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Subject[PATCH tip/core/rcu 5/7] rcu: combine duplicate code, courtesy of CONFIG_PREEMPT_RCU
Date
The CONFIG_PREEMPT_RCU kernel configuration parameter was recently
re-introduced, but as an indication of the type of RCU (preemptible
vs. non-preemptible) instead of as selecting a given implementation.
This commit uses CONFIG_PREEMPT_RCU to combine duplicate code
from include/linux/rcutiny.h and include/linux/rcutree.h into
include/linux/rcupdate.h. This commit also combines a few other pieces
of duplicate code that have accumulated.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcupdate.h | 75 ++++++++++++++++++++++++++++++++++++++++++++--
include/linux/rcutiny.h | 51 -------------------------------
include/linux/rcutree.h | 50 ------------------------------
kernel/rcutree_plugin.h | 9 -----
4 files changed, 72 insertions(+), 113 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 325bad7..89414d6 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -61,16 +61,30 @@ struct rcu_head {
};

/* Exported common interfaces */
+extern void call_rcu_sched(struct rcu_head *head,
+ void (*func)(struct rcu_head *rcu));
+extern void synchronize_sched(void);
extern void rcu_barrier_bh(void);
extern void rcu_barrier_sched(void);
extern void synchronize_sched_expedited(void);
extern int sched_expedited_torture_stats(char *page);

-/* Internal to kernel */
-extern void rcu_init(void);
+static inline void __rcu_read_lock_bh(void)
+{
+ local_bh_disable();
+}
+
+static inline void __rcu_read_unlock_bh(void)
+{
+ local_bh_enable();
+}

#ifdef CONFIG_PREEMPT_RCU

+extern void __rcu_read_lock(void);
+extern void __rcu_read_unlock(void);
+void synchronize_rcu(void);
+
/*
* Defined as a macro as it is a very low level header included from
* areas that don't even know about current. This gives the rcu_read_lock()
@@ -79,7 +93,53 @@ extern void rcu_init(void);
*/
#define rcu_preempt_depth() (current->rcu_read_lock_nesting)

-#endif /* #ifdef CONFIG_PREEMPT_RCU */
+#else /* #ifdef CONFIG_PREEMPT_RCU */
+
+static inline void __rcu_read_lock(void)
+{
+ preempt_disable();
+}
+
+static inline void __rcu_read_unlock(void)
+{
+ preempt_enable();
+}
+
+static inline void synchronize_rcu(void)
+{
+ synchronize_sched();
+}
+
+static inline int rcu_preempt_depth(void)
+{
+ return 0;
+}
+
+#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
+
+/* Internal to kernel */
+extern void rcu_init(void);
+extern void rcu_sched_qs(int cpu);
+extern void rcu_bh_qs(int cpu);
+extern void rcu_check_callbacks(int cpu, int user);
+struct notifier_block;
+
+#ifdef CONFIG_NO_HZ
+
+extern void rcu_enter_nohz(void);
+extern void rcu_exit_nohz(void);
+
+#else /* #ifdef CONFIG_NO_HZ */
+
+static inline void rcu_enter_nohz(void)
+{
+}
+
+static inline void rcu_exit_nohz(void)
+{
+}
+
+#endif /* #else #ifdef CONFIG_NO_HZ */

#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
#include <linux/rcutree.h>
@@ -626,6 +686,8 @@ struct rcu_synchronize {

extern void wakeme_after_rcu(struct rcu_head *head);

+#ifdef CONFIG_PREEMPT_RCU
+
/**
* call_rcu() - Queue an RCU callback for invocation after a grace period.
* @head: structure to be used for queueing the RCU updates.
@@ -642,6 +704,13 @@ extern void wakeme_after_rcu(struct rcu_head *head);
extern void call_rcu(struct rcu_head *head,
void (*func)(struct rcu_head *head));

+#else /* #ifdef CONFIG_PREEMPT_RCU */
+
+/* In classic RCU, call_rcu() is just call_rcu_sched(). */
+#define call_rcu call_rcu_sched
+
+#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
+
/**
* call_rcu_bh() - Queue an RCU for invocation after a quicker grace period.
* @head: structure to be used for queueing the RCU updates.
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index c6b11dc..13877cb 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -27,34 +27,10 @@

#include <linux/cache.h>

-void rcu_sched_qs(int cpu);
-void rcu_bh_qs(int cpu);
-
-#ifdef CONFIG_TINY_RCU
-#define __rcu_read_lock() preempt_disable()
-#define __rcu_read_unlock() preempt_enable()
-#else /* #ifdef CONFIG_TINY_RCU */
-void __rcu_read_lock(void);
-void __rcu_read_unlock(void);
-#endif /* #else #ifdef CONFIG_TINY_RCU */
-#define __rcu_read_lock_bh() local_bh_disable()
-#define __rcu_read_unlock_bh() local_bh_enable()
-extern void call_rcu_sched(struct rcu_head *head,
- void (*func)(struct rcu_head *rcu));
-
#define rcu_init_sched() do { } while (0)

