linux-kernel - [PATCH tip/core/rcu 72/88] rcu: Move rnp->lock wrappers for SRCU use

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Message-Id: <1495749601-21574-72-git-send-email-paulmck@linux.vnet.ibm.com>
Date:   Thu, 25 May 2017 14:59:45 -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 72/88] rcu: Move rnp->lock wrappers for SRCU use

This commit moves the now-generic rnp->lock wrapper macros from
kernel/rcu/tree.h to kernel/rcu/rcu.h, thus allowing SRCU to use them.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/rcu.h  | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 kernel/rcu/tree.h | 53 -----------------------------------------------------
 2 files changed, 53 insertions(+), 53 deletions(-)

diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 6a1e85bd2eac..2a75beb883c8 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -303,6 +303,59 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
 	     cpu <= rnp->grphi; \
 	     cpu = cpumask_next((cpu), cpu_possible_mask))
 
+/*
+ * Wrappers for the rcu_node::lock acquire and release.
+ *
+ * Because the rcu_nodes form a tree, the tree traversal locking will observe
+ * different lock values, this in turn means that an UNLOCK of one level
+ * followed by a LOCK of another level does not imply a full memory barrier;
+ * and most importantly transitivity is lost.
+ *
+ * In order to restore full ordering between tree levels, augment the regular
+ * lock acquire functions with smp_mb__after_unlock_lock().
+ *
+ * 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.
+ */
+#define raw_spin_lock_rcu_node(p)					\
+do {									\
+	raw_spin_lock(&ACCESS_PRIVATE(p, lock));			\
+	smp_mb__after_unlock_lock();					\
+} while (0)
+
+#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, 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)
+
+#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 {									\
+	typecheck(unsigned long, flags);				\
+	raw_spin_lock_irqsave(&ACCESS_PRIVATE(rnp, lock), flags);	\
+	smp_mb__after_unlock_lock();					\
+} while (0)
+
+#define raw_spin_unlock_irqrestore_rcu_node(rnp, flags)			\
+do {									\
+	typecheck(unsigned long, flags);				\
+	raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(rnp, lock), flags);	\
+} while (0)
+
+#define raw_spin_trylock_rcu_node(p)					\
+({									\
+	bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock));	\
+									\
+	if (___locked)							\
+		smp_mb__after_unlock_lock();				\
+	___locked;							\
+})
+
 #endif /* #if defined(SRCU) || !defined(TINY_RCU) */
 
 #ifdef CONFIG_TINY_RCU
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index a7f63f1074b4..baa0bac8da2a 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -565,56 +565,3 @@ static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
 }
 #endif /* #ifdef CONFIG_RCU_TRACE */
-
-/*
- * Wrappers for the rcu_node::lock acquire and release.
- *
- * Because the rcu_nodes form a tree, the tree traversal locking will observe
- * different lock values, this in turn means that an UNLOCK of one level
- * followed by a LOCK of another level does not imply a full memory barrier;
- * and most importantly transitivity is lost.
- *
- * In order to restore full ordering between tree levels, augment the regular
- * lock acquire functions with smp_mb__after_unlock_lock().
- *
- * 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.
- */
-#define raw_spin_lock_rcu_node(p)					\
-do {									\
-	raw_spin_lock(&ACCESS_PRIVATE(p, lock));			\
-	smp_mb__after_unlock_lock();					\
-} while (0)
-
-#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, 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)
-
-#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 {									\
-	typecheck(unsigned long, flags);				\
-	raw_spin_lock_irqsave(&ACCESS_PRIVATE(rnp, lock), flags);	\
-	smp_mb__after_unlock_lock();					\
-} while (0)
-
-#define raw_spin_unlock_irqrestore_rcu_node(rnp, flags)			\
-do {									\
-	typecheck(unsigned long, flags);				\
-	raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(rnp, lock), flags);	\
-} while (0)
-
-#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