/* * Read-Copy Update mechanism for mutual exclusion * * 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 * * Authors: Dipankar Sarma <dipankar@in.ibm.com> *	    Manfred Spraul <manfred@colorfullife.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 - *		http://lse.sourceforge.net/locking/rcupdate.html * */#include <linux/types.h>#include <linux/kernel.h>#include <linux/init.h>#include <linux/spinlock.h>#include <linux/smp.h>#include <linux/interrupt.h>#include <linux/sched.h>#include <asm/atomic.h>#include <linux/bitops.h>#include <linux/percpu.h>#include <linux/notifier.h>#include <linux/cpu.h>#include <linux/mutex.h>#include <linux/module.h>#include <linux/kernel_stat.h>#include <linux/hardirq.h> #ifdef CONFIG_DEBUG_LOCK_ALLOCstatic struct lock_class_key rcu_lock_key;struct lockdep_map rcu_lock_map =	STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);EXPORT_SYMBOL_GPL(rcu_lock_map); static struct lock_class_key rcu_bh_lock_key;struct lockdep_map rcu_bh_lock_map =	STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);EXPORT_SYMBOL_GPL(rcu_bh_lock_map); static struct lock_class_key rcu_sched_lock_key;struct lockdep_map rcu_sched_lock_map =	STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);EXPORT_SYMBOL_GPL(rcu_sched_lock_map);#endif int rcu_scheduler_active __read_mostly;EXPORT_SYMBOL_GPL(rcu_scheduler_active); #ifdef CONFIG_DEBUG_LOCK_ALLOC int debug_lockdep_rcu_enabled(void){	return rcu_scheduler_active && debug_locks &&	       current->lockdep_recursion == 0;}EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); /** * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section? * * Check for bottom half being disabled, which covers both the * CONFIG_PROVE_RCU and not cases.  Note that if someone uses * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled) * will show the situation. * * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. */int rcu_read_lock_bh_held(void){	if (!debug_lockdep_rcu_enabled())		return 1;	return in_softirq();}EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ /* * This function is invoked towards the end of the scheduler's initialization * process.  Before this is called, the idle task might contain * RCU read-side critical sections (during which time, this idle * task is booting the system).  After this function is called, the * idle tasks are prohibited from containing RCU read-side critical * sections. */void rcu_scheduler_starting(void){	WARN_ON(num_online_cpus() != 1);	WARN_ON(nr_context_switches() > 0);	rcu_scheduler_active = 1;} /* * Awaken the corresponding synchronize_rcu() instance now that a * grace period has elapsed. */void wakeme_after_rcu(struct rcu_head  *head){	struct rcu_synchronize *rcu; 	rcu = container_of(head, struct rcu_synchronize, head);	complete(&rcu->completion);} #ifdef CONFIG_PROVE_RCU/* * wrapper function to avoid #include problems. */int rcu_my_thread_group_empty(void){	return thread_group_empty(current);}EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty);#endif /* #ifdef CONFIG_PROVE_RCU */