| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Fri, 8 Feb 2013 16:33:02 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Rusty Russell <rusty@...tcorp.com.au>,
"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
Arjan van de Veen <arjan@...radead.org>,
Paul Turner <pjt@...gle.com>,
Richard Weinberger <rw@...utronix.de>,
Magnus Damm <magnus.damm@...il.com>
Subject: Re: [patch 02/40] stop_machine: Store task reference in a separate
per cpu variable
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@...utronix.de>
Reviewed-by: Paul E. McKenney <paulmck@...ux.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
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists