Date:	Thu, 06 Nov 2008 14:47:44 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] rcupdate: move synchronize_sched() back to rcupdate.c V2


this fix remove ugly macro, and increase readability for rcupdate codes

changed from v1:
use HAVE_SPECIAL_RCU_BH/SCHED instead of define duplicate version of
synchronize_sched().

Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h
index 5f89b62..68e84ff 100644
--- a/include/linux/rcuclassic.h
+++ b/include/linux/rcuclassic.h
@@ -32,6 +32,7 @@
 
 #ifndef __LINUX_RCUCLASSIC_H
 #define __LINUX_RCUCLASSIC_H
+#define HAVE_SPECIAL_RCU_BH
 
 #include <linux/cache.h>
 #include <linux/spinlock.h>
@@ -166,12 +167,7 @@ extern struct lockdep_map rcu_lock_map;
 		local_bh_enable(); \
 	} while (0)
 
-#define __synchronize_sched() synchronize_rcu()
-
-#define call_rcu_sched(head, func) call_rcu(head, func)
-
 extern void __rcu_init(void);
-#define rcu_init_sched()	do { } while (0)
 extern void rcu_check_callbacks(int cpu, int user);
 extern void rcu_restart_cpu(int cpu);
 
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 86f1f5e..7861bee 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -112,6 +112,7 @@ struct rcu_head {
  */
 #define rcu_read_unlock() __rcu_read_unlock()
 
+#ifdef HAVE_SPECIAL_RCU_BH
 /**
  * rcu_read_lock_bh - mark the beginning of a softirq-only RCU critical section
  *
@@ -125,13 +126,19 @@ struct rcu_head {
  */
 #define rcu_read_lock_bh() __rcu_read_lock_bh()
 
-/*
+/**
  * rcu_read_unlock_bh - marks the end of a softirq-only RCU critical section
  *
  * See rcu_read_lock_bh() for more information.
  */
 #define rcu_read_unlock_bh() __rcu_read_unlock_bh()
 
+#else
+#define rcu_bh_qsctr_inc(cpu)
+#define rcu_read_lock_bh()	{ rcu_read_lock(); local_bh_disable(); }
+#define rcu_read_unlock_bh()	{ local_bh_enable(); rcu_read_unlock(); }
+#endif /* HAVE_SPECIAL_RCU_BH */
+
 /**
  * rcu_read_lock_sched - mark the beginning of a RCU-classic critical section
  *
@@ -189,45 +196,6 @@ struct rcu_head {
 		(p) = (v); \
 	})
 
-/* Infrastructure to implement the synchronize_() primitives. */
-
-struct rcu_synchronize {
-	struct rcu_head head;
-	struct completion completion;
-};
-
-extern void wakeme_after_rcu(struct rcu_head  *head);
-
-#define synchronize_rcu_xxx(name, func) \
-void name(void) \
-{ \
-	struct rcu_synchronize rcu; \
-	\
-	init_completion(&rcu.completion); \
-	/* Will wake me after RCU finished. */ \
-	func(&rcu.head, wakeme_after_rcu); \
-	/* Wait for it. */ \
-	wait_for_completion(&rcu.completion); \
-}
-
-/**
- * synchronize_sched - block until all CPUs have exited any non-preemptive
- * kernel code sequences.
- *
- * This means that all preempt_disable code sequences, including NMI and
- * hardware-interrupt handlers, in progress on entry will have completed
- * before this primitive returns.  However, this does not guarantee that
- * softirq handlers will have completed, since in some kernels, these
- * handlers can run in process context, and can block.
- *
- * This primitive provides the guarantees made by the (now removed)
- * synchronize_kernel() API.  In contrast, synchronize_rcu() only
- * guarantees that rcu_read_lock() sections will have completed.
- * In "classic RCU", these two guarantees happen to be one and
- * the same, but can differ in realtime RCU implementations.
- */
-#define synchronize_sched() __synchronize_sched()
-
 /**
  * call_rcu - Queue an RCU callback for invocation after a grace period.
  * @head: structure to be used for queueing the RCU updates.
@@ -242,6 +210,11 @@ void name(void) \
 extern void call_rcu(struct rcu_head *head,
 			      void (*func)(struct rcu_head *head));
 
+
+extern void synchronize_rcu(void);
+extern void rcu_barrier(void);
+
+#ifdef HAVE_SPECIAL_RCU_BH
 /**
  * call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
  * @head: structure to be used for queueing the RCU updates.
@@ -263,11 +236,46 @@ extern void call_rcu(struct rcu_head *head,
 extern void call_rcu_bh(struct rcu_head *head,
 			void (*func)(struct rcu_head *head));
 
