IPI and a pair of
context switches to an IPI and a single pass through the scheduler.
Of course, if the scheduler actually does decide to switch to a different
task, there will still be a pair of context switches, but there would
likely have been a pair of context switches anyway, just a bit later.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 0 insertions, 3 deletions

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 3eee48bcf52b..1b969cef8fe4 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -324,9 +324,6 @@ struct rcu_data {
                                         /*  ticks this CPU has handled */
                                         /*  during and after the last grace */
                                         /* period it is aware of. */
-        struct cpu_stop_work exp_stop_work;
-                                        /* Expedited grace-period control */
-                                        /*  for CPU stopping. */
 
         /* 2) batch handling */
         /*