[deliverable/linux.git] / include / linux / rcuclassic.h

/*
 * Read-Copy Update mechanism for mutual exclusion (classic version)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright IBM Corporation, 2001
 *
 * Author: Dipankar Sarma <dipankar@in.ibm.com>
 *
 * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
 * Papers:
 * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
 * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
 *
 * For detailed explanation of Read-Copy Update mechanism see -
 * 		Documentation/RCU
 *
 */

#ifndef __LINUX_RCUCLASSIC_H
#define __LINUX_RCUCLASSIC_H

#include <linux/cache.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/seqlock.h>

#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
#define RCU_SECONDS_TILL_STALL_CHECK	( 3 * HZ) /* for rcp->jiffies_stall */
#define RCU_SECONDS_TILL_STALL_RECHECK	(30 * HZ) /* for rcp->jiffies_stall */
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */

/* Global control variables for rcupdate callback mechanism. */
struct rcu_ctrlblk {
	long	cur;		/* Current batch number.                      */
	long	completed;	/* Number of the last completed batch         */
	long	pending;	/* Number of the last pending batch           */
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
	unsigned long gp_start;	/* Time at which GP started in jiffies. */
	unsigned long jiffies_stall;
				/* Time at which to check for CPU stalls. */
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */

	int	signaled;

	spinlock_t	lock	____cacheline_internodealigned_in_smp;
	cpumask_t	cpumask; /* CPUs that need to switch in order    */
				 /* for current batch to proceed.        */
} ____cacheline_internodealigned_in_smp;

/* Is batch a before batch b ? */
static inline int rcu_batch_before(long a, long b)
{
	return (a - b) < 0;
}

/* Is batch a after batch b ? */
static inline int rcu_batch_after(long a, long b)
{
	return (a - b) > 0;
}

/* Per-CPU data for Read-Copy UPdate. */
struct rcu_data {
	/* 1) quiescent state handling : */
	long		quiescbatch;     /* Batch # for grace period */
	int		passed_quiesc;	 /* User-mode/idle loop etc. */
	int		qs_pending;	 /* core waits for quiesc state */

	/* 2) batch handling */
	/*
	 * if nxtlist is not NULL, then:
	 * batch:
	 *	The batch # for the last entry of nxtlist
	 * [*nxttail[1], NULL = *nxttail[2]):
	 *	Entries that batch # <= batch
	 * [*nxttail[0], *nxttail[1]):
	 *	Entries that batch # <= batch - 1
	 * [nxtlist, *nxttail[0]):
	 *	Entries that batch # <= batch - 2
	 *	The grace period for these entries has completed, and
	 *	the other grace-period-completed entries may be moved
	 *	here temporarily in rcu_process_callbacks().
	 */
	long  	       	batch;
	struct rcu_head *nxtlist;
	struct rcu_head **nxttail[3];
	long            qlen; 	 	 /* # of queued callbacks */
	struct rcu_head *donelist;
	struct rcu_head **donetail;
	long		blimit;		 /* Upper limit on a processed batch */
	int cpu;
	struct rcu_head barrier;
};

DECLARE_PER_CPU(struct rcu_data, rcu_data);
DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);

/*
 * Increment the quiescent state counter.
 * The counter is a bit degenerated: We do not need to know
 * how many quiescent states passed, just if there was at least
 * one since the start of the grace period. Thus just a flag.
 */
static inline void rcu_qsctr_inc(int cpu)
{
	struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
	rdp->passed_quiesc = 1;
}
static inline void rcu_bh_qsctr_inc(int cpu)
{
	struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
	rdp->passed_quiesc = 1;
}

extern int rcu_pending(int cpu);
extern int rcu_needs_cpu(int cpu);