-/* Exported common interfaces */
-extern void synchronize_rcu(void);
-extern void rcu_barrier(void);
 extern void rcu_barrier_bh(void);
+#else
+
+#define call_rcu_bh call_rcu
+#define rcu_barrier_bh rcu_barrier
+
+/*
+ * Return the number of RCU batches processed thus far. Useful for debug
+ * and statistic. The _bh variant is identifcal to straight RCU
+ */
+static inline long rcu_batches_completed_bh(void)
+{
+	return rcu_batches_completed();
+}
+#endif /* HAVE_SPECIAL_RCU_BH */
+
+#ifdef HAVE_SPECIAL_RCU_SCHED
+/**
+ * call_rcu_sched - Queue RCU callback for invocation after sched grace period.
+ * @head: structure to be used for queueing the RCU updates.
+ * @func: actual update function to be invoked after the grace period
+ *
+ * The update function will be invoked some time after a full
+ * synchronize_sched()-style grace period elapses, in other words after
+ * all currently executing preempt-disabled sections of code (including
+ * hardirq handlers, NMI handlers, and local_irq_save() blocks) have
+ * completed.
+ */
+extern void call_rcu_sched(struct rcu_head *head,
+			   void (*func)(struct rcu_head *head));
+
+extern void synchronize_sched(void);
 extern void rcu_barrier_sched(void);
+#else
+#define call_rcu_sched call_rcu
+#define synchronize_sched synchronize_rcu
+#define rcu_barrier_sched rcu_barrier
+
+#define rcu_init_sched()	do { } while (0)
+#endif /* HAVE_SPECIAL_RCU_SCHED */
 
 /* Internal to kernel */
 extern void rcu_init(void);
diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h
index 3e05c09..f30d1c8 100644
--- a/include/linux/rcupreempt.h
+++ b/include/linux/rcupreempt.h
@@ -32,6 +32,7 @@
 
 #ifndef __LINUX_RCUPREEMPT_H
 #define __LINUX_RCUPREEMPT_H
+#define HAVE_SPECIAL_RCU_SCHED
 
 #include <linux/cache.h>
 #include <linux/spinlock.h>
@@ -56,54 +57,18 @@ static inline void rcu_qsctr_inc(int cpu)
 
 	rdssp->sched_qs++;
 }
-#define rcu_bh_qsctr_inc(cpu)
-
-/*
- * Someone might want to pass call_rcu_bh as a function pointer.
- * So this needs to just be a rename and not a macro function.
- *  (no parentheses)
- */
-#define call_rcu_bh	 	call_rcu
-
-/**
- * call_rcu_sched - Queue RCU callback for invocation after sched grace period.
- * @head: structure to be used for queueing the RCU updates.
- * @func: actual update function to be invoked after the grace period
- *
- * The update function will be invoked some time after a full
- * synchronize_sched()-style grace period elapses, in other words after
- * all currently executing preempt-disabled sections of code (including
- * hardirq handlers, NMI handlers, and local_irq_save() blocks) have
- * completed.
- */
-extern void call_rcu_sched(struct rcu_head *head,
-			   void (*func)(struct rcu_head *head));
 
 extern void __rcu_read_lock(void)	__acquires(RCU);
 extern void __rcu_read_unlock(void)	__releases(RCU);
 extern int rcu_pending(int cpu);
 extern int rcu_needs_cpu(int cpu);
 
-#define __rcu_read_lock_bh()	{ rcu_read_lock(); local_bh_disable(); }
-#define __rcu_read_unlock_bh()	{ local_bh_enable(); rcu_read_unlock(); }
-
-extern void __synchronize_sched(void);
-
 extern void __rcu_init(void);
 extern void rcu_init_sched(void);
 extern void rcu_check_callbacks(int cpu, int user);
 extern void rcu_restart_cpu(int cpu);
 extern long rcu_batches_completed(void);
 
-/*
- * Return the number of RCU batches processed thus far. Useful for debug
- * and statistic. The _bh variant is identifcal to straight RCU
- */
-static inline long rcu_batches_completed_bh(void)
-{
-	return rcu_batches_completed();
-}
-
 #ifdef CONFIG_RCU_TRACE
 struct rcupreempt_trace;
 extern long *rcupreempt_flipctr(int cpu);
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index ad63af8..70cff32 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -56,11 +56,16 @@ static atomic_t rcu_barrier_cpu_count;
 static DEFINE_MUTEX(rcu_barrier_mutex);
 static struct completion rcu_barrier_completion;
 