-extern void synchronize_sched(void);
-
#ifdef CONFIG_TINY_RCU

-#define call_rcu call_rcu_sched
-
-static inline void synchronize_rcu(void)
-{
- synchronize_sched();
-}
-
static inline void synchronize_rcu_expedited(void)
{
synchronize_sched(); /* Only one CPU, so pretty fast anyway!!! */
@@ -67,7 +43,6 @@ static inline void rcu_barrier(void)

#else /* #ifdef CONFIG_TINY_RCU */

-void synchronize_rcu(void);
void rcu_barrier(void);
void synchronize_rcu_expedited(void);

@@ -83,25 +58,6 @@ static inline void synchronize_rcu_bh_expedited(void)
synchronize_sched();
}

-struct notifier_block;
-
-#ifdef CONFIG_NO_HZ
-
-extern void rcu_enter_nohz(void);
-extern void rcu_exit_nohz(void);
-
-#else /* #ifdef CONFIG_NO_HZ */
-
-static inline void rcu_enter_nohz(void)
-{
-}
-
-static inline void rcu_exit_nohz(void)
-{
-}
-
-#endif /* #else #ifdef CONFIG_NO_HZ */
-
#ifdef CONFIG_TINY_RCU

static inline void rcu_preempt_note_context_switch(void)
@@ -117,11 +73,6 @@ static inline int rcu_needs_cpu(int cpu)
return 0;
}

-static inline int rcu_preempt_depth(void)
-{
- return 0;
-}
-
#else /* #ifdef CONFIG_TINY_RCU */

void rcu_preempt_note_context_switch(void);
@@ -141,8 +92,6 @@ static inline void rcu_note_context_switch(int cpu)
rcu_preempt_note_context_switch();
}

-extern void rcu_check_callbacks(int cpu, int user);
-
/*
* Return the number of grace periods.
*/
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 54a20c1..95518e6 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -30,59 +30,23 @@
#ifndef __LINUX_RCUTREE_H
#define __LINUX_RCUTREE_H

-struct notifier_block;
-
-extern void rcu_sched_qs(int cpu);
-extern void rcu_bh_qs(int cpu);
extern void rcu_note_context_switch(int cpu);
extern int rcu_needs_cpu(int cpu);
extern void rcu_cpu_stall_reset(void);

#ifdef CONFIG_TREE_PREEMPT_RCU

-extern void __rcu_read_lock(void);
-extern void __rcu_read_unlock(void);
-extern void synchronize_rcu(void);
extern void exit_rcu(void);

#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */

-static inline void __rcu_read_lock(void)
-{
- preempt_disable();
-}
-
-static inline void __rcu_read_unlock(void)
-{
- preempt_enable();
-}
-
-#define synchronize_rcu synchronize_sched
-
static inline void exit_rcu(void)
{
}

-static inline int rcu_preempt_depth(void)
-{
- return 0;
-}
-
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */

-static inline void __rcu_read_lock_bh(void)
-{
- local_bh_disable();
-}
-static inline void __rcu_read_unlock_bh(void)
-{
- local_bh_enable();
-}
-
-extern void call_rcu_sched(struct rcu_head *head,
- void (*func)(struct rcu_head *rcu));
extern void synchronize_rcu_bh(void);
-extern void synchronize_sched(void);
extern void synchronize_rcu_expedited(void);

static inline void synchronize_rcu_bh_expedited(void)
@@ -92,8 +56,6 @@ static inline void synchronize_rcu_bh_expedited(void)

extern void rcu_barrier(void);

-extern void rcu_check_callbacks(int cpu, int user);
-
extern long rcu_batches_completed(void);
extern long rcu_batches_completed_bh(void);
extern long rcu_batches_completed_sched(void);
@@ -101,18 +63,6 @@ extern void rcu_force_quiescent_state(void);
extern void rcu_bh_force_quiescent_state(void);
extern void rcu_sched_force_quiescent_state(void);

-#ifdef CONFIG_NO_HZ
-void rcu_enter_nohz(void);
-void rcu_exit_nohz(void);
-#else /* CONFIG_NO_HZ */
-static inline void rcu_enter_nohz(void)
-{
-}
-static inline void rcu_exit_nohz(void)
-{
-}
-#endif /* CONFIG_NO_HZ */
-
/* A context switch is a grace period for RCU-sched and RCU-bh. */
static inline int rcu_blocking_is_gp(void)
{
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 561410f..87f60f0 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -939,15 +939,6 @@ static void rcu_preempt_process_callbacks(void)
}

/*
- * In classic RCU, call_rcu() is just call_rcu_sched().
- */
-void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
-{
- call_rcu_sched(head, func);
-}
-EXPORT_SYMBOL_GPL(call_rcu);
-
-/*
* Wait for an rcu-preempt grace period, but make it happen quickly.
* But because preemptable RCU does not exist, map to rcu-sched.
*/
--
1.7.0.6


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