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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/cpumask.h>
#include <linux/seqlock.h>
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
#define RCU_SECONDS_TILL_STALL_CHECK (10 * 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;
DECLARE_BITMAP(cpumask, NR_CPUS); /* CPUs that need to switch 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;
};
/*
* 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.
*/
extern void rcu_qsctr_inc(int cpu);
extern void rcu_bh_qsctr_inc(int cpu);
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)
/* A context switch is a grace period for rcuclassic. */
static inline int rcu_blocking_is_gp(void)
{
return num_online_cpus() == 1;
}
#endif /* __LINUX_RCUCLASSIC_H */
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