128 lines
4.2 KiB
C
128 lines
4.2 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion (RT implementation)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2006
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*
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* Author: Paul McKenney <paulmck@us.ibm.com>
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*
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* Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com>
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* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
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* Papers:
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* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
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* http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
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*
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* For detailed explanation of Read-Copy Update mechanism see -
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* Documentation/RCU
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*
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*/
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#ifndef __LINUX_RCUPREEMPT_H
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#define __LINUX_RCUPREEMPT_H
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#include <linux/cache.h>
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#include <linux/spinlock.h>
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#include <linux/threads.h>
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#include <linux/smp.h>
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#include <linux/cpumask.h>
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#include <linux/seqlock.h>
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extern void rcu_qsctr_inc(int cpu);
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static inline void rcu_bh_qsctr_inc(int cpu) { }
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/*
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* Someone might want to pass call_rcu_bh as a function pointer.
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* So this needs to just be a rename and not a macro function.
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* (no parentheses)
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*/
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#define call_rcu_bh call_rcu
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/**
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* call_rcu_sched - Queue RCU callback for invocation after sched grace period.
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* @head: structure to be used for queueing the RCU updates.
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* @func: actual update function to be invoked after the grace period
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*
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* The update function will be invoked some time after a full
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* synchronize_sched()-style grace period elapses, in other words after
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* all currently executing preempt-disabled sections of code (including
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* hardirq handlers, NMI handlers, and local_irq_save() blocks) have
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* completed.
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*/
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extern void call_rcu_sched(struct rcu_head *head,
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void (*func)(struct rcu_head *head));
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extern void __rcu_read_lock(void) __acquires(RCU);
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extern void __rcu_read_unlock(void) __releases(RCU);
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extern int rcu_pending(int cpu);
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extern int rcu_needs_cpu(int cpu);
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#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); }
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#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); }
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extern void __synchronize_sched(void);
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extern void __rcu_init(void);
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extern void rcu_init_sched(void);
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extern void rcu_check_callbacks(int cpu, int user);
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extern void rcu_restart_cpu(int cpu);
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extern long rcu_batches_completed(void);
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/*
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* Return the number of RCU batches processed thus far. Useful for debug
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* and statistic. The _bh variant is identifcal to straight RCU
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*/
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static inline long rcu_batches_completed_bh(void)
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{
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return rcu_batches_completed();
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}
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#ifdef CONFIG_RCU_TRACE
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struct rcupreempt_trace;
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extern long *rcupreempt_flipctr(int cpu);
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extern long rcupreempt_data_completed(void);
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extern int rcupreempt_flip_flag(int cpu);
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extern int rcupreempt_mb_flag(int cpu);
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extern char *rcupreempt_try_flip_state_name(void);
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extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
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#endif
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struct softirq_action;
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#ifdef CONFIG_NO_HZ
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extern void rcu_enter_nohz(void);
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extern void rcu_exit_nohz(void);
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#else
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# define rcu_enter_nohz() do { } while (0)
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# define rcu_exit_nohz() do { } while (0)
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#endif
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/*
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* A context switch is a grace period for rcupreempt synchronize_rcu()
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* only during early boot, before the scheduler has been initialized.
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* So, how the heck do we get a context switch? Well, if the caller
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* invokes synchronize_rcu(), they are willing to accept a context
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* switch, so we simply pretend that one happened.
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*
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* After boot, there might be a blocked or preempted task in an RCU
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* read-side critical section, so we cannot then take the fastpath.
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*/
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static inline int rcu_blocking_is_gp(void)
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{
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return num_online_cpus() == 1 && !rcu_scheduler_active;
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}
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#endif /* __LINUX_RCUPREEMPT_H */
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