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Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: rcu: Fix whitespace inconsistencies rcu: Fix thinko, actually initialize full tree rcu: Apply results of code inspection of kernel/rcutree_plugin.h rcu: Add WARN_ON_ONCE() consistency checks covering state transitions rcu: Fix synchronize_rcu() for TREE_PREEMPT_RCU rcu: Simplify rcu_read_unlock_special() quiescent-state accounting rcu: Add debug checks to TREE_PREEMPT_RCU for premature grace periods rcu: Kconfig help needs to say that TREE_PREEMPT_RCU scales down rcutorture: Occasionally delay readers enough to make RCU force_quiescent_state rcu: Initialize multi-level RCU grace periods holding locks rcu: Need to update rnp->gpnum if preemptable RCU is to be reliable
This commit is contained in:
Linus Torvalds
commit
b8c7f1dc5c
@ -102,7 +102,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
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*/
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#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \
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for (pos = rcu_dereference((head)->first); \
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(!is_a_nulls(pos)) && \
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(!is_a_nulls(pos)) && \
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({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \
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pos = rcu_dereference(pos->next))
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@ -1,5 +1,5 @@
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/*
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* Read-Copy Update mechanism for mutual exclusion
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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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@ -18,7 +18,7 @@
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* Copyright IBM Corporation, 2001
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*
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* Author: Dipankar Sarma <dipankar@in.ibm.com>
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*
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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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@ -26,7 +26,7 @@
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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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* http://lse.sourceforge.net/locking/rcupdate.html
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*
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*/
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@ -52,8 +52,13 @@ struct rcu_head {
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};
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/* Exported common interfaces */
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#ifdef CONFIG_TREE_PREEMPT_RCU
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extern void synchronize_rcu(void);
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#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
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#define synchronize_rcu synchronize_sched
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#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
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extern void synchronize_rcu_bh(void);
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extern void synchronize_sched(void);
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extern void rcu_barrier(void);
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extern void rcu_barrier_bh(void);
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extern void rcu_barrier_sched(void);
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@ -261,24 +266,6 @@ struct rcu_synchronize {
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extern void wakeme_after_rcu(struct rcu_head *head);
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/**
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* synchronize_sched - block until all CPUs have exited any non-preemptive
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* kernel code sequences.
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*
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* This means that all preempt_disable code sequences, including NMI and
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* hardware-interrupt handlers, in progress on entry will have completed
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* before this primitive returns. However, this does not guarantee that
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* softirq handlers will have completed, since in some kernels, these
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* handlers can run in process context, and can block.
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*
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* This primitive provides the guarantees made by the (now removed)
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* synchronize_kernel() API. In contrast, synchronize_rcu() only
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* guarantees that rcu_read_lock() sections will have completed.
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* In "classic RCU", these two guarantees happen to be one and
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* the same, but can differ in realtime RCU implementations.
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*/
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#define synchronize_sched() __synchronize_sched()
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/**
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* call_rcu - Queue an RCU callback for invocation after a grace period.
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* @head: structure to be used for queueing the RCU updates.
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@ -24,7 +24,7 @@
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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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* Documentation/RCU
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*/
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#ifndef __LINUX_RCUTREE_H
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@ -53,6 +53,8 @@ static inline void __rcu_read_unlock(void)
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preempt_enable();
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}
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#define __synchronize_sched() synchronize_rcu()
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static inline void exit_rcu(void)
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{
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}
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@ -68,8 +70,6 @@ static inline void __rcu_read_unlock_bh(void)
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local_bh_enable();
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}
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#define __synchronize_sched() synchronize_rcu()
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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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@ -1755,7 +1755,6 @@ extern cputime_t task_gtime(struct task_struct *p);
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#define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */
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#define RCU_READ_UNLOCK_NEED_QS (1 << 1) /* RCU core needs CPU response. */
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#define RCU_READ_UNLOCK_GOT_QS (1 << 2) /* CPU has responded to RCU core. */
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static inline void rcu_copy_process(struct task_struct *p)
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{
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@ -331,7 +331,8 @@ config TREE_PREEMPT_RCU
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This option selects the RCU implementation that is
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designed for very large SMP systems with hundreds or
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thousands of CPUs, but for which real-time response
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is also required.
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is also required. It also scales down nicely to
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smaller systems.
