From: Oleg Nesterov <oleg@tv-sign.ru>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: ego@in.ibm.com, Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Srivatsa Vaddagiri <vatsa@in.ibm.com>,
Dipankar Sarma <dipankar@in.ibm.com>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC PATCH 4/5] Remove CPU_DEAD/CPU_UP_CANCELLED handling from workqueue.c
Date: Wed, 24 Oct 2007 17:44:04 +0400 [thread overview]
Message-ID: <20071024134404.GB82@tv-sign.ru> (raw)
In-Reply-To: <200710241721.05163.rusty@rustcorp.com.au>
On 10/24, Rusty Russell wrote:
>
> On Wednesday 24 October 2007 15:37:16 Gautham R Shenoy wrote:
> > @@ -712,7 +712,7 @@ static void start_workqueue_thread(struc
> >
> > if (p != NULL) {
> > if (cpu >= 0)
> > - kthread_bind(p, cpu);
> > + set_cpus_allowed(p, cpumask_of_cpu(cpu));
> > wake_up_process(p);
> > }
>
> Hi Gautham!
>
> This works, although the change is unnecessary.
kthread_bind() changes ->cpu/->cpus_allowed without any locks.
Currently this is possible because nobody can wakeup the new thread
after wait_task_inactive() succeeds. With this patch this is not true
any longer, cwq->thread can sleep, for example, on cwq->more_work.
Oleg.
next prev parent reply other threads:[~2007-10-24 13:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-24 5:29 [RFC PATCH 0/5] Refcount based Cpu Hotplug. V2 Gautham R Shenoy
2007-10-24 5:30 ` [RFC PATCH 1/5] Refcount Based Cpu Hotplug implementation Gautham R Shenoy
2007-10-24 5:32 ` [RFC PATCH 2/5] Replace lock_cpu_hotplug() with get_online_cpus() Gautham R Shenoy
2007-10-24 5:34 ` [RFC PATCH 3/5] Replace per-subsystem mutexes " Gautham R Shenoy
2007-10-24 5:37 ` [RFC PATCH 4/5] Remove CPU_DEAD/CPU_UP_CANCELLED handling from workqueue.c Gautham R Shenoy
2007-10-24 7:21 ` Rusty Russell
2007-10-24 8:35 ` Gautham R Shenoy
2007-10-24 13:44 ` Oleg Nesterov [this message]
2007-10-24 13:38 ` Oleg Nesterov
2007-10-24 17:45 ` Gautham R Shenoy
2007-10-24 18:14 ` Oleg Nesterov
2007-10-24 5:39 ` [RFC PATCH 5/5] Update get_online_cpus() in Documentation/cpu-hotplug.c Gautham R Shenoy
2007-10-24 17:04 ` [RFC PATCH 0/5] Refcount based Cpu Hotplug. V2 Christoph Lameter
2007-10-24 18:00 ` Gautham R Shenoy
2007-10-24 18:17 ` Oleg Nesterov
2007-10-24 18:22 ` Gautham R Shenoy
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