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Message-ID: <20080414040235.GC30495@linux.vnet.ibm.com>
Date: Sun, 13 Apr 2008 21:02:35 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mathieu.desnoyers@...ymtl.ca, mingo@...e.hu,
akpm@...ux-foundation.org, hch@...radead.org, mmlnx@...ibm.com,
dipankar@...ibm.com, dsmith@...hat.com, rostedt@...dmis.org,
adrian.bunk@...ial.fi, a.p.zijlstra@...llo.nl, ego@...ibm.com,
niv@...ibm.com, dvhltc@...ibm.com, rusty@....ibm.com,
jkenisto@...ux.vnet.ibm.com, oleg@...sign.ru,
jamesclhuang@...oo.com
Subject: [PATCH 3/5] Add rcu_barrier_sched() and rcu_barrier_bh()
Add rcu_barrier_sched() and rcu_barrier_bh(). With these in place,
rcutorture no longer gives the occasional oops when repeatedly starting
and stopping torturing rcu_bh. Also adds the API needed to flush out
pre-existing call_rcu_sched() callbacks.
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
---
include/linux/rcupdate.h | 2 +
kernel/rcupdate.c | 55 +++++++++++++++++++++++++++++++++++++++++------
2 files changed, 51 insertions(+), 6 deletions(-)
diff -urpNa -X dontdiff linux-2.6.25-rc6-C2-rcuclassic-fixes/include/linux/rcupdate.h linux-2.6.25-rc6-C3-rcu_barrier_sched/include/linux/rcupdate.h
--- linux-2.6.25-rc6-C2-rcuclassic-fixes/include/linux/rcupdate.h 2008-03-20 21:10:42.000000000 -0700
+++ linux-2.6.25-rc6-C3-rcu_barrier_sched/include/linux/rcupdate.h 2008-04-09 13:40:53.000000000 -0700
@@ -260,6 +260,8 @@ extern void call_rcu_bh(struct rcu_head
/* Exported common interfaces */
extern void synchronize_rcu(void);
extern void rcu_barrier(void);
+extern void rcu_barrier_bh(void);
+extern void rcu_barrier_sched(void);
extern long rcu_batches_completed(void);
extern long rcu_batches_completed_bh(void);
diff -urpNa -X dontdiff linux-2.6.25-rc6-C2-rcuclassic-fixes/kernel/rcupdate.c linux-2.6.25-rc6-C3-rcu_barrier_sched/kernel/rcupdate.c
--- linux-2.6.25-rc6-C2-rcuclassic-fixes/kernel/rcupdate.c 2008-03-20 21:10:39.000000000 -0700
+++ linux-2.6.25-rc6-C3-rcu_barrier_sched/kernel/rcupdate.c 2008-04-09 13:54:53.000000000 -0700
@@ -45,6 +45,12 @@
#include <linux/mutex.h>
#include <linux/module.h>
+enum rcu_barrier {
+ RCU_BARRIER_STD,
+ RCU_BARRIER_BH,
+ RCU_BARRIER_SCHED,
+};
+
static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL};
static atomic_t rcu_barrier_cpu_count;
static DEFINE_MUTEX(rcu_barrier_mutex);
@@ -83,19 +89,30 @@ static void rcu_barrier_callback(struct
/*
* Called with preemption disabled, and from cross-cpu IRQ context.
*/
-static void rcu_barrier_func(void *notused)
+static void rcu_barrier_func(void *type)
{
int cpu = smp_processor_id();
struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu);
atomic_inc(&rcu_barrier_cpu_count);
- call_rcu(head, rcu_barrier_callback);
+ switch ((enum rcu_barrier)type) {
+ case RCU_BARRIER_STD:
+ call_rcu(head, rcu_barrier_callback);
+ break;
+ case RCU_BARRIER_BH:
+ call_rcu_bh(head, rcu_barrier_callback);
+ break;
+ case RCU_BARRIER_SCHED:
+ call_rcu_sched(head, rcu_barrier_callback);
+ break;
+ }
}
-/**
- * rcu_barrier - Wait until all the in-flight RCUs are complete.
+/*
+ * Orchestrate the specified type of RCU barrier, waiting for all
+ * RCU callbacks of the specified type to complete.
*/
-void rcu_barrier(void)
+static void _rcu_barrier(enum rcu_barrier type)
{
BUG_ON(in_interrupt());
/* Take cpucontrol mutex to protect against CPU hotplug */
@@ -111,13 +128,39 @@ void rcu_barrier(void)
* until all the callbacks are queued.
*/
rcu_read_lock();
- on_each_cpu(rcu_barrier_func, NULL, 0, 1);
+ on_each_cpu(rcu_barrier_func, (void *)type, 0, 1);
rcu_read_unlock();
wait_for_completion(&rcu_barrier_completion);
mutex_unlock(&rcu_barrier_mutex);
}
+
+/**
+ * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete.
+ */
+void rcu_barrier(void)
+{
+ _rcu_barrier(RCU_BARRIER_STD);
+}
EXPORT_SYMBOL_GPL(rcu_barrier);
+/**
+ * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete.
+ */
+void rcu_barrier_bh(void)
+{
+ _rcu_barrier(RCU_BARRIER_BH);
+}
+EXPORT_SYMBOL_GPL(rcu_barrier_bh);
+
+/**
+ * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks.
+ */
+void rcu_barrier_sched(void)
+{
+ _rcu_barrier(RCU_BARRIER_SCHED);
+}
+EXPORT_SYMBOL_GPL(rcu_barrier_sched);
+
void __init rcu_init(void)
{
__rcu_init();
--
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