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endchoice
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@ -19,7 +19,7 @@
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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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*
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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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@ -27,7 +27,7 @@
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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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* 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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@ -74,6 +74,8 @@ void wakeme_after_rcu(struct rcu_head *head)
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complete(&rcu->completion);
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}
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#ifdef CONFIG_TREE_PREEMPT_RCU
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/**
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* synchronize_rcu - wait until a grace period has elapsed.
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*
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@ -87,7 +89,7 @@ void synchronize_rcu(void)
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{
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struct rcu_synchronize rcu;
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if (rcu_blocking_is_gp())
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if (!rcu_scheduler_active)
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return;
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init_completion(&rcu.completion);
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@ -98,6 +100,46 @@ void synchronize_rcu(void)
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}
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EXPORT_SYMBOL_GPL(synchronize_rcu);
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#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
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/**
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* synchronize_sched - wait until an rcu-sched grace period has elapsed.
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*
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* Control will return to the caller some time after a full rcu-sched
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* grace period has elapsed, in other words after all currently executing
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* rcu-sched read-side critical sections have completed. These read-side
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* critical sections are delimited by rcu_read_lock_sched() and
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* rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(),
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* local_irq_disable(), and so on may be used in place of
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* rcu_read_lock_sched().
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*
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* This means that all preempt_disable code sequences, including NMI and
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* hardware-interrupt handlers, in progress on entry will have completed
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* before this primitive returns. However, this does not guarantee that
|
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* softirq handlers will have completed, since in some kernels, these
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* handlers can run in process context, and can block.
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*
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* This primitive provides the guarantees made by the (now removed)
|
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* synchronize_kernel() API. In contrast, synchronize_rcu() only
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* guarantees that rcu_read_lock() sections will have completed.
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* In "classic RCU", these two guarantees happen to be one and
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* the same, but can differ in realtime RCU implementations.
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*/
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void synchronize_sched(void)
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{
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struct rcu_synchronize rcu;
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if (rcu_blocking_is_gp())
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return;
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init_completion(&rcu.completion);
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/* Will wake me after RCU finished. */
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call_rcu_sched(&rcu.head, wakeme_after_rcu);
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/* Wait for it. */
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wait_for_completion(&rcu.completion);
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}
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EXPORT_SYMBOL_GPL(synchronize_sched);
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/**
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* synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
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*
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@ -18,7 +18,7 @@
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* Copyright (C) IBM Corporation, 2005, 2006
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*
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* Authors: Paul E. McKenney <paulmck@us.ibm.com>
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* Josh Triplett <josh@freedesktop.org>
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* Josh Triplett <josh@freedesktop.org>
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*
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* See also: Documentation/RCU/torture.txt
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*/
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@ -50,7 +50,7 @@
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
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"Josh Triplett <josh@freedesktop.org>");
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"Josh Triplett <josh@freedesktop.org>");
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static int nreaders = -1; /* # reader threads, defaults to 2*ncpus */
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static int nfakewriters = 4; /* # fake writer threads */
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@ -110,8 +110,8 @@ struct rcu_torture {
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};
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static LIST_HEAD(rcu_torture_freelist);
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static struct rcu_torture *rcu_torture_current = NULL;
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static long rcu_torture_current_version = 0;
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static struct rcu_torture *rcu_torture_current;
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static long rcu_torture_current_version;
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static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
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static DEFINE_SPINLOCK(rcu_torture_lock);
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static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
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@ -124,11 +124,11 @@ static atomic_t n_rcu_torture_alloc_fail;
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static atomic_t n_rcu_torture_free;
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static atomic_t n_rcu_torture_mberror;
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static atomic_t n_rcu_torture_error;
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static long n_rcu_torture_timers = 0;
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static long n_rcu_torture_timers;
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static struct list_head rcu_torture_removed;
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static cpumask_var_t shuffle_tmp_mask;
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static int stutter_pause_test = 0;
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static int stutter_pause_test;
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#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
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#define RCUTORTURE_RUNNABLE_INIT 1
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@ -267,7 +267,8 @@ struct rcu_torture_ops {
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int irq_capable;
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char *name;
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};
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static struct rcu_torture_ops *cur_ops = NULL;
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static struct rcu_torture_ops *cur_ops;
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/*
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* Definitions for rcu torture testing.
