2005-04-17 06:20:36 +08:00
|
|
|
/*
|
|
|
|
|
* 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.
|
|
|
|
|
*
|
2008-01-26 04:08:24 +08:00
|
|
|
* Copyright IBM Corporation, 2001
|
2005-04-17 06:20:36 +08:00
|
|
|
*
|
|
|
|
|
* Authors: Dipankar Sarma <dipankar@in.ibm.com>
|
|
|
|
|
* Manfred Spraul <manfred@colorfullife.com>
|
2009-09-19 01:28:19 +08:00
|
|
|
*
|
2005-04-17 06:20:36 +08:00
|
|
|
* 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 -
|
2009-09-19 01:28:19 +08:00
|
|
|
* http://lse.sourceforge.net/locking/rcupdate.html
|
2005-04-17 06:20:36 +08:00
|
|
|
*
|
|
|
|
|
*/
|
|
|
|
|
#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>
|
2006-03-23 19:00:19 +08:00
|
|
|
#include <linux/mutex.h>
|
2008-01-26 04:08:24 +08:00
|
|
|
#include <linux/module.h>
|
2010-03-16 08:03:43 +08:00
|
|
|
#include <linux/hardirq.h>
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2009-09-24 07:18:13 +08:00
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
|
|
|
static 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);
|
rcu: Introduce lockdep-based checking to RCU read-side primitives
Inspection is proving insufficient to catch all RCU misuses,
which is understandable given that rcu_dereference() might be
protected by any of four different flavors of RCU (RCU, RCU-bh,
RCU-sched, and SRCU), and might also/instead be protected by any
of a number of locking primitives. It is therefore time to
enlist the aid of lockdep.
This set of patches is inspired by earlier work by Peter
Zijlstra and Thomas Gleixner, and takes the following approach:
o Set up separate lockdep classes for RCU, RCU-bh, and RCU-sched.
o Set up separate lockdep classes for each instance of SRCU.
o Create primitives that check for being in an RCU read-side
critical section. These return exact answers if lockdep is
fully enabled, but if unsure, report being in an RCU read-side
critical section. (We want to avoid false positives!)
The primitives are:
For RCU: rcu_read_lock_held(void)
For RCU-bh: rcu_read_lock_bh_held(void)
For RCU-sched: rcu_read_lock_sched_held(void)
For SRCU: srcu_read_lock_held(struct srcu_struct *sp)
o Add rcu_dereference_check(), which takes a second argument
in which one places a boolean expression based on the above
primitives and/or lockdep_is_held().
o A new kernel configuration parameter, CONFIG_PROVE_RCU, enables
rcu_dereference_check(). This depends on CONFIG_PROVE_LOCKING,
and should be quite helpful during the transition period while
CONFIG_PROVE_RCU-unaware patches are in flight.
The existing rcu_dereference() primitive does no checking, but
upcoming patches will change that.
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: <1266887105-1528-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-23 09:04:45 +08:00
|
|
|
|
|
|
|
|
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);
|
2009-09-24 07:18:13 +08:00
|
|
|
#endif
|
|
|
|
|
|
2010-03-16 08:03:43 +08:00
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
|
|
|
|
2010-04-16 03:50:39 +08:00
|
|
|
int debug_lockdep_rcu_enabled(void)
|
|
|
|
|
{
|
|
|
|
|
return rcu_scheduler_active && debug_locks &&
|
|
|
|
|
current->lockdep_recursion == 0;
|
|
|
|
|
}
|
|
|
|
|
EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
|
|
|
|
|
|
2010-03-16 08:03:43 +08:00
|
|
|
/**
|
|
|
|
|
* 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 */
|
|
|
|
|
|
2008-02-14 07:03:15 +08:00
|
|
|
/*
|
|
|
|
|
* Awaken the corresponding synchronize_rcu() instance now that a
|
|
|
|
|
* grace period has elapsed.
|
|
|
|
|
*/
|
rcu: add call_rcu_sched()
Fourth cut of patch to provide the call_rcu_sched(). This is again to
synchronize_sched() as call_rcu() is to synchronize_rcu().
Should be fine for experimental and -rt use, but not ready for inclusion.
With some luck, I will be able to tell Andrew to come out of hiding on
the next round.
Passes multi-day rcutorture sessions with concurrent CPU hotplugging.
Fixes since the first version include a bug that could result in
indefinite blocking (spotted by Gautham Shenoy), better resiliency
against CPU-hotplug operations, and other minor fixes.
Fixes since the second version include reworking grace-period detection
to avoid deadlocks that could happen when running concurrently with
CPU hotplug, adding Mathieu's fix to avoid the softlockup messages,
as well as Mathieu's fix to allow use earlier in boot.
Fixes since the third version include a wrong-CPU bug spotted by
Andrew, getting rid of the obsolete synchronize_kernel API that somehow
snuck back in, merging spin_unlock() and local_irq_restore() in a
few places, commenting the code that checks for quiescent states based
on interrupting from user-mode execution or the idle loop, removing
some inline attributes, and some code-style changes.
Known/suspected shortcomings:
o I still do not entirely trust the sleep/wakeup logic. Next step
will be to use a private snapshot of the CPU online mask in
rcu_sched_grace_period() -- if the CPU wasn't there at the start
of the grace period, we don't need to hear from it. And the
bit about accounting for changes in online CPUs inside of
rcu_sched_grace_period() is ugly anyway.
o It might be good for rcu_sched_grace_period() to invoke
resched_cpu() when a given CPU wasn't responding quickly,
but resched_cpu() is declared static...
This patch also fixes a long-standing bug in the earlier preemptable-RCU
implementation of synchronize_rcu() that could result in loss of
concurrent external changes to a task's CPU affinity mask. I still cannot
remember who reported this...
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-13 03:21:05 +08:00
|
|
|
void wakeme_after_rcu(struct rcu_head *head)
|
2006-03-08 13:55:33 +08:00
|
|
|
{
|
2008-01-26 04:08:24 +08:00
|
|
|
struct rcu_synchronize *rcu;
|
|
|
|
|
|
|
|
|
|
rcu = container_of(head, struct rcu_synchronize, head);
|
|
|
|
|
complete(&rcu->completion);
|
2006-03-08 13:55:33 +08:00
|
|
|
}
|
2010-05-07 00:28:41 +08:00
|
|
|
|
|
|
|
|
#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 */
|
