linux-kernel - Re: [PATCH 2/7] freezer: add missing mb's to freezer_count() and freezer_should

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Message-ID: <20121024185710.GA12182@atj.dyndns.org>
Date:	Wed, 24 Oct 2012 14:57:10 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	rjw@...k.pl, linux-kernel@...r.kernel.org, lizefan@...wei.com,
	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH 2/7] freezer: add missing mb's to freezer_count() and
 freezer_should_skip()

Hello, Oleg.

On Tue, Oct 23, 2012 at 05:39:19PM +0200, Oleg Nesterov wrote:
> > Hmm....  Guess we should drop __ from set_current_state.
> 
> Yes.
> 
> Or we can change ptrace_stop() and do_signal_stop() to use freezer_do_not_count/
> freezer_count and remove task_is_stopped_or_traced() from update_if_frozen()
> and try_to_freeze_tasks(). But this means that do_signal_stop() will call
> try_to_freeze() twice, unless we add __freezer_count() which only clears
> PF_FREEZER_SKIP.

Ooh, I like this idea.  If we have a mechanism to mark a task "frozen
enough", it makes sense to use it universally.  As long as
try_to_freeze() invocation stays outside fast path, I don't think
invoking it twice really matters.  Can you please cook up a patch for
it?

Thanks.

--
tejun
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