From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Rusty Russell <rusty@rustcorp.com.au>,
"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: Re: [patch 02/40] stop_machine: Store task reference in a separate per cpu variable
Date: Fri, 8 Feb 2013 16:33:02 -0800 [thread overview]
Message-ID: <20130209003302.GW2666@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130131120741.626690384@linutronix.de>
On Thu, Jan 31, 2013 at 12:11:13PM -0000, Thomas Gleixner wrote:
> 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>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> 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
>
>
next prev parent reply other threads:[~2013-02-09 0:33 UTC|newest]
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 ` [patch 02/40] stop_machine: Store task reference in a separate per cpu variable Thomas Gleixner
2013-02-09 0:33 ` Paul E. McKenney [this message]
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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