[PATCH RFC tip/core/rcu 1/5] rcu: Prepare for expedited GP driving normal GP

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

This is a pure code-movement commit in preparation for changes that
allow short-circuiting of normal grace-period processing due to
concurrent execution of an expedited grace period.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 108 +++++++++++++++++++++++++++---------------------------
 1 file changed, 54 insertions(+), 54 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 041968e3b7ce..bea9b9c80d91 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1393,6 +1393,60 @@ void rcu_cpu_stall_reset(void)
 		WRITE_ONCE(rsp->jiffies_stall, jiffies + ULONG_MAX / 2);
 }
 
+/* Adjust sequence number for start of update-side operation. */
+static void rcu_seq_start(unsigned long *sp)
+{
+	WRITE_ONCE(*sp, *sp + 1);
+	smp_mb(); /* Ensure update-side operation after counter increment. */
+	WARN_ON_ONCE(!(*sp & 0x1));
+}
+
+/* Adjust sequence number for end of update-side operation. */
+static void rcu_seq_end(unsigned long *sp)
+{
+	smp_mb(); /* Ensure update-side operation before counter increment. */
+	WRITE_ONCE(*sp, *sp + 1);
+	WARN_ON_ONCE(*sp & 0x1);
+}
+
+/* Take a snapshot of the update side's sequence number. */
+static unsigned long rcu_seq_snap(unsigned long *sp)
+{
+	unsigned long s;
+
+	smp_mb(); /* Caller's modifications seen first by other CPUs. */
+	s = (READ_ONCE(*sp) + 3) & ~0x1;
+	smp_mb(); /* Above access must not bleed into critical section. */
+	return s;
+}
+
+/*
+ * Given a snapshot from rcu_seq_snap(), determine whether or not a
+ * full update-side operation has occurred.
+ */
+static bool rcu_seq_done(unsigned long *sp, unsigned long s)
+{
+	return ULONG_CMP_GE(READ_ONCE(*sp), s);
+}
+
+/* Wrapper functions for expedited grace periods.  */
+static void rcu_exp_gp_seq_start(struct rcu_state *rsp)
+{
+	rcu_seq_start(&rsp->expedited_sequence);
+}
+static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
+{
+	rcu_seq_end(&rsp->expedited_sequence);
+}
+static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
+{
+	return rcu_seq_snap(&rsp->expedited_sequence);
+}
+static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
+{
+	return rcu_seq_done(&rsp->expedited_sequence, s);
+}
+
 /*
  * Initialize the specified rcu_data structure's default callback list
  * to empty.  The default callback list is the one that is not used by
@@ -3307,60 +3361,6 @@ void cond_synchronize_sched(unsigned long oldstate)
 }
 EXPORT_SYMBOL_GPL(cond_synchronize_sched);
 
-/* Adjust sequence number for start of update-side operation. */
-static void rcu_seq_start(unsigned long *sp)
-{
-	WRITE_ONCE(*sp, *sp + 1);
-	smp_mb(); /* Ensure update-side operation after counter increment. */
-	WARN_ON_ONCE(!(*sp & 0x1));
-}
-
-/* Adjust sequence number for end of update-side operation. */
-static void rcu_seq_end(unsigned long *sp)
-{
-	smp_mb(); /* Ensure update-side operation before counter increment. */
-	WRITE_ONCE(*sp, *sp + 1);
-	WARN_ON_ONCE(*sp & 0x1);
-}
-
-/* Take a snapshot of the update side's sequence number. */
-static unsigned long rcu_seq_snap(unsigned long *sp)
-{
-	unsigned long s;
-
-	smp_mb(); /* Caller's modifications seen first by other CPUs. */
-	s = (READ_ONCE(*sp) + 3) & ~0x1;
-	smp_mb(); /* Above access must not bleed into critical section. */
-	return s;
-}
-
-/*
- * Given a snapshot from rcu_seq_snap(), determine whether or not a
- * full update-side operation has occurred.
- */
-static bool rcu_seq_done(unsigned long *sp, unsigned long s)
-{
-	return ULONG_CMP_GE(READ_ONCE(*sp), s);
-}
-
-/* Wrapper functions for expedited grace periods.  */
-static void rcu_exp_gp_seq_start(struct rcu_state *rsp)
-{
-	rcu_seq_start(&rsp->expedited_sequence);
-}
-static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
-{
-	rcu_seq_end(&rsp->expedited_sequence);
-}
-static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
-{
-	return rcu_seq_snap(&rsp->expedited_sequence);
-}
-static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
-{
-	return rcu_seq_done(&rsp->expedited_sequence, s);
-}
-
 /* Common code for synchronize_{rcu,sched}_expedited() work-done checking. */
 static bool sync_exp_work_done(struct rcu_state *rsp, struct rcu_node *rnp,
 			       atomic_long_t *stat, unsigned long s)
-- 
1.8.1.5