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@ -281,14 +282,17 @@ static int rcu_torture_read_lock(void) __acquires(RCU)
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static void rcu_read_delay(struct rcu_random_state *rrsp)
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{
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long delay;
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const long longdelay = 200;
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const unsigned long shortdelay_us = 200;
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const unsigned long longdelay_ms = 50;
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/* We want there to be long-running readers, but not all the time. */
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/* We want a short delay sometimes to make a reader delay the grace
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* period, and we want a long delay occasionally to trigger
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* force_quiescent_state. */
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delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
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if (!delay)
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udelay(longdelay);
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if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
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mdelay(longdelay_ms);
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if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
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udelay(shortdelay_us);
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}
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static void rcu_torture_read_unlock(int idx) __releases(RCU)
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@ -339,8 +343,8 @@ static struct rcu_torture_ops rcu_ops = {
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.sync = synchronize_rcu,
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.cb_barrier = rcu_barrier,
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.stats = NULL,
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.irq_capable = 1,
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.name = "rcu"
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.irq_capable = 1,
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.name = "rcu"
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};
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||||
static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
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@ -638,7 +642,8 @@ rcu_torture_writer(void *arg)
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do {
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schedule_timeout_uninterruptible(1);
|
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if ((rp = rcu_torture_alloc()) == NULL)
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rp = rcu_torture_alloc();
|
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if (rp == NULL)
|
||||
continue;
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rp->rtort_pipe_count = 0;
|
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udelay(rcu_random(&rand) & 0x3ff);
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@ -1110,7 +1115,7 @@ rcu_torture_init(void)
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printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
|
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torture_type);
|
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mutex_unlock(&fullstop_mutex);
|
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return (-EINVAL);
|
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return -EINVAL;
|
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}
|
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if (cur_ops->init)
|
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cur_ops->init(); /* no "goto unwind" prior to this point!!! */
|
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@ -1161,7 +1166,7 @@ rcu_torture_init(void)
|
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goto unwind;
|
||||
}
|
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fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
|
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GFP_KERNEL);
|
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GFP_KERNEL);
|
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if (fakewriter_tasks == NULL) {
|
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VERBOSE_PRINTK_ERRSTRING("out of memory");
|
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firsterr = -ENOMEM;
|
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@ -1170,7 +1175,7 @@ rcu_torture_init(void)
|
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for (i = 0; i < nfakewriters; i++) {
|
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VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
|
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fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
|
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"rcu_torture_fakewriter");
|
