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Commit 82e8c565 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Paul E. McKenney
Browse files

rcu_sync: Simplify rcu_sync using new rcu_sync_ops structure 



This commit adds the new struct rcu_sync_ops which holds sync/call
methods, and turns the function pointers in rcu_sync_struct into an array
of struct rcu_sync_ops.  This simplifies the "init" helpers by collapsing
a switch statement and explicit multiple definitions into a simple
assignment and a helper macro, respectively.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent cc44ca84

include/linux/rcu_sync.h

+23 −37
Original line number Diff line number Diff line
@@ -26,6 +26,8 @@ 
#include <linux/wait.h>

#include <linux/rcupdate.h>



enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };



/* Structure to mediate between updaters and fastpath-using readers.  */

struct rcu_sync {

	int			gp_state;
@@ -35,43 +37,9 @@ struct rcu_sync { 
	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 name = __RCU_SCHED_SYNC_INIT(name)



#define DEFINE_RCU_BH_SYNC(name)					\

	struct rcu_sync name = __RCU_BH_SYNC_INIT(name)



#define DEFINE_RCU_SYNC(name)						\

	struct rcu_sync name = __RCU_SYNC_INIT(name)



/**

 * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?

 * @rsp: Pointer to rcu_sync structure to use for synchronization
@@ -85,10 +53,28 @@ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) 
	return !rsp->gp_state; /* GP_IDLE */

}



enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };



extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);

extern void rcu_sync_enter(struct rcu_sync *);

extern void rcu_sync_exit(struct rcu_sync *);



#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_RCU_SYNC_H_ */

kernel/rcu/sync.c

+22 −20
Original line number Diff line number Diff line
@@ -23,6 +23,24 @@ 
#include <linux/rcu_sync.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 };
@@ -37,23 +55,7 @@ void rcu_sync_init(struct rcu_sync *rsp, enum rcu_sync_type type) 
{

	memset(rsp, 0, sizeof(*rsp));

	init_waitqueue_head(&rsp->gp_wait);



	switch (type) {

	case RCU_SYNC:

		rsp->sync = synchronize_rcu;

		rsp->call = call_rcu;

		break;



	case RCU_SCHED_SYNC:

		rsp->sync = synchronize_sched;

		rsp->call = call_rcu_sched;

		break;



	case RCU_BH_SYNC:

		rsp->sync = synchronize_rcu_bh;

		rsp->call = call_rcu_bh;

		break;

	}

	rsp->gp_type = type;

}



/**
@@ -85,7 +87,7 @@ void rcu_sync_enter(struct rcu_sync *rsp) 
	BUG_ON(need_wait && need_sync);



	if (need_sync) {

		rsp->sync();

		gp_ops[rsp->gp_type].sync();

		rsp->gp_state = GP_PASSED;

		wake_up_all(&rsp->gp_wait);

	} else if (need_wait) {
@@ -138,7 +140,7 @@ static void rcu_sync_func(struct rcu_head *rcu) 
		 * to catch a later GP.

		 */

		rsp->cb_state = CB_PENDING;

		rsp->call(&rsp->cb_head, rcu_sync_func);

		gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func);

	} else {

		/*

		 * We're at least a GP after rcu_sync_exit(); eveybody will now
@@ -166,7 +168,7 @@ void rcu_sync_exit(struct rcu_sync *rsp) 
	if (!--rsp->gp_count) {

		if (rsp->cb_state == CB_IDLE) {

			rsp->cb_state = CB_PENDING;

			rsp->call(&rsp->cb_head, rcu_sync_func);

			gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func);

		} else if (rsp->cb_state == CB_PENDING) {

			rsp->cb_state = CB_REPLAY;

		}