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 #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
  43 #define rcu_qsctr_inc(cpu)
  44 #define rcu_bh_qsctr_inc(cpu)
  45 #define call_rcu_bh(head, rcu) call_rcu(head, rcu)
  46
  47 extern void __rcu_read_lock(void)       __acquires(RCU);
  48 extern void __rcu_read_unlock(void)     __releases(RCU);
  49 extern int rcu_pending(int cpu);
  50 extern int rcu_needs_cpu(int cpu);
  51
  52 #define __rcu_read_lock_bh()    { rcu_read_lock(); local_bh_disable(); }
  53 #define __rcu_read_unlock_bh()  { local_bh_enable(); rcu_read_unlock(); }
  54
  55 extern void __synchronize_sched(void);
  56
  57 extern void __rcu_init(void);
  58 extern void rcu_check_callbacks(int cpu, int user);
  59 extern void rcu_restart_cpu(int cpu);
  60 extern long rcu_batches_completed(void);
  61
  62 /*
  63  * Return the number of RCU batches processed thus far. Useful for debug
  64  * and statistic. The _bh variant is identifcal to straight RCU
  65  */
  66 static inline long rcu_batches_completed_bh(void)
  67 {
  68         return rcu_batches_completed();
  69 }
  70
  71 #ifdef CONFIG_RCU_TRACE
  72 struct rcupreempt_trace;
  73 extern long *rcupreempt_flipctr(int cpu);
  74 extern long rcupreempt_data_completed(void);
  75 extern int rcupreempt_flip_flag(int cpu);
  76 extern int rcupreempt_mb_flag(int cpu);
  77 extern char *rcupreempt_try_flip_state_name(void);
  78 extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
  79 #endif
  80
  81 struct softirq_action;
  82
  83 #ifdef CONFIG_NO_HZ
  84 DECLARE_PER_CPU(long, dynticks_progress_counter);
  85
  86 static inline void rcu_enter_nohz(void)
  87 {
  88         smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
  89         __get_cpu_var(dynticks_progress_counter)++;
  90         WARN_ON(__get_cpu_var(dynticks_progress_counter) & 0x1);
  91 }
  92
  93 static inline void rcu_exit_nohz(void)
  94 {
  95         __get_cpu_var(dynticks_progress_counter)++;
  96         smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
  97         WARN_ON(!(__get_cpu_var(dynticks_progress_counter) & 0x1));
  98 }
  99
 100 #else /* CONFIG_NO_HZ */
 101 #define rcu_enter_nohz()        do { } while (0)
 102 #define rcu_exit_nohz()         do { } while (0)
 103 #endif /* CONFIG_NO_HZ */
 104
 105 #endif /* __LINUX_RCUPREEMPT_H */