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"rcu_torture_fakewriter");
|
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if (IS_ERR(fakewriter_tasks[i])) {
|
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firsterr = PTR_ERR(fakewriter_tasks[i]);
|
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VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
|
||||
|
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105
kernel/rcutree.c
105
kernel/rcutree.c
@ -25,7 +25,7 @@
|
||||
* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
|
||||
*
|
||||
* For detailed explanation of Read-Copy Update mechanism see -
|
||||
* Documentation/RCU
|
||||
* Documentation/RCU
|
||||
*/
|
||||
#include <linux/types.h>
|
||||
#include <linux/kernel.h>
|
||||
@ -107,27 +107,23 @@ static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_state *rsp,
|
||||
*/
|
||||
void rcu_sched_qs(int cpu)
|
||||
{
|
||||
unsigned long flags;
|
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struct rcu_data *rdp;
|
||||
|
||||
local_irq_save(flags);
|
||||
rdp = &per_cpu(rcu_sched_data, cpu);
|
||||
rdp->passed_quiesc = 1;
|
||||
rdp->passed_quiesc_completed = rdp->completed;
|
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rcu_preempt_qs(cpu);
|
||||
local_irq_restore(flags);
|
||||
barrier();
|
||||
rdp->passed_quiesc = 1;
|
||||
rcu_preempt_note_context_switch(cpu);
|
||||
}
|
||||
|
||||
void rcu_bh_qs(int cpu)
|
||||
{
|
||||
unsigned long flags;
|
||||
struct rcu_data *rdp;
|
||||
|
||||
local_irq_save(flags);
|
||||
rdp = &per_cpu(rcu_bh_data, cpu);
|
||||
rdp->passed_quiesc = 1;
|
||||
rdp->passed_quiesc_completed = rdp->completed;
|
||||
local_irq_restore(flags);
|
||||
barrier();
|
||||
rdp->passed_quiesc = 1;
|
||||
}
|
||||
|
||||
#ifdef CONFIG_NO_HZ
|
||||
@ -605,8 +601,6 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
|
||||
{
|
||||
struct rcu_data *rdp = rsp->rda[smp_processor_id()];
|
||||
struct rcu_node *rnp = rcu_get_root(rsp);
|
||||
struct rcu_node *rnp_cur;
|
||||
struct rcu_node *rnp_end;
|
||||
|
||||
if (!cpu_needs_another_gp(rsp, rdp)) {
|
||||
spin_unlock_irqrestore(&rnp->lock, flags);
|
||||
@ -615,6 +609,7 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
|
||||
|
||||
/* Advance to a new grace period and initialize state. */
|
||||
rsp->gpnum++;
|
||||
WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT);
|
||||
rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */
|
||||
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
|
||||
record_gp_stall_check_time(rsp);
|
||||
@ -631,7 +626,9 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
|
||||
|
||||
/* Special-case the common single-level case. */
|
||||
if (NUM_RCU_NODES == 1) {
|
||||
rcu_preempt_check_blocked_tasks(rnp);
|
||||
rnp->qsmask = rnp->qsmaskinit;
|
||||
rnp->gpnum = rsp->gpnum;
|
||||
rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */
|
||||
spin_unlock_irqrestore(&rnp->lock, flags);
|
||||
return;
|
||||
@ -644,42 +641,28 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
|
||||
spin_lock(&rsp->onofflock); /* irqs already disabled. */
|
||||
|
||||
/*
|
||||
* Set the quiescent-state-needed bits in all the non-leaf RCU
|
||||
* nodes for all currently online CPUs. This operation relies
|
||||
* on the layout of the hierarchy within the rsp->node[] array.
|
||||
* Note that other CPUs will access only the leaves of the
|
||||
* hierarchy, which still indicate that no grace period is in
|
||||
* progress. In addition, we have excluded CPU-hotplug operations.
|
||||
*
|
||||
* We therefore do not need to hold any locks. Any required
|
||||
* memory barriers will be supplied by the locks guarding the
|
||||
* leaf rcu_nodes in the hierarchy.
|
||||
*/
|
||||
|
||||
rnp_end = rsp->level[NUM_RCU_LVLS - 1];
|
||||
for (rnp_cur = &rsp->node[0]; rnp_cur < rnp_end; rnp_cur++)
|
||||
rnp_cur->qsmask = rnp_cur->qsmaskinit;
|
||||
|
||||
/*
|
||||
* Now set up the leaf nodes. Here we must be careful. First,
|
||||
* we need to hold the lock in order to exclude other CPUs, which
|
||||
* might be contending for the leaf nodes' locks. Second, as
|
||||
* soon as we initialize a given leaf node, its CPUs might run
|
||||
* up the rest of the hierarchy. We must therefore acquire locks
|
||||
* for each node that we touch during this stage. (But we still
|
||||
* are excluding CPU-hotplug operations.)
|
||||
* Set the quiescent-state-needed bits in all the rcu_node
|
||||
* structures for all currently online CPUs in breadth-first
|
||||
* order, starting from the root rcu_node structure. This
|
||||
* operation relies on the layout of the hierarchy within the
|
||||
* rsp->node[] array. Note that other CPUs will access only
|
||||
* the leaves of the hierarchy, which still indicate that no
|
||||
* grace period is in progress, at least until the corresponding
|
||||
* leaf node has been initialized. In addition, we have excluded
|
||||
* CPU-hotplug operations.
|
||||
*
|
||||
* Note that the grace period cannot complete until we finish
|
||||
* the initialization process, as there will be at least one
|
||||
* qsmask bit set in the root node until that time, namely the
|
||||
* one corresponding to this CPU.
|
||||
* one corresponding to this CPU, due to the fact that we have
|
||||
* irqs disabled.
