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Subject[PATCH tip/core/rcu 08/28] rcu: Abstract common code for RCU grace-period-wait primitives
Date
Pull the code that waits for an RCU grace period into a single function,
which is then called by synchronize_rcu() and friends in the case of
TREE_RCU and TREE_PREEMPT_RCU, and from rcu_barrier() and friends in
the case of TINY_RCU and TINY_PREEMPT_RCU.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcupdate.h | 130 ++++++++++++++++++++++++++--------------------
include/linux/rcutiny.h | 16 +++++-
include/linux/rcutree.h | 2 +
kernel/rcupdate.c | 21 +++++++-
kernel/rcutiny.c | 28 ----------
kernel/rcutiny_plugin.h | 14 -----
kernel/rcutree.c | 22 +-------
kernel/rcutree_plugin.h | 11 +----
8 files changed, 113 insertions(+), 131 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index ad09eb8..9db50df 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -67,11 +67,73 @@ static inline void rcutorture_record_progress(unsigned long vernum)
#include <linux/types.h>

/* Exported common interfaces */
+
+#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.
+ * @func: actual callback function to be invoked after the grace period
+ *
+ * The callback function will be invoked some time after a full grace
+ * period elapses, in other words after all pre-existing RCU read-side
+ * critical sections have completed. However, the callback function
+ * might well execute concurrently with RCU read-side critical sections
+ * that started after call_rcu() was invoked. RCU read-side critical
+ * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
+ * and may be nested.
+ */
+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.
+ * @func: actual callback function to be invoked after the grace period
+ *
+ * The callback function will be invoked some time after a full grace
+ * period elapses, in other words after all currently executing RCU
+ * read-side critical sections have completed. call_rcu_bh() assumes
+ * that the read-side critical sections end on completion of a softirq
+ * handler. This means that read-side critical sections in process
+ * context must not be interrupted by softirqs. This interface is to be
+ * used when most of the read-side critical sections are in softirq context.
+ * RCU read-side critical sections are delimited by :
+ * - rcu_read_lock() and rcu_read_unlock(), if in interrupt context.
+ * OR
+ * - rcu_read_lock_bh() and rcu_read_unlock_bh(), if in process context.
+ * These may be nested.
+ */
+extern void call_rcu_bh(struct rcu_head *head,
+ void (*func)(struct rcu_head *head));
+
+/**
+ * call_rcu_sched() - Queue an RCU for invocation after sched grace period.
+ * @head: structure to be used for queueing the RCU updates.
+ * @func: actual callback function to be invoked after the grace period
+ *
+ * The callback function will be invoked some time after a full grace
+ * period elapses, in other words after all currently executing RCU
+ * read-side critical sections have completed. call_rcu_sched() assumes
+ * that the read-side critical sections end on enabling of preemption
+ * or on voluntary preemption.
+ * RCU read-side critical sections are delimited by :
+ * - rcu_read_lock_sched() and rcu_read_unlock_sched(),
+ * OR
+ * anything that disables preemption.
+ * These may be nested.
+ */
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);

static inline void __rcu_read_lock_bh(void)
{
@@ -144,6 +206,15 @@ static inline void rcu_exit_nohz(void)

#endif /* #else #ifdef CONFIG_NO_HZ */

+/*
+ * Infrastructure to implement the synchronize_() primitives in
+ * TREE_RCU and rcu_barrier_() primitives in TINY_RCU.
+ */
+
+typedef void call_rcu_func_t(struct rcu_head *head,
+ void (*func)(struct rcu_head *head));
+void wait_rcu_gp(call_rcu_func_t crf);
+
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
#include <linux/rcutree.h>
#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
@@ -724,61 +795,6 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
#define RCU_INIT_POINTER(p, v) \
p = (typeof(*v) __force __rcu *)(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);
-
-#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.
- * @func: actual callback function to be invoked after the grace period
- *
- * The callback function will be invoked some time after a full grace
- * period elapses, in other words after all pre-existing RCU read-side
- * critical sections have completed. However, the callback function
- * might well execute concurrently with RCU read-side critical sections
- * that started after call_rcu() was invoked. RCU read-side critical
- * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
- * and may be nested.
- */
-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.
- * @func: actual callback function to be invoked after the grace period
- *
- * The callback function will be invoked some time after a full grace
- * period elapses, in other words after all currently executing RCU
- * read-side critical sections have completed. call_rcu_bh() assumes
- * that the read-side critical sections end on completion of a softirq
- * handler. This means that read-side critical sections in process
- * context must not be interrupted by softirqs. This interface is to be
- * used when most of the read-side critical sections are in softirq context.
- * RCU read-side critical sections are delimited by :
- * - rcu_read_lock() and rcu_read_unlock(), if in interrupt context.
- * OR
- * - rcu_read_lock_bh() and rcu_read_unlock_bh(), if in process context.
- * These may be nested.
- */
-extern void call_rcu_bh(struct rcu_head *head,
- void (*func)(struct rcu_head *head));
-
/*
* debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
* by call_rcu() and rcu callback execution, and are therefore not part of the
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 52b3e02..4eab233 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -31,6 +31,16 @@ static inline void rcu_init(void)
{
}