#ifdef CONFIG_DEBUG_LOCK_ALLOC
extern struct lockdep_map rcu_lock_map;
# define rcu_read_acquire()	\
			lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
# define rcu_read_release()	lock_release(&rcu_lock_map, 1, _THIS_IP_)
#else
# define rcu_read_acquire()	do { } while (0)
# define rcu_read_release()	do { } while (0)
#endif

#define __rcu_read_lock() \
	do { \
		preempt_disable(); \
		__acquire(RCU); \
		rcu_read_acquire(); \
	} while (0)
#define __rcu_read_unlock() \
	do { \
		rcu_read_release(); \
		__release(RCU); \
		preempt_enable(); \
	} while (0)
#define __rcu_read_lock_bh() \
	do { \
		local_bh_disable(); \
		__acquire(RCU_BH); \
		rcu_read_acquire(); \
	} while (0)
#define __rcu_read_unlock_bh() \
	do { \
		rcu_read_release(); \
		__release(RCU_BH); \
		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);

extern long rcu_batches_completed(void);
extern long rcu_batches_completed_bh(void);

#define rcu_enter_nohz()	do { } while (0)
#define rcu_exit_nohz()		do { } while (0)

#endif /* __LINUX_RCUCLASSIC_H */
Commit	Line	Data
01c1c660 PM	1	/*
	2	* Read-Copy Update mechanism for mutual exclusion (classic version)
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2 of the License, or
	7	* (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, write to the Free Software
	16	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	17	*
	18	* Copyright IBM Corporation, 2001
	19	*
	20	* Author: Dipankar Sarma <dipankar@in.ibm.com>
	21	*
	22	* Based on the original work by Paul McKenney <paulmck@us.ibm.com>
	23	* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
	24	* Papers:
	25	* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
	26	* http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
	27	*
	28	* For detailed explanation of Read-Copy Update mechanism see -
	29	* Documentation/RCU
	30	*
	31	*/
	32
	33	#ifndef __LINUX_RCUCLASSIC_H
	34	#define __LINUX_RCUCLASSIC_H
	35
01c1c660 PM	36	#include <linux/cache.h>
	37	#include <linux/spinlock.h>
	38	#include <linux/threads.h>
	39	#include <linux/percpu.h>
	40	#include <linux/cpumask.h>
	41	#include <linux/seqlock.h>
	42
2133b5d7 PM	43	#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
	44	#define RCU_SECONDS_TILL_STALL_CHECK ( 3 * HZ) /* for rcp->jiffies_stall */
	45	#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rcp->jiffies_stall */
	46	#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
01c1c660 PM	47
	48	/* Global control variables for rcupdate callback mechanism. */
	49	struct rcu_ctrlblk {
	50	long cur; /* Current batch number. */
	51	long completed; /* Number of the last completed batch */
3cac97cb	52	long pending; /* Number of the last pending batch */
2133b5d7 PM	53	#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
	54	unsigned long gp_start; /* Time at which GP started in jiffies. */
	55	unsigned long jiffies_stall;
	56	/* Time at which to check for CPU stalls. */
	57	#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
01c1c660 PM	58
	59	int signaled;
	60
	61	spinlock_t lock ____cacheline_internodealigned_in_smp;
	62	cpumask_t cpumask; /* CPUs that need to switch in order */
	63	/* for current batch to proceed. */
	64	} ____cacheline_internodealigned_in_smp;
	65
	66	/* Is batch a before batch b ? */
	67	static inline int rcu_batch_before(long a, long b)
	68	{
	69	return (a - b) < 0;
	70	}
	71
	72	/* Is batch a after batch b ? */
	73	static inline int rcu_batch_after(long a, long b)
	74	{
	75	return (a - b) > 0;
	76	}
	77
5127bed5	78	/* Per-CPU data for Read-Copy UPdate. */
