include/linux/rcupreempt.h

   1 /*
   2  * Read-Copy Update mechanism for mutual exclusion (RT implementation)
   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 (C) IBM Corporation, 2006
  19  *
  20  * Author:  Paul McKenney <paulmck@us.ibm.com>
  21  *
  22  * Based on the original work by Paul McKenney <paul.mckenney@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_RCUPREEMPT_H
  34 #define __LINUX_RCUPREEMPT_H
  35
  36 #ifdef __KERNEL__
  37
  38 #include <linux/cache.h>
  39 #include <linux/spinlock.h>
  40 #include <linux/threads.h>
  41 #include <linux/percpu.h>
  42 #include <linux/cpumask.h>
  43 #include <linux/seqlock.h>
  44
  45 #define rcu_qsctr_inc(cpu)
  46 #define rcu_bh_qsctr_inc(cpu)
  47 #define call_rcu_bh(head, rcu) call_rcu(head, rcu)
  48
  49 extern void __rcu_read_lock(void)       __acquires(RCU);
  50 extern void __rcu_read_unlock(void)     __releases(RCU);
  51 extern int rcu_pending(int cpu);
  52 extern int rcu_needs_cpu(int cpu);
  53
  54 #define __rcu_read_lock_bh()    { rcu_read_lock(); local_bh_disable(); }
  55 #define __rcu_read_unlock_bh()  { local_bh_enable(); rcu_read_unlock(); }
  56
  57 extern void __synchronize_sched(void);
  58
  59 extern void __rcu_init(void);
  60 extern void rcu_check_callbacks(int cpu, int user);
  61 extern void rcu_restart_cpu(int cpu);
  62 extern long rcu_batches_completed(void);
  63
  64 /*
  65  * Return the number of RCU batches processed thus far. Useful for debug
  66  * and statistic. The _bh variant is identifcal to straight RCU
  67  */
  68 static inline long rcu_batches_completed_bh(void)
  69 {
  70         return rcu_batches_completed();
  71 }
  72
  73 #ifdef CONFIG_RCU_TRACE
  74 struct rcupreempt_trace;
  75 extern long *rcupreempt_flipctr(int cpu);
  76 extern long rcupreempt_data_completed(void);
  77 extern int rcupreempt_flip_flag(int cpu);
  78 extern int rcupreempt_mb_flag(int cpu);
  79 extern char *rcupreempt_try_flip_state_name(void);
  80 extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
  81 #endif
  82
  83 struct softirq_action;
  84
  85 #ifdef CONFIG_NO_HZ
  86 DECLARE_PER_CPU(long, dynticks_progress_counter);
  87
  88 static inline void rcu_enter_nohz(void)
  89 {
  90         smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
  91         __get_cpu_var(dynticks_progress_counter)++;
  92         WARN_ON(__get_cpu_var(dynticks_progress_counter) & 0x1);
  93 }
  94
  95 static inline void rcu_exit_nohz(void)
  96 {
  97         __get_cpu_var(dynticks_progress_counter)++;
  98         smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
  99         WARN_ON(!(__get_cpu_var(dynticks_progress_counter) & 0x1));
 100 }
 101
 102 #else /* CONFIG_NO_HZ */
 103 #define rcu_enter_nohz()        do { } while (0)
 104 #define rcu_exit_nohz()         do { } while (0)
 105 #endif /* CONFIG_NO_HZ */
 106
 107 #endif /* __KERNEL__ */
 108 #endif /* __LINUX_RCUPREEMPT_H */