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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
	Arjan van de Veen <arjan@infradead.org>,
	Paul Turner <pjt@google.com>,
	Richard Weinberger <rw@linutronix.de>,
	Magnus Damm <magnus.damm@gmail.com>
Subject: [patch 02/40] stop_machine: Store task reference in a separate per cpu variable
Date: Thu, 31 Jan 2013 12:11:13 -0000
Message-ID: <20130131120741.626690384@linutronix.de> (raw)
In-Reply-To: <20130131120348.372374706@linutronix.de>


[-- Attachment #0: stop-machine-store-thread-separate.patch --]
[-- Type: text/plain, Size: 4222 bytes --]

To allow the stopper thread being managed by the smpboot thread
infrastructure separate out the task storage from the stopper data
structure.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/stop_machine.c |   32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

Index: linux-2.6/kernel/stop_machine.c
===================================================================
--- linux-2.6.orig/kernel/stop_machine.c
+++ linux-2.6/kernel/stop_machine.c
@@ -37,10 +37,10 @@ struct cpu_stopper {
 	spinlock_t		lock;
 	bool			enabled;	/* is this stopper enabled? */
 	struct list_head	works;		/* list of pending works */
-	struct task_struct	*thread;	/* stopper thread */
 };
 
 static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
+static DEFINE_PER_CPU(struct task_struct *, cpu_stopper_task);
 static bool stop_machine_initialized = false;
 
 static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
@@ -62,16 +62,18 @@ static void cpu_stop_signal_done(struct 
 }
 
 /* queue @work to @stopper.  if offline, @work is completed immediately */
-static void cpu_stop_queue_work(struct cpu_stopper *stopper,
-				struct cpu_stop_work *work)
+static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
 {
+	struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
+	struct task_struct *p = per_cpu(cpu_stopper_task, cpu);
+
 	unsigned long flags;
 
 	spin_lock_irqsave(&stopper->lock, flags);
 
 	if (stopper->enabled) {
 		list_add_tail(&work->list, &stopper->works);
-		wake_up_process(stopper->thread);
+		wake_up_process(p);
 	} else
 		cpu_stop_signal_done(work->done, false);
 
@@ -108,7 +110,7 @@ int stop_one_cpu(unsigned int cpu, cpu_s
 	struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done };
 
 	cpu_stop_init_done(&done, 1);
-	cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), &work);
+	cpu_stop_queue_work(cpu, &work);
 	wait_for_completion(&done.completion);
 	return done.executed ? done.ret : -ENOENT;
 }
@@ -130,7 +132,7 @@ void stop_one_cpu_nowait(unsigned int cp
 			struct cpu_stop_work *work_buf)
 {
 	*work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, };
-	cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), work_buf);
+	cpu_stop_queue_work(cpu, work_buf);
 }
 
 /* static data for stop_cpus */
@@ -159,8 +161,7 @@ static void queue_stop_cpus_work(const s
 	 */
 	preempt_disable();
 	for_each_cpu(cpu, cpumask)
-		cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu),
-				    &per_cpu(stop_cpus_work, cpu));
+		cpu_stop_queue_work(cpu, &per_cpu(stop_cpus_work, cpu));
 	preempt_enable();
 }
 
@@ -304,12 +305,11 @@ static int __cpuinit cpu_stop_cpu_callba
 {
 	unsigned int cpu = (unsigned long)hcpu;
 	struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
-	struct task_struct *p;
+	struct task_struct *p = per_cpu(cpu_stopper_task, cpu);
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_UP_PREPARE:
-		BUG_ON(stopper->thread || stopper->enabled ||
-		       !list_empty(&stopper->works));
+		BUG_ON(p || stopper->enabled || !list_empty(&stopper->works));
 		p = kthread_create_on_node(cpu_stopper_thread,
 					   stopper,
 					   cpu_to_node(cpu),
@@ -319,12 +319,12 @@ static int __cpuinit cpu_stop_cpu_callba
 		get_task_struct(p);
 		kthread_bind(p, cpu);
 		sched_set_stop_task(cpu, p);
-		stopper->thread = p;
+		per_cpu(cpu_stopper_task, cpu) = p;
 		break;
 
 	case CPU_ONLINE:
 		/* strictly unnecessary, as first user will wake it */
-		wake_up_process(stopper->thread);
+		wake_up_process(p);
 		/* mark enabled */
 		spin_lock_irq(&stopper->lock);
 		stopper->enabled = true;
@@ -339,7 +339,7 @@ static int __cpuinit cpu_stop_cpu_callba
 
 		sched_set_stop_task(cpu, NULL);
 		/* kill the stopper */
-		kthread_stop(stopper->thread);
+		kthread_stop(p);
 		/* drain remaining works */
 		spin_lock_irq(&stopper->lock);
 		list_for_each_entry(work, &stopper->works, list)
@@ -347,8 +347,8 @@ static int __cpuinit cpu_stop_cpu_callba
 		stopper->enabled = false;
 		spin_unlock_irq(&stopper->lock);
 		/* release the stopper */
-		put_task_struct(stopper->thread);
-		stopper->thread = NULL;
+		put_task_struct(p);
+		per_cpu(cpu_stopper_task, cpu) = NULL;
 		break;
 	}
 #endif