|
||||
*/
|
||||
rnp_end = &rsp->node[NUM_RCU_NODES];
|
||||
rnp_cur = rsp->level[NUM_RCU_LVLS - 1];
|
||||
for (; rnp_cur < rnp_end; rnp_cur++) {
|
||||
spin_lock(&rnp_cur->lock); /* irqs already disabled. */
|
||||
rnp_cur->qsmask = rnp_cur->qsmaskinit;
|
||||
spin_unlock(&rnp_cur->lock); /* irqs already disabled. */
|
||||
for (rnp = &rsp->node[0]; rnp < &rsp->node[NUM_RCU_NODES]; rnp++) {
|
||||
spin_lock(&rnp->lock); /* irqs already disabled. */
|
||||
rcu_preempt_check_blocked_tasks(rnp);
|
||||
rnp->qsmask = rnp->qsmaskinit;
|
||||
rnp->gpnum = rsp->gpnum;
|
||||
spin_unlock(&rnp->lock); /* irqs already disabled. */
|
||||
}
|
||||
|
||||
rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */
|
||||
@ -722,6 +705,7 @@ rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
|
||||
static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags)
|
||||
__releases(rnp->lock)
|
||||
{
|
||||
WARN_ON_ONCE(rsp->completed == rsp->gpnum);
|
||||
rsp->completed = rsp->gpnum;
|
||||
rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
|
||||
rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
|
||||
@ -739,6 +723,8 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
|
||||
unsigned long flags)
|
||||
__releases(rnp->lock)
|
||||
{
|
||||
struct rcu_node *rnp_c;
|
||||
|
||||
/* Walk up the rcu_node hierarchy. */
|
||||
for (;;) {
|
||||
if (!(rnp->qsmask & mask)) {
|
||||
@ -762,8 +748,10 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
|
||||
break;
|
||||
}
|
||||
spin_unlock_irqrestore(&rnp->lock, flags);
|
||||
rnp_c = rnp;
|
||||
rnp = rnp->parent;
|
||||
spin_lock_irqsave(&rnp->lock, flags);
|
||||
WARN_ON_ONCE(rnp_c->qsmask);
|
||||
}
|
||||
|
||||
/*
|
||||
@ -776,10 +764,10 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
|
||||
|
||||
/*
|
||||
* Record a quiescent state for the specified CPU, which must either be
|
||||
* the current CPU or an offline CPU. The lastcomp argument is used to
|
||||
* make sure we are still in the grace period of interest. We don't want
|
||||
* to end the current grace period based on quiescent states detected in
|
||||
* an earlier grace period!
|
||||
* the current CPU. The lastcomp argument is used to make sure we are
|
||||
* still in the grace period of interest. We don't want to end the current
|
||||
* grace period based on quiescent states detected in an earlier grace
|
||||
* period!
|
||||
*/
|
||||
static void
|
||||
cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
|
||||
@ -814,7 +802,6 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
|
||||
* This GP can't end until cpu checks in, so all of our
|
||||
* callbacks can be processed during the next GP.
|
||||
*/
|
||||
rdp = rsp->rda[smp_processor_id()];
|
||||
rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
|
||||
|
||||
cpu_quiet_msk(mask, rsp, rnp, flags); /* releases rnp->lock */
|
||||
@ -872,7 +859,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
|
||||
spin_lock_irqsave(&rsp->onofflock, flags);
|
||||
|
||||
/* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */
|
||||
rnp = rdp->mynode;
|
||||
rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */
|
||||
mask = rdp->grpmask; /* rnp->grplo is constant. */
|
||||
do {
|
||||
spin_lock(&rnp->lock); /* irqs already disabled. */
|
||||
@ -881,7 +868,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
|
||||
spin_unlock(&rnp->lock); /* irqs remain disabled. */
|
||||
break;
|
||||
}
|
||||
rcu_preempt_offline_tasks(rsp, rnp);
|
||||
rcu_preempt_offline_tasks(rsp, rnp, rdp);
|
||||
mask = rnp->grpmask;
|
||||
spin_unlock(&rnp->lock); /* irqs remain disabled. */
|
||||
rnp = rnp->parent;
|
||||
@ -890,9 +877,6 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
|
||||
|
||||
spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
|
||||
|
||||
/* Being offline is a quiescent state, so go record it. */
|
||||
cpu_quiet(cpu, rsp, rdp, lastcomp);
|
||||
|
||||
/*
|
||||
* Move callbacks from the outgoing CPU to the running CPU.
|
||||
* Note that the outgoing CPU is now quiscent, so it is now
|
||||
@ -1457,20 +1441,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
|
||||
rnp = rnp->parent;
|
||||
} while (rnp != NULL && !(rnp->qsmaskinit & mask));
|
||||
|
||||
spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
|
||||
|
||||
/*
|
||||
* A new grace period might start here. If so, we will be part of
|
||||
* it, and its gpnum will be greater than ours, so we will
|
||||
* participate. It is also possible for the gpnum to have been
|
||||
* incremented before this function was called, and the bitmasks
|
||||
* to not be filled out until now, in which case we will also
|
||||
* participate due to our gpnum being behind.
