[PATCH 8/8] rcu/sync: remove un-used rcu_sync_enter_start function

[Boqun Feng]

From: Onkarnath <onkarnath.1@xxxxxxxxxxx>

With commit '6a010a49b63a ("cgroup: Make !percpu threadgroup_rwsem
operations optional")' usage of rcu_sync_enter_start is removed.

So this function can also be removed.

In the words of Oleg Nesterov:

	__rcu_sync_enter(wait => false) is a better alternative if
	someone needs rcu_sync_enter_start() again.

Link: https://lore.kernel.org/all/20220725121208.GB28662@xxxxxxxxxx/
Signed-off-by: Onkarnath <onkarnath.1@xxxxxxxxxxx>
Signed-off-by: Maninder Singh <maninder1.s@xxxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 include/linux/rcu_sync.h |  1 -
 kernel/rcu/sync.c        | 16 ----------------
 2 files changed, 17 deletions(-)

diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
index 0027d4c8087c..3860dbb9107a 100644
--- a/include/linux/rcu_sync.h
+++ b/include/linux/rcu_sync.h
@@ -37,7 +37,6 @@ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
 }
 
 extern void rcu_sync_init(struct rcu_sync *);
-extern void rcu_sync_enter_start(struct rcu_sync *);
 extern void rcu_sync_enter(struct rcu_sync *);
 extern void rcu_sync_exit(struct rcu_sync *);
 extern void rcu_sync_dtor(struct rcu_sync *);
diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c
index e550f97779b8..86df878a2fee 100644
--- a/kernel/rcu/sync.c
+++ b/kernel/rcu/sync.c
@@ -24,22 +24,6 @@ void rcu_sync_init(struct rcu_sync *rsp)
 	init_waitqueue_head(&rsp->gp_wait);
 }
 
-/**
- * rcu_sync_enter_start - Force readers onto slow path for multiple updates
- * @rsp: Pointer to rcu_sync structure to use for synchronization
- *
- * Must be called after rcu_sync_init() and before first use.
- *
- * Ensures rcu_sync_is_idle() returns false and rcu_sync_{enter,exit}()
- * pairs turn into NO-OPs.
- */
-void rcu_sync_enter_start(struct rcu_sync *rsp)
-{
-	rsp->gp_count++;
-	rsp->gp_state = GP_PASSED;
-}
-
-
 static void rcu_sync_func(struct rcu_head *rhp);
 
 static void rcu_sync_call(struct rcu_sync *rsp)
-- 
2.43.0