From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
josht@linux.vnet.ibm.com, akpm@linux-foundation.org,
mathieu.desnoyers@polymtl.ca, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org,
hugh.dickins@tiscali.co.uk, benh@kernel.crashing.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH -tip/core/rcu 3/6] Simplify RCU CPU-hotplug notification
Date: Sat, 15 Aug 2009 09:53:48 -0700 [thread overview]
Message-ID: <12503552312510-git-send-email-> (raw)
In-Reply-To: <20090815165153.GA8886@linux.vnet.ibm.com>
From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Use the new cpu_notifier() API to simplify RCU's CPU-hotplug
notifiers, collapsing down to a single such notifier. This
makes it trivial to provide the notifier-ordering guarantee
that rcu_barrier() depends on. Also remove redundant
open_softirq() calls from Hierarchical RCU notifier.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcupdate.c | 16 +++++++++++++++-
kernel/rcupreempt.c | 25 ++-----------------------
kernel/rcutree.c | 17 +++++------------
3 files changed, 22 insertions(+), 36 deletions(-)
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index eae29c2..8df1156 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -217,9 +217,13 @@ static void rcu_migrate_callback(struct rcu_head *notused)
wake_up(&rcu_migrate_wq);
}
+extern int rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu);
+
static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
unsigned long action, void *hcpu)
{
+ rcu_cpu_notify(self, action, hcpu);
if (action == CPU_DYING) {
/*
* preempt_disable() in on_each_cpu() prevents stop_machine(),
@@ -244,8 +248,18 @@ static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
void __init rcu_init(void)
{
+ int i;
+
__rcu_init();
- hotcpu_notifier(rcu_barrier_cpu_hotplug, 0);
+ cpu_notifier(rcu_barrier_cpu_hotplug, 0);
+
+ /*
+ * We don't need protection against CPU-hotplug here because
+ * this is called early in boot, before either interrupts
+ * or the scheduler are operational.
+ */
+ for_each_online_cpu(i)
+ rcu_barrier_cpu_hotplug(NULL, CPU_UP_PREPARE, (void *)(long)i);
}
void rcu_scheduler_starting(void)
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index beb0e65..9b87f51 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -1417,8 +1417,8 @@ int rcu_pending(int cpu)
return 0;
}
-static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
+int __cpuinit rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
@@ -1439,10 +1439,6 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
return NOTIFY_OK;
}
-static struct notifier_block __cpuinitdata rcu_nb = {
- .notifier_call = rcu_cpu_notify,
-};
-
void __init __rcu_init(void)
{
int cpu;
@@ -1471,23 +1467,6 @@ void __init __rcu_init(void)
rdp->waitschedtail = &rdp->waitschedlist;
rdp->rcu_sched_sleeping = 0;
}
- register_cpu_notifier(&rcu_nb);
-
- /*
- * We don't need protection against CPU-Hotplug here
- * since
- * a) If a CPU comes online while we are iterating over the
- * cpu_online_mask below, we would only end up making a
- * duplicate call to rcu_online_cpu() which sets the corresponding
- * CPU's mask in the rcu_cpu_online_map.
- *
- * b) A CPU cannot go offline at this point in time since the user
- * does not have access to the sysfs interface, nor do we
- * suspend the system.
- */
- for_each_online_cpu(cpu)
- rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long) cpu);
-
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
}
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index f3e4327..75762cd 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1132,6 +1132,8 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
{
unsigned long flags;
+ WARN_ON_ONCE(rdp->beenonline == 0);
+
/*
* If an RCU GP has gone long enough, go check for dyntick
* idle CPUs and, if needed, send resched IPIs.
@@ -1416,14 +1418,13 @@ static void __cpuinit rcu_online_cpu(int cpu)
{
rcu_init_percpu_data(cpu, &rcu_state);
rcu_init_percpu_data(cpu, &rcu_bh_state);
- open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
}
/*
* Handle CPU online/offline notifcation events.
