d9f1bb6ad7
Before the scheduler starts, all tasks are non-preemptible by definition. So, during that time, rcu_read_lock_sched_held() needs to always return "true". This patch makes that be so. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267135607-7056-2-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
123 lines
3.1 KiB
C
123 lines
3.1 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion (tree-based version)
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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 IBM Corporation, 2008
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*
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* Author: Dipankar Sarma <dipankar@in.ibm.com>
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* Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical algorithm
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*
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* Based on the original work by Paul McKenney <paulmck@us.ibm.com>
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* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
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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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#ifndef __LINUX_RCUTREE_H
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#define __LINUX_RCUTREE_H
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struct notifier_block;
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extern void rcu_sched_qs(int cpu);
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extern void rcu_bh_qs(int cpu);
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extern int rcu_needs_cpu(int cpu);
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extern int rcu_expedited_torture_stats(char *page);
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#ifdef CONFIG_TREE_PREEMPT_RCU
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extern void __rcu_read_lock(void);
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extern void __rcu_read_unlock(void);
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extern void synchronize_rcu(void);
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extern void exit_rcu(void);
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/*
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* Defined as macro as it is a very low level header
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* included from areas that don't even know about current
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*/
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#define rcu_preempt_depth() (current->rcu_read_lock_nesting)
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#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
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static inline void __rcu_read_lock(void)
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{
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preempt_disable();
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}
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static inline void __rcu_read_unlock(void)
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{
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preempt_enable();
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}
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#define synchronize_rcu synchronize_sched
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static inline void exit_rcu(void)
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{
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}
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static inline int rcu_preempt_depth(void)
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{
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return 0;
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}
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#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
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static inline void __rcu_read_lock_bh(void)
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{
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local_bh_disable();
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}
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static inline void __rcu_read_unlock_bh(void)
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{
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local_bh_enable();
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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 *rcu));
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extern void synchronize_rcu_expedited(void);
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static inline void synchronize_rcu_bh_expedited(void)
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{
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synchronize_sched_expedited();
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}
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extern void rcu_check_callbacks(int cpu, int user);
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extern long rcu_batches_completed(void);
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extern long rcu_batches_completed_bh(void);
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extern long rcu_batches_completed_sched(void);
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extern void rcu_force_quiescent_state(void);
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extern void rcu_bh_force_quiescent_state(void);
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extern void rcu_sched_force_quiescent_state(void);
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#ifdef CONFIG_NO_HZ
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void rcu_enter_nohz(void);
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void rcu_exit_nohz(void);
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#else /* CONFIG_NO_HZ */
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static inline void rcu_enter_nohz(void)
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{
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}
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static inline void rcu_exit_nohz(void)
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{
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}
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#endif /* CONFIG_NO_HZ */
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/* A context switch is a grace period for RCU-sched and RCU-bh. */
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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;
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}
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#endif /* __LINUX_RCUTREE_H */
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