[PATCH tip/core/rcu 02/22] rcu: Inline rcu_preempt_do_callback() into its sole caller

From: Paul E. McKenney
Date: Sun Apr 22 2018 - 22:31:30 EST

From: Byungchul Park <byungchul.park@xxxxxxx>

The rcu_preempt_do_callbacks() function was introduced in commit
09223371dea(rcu: Use softirq to address performance regression), where it
was necessary to handle kernel builds both containing and not containing
RCU-preempt. Since then, various changes (most notably f8b7fc6b51
("rcu: use softirq instead of kthreads except when RCU_BOOST=y")) have
resulted in this function being invoked only from rcu_kthread_do_work(),
which is present only in kernels containing RCU-preempt, which in turn
means that the rcu_preempt_do_callbacks() function is no longer needed.

This commit therefore inlines rcu_preempt_do_callbacks() into its
sole remaining caller and also removes the rcu_state_p and rcu_data_p
indirection for added clarity.

Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
[ paulmck: Remove the rcu_state_p and rcu_data_p indirection. ]
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
kernel/rcu/tree.h | 1 -
kernel/rcu/tree_plugin.h | 11 +----------
2 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index f491ab4f2e8e..3a0dc30100e8 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -438,7 +438,6 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
static void invoke_rcu_callbacks_kthread(void);
static bool rcu_is_callbacks_kthread(void);
-static void rcu_preempt_do_callbacks(void);
static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
struct rcu_node *rnp);
#endif /* #ifdef CONFIG_RCU_BOOST */
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 84fbee4686d3..6c5df18bbf2f 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -685,15 +685,6 @@ static void rcu_preempt_check_callbacks(void)
t->rcu_read_unlock_special.b.need_qs = true;

-static void rcu_preempt_do_callbacks(void)
- rcu_do_batch(rcu_state_p, this_cpu_ptr(rcu_data_p));
-#endif /* #ifdef CONFIG_RCU_BOOST */
* call_rcu() - Queue an RCU callback for invocation after a grace period.
* @head: structure to be used for queueing the RCU updates.
@@ -1140,7 +1131,7 @@ static void rcu_kthread_do_work(void)
rcu_do_batch(&rcu_sched_state, this_cpu_ptr(&rcu_sched_data));
rcu_do_batch(&rcu_bh_state, this_cpu_ptr(&rcu_bh_data));
- rcu_preempt_do_callbacks();
+ rcu_do_batch(&rcu_preempt_state, this_cpu_ptr(&rcu_preempt_data));

static void rcu_cpu_kthread_setup(unsigned int cpu)