*/
-static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
+int __cpuinit rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
@@ -1532,10 +1533,6 @@ do { \
} \
} while (0)
-static struct notifier_block __cpuinitdata rcu_nb = {
- .notifier_call = rcu_cpu_notify,
-};
-
void __init __rcu_init(void)
{
int i; /* All used by RCU_DATA_PTR_INIT(). */
@@ -1554,11 +1551,7 @@ void __init __rcu_init(void)
RCU_DATA_PTR_INIT(&rcu_bh_state, rcu_bh_data);
for_each_possible_cpu(i)
rcu_boot_init_percpu_data(i, &rcu_bh_state);
-
- for_each_online_cpu(i)
- rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long)i);
- /* Register notifier for non-boot CPUs */
- register_cpu_notifier(&rcu_nb);
+ open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
}
module_param(blimit, int, 0);
--
1.5.2.5
next prev parent reply other threads:[~2009-08-15 16:54 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-15 16:51 [PATCH -tip/core/rcu 1/6] Cleanups and fixes for RCU in face of heavy CPU-hotplug stress Paul E. McKenney
2009-08-15 16:53 ` [PATCH -tip/core/rcu 1/6] Split hierarchical RCU initialization into boot-time and CPU-online pieces Paul E. McKenney
2009-08-15 17:07 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-15 16:53 ` [PATCH -tip/core/rcu 2/6] Introduce cpu_notifier() to handle !HOTPLUG_CPU case Paul E. McKenney
2009-08-15 17:07 ` [tip:core/rcu] cpu hotplug: " tip-bot for Paul E. McKenney
2009-08-17 17:21 ` [PATCH -tip/core/rcu 2/6] " Josh Triplett
2009-08-17 18:28 ` Paul E. McKenney
2009-08-15 16:53 ` Paul E. McKenney [this message]
2009-08-15 17:07 ` [tip:core/rcu] rcu: Simplify RCU CPU-hotplug notification tip-bot for Paul E. McKenney
2009-08-20 4:02 ` [PATCH -tip/core/rcu 3/6] " Lai Jiangshan
2009-08-20 4:21 ` Paul E. McKenney
2009-08-15 16:53 ` [PATCH -tip/core/rcu 4/6] Make preemptable RCU scan all CPUs when summing RCU counters Paul E. McKenney
2009-08-15 17:07 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-15 16:53 ` [PATCH -tip/core/rcu 5/6] Make rcupreempt_trace.c look at offline CPUs Paul E. McKenney
2009-08-15 17:07 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-15 16:53 ` [PATCH -tip/core/rcu 6/6] Fix typo in rcu_irq_exit() comment header Paul E. McKenney
2009-08-15 17:00 ` Ingo Molnar
2009-08-15 17:10 ` Paul E. McKenney
2009-08-15 17:11 ` Ingo Molnar
2009-08-15 17:08 ` [tip:core/rcu] rcu: " tip-bot for Josh Triplett
2009-08-17 18:24 ` [PATCH -tip/core/rcu 1/6] Cleanups and fixes for RCU in face of heavy CPU-hotplug stress Josh Triplett
2009-08-17 19:20 ` Paul E. McKenney
2009-08-18 15:26 ` Ingo Molnar
2009-08-18 20:07 ` Paul E. McKenney
2009-08-19 6:06 ` Paul E. McKenney
2009-08-19 11:59 ` Ingo Molnar
2009-08-19 12:09 ` [tip:core/rcu] rcu: Delay rcu_barrier() wait until beginning of next CPU-hotunplug operation tip-bot for Paul E. McKenney
2009-08-19 15:24 ` [PATCH -tip/core/rcu 1/6] Cleanups and fixes for RCU in face of heavy CPU-hotplug stress Mathieu Desnoyers
2009-08-19 16:38 ` Paul E. McKenney
2009-08-19 18:10 ` Mathieu Desnoyers
2009-08-19 18:31 ` Paul E. McKenney
2009-08-20 14:03 ` Mathieu Desnoyers
2009-08-21 14:17 ` Ingo Molnar
2009-08-21 14:29 ` Steven Rostedt
2009-08-21 14:44 ` Ingo Molnar
2009-08-21 15:00 ` Mathieu Desnoyers
2009-08-21 15:37 ` Paul E. McKenney
2009-08-21 14:58 ` Mathieu Desnoyers
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