+struct rcu_synchronize {
+	struct rcu_head head;
+	struct completion completion;
+};
+
 /*
  * Awaken the corresponding synchronize_rcu() instance now that a
  * grace period has elapsed.
  */
-void wakeme_after_rcu(struct rcu_head  *head)
+static void wakeme_after_rcu(struct rcu_head  *head)
 {
 	struct rcu_synchronize *rcu;
 
@@ -77,10 +82,48 @@ void wakeme_after_rcu(struct rcu_head  *head)
  * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
  * and may be nested.
  */
-void synchronize_rcu(void);	/* Makes kernel-doc tools happy */
-synchronize_rcu_xxx(synchronize_rcu, call_rcu)
+void synchronize_rcu(void)
+{
+	struct rcu_synchronize rcu;
+
+	init_completion(&rcu.completion);
+	/* Will wake me after RCU finished. */
+	call_rcu(&rcu.head, wakeme_after_rcu);
+	/* Wait for it. */
+	wait_for_completion(&rcu.completion);
+}
 EXPORT_SYMBOL_GPL(synchronize_rcu);
 
+#ifdef HAVE_SPECIAL_RCU_SCHED
+/**
+ * synchronize_sched - block until all CPUs have exited any non-preemptive
+ * kernel code sequences.
+ *
+ * This means that all preempt_disable code sequences, including NMI and
+ * hardware-interrupt handlers, in progress on entry will have completed
+ * before this primitive returns.  However, this does not guarantee that
+ * softirq handlers will have completed, since in some kernels, these
+ * handlers can run in process context, and can block.
+ *
+ * This primitive provides the guarantees made by the (now removed)
+ * synchronize_kernel() API.  In contrast, synchronize_rcu() only
+ * guarantees that rcu_read_lock() sections will have completed.
+ * In "classic RCU", these two guarantees happen to be one and
+ * the same, but can differ in realtime RCU implementations.
+ */
+void synchronize_sched(void)
+{
+	struct rcu_synchronize rcu;
+
+	init_completion(&rcu.completion);
+	/* Will wake me after RCU finished. */
+	call_rcu_sched(&rcu.head, wakeme_after_rcu);
+	/* Wait for it. */
+	wait_for_completion(&rcu.completion);
+}
+EXPORT_SYMBOL_GPL(synchronize_sched);
+#endif /* HAVE_SPECIAL_RCU_SCHED */
+
 static void rcu_barrier_callback(struct rcu_head *notused)
 {
 	if (atomic_dec_and_test(&rcu_barrier_cpu_count))
@@ -145,6 +188,7 @@ void rcu_barrier(void)
 }
 EXPORT_SYMBOL_GPL(rcu_barrier);
 
+#ifdef HAVE_SPECIAL_RCU_BH
 /**
  * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete.
  */
@@ -153,7 +197,9 @@ void rcu_barrier_bh(void)
 	_rcu_barrier(RCU_BARRIER_BH);
 }
 EXPORT_SYMBOL_GPL(rcu_barrier_bh);
+#endif /* HAVE_SPECIAL_RCU_BH */
 
+#ifdef HAVE_SPECIAL_RCU_SCHED
 /**
  * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks.
  */
@@ -162,6 +208,7 @@ void rcu_barrier_sched(void)
 	_rcu_barrier(RCU_BARRIER_SCHED);
 }
 EXPORT_SYMBOL_GPL(rcu_barrier_sched);
+#endif /* HAVE_SPECIAL_RCU_SCHED */
 
 void __init rcu_init(void)
 {
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index 59236e8..2068ad9 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -1161,15 +1161,6 @@ void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
 EXPORT_SYMBOL_GPL(call_rcu_sched);
 
 /*
- * Wait until all currently running preempt_disable() code segments
- * (including hardware-irq-disable segments) complete.  Note that
- * in -rt this does -not- necessarily result in all currently executing
- * interrupt -handlers- having completed.
- */
-synchronize_rcu_xxx(__synchronize_sched, call_rcu_sched)
-EXPORT_SYMBOL_GPL(__synchronize_sched);
-
-/*
  * kthread function that manages call_rcu_sched grace periods.
  */
 static int rcu_sched_grace_period(void *arg)


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