|
||||
*/
|
||||
|
||||
/* Since it is coming online, the CPU is in a quiescent state. */
|
||||
cpu_quiet(cpu, rsp, rdp, lastcomp);
|
||||
local_irq_restore(flags);
|
||||
spin_unlock_irqrestore(&rsp->onofflock, flags);
|
||||
}
|
||||
|
||||
static void __cpuinit rcu_online_cpu(int cpu)
|
||||
|
||||
@ -142,7 +142,7 @@ struct rcu_data {
|
||||
*/
|
||||
struct rcu_head *nxtlist;
|
||||
struct rcu_head **nxttail[RCU_NEXT_SIZE];
|
||||
long qlen; /* # of queued callbacks */
|
||||
long qlen; /* # of queued callbacks */
|
||||
long blimit; /* Upper limit on a processed batch */
|
||||
|
||||
#ifdef CONFIG_NO_HZ
|
||||
|
||||
@ -64,22 +64,31 @@ EXPORT_SYMBOL_GPL(rcu_batches_completed);
|
||||
* not in a quiescent state. There might be any number of tasks blocked
|
||||
* while in an RCU read-side critical section.
|
||||
*/
|
||||
static void rcu_preempt_qs_record(int cpu)
|
||||
static void rcu_preempt_qs(int cpu)
|
||||
{
|
||||
struct rcu_data *rdp = &per_cpu(rcu_preempt_data, cpu);
|
||||
rdp->passed_quiesc = 1;
|
||||
rdp->passed_quiesc_completed = rdp->completed;
|
||||
barrier();
|
||||
rdp->passed_quiesc = 1;
|
||||
}
|
||||
|
||||
/*
|
||||
* We have entered the scheduler or are between softirqs in ksoftirqd.
|
||||
* If we are in an RCU read-side critical section, we need to reflect
|
||||
* that in the state of the rcu_node structure corresponding to this CPU.
|
||||
* Caller must disable hardirqs.
|
||||
* We have entered the scheduler, and the current task might soon be
|
||||
* context-switched away from. If this task is in an RCU read-side
|
||||
* critical section, we will no longer be able to rely on the CPU to
|
||||
* record that fact, so we enqueue the task on the appropriate entry
|
||||
* of the blocked_tasks[] array. The task will dequeue itself when
|
||||
* it exits the outermost enclosing RCU read-side critical section.
|
||||
* Therefore, the current grace period cannot be permitted to complete
|
||||
* until the blocked_tasks[] entry indexed by the low-order bit of
|
||||
* rnp->gpnum empties.
|
||||
*
|
||||
* Caller must disable preemption.
|
||||
*/
|
||||
static void rcu_preempt_qs(int cpu)
|
||||
static void rcu_preempt_note_context_switch(int cpu)
|
||||
{
|
||||
struct task_struct *t = current;
|
||||
unsigned long flags;
|
||||
int phase;
|
||||
struct rcu_data *rdp;
|
||||
struct rcu_node *rnp;
|
||||
@ -90,7 +99,7 @@ static void rcu_preempt_qs(int cpu)
|
||||
/* Possibly blocking in an RCU read-side critical section. */
|
||||
rdp = rcu_preempt_state.rda[cpu];
|
||||
rnp = rdp->mynode;
|
||||
spin_lock(&rnp->lock);
|
||||
spin_lock_irqsave(&rnp->lock, flags);
|
||||
t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;
|
||||
t->rcu_blocked_node = rnp;
|
||||
|
||||
@ -103,11 +112,15 @@ static void rcu_preempt_qs(int cpu)
|
||||
* state for the current grace period), then as long
|
||||
* as that task remains queued, the current grace period
|
||||
* cannot end.
|
||||
*
|
||||
* But first, note that the current CPU must still be
|
||||
* on line!
|
||||
*/
|
||||
phase = !(rnp->qsmask & rdp->grpmask) ^ (rnp->gpnum & 0x1);
|
||||
WARN_ON_ONCE((rdp->grpmask & rnp->qsmaskinit) == 0);
|
||||
WARN_ON_ONCE(!list_empty(&t->rcu_node_entry));
|
||||
phase = (rnp->gpnum + !(rnp->qsmask & rdp->grpmask)) & 0x1;
|
||||
list_add(&t->rcu_node_entry, &rnp->blocked_tasks[phase]);
|
||||
smp_mb(); /* Ensure later ctxt swtch seen after above. */
|
||||
spin_unlock(&rnp->lock);
|
||||
spin_unlock_irqrestore(&rnp->lock, flags);
|
||||
}
|
||||
|
||||
/*
|
||||
@ -119,9 +132,10 @@ static void rcu_preempt_qs(int cpu)
|
||||
* grace period, then the fact that the task has been enqueued
|
||||
* means that we continue to block the current grace period.
