From d4efe6c5ad91f9a1f2f1d66b7fbfc87e320b2abc Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Fri, 28 Apr 2017 14:16:16 -0700
Subject: [PATCH] srcu: Shrink Tiny SRCU a bit

In Tiny SRCU, __srcu_read_lock() is a trivial function, outweighed by
its EXPORT_SYMBOL_GPL(), and on many architectures, its call sequence.
This commit therefore moves it to srcutiny.h so that it can be inlined.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/linux/srcutiny.h | 15 +++++++++++++++
 kernel/rcu/srcutiny.c    | 16 ----------------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index b8859179b001e..b6edd9c8fdce4 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -63,6 +63,21 @@ void srcu_drive_gp(struct work_struct *wp);
 
 void synchronize_srcu(struct srcu_struct *sp);
 
+/*
+ * Counts the new reader in the appropriate per-CPU element of the
+ * srcu_struct.  Can be invoked from irq/bh handlers, but the matching
+ * __srcu_read_unlock() must be in the same handler instance.  Returns an
+ * index that must be passed to the matching srcu_read_unlock().
+ */
+static inline int __srcu_read_lock(struct srcu_struct *sp)
+{
+	int idx;
+
+	idx = READ_ONCE(sp->srcu_idx);
+	WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1);
+	return idx;
+}
+
 static inline void synchronize_srcu_expedited(struct srcu_struct *sp)
 {
 	synchronize_srcu(sp);
diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
index 32798eb14853d..988543721d5d2 100644
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -95,22 +95,6 @@ void cleanup_srcu_struct(struct srcu_struct *sp)
 }
 EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
 
-/*
- * Counts the new reader in the appropriate per-CPU element of the
- * srcu_struct.  Can be invoked from irq/bh handlers, but the matching
- * __srcu_read_unlock() must be in the same handler instance.  Returns an
- * index that must be passed to the matching srcu_read_unlock().
- */
-int __srcu_read_lock(struct srcu_struct *sp)
-{
-	int idx;
-
-	idx = READ_ONCE(sp->srcu_idx);
-	WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1);
-	return idx;
-}
-EXPORT_SYMBOL_GPL(__srcu_read_lock);
-
 /*
  * Removes the count for the old reader from the appropriate element of
  * the srcu_struct.
-- 
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