  parent reply index

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-31 15:44 [patch 00/40] CPU hotplug rework - episode I Thomas Gleixner
2013-01-31 12:11 ` [patch 01/40] smpboot: Allow selfparking per cpu threads Thomas Gleixner
2013-02-09  0:29   ` Paul E. McKenney
2013-02-14 17:46   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2013-01-31 12:11 ` Thomas Gleixner [this message]
2013-02-09  0:33   ` [patch 02/40] stop_machine: Store task reference in a separate per cpu variable Paul E. McKenney
2013-02-14 17:47   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2013-01-31 12:11 ` [patch 03/40] stop_machine: Use smpboot threads Thomas Gleixner
2013-02-09  0:39   ` Paul E. McKenney
2013-02-14 17:49   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2013-01-31 12:11 ` [patch 04/40] cpu: Restructure FROZEN state handling Thomas Gleixner
2013-02-09  0:52   ` Paul E. McKenney
2014-10-09 16:53   ` Borislav Petkov
2013-01-31 12:11 ` [patch 05/40] cpu: Restructure cpu_down code Thomas Gleixner
2013-02-09  0:49   ` Paul E. McKenney
2014-10-09 17:05   ` Borislav Petkov
2013-01-31 12:11 ` [patch 06/40] cpu: hotplug: Split out cpu down functions Thomas Gleixner
2013-02-09  0:54   ` Paul E. McKenney
2013-01-31 12:11 ` [patch 07/40] cpu: hotplug: Convert to a state machine for the control processor Thomas Gleixner
2013-02-11 20:09   ` Paul E. McKenney
2013-01-31 12:11 ` [patch 08/40] cpu: hotplug: Convert the hotplugged processor work to a state machine Thomas Gleixner
2013-02-11 20:17   ` Paul E. McKenney
2013-01-31 12:11 ` [patch 10/40] sched: Convert to state machine callbacks Thomas Gleixner
2013-02-11 23:46   ` Paul E. McKenney
2013-01-31 12:11 ` [patch 09/40] cpu: hotplug: Implement setup/removal interface Thomas Gleixner
2013-02-01 13:44   ` Hillf Danton
2013-02-01 13:52     ` Thomas Gleixner
2013-01-31 12:11 ` [patch 11/40] x86: uncore: Move teardown callback to CPU_DEAD Thomas Gleixner
2013-01-31 12:11 ` [patch 12/40] x86: uncore: Convert to hotplug state machine Thomas Gleixner
2013-01-31 12:11 ` [patch 13/40] perf: " Thomas Gleixner
2013-01-31 12:11 ` [patch 14/40] x86: perf: Convert the core to the " Thomas Gleixner
2013-01-31 12:11 ` [patch 16/40] blackfin: perf: Convert hotplug notifier to " Thomas Gleixner
2013-01-31 12:11 ` [patch 15/40] x86: perf: Convert AMD IBS to hotplug " Thomas Gleixner
2013-01-31 12:11 ` [patch 17/40] powerpc: perf: Convert book3s notifier to state machine callbacks Thomas Gleixner
2013-01-31 12:11 ` [patch 18/40] s390: perf: Convert the hotplug " Thomas Gleixner
2013-01-31 12:11 ` [patch 19/40] sh: perf: Convert the hotplug notifiers " Thomas Gleixner
2013-01-31 12:11 ` [patch 21/40] sched: Convert the migration callback to hotplug states Thomas Gleixner
2013-01-31 12:11 ` [patch 20/40] perf: Remove perf cpu notifier code Thomas Gleixner
2013-01-31 12:11 ` [patch 22/40] workqueue: Convert to state machine callbacks Thomas Gleixner
2013-01-31 12:11 ` [patch 23/40] cpufreq: Convert to hotplug state machine Thomas Gleixner
2013-01-31 12:11 ` [patch 24/40] arm64: Convert generic timers " Thomas Gleixner
2013-01-31 12:11 ` [patch 25/40] arm: Convert VFP hotplug notifiers to " Thomas Gleixner
2013-01-31 12:11 ` [patch 26/40] arm: perf: Convert to hotplug " Thomas Gleixner
2013-01-31 12:11 ` [patch 27/40] virt: Convert kvm hotplug to " Thomas Gleixner
2013-01-31 12:11 ` [patch 28/40] cpuhotplug: Remove CPU_STARTING notifier Thomas Gleixner
2013-01-31 12:11 ` [patch 29/40] s390: Convert vtime to hotplug state machine Thomas Gleixner
2013-01-31 12:11 ` [patch 30/40] x86: tboot: Convert " Thomas Gleixner
2013-01-31 12:11 ` [patch 31/40] sched: Convert fair nohz balancer " Thomas Gleixner
2013-01-31 12:11 ` [patch 33/40] hrtimer: Convert " Thomas Gleixner
2013-01-31 12:11 ` [patch 32/40] rcu: Convert rcutree " Thomas Gleixner
2013-02-12  0:01   ` Paul E. McKenney
2013-02-12 15:50     ` Paul E. McKenney
2013-01-31 12:11 ` [patch 34/40] cpuhotplug: Remove CPU_DYING notifier Thomas Gleixner
2013-01-31 12:11 ` [patch 35/40] timers: Convert to hotplug state machine Thomas Gleixner
2013-01-31 12:11 ` [patch 36/40] profile: Convert ot " Thomas Gleixner
2013-01-31 12:11 ` [patch 37/40] x86: x2apic: Convert to cpu " Thomas Gleixner
2013-01-31 12:11 ` [patch 38/40] smp: Convert core to " Thomas Gleixner
2013-01-31 12:11 ` [patch 39/40] relayfs: Convert " Thomas Gleixner
2013-01-31 12:11 ` [patch 40/40] slab: " Thomas Gleixner
2013-01-31 20:23 ` [patch 00/40] CPU hotplug rework - episode I Andrew Morton
2013-01-31 21:48   ` Thomas Gleixner
2013-01-31 21:59     ` Linus Torvalds
2013-01-31 22:44       ` Thomas Gleixner
2013-01-31 22:55         ` Linus Torvalds
2013-02-01 10:51           ` Thomas Gleixner
2013-02-07  4:01             ` Rusty Russell
2013-02-09  0:28 ` Paul E. McKenney

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