|
||||
*/
|
||||
rcu_preempt_qs_record(cpu);
|
||||
t->rcu_read_unlock_special &= ~(RCU_READ_UNLOCK_NEED_QS |
|
||||
RCU_READ_UNLOCK_GOT_QS);
|
||||
rcu_preempt_qs(cpu);
|
||||
local_irq_save(flags);
|
||||
t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
|
||||
local_irq_restore(flags);
|
||||
}
|
||||
|
||||
/*
|
||||
@ -157,7 +171,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
|
||||
special = t->rcu_read_unlock_special;
|
||||
if (special & RCU_READ_UNLOCK_NEED_QS) {
|
||||
t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
|
||||
t->rcu_read_unlock_special |= RCU_READ_UNLOCK_GOT_QS;
|
||||
rcu_preempt_qs(smp_processor_id());
|
||||
}
|
||||
|
||||
/* Hardware IRQ handlers cannot block. */
|
||||
@ -177,10 +191,10 @@ static void rcu_read_unlock_special(struct task_struct *t)
|
||||
*/
|
||||
for (;;) {
|
||||
rnp = t->rcu_blocked_node;
|
||||
spin_lock(&rnp->lock);
|
||||
spin_lock(&rnp->lock); /* irqs already disabled. */
|
||||
if (rnp == t->rcu_blocked_node)
|
||||
break;
|
||||
spin_unlock(&rnp->lock);
|
||||
spin_unlock(&rnp->lock); /* irqs remain disabled. */
|
||||
}
|
||||
empty = list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]);
|
||||
list_del_init(&t->rcu_node_entry);
|
||||
@ -194,9 +208,8 @@ static void rcu_read_unlock_special(struct task_struct *t)
|
||||
*/
|
||||
if (!empty && rnp->qsmask == 0 &&
|
||||
list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1])) {
|
||||
t->rcu_read_unlock_special &=
|
||||
~(RCU_READ_UNLOCK_NEED_QS |
|
||||
RCU_READ_UNLOCK_GOT_QS);
|
||||
struct rcu_node *rnp_p;
|
||||
|
||||
if (rnp->parent == NULL) {
|
||||
/* Only one rcu_node in the tree. */
|
||||
cpu_quiet_msk_finish(&rcu_preempt_state, flags);
|
||||
@ -205,9 +218,10 @@ static void rcu_read_unlock_special(struct task_struct *t)
|
||||
/* Report up the rest of the hierarchy. */
|
||||
mask = rnp->grpmask;
|
||||
spin_unlock_irqrestore(&rnp->lock, flags);
|
||||
rnp = rnp->parent;
|
||||
spin_lock_irqsave(&rnp->lock, flags);
|
||||
cpu_quiet_msk(mask, &rcu_preempt_state, rnp, flags);
|
||||
rnp_p = rnp->parent;
|
||||
spin_lock_irqsave(&rnp_p->lock, flags);
|
||||
WARN_ON_ONCE(rnp->qsmask);
|
||||
cpu_quiet_msk(mask, &rcu_preempt_state, rnp_p, flags);
|
||||
return;
|
||||
}
|
||||
spin_unlock(&rnp->lock);
|
||||
@ -258,6 +272,19 @@ static void rcu_print_task_stall(struct rcu_node *rnp)
|
||||
|
||||
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
|
||||
|
||||
/*
|
||||
* Check that the list of blocked tasks for the newly completed grace
|
||||
* period is in fact empty. It is a serious bug to complete a grace
|
||||
* period that still has RCU readers blocked! This function must be
|
||||
* invoked -before- updating this rnp's ->gpnum, and the rnp's ->lock
|
||||
* must be held by the caller.
|
||||
*/
|
||||
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
|
||||
{
|
||||
WARN_ON_ONCE(!list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]));
|
||||
WARN_ON_ONCE(rnp->qsmask);
|
||||
}
|
||||
|
||||
/*
|
||||
* Check for preempted RCU readers for the specified rcu_node structure.
