[PATCH tip/core/rcu 22/24] rcu: Remove !PREEMPT code from rcu_note_voluntary_context_switch()

From: Paul E. McKenney
Date: Wed Aug 29 2018 - 18:56:07 EST


Because RCU-tasks exists only in PREEMPT kernels and because RCU-sched
no longer exists in PREEMPT kernels, it is no longer necessary for the
rcu_note_voluntary_context_switch() macro to do anything for !PREEMPT
kernels. This commit therefore removes !PREEMPT-related code from
this macro, namely, the rcu_all_qs().

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/rcupdate.h | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index d6d543b60a9f..e4f821165d0b 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -150,18 +150,14 @@ static inline void rcu_init_nohz(void) { }
if (READ_ONCE((t)->rcu_tasks_holdout)) \
WRITE_ONCE((t)->rcu_tasks_holdout, false); \
} while (0)
-#define rcu_note_voluntary_context_switch(t) \
- do { \
- rcu_all_qs(); \
- rcu_tasks_qs(t); \
- } while (0)
+#define rcu_note_voluntary_context_switch(t) rcu_tasks_qs(t)
void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func);
void synchronize_rcu_tasks(void);
void exit_tasks_rcu_start(void);
void exit_tasks_rcu_finish(void);
#else /* #ifdef CONFIG_TASKS_RCU */
#define rcu_tasks_qs(t) do { } while (0)
-#define rcu_note_voluntary_context_switch(t) rcu_all_qs()
+#define rcu_note_voluntary_context_switch(t) do { } while (0)
#define call_rcu_tasks call_rcu
#define synchronize_rcu_tasks synchronize_rcu
static inline void exit_tasks_rcu_start(void) { }
--
2.17.1