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rcu: Fix synchronize_rcu() for TREE_PREEMPT_RCU

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The redirection of synchronize_sched() to synchronize_rcu() was
appropriate for TREE_RCU, but not for TREE_PREEMPT_RCU.

Fix this by creating an underlying synchronize_sched().  TREE_RCU
then redirects synchronize_rcu() to synchronize_sched(), while
TREE_PREEMPT_RCU has its own version of synchronize_rcu().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
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
LKML-Reference: <12528585111916-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney 2009-09-13 09:15:11 -07:00 committed by Ingo Molnar
parent c3422bea5f
commit 16e3081191
3 changed files with 50 additions and 21 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

23
include/linux/rcupdate.h
View file

@ -52,8 +52,13 @@ struct rcu_head {
};
/* Exported common interfaces */
#ifdef CONFIG_TREE_PREEMPT_RCU
extern void synchronize_rcu(void);
#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
#define synchronize_rcu synchronize_sched
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
extern void synchronize_rcu_bh(void);
extern void synchronize_sched(void);
extern void rcu_barrier(void);
extern void rcu_barrier_bh(void);
extern void rcu_barrier_sched(void);
@ -261,24 +266,6 @@ struct rcu_synchronize {
extern void wakeme_after_rcu(struct rcu_head *head);
/**
* synchronize_sched - block until all CPUs have exited any non-preemptive
* kernel code sequences.
*
* This means that all preempt_disable code sequences, including NMI and
* hardware-interrupt handlers, in progress on entry will have completed
* before this primitive returns. However, this does not guarantee that
* softirq handlers will have completed, since in some kernels, these
* handlers can run in process context, and can block.
*
* This primitive provides the guarantees made by the (now removed)
* synchronize_kernel() API. In contrast, synchronize_rcu() only
* guarantees that rcu_read_lock() sections will have completed.
* In "classic RCU", these two guarantees happen to be one and
* the same, but can differ in realtime RCU implementations.
*/
#define synchronize_sched() __synchronize_sched()
/**
* call_rcu - Queue an RCU callback for invocation after a grace period.
* @head: structure to be used for queueing the RCU updates.

4
include/linux/rcutree.h
View file

@ -53,6 +53,8 @@ static inline void __rcu_read_unlock(void)
preempt_enable();
}
#define __synchronize_sched() synchronize_rcu()
static inline void exit_rcu(void)
{
}
@ -68,8 +70,6 @@ static inline void __rcu_read_unlock_bh(void)
local_bh_enable();
}
#define __synchronize_sched() synchronize_rcu()
extern void call_rcu_sched(struct rcu_head *head,
void (*func)(struct rcu_head *rcu));

44
kernel/rcupdate.c
View file

@ -74,6 +74,8 @@ void wakeme_after_rcu(struct rcu_head *head)
complete(&rcu->completion);
}
#ifdef CONFIG_TREE_PREEMPT_RCU
/**
* synchronize_rcu - wait until a grace period has elapsed.
*
@ -87,7 +89,7 @@ void synchronize_rcu(void)
{
struct rcu_synchronize rcu;
if (rcu_blocking_is_gp())
if (!rcu_scheduler_active)
return;
init_completion(&rcu.completion);
@ -98,6 +100,46 @@ void synchronize_rcu(void)
}
EXPORT_SYMBOL_GPL(synchronize_rcu);
#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
/**
* synchronize_sched - wait until an rcu-sched grace period has elapsed.
*
* Control will return to the caller some time after a full rcu-sched
* grace period has elapsed, in other words after all currently executing
* rcu-sched read-side critical sections have completed. These read-side
* critical sections are delimited by rcu_read_lock_sched() and
* rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(),
* local_irq_disable(), and so on may be used in place of
* rcu_read_lock_sched().
*
* This means that all preempt_disable code sequences, including NMI and
* hardware-interrupt handlers, in progress on entry will have completed
* before this primitive returns. However, this does not guarantee that
* softirq handlers will have completed, since in some kernels, these
* handlers can run in process context, and can block.
*
* This primitive provides the guarantees made by the (now removed)
* synchronize_kernel() API. In contrast, synchronize_rcu() only
* guarantees that rcu_read_lock() sections will have completed.
* In "classic RCU", these two guarantees happen to be one and
* the same, but can differ in realtime RCU implementations.
*/
void synchronize_sched(void)
{
struct rcu_synchronize rcu;
if (rcu_blocking_is_gp())
return;
init_completion(&rcu.completion);
/* Will wake me after RCU finished. */
call_rcu_sched(&rcu.head, wakeme_after_rcu);
/* Wait for it. */
wait_for_completion(&rcu.completion);
}
EXPORT_SYMBOL_GPL(synchronize_sched);
/**
* synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
*