|
||||
* If the caller needs a reliable answer, it must hold the rcu_node's
|
||||
@ -280,7 +307,8 @@ static int rcu_preempted_readers(struct rcu_node *rnp)
|
||||
* The caller must hold rnp->lock with irqs disabled.
|
||||
*/
|
||||
static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
|
||||
struct rcu_node *rnp)
|
||||
struct rcu_node *rnp,
|
||||
struct rcu_data *rdp)
|
||||
{
|
||||
int i;
|
||||
struct list_head *lp;
|
||||
@ -292,6 +320,9 @@ static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
|
||||
WARN_ONCE(1, "Last CPU thought to be offlined?");
|
||||
return; /* Shouldn't happen: at least one CPU online. */
|
||||
}
|
||||
WARN_ON_ONCE(rnp != rdp->mynode &&
|
||||
(!list_empty(&rnp->blocked_tasks[0]) ||
|
||||
!list_empty(&rnp->blocked_tasks[1])));
|
||||
|
||||
/*
|
||||
* Move tasks up to root rcu_node. Rely on the fact that the
|
||||
@ -335,20 +366,12 @@ static void rcu_preempt_check_callbacks(int cpu)
|
||||
struct task_struct *t = current;
|
||||
|
||||
if (t->rcu_read_lock_nesting == 0) {
|
||||
t->rcu_read_unlock_special &=
|
||||
~(RCU_READ_UNLOCK_NEED_QS | RCU_READ_UNLOCK_GOT_QS);
|
||||
rcu_preempt_qs_record(cpu);
|
||||
t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
|
||||
rcu_preempt_qs(cpu);
|
||||
return;
|
||||
}
|
||||
if (per_cpu(rcu_preempt_data, cpu).qs_pending) {
|
||||
if (t->rcu_read_unlock_special & RCU_READ_UNLOCK_GOT_QS) {
|
||||
rcu_preempt_qs_record(cpu);
|
||||
t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_GOT_QS;
|
||||
} else if (!(t->rcu_read_unlock_special &
|
||||
RCU_READ_UNLOCK_NEED_QS)) {
|
||||
t->rcu_read_unlock_special |= RCU_READ_UNLOCK_NEED_QS;
|
||||
}
|
||||
}
|
||||
if (per_cpu(rcu_preempt_data, cpu).qs_pending)
|
||||
t->rcu_read_unlock_special |= RCU_READ_UNLOCK_NEED_QS;
|
||||
}
|
||||
|
||||
/*
|
||||
@ -434,7 +457,7 @@ EXPORT_SYMBOL_GPL(rcu_batches_completed);
|
||||
* Because preemptable RCU does not exist, we never have to check for
|
||||
* CPUs being in quiescent states.
|
||||
*/
|
||||
static void rcu_preempt_qs(int cpu)
|
||||
static void rcu_preempt_note_context_switch(int cpu)
|
||||
{
|
||||
}
|
||||
|
||||
@ -450,6 +473,16 @@ static void rcu_print_task_stall(struct rcu_node *rnp)
|
||||
|
||||
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
|
||||
|
||||
/*
|
||||
* Because there is no preemptable RCU, there can be no readers blocked,
|
||||
* so there is no need to check for blocked tasks. So check only for
|
||||
* bogus qsmask values.
|
||||
*/
|
||||
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
|
||||
{
|
||||
WARN_ON_ONCE(rnp->qsmask);
|
||||
}
|
||||
|
||||
/*
|
||||
* Because preemptable RCU does not exist, there are never any preempted
|
||||
* RCU readers.
|
||||
@ -466,7 +499,8 @@ static int rcu_preempted_readers(struct rcu_node *rnp)
|
||||
* tasks that were blocked within RCU read-side critical sections.
|
||||
*/
|
||||
static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
|
||||
struct rcu_node *rnp)
|
||||
struct rcu_node *rnp,
|
||||
struct rcu_data *rdp)
|
||||
{
|
||||
}
|
||||
|
||||
|
||||
@ -20,7 +20,7 @@
|
||||
* Papers: http://www.rdrop.com/users/paulmck/RCU
|
||||
*
|
||||
* For detailed explanation of Read-Copy Update mechanism see -
|
||||
* Documentation/RCU
|
||||
* Documentation/RCU
|
||||
*
|
||||
*/
|
||||
#include <linux/types.h>
|
||||
|
||||
Loading…
Reference in New Issue
Block a user