bc293d62b2
The lockdep facility temporarily disables lockdep checking by incrementing the current->lockdep_recursion variable. Such disabling happens in NMIs and in other situations where lockdep might expect to recurse on itself. This patch therefore checks current->lockdep_recursion, disabling RCU lockdep splats when this variable is non-zero. In addition, this patch removes the "likely()", as suggested by Lai Jiangshan. Reported-by: Frederic Weisbecker <fweisbec@gmail.com> Reported-by: David Miller <davem@davemloft.net> Tested-by: Frederic Weisbecker <fweisbec@gmail.com> 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 Cc: eric.dumazet@gmail.com LKML-Reference: <20100415195039.GA22623@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
124 lines
3.9 KiB
C
124 lines
3.9 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion
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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, 2001
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*
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* Authors: Dipankar Sarma <dipankar@in.ibm.com>
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* Manfred Spraul <manfred@colorfullife.com>
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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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* Papers:
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* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
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* http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
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*
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* For detailed explanation of Read-Copy Update mechanism see -
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* http://lse.sourceforge.net/locking/rcupdate.html
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*
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/smp.h>
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#include <linux/interrupt.h>
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#include <linux/sched.h>
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#include <asm/atomic.h>
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#include <linux/bitops.h>
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#include <linux/percpu.h>
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/mutex.h>
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#include <linux/module.h>
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#include <linux/kernel_stat.h>
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#include <linux/hardirq.h>
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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static struct lock_class_key rcu_lock_key;
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struct lockdep_map rcu_lock_map =
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STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
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EXPORT_SYMBOL_GPL(rcu_lock_map);
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static struct lock_class_key rcu_bh_lock_key;
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struct lockdep_map rcu_bh_lock_map =
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STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
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EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
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static struct lock_class_key rcu_sched_lock_key;
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struct lockdep_map rcu_sched_lock_map =
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STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
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EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
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#endif
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int rcu_scheduler_active __read_mostly;
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EXPORT_SYMBOL_GPL(rcu_scheduler_active);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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int debug_lockdep_rcu_enabled(void)
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{
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return rcu_scheduler_active && debug_locks &&
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current->lockdep_recursion == 0;
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}
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EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
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/**
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* rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
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*
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* Check for bottom half being disabled, which covers both the
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* CONFIG_PROVE_RCU and not cases. Note that if someone uses
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* rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
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* will show the situation.
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*
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* Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
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*/
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int rcu_read_lock_bh_held(void)
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{
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if (!debug_lockdep_rcu_enabled())
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return 1;
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return in_softirq();
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}
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EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
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#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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/*
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* This function is invoked towards the end of the scheduler's initialization
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* process. Before this is called, the idle task might contain
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* RCU read-side critical sections (during which time, this idle
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* task is booting the system). After this function is called, the
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* idle tasks are prohibited from containing RCU read-side critical
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* sections.
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*/
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void rcu_scheduler_starting(void)
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{
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WARN_ON(num_online_cpus() != 1);
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WARN_ON(nr_context_switches() > 0);
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rcu_scheduler_active = 1;
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}
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/*
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* Awaken the corresponding synchronize_rcu() instance now that a
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* grace period has elapsed.
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*/
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void wakeme_after_rcu(struct rcu_head *head)
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{
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struct rcu_synchronize *rcu;
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rcu = container_of(head, struct rcu_synchronize, head);
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complete(&rcu->completion);
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}
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