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/*
* 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>
/* Global control variables for rcupdate callback mechanism. */
struct rcu_ctrlblk {
long cur; /* Current batch number. */
long completed; /* Number of the last completed batch */
int next_pending; /* Is the next batch already waiting? */
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.
* nxtlist - new callbacks are added here
* curlist - current batch for which quiescent cycle started if any
*/
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 */
long batch; /* Batch # for current RCU batch */
struct rcu_head *nxtlist;
struct rcu_head **nxttail;
long qlen; /* # of queued callbacks */
struct rcu_head *curlist;
struct rcu_head **curtail;
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, _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()
extern void __rcu_init(void);
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 */
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