/* * 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() #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) #endif /* __LINUX_RCUCLASSIC_H */