From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Subbaraman Narayanamurthy <subbaram@codeaurora.org>,
daniel@numascale.com, yuyang.du@intel.com,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH]: kthread: Fix memory ordering in __kthread_parkme
Date: Fri, 7 Nov 2014 19:41:03 +0100 [thread overview]
Message-ID: <20141107184103.GA16043@redhat.com> (raw)
In-Reply-To: <20141107102855.GA29390@twins.programming.kicks-ass.net>
On 11/07, Peter Zijlstra wrote:
>
> static void __kthread_parkme(struct kthread *self)
> {
> - __set_current_state(TASK_PARKED);
> + set_current_state(TASK_PARKED);
> while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) {
> if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags))
> complete(&self->parked);
> schedule();
> - __set_current_state(TASK_PARKED);
> + set_current_state(TASK_PARKED);
> }
Perhaps it makses sense to do set_current_state(PARKED) once at the start
of "for (;;)" loop, but this is cosmetic.
What if kthread_unpark() is called right after test_bit(KTHREAD_SHOULD_PARK)
and KTHREAD_IS_PARKED is not set? It seems that __kthread_unpark() should
call wake_up_state() unconditionally ?
Oleg.
next prev parent reply other threads:[~2014-11-07 18:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-06 15:01 hotplug thread issues Peter Zijlstra
2014-11-07 9:39 ` Thomas Gleixner
2014-11-07 10:28 ` [PATCH]: kthread: Fix memory ordering in __kthread_parkme Peter Zijlstra
2014-11-07 18:41 ` Oleg Nesterov [this message]
2014-11-07 21:27 ` Peter Zijlstra
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