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Groups > linux.kernel > #1211281

[PATCH v2 2/8] rcusync: Introduce struct rcu_sync_ops

From Oleg Nesterov <oleg@redhat.com>
Newsgroups linux.kernel
Subject [PATCH v2 2/8] rcusync: Introduce struct rcu_sync_ops
Date 2015-08-21 19:50 +0200
Message-ID <pZYBY-2dA-25@gated-at.bofh.it> (permalink)
References <pZYBY-2dA-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Add the new struct rcu_sync_ops which holds sync/call methods, and
turn the function pointers in rcu_sync_struct into an array of struct
rcu_sync_ops.

This simplifies the "init" helpers, and this way it is simpler to add
the new methods we need, especially ifdef'ed.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/rcusync.h |   60 ++++++++++++++++++-----------------------------
 kernel/rcu/sync.c       |   43 +++++++++++++++++----------------
 2 files changed, 45 insertions(+), 58 deletions(-)

diff --git a/include/linux/rcusync.h b/include/linux/rcusync.h
index f13f95c..ff86315 100644
--- a/include/linux/rcusync.h
+++ b/include/linux/rcusync.h
@@ -4,6 +4,8 @@
 #include <linux/wait.h>
 #include <linux/rcupdate.h>
 
+enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
+
 struct rcu_sync_struct {
 	int			gp_state;
 	int			gp_count;
@@ -12,52 +14,36 @@ struct rcu_sync_struct {
 	int			cb_state;
 	struct rcu_head		cb_head;
 
-	void (*sync)(void);
-	void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
+	enum rcu_sync_type	gp_type;
 };
 
-#define ___RCU_SYNC_INIT(name)						\
-	.gp_state = 0,							\
-	.gp_count = 0,							\
-	.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait),		\
-	.cb_state = 0
-
-#define __RCU_SCHED_SYNC_INIT(name) {					\
-	___RCU_SYNC_INIT(name),						\
-	.sync = synchronize_sched,					\
-	.call = call_rcu_sched,						\
-}
-
-#define __RCU_BH_SYNC_INIT(name) {					\
-	___RCU_SYNC_INIT(name),						\
-	.sync = synchronize_rcu_bh,					\
-	.call = call_rcu_bh,						\
-}
-
-#define __RCU_SYNC_INIT(name) {						\
-	___RCU_SYNC_INIT(name),						\
-	.sync = synchronize_rcu,					\
-	.call = call_rcu,						\
-}
-
-#define DEFINE_RCU_SCHED_SYNC(name)					\
-	struct rcu_sync_struct name = __RCU_SCHED_SYNC_INIT(name)
-
-#define DEFINE_RCU_BH_SYNC(name)					\
-	struct rcu_sync_struct name = __RCU_BH_SYNC_INIT(name)
-
-#define DEFINE_RCU_SYNC(name)						\
-	struct rcu_sync_struct name = __RCU_SYNC_INIT(name)
-
 static inline bool rcu_sync_is_idle(struct rcu_sync_struct *rss)
 {
 	return !rss->gp_state; /* GP_IDLE */
 }
 
-enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
-
 extern void rcu_sync_init(struct rcu_sync_struct *, enum rcu_sync_type);
 extern void rcu_sync_enter(struct rcu_sync_struct *);
 extern void rcu_sync_exit(struct rcu_sync_struct *);
 
+#define __RCU_SYNC_INITIALIZER(name, type) {				\
+		.gp_state = 0,						\
+		.gp_count = 0,						\
+		.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait),	\
+		.cb_state = 0,						\
+		.gp_type = type,					\
+	}
+
+#define	__DEFINE_RCU_SYNC(name, type)	\
+	struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type)
+
+#define DEFINE_RCU_SYNC(name)		\
+	__DEFINE_RCU_SYNC(name, RCU_SYNC)
+
+#define DEFINE_RCU_SCHED_SYNC(name)	\
+	__DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC)
+
+#define DEFINE_RCU_BH_SYNC(name)	\
+	__DEFINE_RCU_SYNC(name, RCU_BH_SYNC)
+
 #endif /* _LINUX_RCUSYNC_H_ */
diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c
index f84176a..99051b7 100644
--- a/kernel/rcu/sync.c
+++ b/kernel/rcu/sync.c
@@ -1,7 +1,24 @@
-
 #include <linux/rcusync.h>
 #include <linux/sched.h>
 
+static const struct {
+	void (*sync)(void);
+	void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
+} gp_ops[] = {
+	[RCU_SYNC] = {
+		.sync = synchronize_rcu,
+		.call = call_rcu,
+	},
+	[RCU_SCHED_SYNC] = {
+		.sync = synchronize_sched,
+		.call = call_rcu_sched,
+	},
+	[RCU_BH_SYNC] = {
+		.sync = synchronize_rcu_bh,
+		.call = call_rcu_bh,
+	},
+};
+
 enum { GP_IDLE = 0, GP_PENDING, GP_PASSED };
 enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY };
 