01c1c660 PM	79	struct rcu_data {
	80	/* 1) quiescent state handling : */
	81	long quiescbatch; /* Batch # for grace period */
	82	int passed_quiesc; /* User-mode/idle loop etc. */
	83	int qs_pending; /* core waits for quiesc state */
	84
	85	/* 2) batch handling */
5127bed5 LJ	86	/*
	87	* if nxtlist is not NULL, then:
	88	* batch:
	89	* The batch # for the last entry of nxtlist
	90	* [nxttail[1], NULL = nxttail[2]):
	91	* Entries that batch # <= batch
	92	* [nxttail[0], nxttail[1]):
	93	* Entries that batch # <= batch - 1
	94	* [nxtlist, *nxttail[0]):
	95	* Entries that batch # <= batch - 2
	96	* The grace period for these entries has completed, and
	97	* the other grace-period-completed entries may be moved
	98	* here temporarily in rcu_process_callbacks().
	99	*/
	100	long batch;
01c1c660	101	struct rcu_head *nxtlist;
5127bed5	102	struct rcu_head **nxttail[3];
01c1c660	103	long qlen; /* # of queued callbacks */
01c1c660 PM	104	struct rcu_head *donelist;
	105	struct rcu_head **donetail;
	106	long blimit; /* Upper limit on a processed batch */
	107	int cpu;
	108	struct rcu_head barrier;
	109	};
	110
	111	DECLARE_PER_CPU(struct rcu_data, rcu_data);
	112	DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
	113
	114	/*
	115	* Increment the quiescent state counter.
	116	* The counter is a bit degenerated: We do not need to know
	117	* how many quiescent states passed, just if there was at least
	118	* one since the start of the grace period. Thus just a flag.
	119	*/
	120	static inline void rcu_qsctr_inc(int cpu)
	121	{
	122	struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
	123	rdp->passed_quiesc = 1;
	124	}
	125	static inline void rcu_bh_qsctr_inc(int cpu)
	126	{
	127	struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
	128	rdp->passed_quiesc = 1;
	129	}
	130
	131	extern int rcu_pending(int cpu);
	132	extern int rcu_needs_cpu(int cpu);
	133
	134	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	135	extern struct lockdep_map rcu_lock_map;
	136	# define rcu_read_acquire() \
7531e2f3	137	lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
01c1c660 PM	138	# define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_)
	139	#else
	140	# define rcu_read_acquire() do { } while (0)
	141	# define rcu_read_release() do { } while (0)
	142	#endif
	143
	144	#define __rcu_read_lock() \
	145	do { \
	146	preempt_disable(); \
	147	__acquire(RCU); \
	148	rcu_read_acquire(); \
	149	} while (0)
	150	#define __rcu_read_unlock() \
	151	do { \
	152	rcu_read_release(); \
	153	__release(RCU); \
	154	preempt_enable(); \
	155	} while (0)
	156	#define __rcu_read_lock_bh() \
	157	do { \
	158	local_bh_disable(); \
	159	__acquire(RCU_BH); \
	160	rcu_read_acquire(); \
	161	} while (0)
	162	#define __rcu_read_unlock_bh() \
	163	do { \
	164	rcu_read_release(); \
	165	__release(RCU_BH); \
	166	local_bh_enable(); \
	167	} while (0)
	168
	169	#define __synchronize_sched() synchronize_rcu()
	170
4446a36f PM	171	#define call_rcu_sched(head, func) call_rcu(head, func)
4446a36f PM	172
01c1c660	173	extern void __rcu_init(void);
4446a36f	174	#define rcu_init_sched() do { } while (0)
01c1c660 PM	175	extern void rcu_check_callbacks(int cpu, int user);
	176	extern void rcu_restart_cpu(int cpu);
	177
e260be67 PM	178	extern long rcu_batches_completed(void);
	179	extern long rcu_batches_completed_bh(void);
	180
2232c2d8 SR	181	#define rcu_enter_nohz() do { } while (0)
	182	#define rcu_exit_nohz() do { } while (0)
	183
01c1c660	184	#endif /* __LINUX_RCUCLASSIC_H */