[PATCH tip/core/rcu 43/88] sched: Rely on synchronize_rcu_mult() de-duplication

From: Paul E. McKenney
Date: Thu May 25 2017 - 18:17:58 EST


The synchronize_rcu_mult() function now detects duplicate requests
for the same grace-period flavor and waits only once for each flavor.
This commit therefore removes the ugly #ifdef from sched_cpu_deactivate()
because synchronize_rcu_mult(call_rcu, call_rcu_sched) now does what
the #ifdef used to be needed for.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/sched/core.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 759f4bd52cd6..605564742de1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5849,15 +5849,9 @@ int sched_cpu_deactivate(unsigned int cpu)
* users of this state to go away such that all new such users will
* observe it.
*
- * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
- * not imply sync_sched(), so wait for both.
- *
* Do sync before park smpboot threads to take care the rcu boost case.
*/
- if (IS_ENABLED(CONFIG_PREEMPT))
- synchronize_rcu_mult(call_rcu, call_rcu_sched);
- else
- synchronize_rcu();
+ synchronize_rcu_mult(call_rcu, call_rcu_sched);

if (!sched_smp_initialized)
return 0;
--
2.5.2