linux-kernel - [PATCH tip/core/rcu 71/88] rcu: Convert rnp->lock wrappers to macros for SRCU use

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Date:   Thu, 25 May 2017 14:59:44 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, bobby.prani@...il.com,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 71/88] rcu: Convert rnp->lock wrappers to macros for SRCU use

Use of smp_mb__after_unlock_lock() would allow SRCU to omit a full
memory barrier during callback execution, so this commit converts
raw_spin_lock_rcu_node() from inline functions to type-generic macros
to allow them to handle locks in srcu_node structures as well as
rcu_node structures.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/tree.h | 47 +++++++++++++++++++++--------------------------
 1 file changed, 21 insertions(+), 26 deletions(-)

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index ddfa34d020ba..a7f63f1074b4 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -580,27 +580,22 @@ static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
  * As ->lock of struct rcu_node is a __private field, therefore one should use
  * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
  */
-static inline void raw_spin_lock_rcu_node(struct rcu_node *rnp)
-{
-	raw_spin_lock(&ACCESS_PRIVATE(rnp, lock));
-	smp_mb__after_unlock_lock();
-}
+#define raw_spin_lock_rcu_node(p)					\
+do {									\
+	raw_spin_lock(&ACCESS_PRIVATE(p, lock));			\
+	smp_mb__after_unlock_lock();					\
+} while (0)
 
-static inline void raw_spin_unlock_rcu_node(struct rcu_node *rnp)
-{
-	raw_spin_unlock(&ACCESS_PRIVATE(rnp, lock));
-}
+#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock))
 
-static inline void raw_spin_lock_irq_rcu_node(struct rcu_node *rnp)
-{
-	raw_spin_lock_irq(&ACCESS_PRIVATE(rnp, lock));
-	smp_mb__after_unlock_lock();
-}
+#define raw_spin_lock_irq_rcu_node(p)					\
+do {									\
+	raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock));			\
+	smp_mb__after_unlock_lock();					\
+} while (0)
 
-static inline void raw_spin_unlock_irq_rcu_node(struct rcu_node *rnp)
-{
-	raw_spin_unlock_irq(&ACCESS_PRIVATE(rnp, lock));
-}
+#define raw_spin_unlock_irq_rcu_node(p)					\
+	raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock))
 
 #define raw_spin_lock_irqsave_rcu_node(rnp, flags)			\
 do {									\
@@ -615,11 +610,11 @@ do {									\
 	raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(rnp, lock), flags);	\
 } while (0)
 
-static inline bool raw_spin_trylock_rcu_node(struct rcu_node *rnp)
-{
-	bool locked = raw_spin_trylock(&ACCESS_PRIVATE(rnp, lock));
-
-	if (locked)
-		smp_mb__after_unlock_lock();
-	return locked;
-}
+#define raw_spin_trylock_rcu_node(p)					\
+({									\
+	bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock));	\
+									\
+	if (___locked)							\
+		smp_mb__after_unlock_lock();				\
+	___locked;							\
+})
-- 
2.5.2