+static inline void rcu_barrier_bh(void)
+{
+ wait_rcu_gp(call_rcu_bh);
+}
+
+static inline void rcu_barrier_sched(void)
+{
+ wait_rcu_gp(call_rcu_sched);
+}
+
#ifdef CONFIG_TINY_RCU

static inline void synchronize_rcu_expedited(void)
@@ -45,9 +55,13 @@ static inline void rcu_barrier(void)

#else /* #ifdef CONFIG_TINY_RCU */

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

+static inline void rcu_barrier(void)
+{
+ wait_rcu_gp(call_rcu);
+}
+
#endif /* #else #ifdef CONFIG_TINY_RCU */

static inline void synchronize_rcu_bh(void)
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index e65d066..6745846 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -67,6 +67,8 @@ static inline void synchronize_rcu_bh_expedited(void)
}

extern void rcu_barrier(void);
+extern void rcu_barrier_bh(void);
+extern void rcu_barrier_sched(void);

extern unsigned long rcutorture_testseq;
extern unsigned long rcutorture_vernum;
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 7784bd2..a088c90 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -94,11 +94,16 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);

#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

+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;

@@ -106,6 +111,20 @@ void wakeme_after_rcu(struct rcu_head *head)
complete(&rcu->completion);
}

+void wait_rcu_gp(call_rcu_func_t crf)
+{
+ struct rcu_synchronize rcu;
+
+ init_rcu_head_on_stack(&rcu.head);
+ init_completion(&rcu.completion);
+ /* Will wake me after RCU finished. */
+ crf(&rcu.head, wakeme_after_rcu);
+ /* Wait for it. */
+ wait_for_completion(&rcu.completion);
+ destroy_rcu_head_on_stack(&rcu.head);
+}
+EXPORT_SYMBOL_GPL(wait_rcu_gp);
+
#ifdef CONFIG_PROVE_RCU
/*
* wrapper function to avoid #include problems.
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index 421abfd..775d69a 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -280,34 +280,6 @@ void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
}
EXPORT_SYMBOL_GPL(call_rcu_bh);

-void rcu_barrier_bh(void)
-{
- struct rcu_synchronize rcu;
-
- init_rcu_head_on_stack(&rcu.head);
- init_completion(&rcu.completion);
- /* Will wake me after RCU finished. */
- call_rcu_bh(&rcu.head, wakeme_after_rcu);
- /* Wait for it. */
- wait_for_completion(&rcu.completion);
- destroy_rcu_head_on_stack(&rcu.head);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier_bh);
-
-void rcu_barrier_sched(void)
-{
- struct rcu_synchronize rcu;
-
- init_rcu_head_on_stack(&rcu.head);
- 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);
- destroy_rcu_head_on_stack(&rcu.head);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier_sched);
-
/*
* Spawn the kthread that invokes RCU callbacks.
*/
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index f259c67..6b0cedb 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -697,20 +697,6 @@ void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
}
EXPORT_SYMBOL_GPL(call_rcu);

-void rcu_barrier(void)
-{
- struct rcu_synchronize rcu;
-
- init_rcu_head_on_stack(&rcu.head);
- 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);
- destroy_rcu_head_on_stack(&rcu.head);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier);
-
/*
* synchronize_rcu - wait until a grace period has elapsed.
*
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index c67b9f4..305dfae 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1916,18 +1916,9 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
*/
void synchronize_sched(void)
{
- struct rcu_synchronize rcu;
-
if (rcu_blocking_is_gp())
return;
-
- init_rcu_head_on_stack(&rcu.head);
- 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);
- destroy_rcu_head_on_stack(&rcu.head);
+ wait_rcu_gp(call_rcu_sched);
}
EXPORT_SYMBOL_GPL(synchronize_sched);

@@ -1942,18 +1933,9 @@ EXPORT_SYMBOL_GPL(synchronize_sched);
*/
void synchronize_rcu_bh(void)
{
- struct rcu_synchronize rcu;
-
if (rcu_blocking_is_gp())
return;
-
- init_rcu_head_on_stack(&rcu.head);
- init_completion(&rcu.completion);
- /* Will wake me after RCU finished. */
- call_rcu_bh(&rcu.head, wakeme_after_rcu);
- /* Wait for it. */
- wait_for_completion(&rcu.completion);
- destroy_rcu_head_on_stack(&rcu.head);
+ wait_rcu_gp(call_rcu_bh);
}
EXPORT_SYMBOL_GPL(synchronize_rcu_bh);

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 40a6db7..37caa15 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -624,18 +624,9 @@ EXPORT_SYMBOL_GPL(call_rcu);
*/
void synchronize_rcu(void)
{
- struct rcu_synchronize rcu;
-
if (!rcu_scheduler_active)
return;
-
- init_rcu_head_on_stack(&rcu.head);
- 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);
- destroy_rcu_head_on_stack(&rcu.head);
+ wait_rcu_gp(call_rcu);
}
EXPORT_SYMBOL_GPL(synchronize_rcu);

--
1.7.3.2


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