@@ -11,23 +28,7 @@ void rcu_sync_init(struct rcu_sync_struct *rss, enum rcu_sync_type type)
 {
 	memset(rss, 0, sizeof(*rss));
 	init_waitqueue_head(&rss->gp_wait);
-
-	switch (type) {
-	case RCU_SYNC:
-		rss->sync = synchronize_rcu;
-		rss->call = call_rcu;
-		break;
-
-	case RCU_SCHED_SYNC:
-		rss->sync = synchronize_sched;
-		rss->call = call_rcu_sched;
-		break;
-
-	case RCU_BH_SYNC:
-		rss->sync = synchronize_rcu_bh;
-		rss->call = call_rcu_bh;
-		break;
-	}
+	rss->gp_type = type;
 }
 
 void rcu_sync_enter(struct rcu_sync_struct *rss)
@@ -44,7 +45,7 @@ void rcu_sync_enter(struct rcu_sync_struct *rss)
 	BUG_ON(need_wait && need_sync);
 
 	if (need_sync) {
-		rss->sync();
+		gp_ops[rss->gp_type].sync();
 		rss->gp_state = GP_PASSED;
 		wake_up_all(&rss->gp_wait);
 	} else if (need_wait) {
@@ -81,7 +82,7 @@ static void rcu_sync_func(struct rcu_head *rcu)
 		 * to catch a later GP.
 		 */
 		rss->cb_state = CB_PENDING;
-		rss->call(&rss->cb_head, rcu_sync_func);
+		gp_ops[rss->gp_type].call(&rss->cb_head, rcu_sync_func);
 	} else {
 		/*
 		 * We're at least a GP after rcu_sync_exit(); eveybody will now
@@ -99,7 +100,7 @@ void rcu_sync_exit(struct rcu_sync_struct *rss)
 	if (!--rss->gp_count) {
 		if (rss->cb_state == CB_IDLE) {
 			rss->cb_state = CB_PENDING;
-			rss->call(&rss->cb_head, rcu_sync_func);
+			gp_ops[rss->gp_type].call(&rss->cb_head, rcu_sync_func);
 		} else if (rss->cb_state == CB_PENDING) {
 			rss->cb_state = CB_REPLAY;
 		}
-- 
1.5.5.1

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Thread

[PATCH v2 0/8] Add rcu_sync infrastructure to avoid _expedited()  in percpu-rwsem Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 3/8] rcusync: Add the CONFIG_PROVE_RCU checks Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 6/8] percpu-rwsem: change it to rely on rss_sync  infrastructure Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 5/8] percpu-rwsem: make percpu_free_rwsem() after  kzalloc() safe Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 8/8] percpu-rwsem: cleanup the lockdep annotations in  percpu_down_read() Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 4/8] rcusync: Introduce rcu_sync_dtor() Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 7/8] percpu-rwsem: fix the comments outdated by rcu_sync Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 2/8] rcusync: Introduce struct rcu_sync_ops Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  [PATCH v2 1/8] rcu: Create rcu_sync infrastructure Oleg Nesterov <oleg@redhat.com> - 2015-08-21 19:50 +0200
  Re: [PATCH v2 0/8] Add rcu_sync infrastructure to avoid _expedited()  in percpu-rwsem "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-08-22 18:40 +0200
    Re: [PATCH v2 0/8] Add rcu_sync infrastructure to avoid  _expedited() in percpu-rwsem Oleg Nesterov <oleg@redhat.com> - 2015-08-24 17:40 +0200
      parse_args() is too unforgivable? Oleg Nesterov <oleg@redhat.com> - 2015-08-24 20:40 +0200
        Re: parse_args() is too unforgivable? Rusty Russell <rusty@rustcorp.com.au> - 2015-08-25 03:40 +0200
          [PATCH 0/1] params: don't ignore the rest of cmdline if  parse_one() fails Oleg Nesterov <oleg@redhat.com> - 2015-08-25 17:30 +0200
            [PATCH 1/1] params: don't ignore the rest of cmdline if  parse_one() fails Oleg Nesterov <oleg@redhat.com> - 2015-08-25 17:30 +0200
              Re: [PATCH 1/1] params: don't ignore the rest of cmdline if parse_one() fails Rusty Russell <rusty@rustcorp.com.au> - 2015-08-26 03:20 +0200
      Re: [PATCH v2 0/8] Add rcu_sync infrastructure to avoid  _expedited() in percpu-rwsem "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-08-26 02:30 +0200
        Re: [PATCH v2 0/8] Add rcu_sync infrastructure to avoid  _expedited() in percpu-rwsem Oleg Nesterov <oleg@redhat.com> - 2015-08-26 14:20 +0200
          Re: [PATCH v2 0/8] Add rcu_sync infrastructure to avoid  _expedited() in percpu-rwsem Oleg Nesterov <oleg@redhat.com> - 2015-08-26 15:00 +0200
            Re: [PATCH v2 0/8] Add rcu_sync infrastructure to avoid  _expedited() in percpu-rwsem "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-08-26 16:40 +0200

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