Date: Tue, 14 Dec 2010 17:42:03 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: "Suzuki K. Poulose" <suzuki@in.ibm.com>
Cc: linux-kernel@vger.kernel.org,
        Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
        Christoph Hellwig <hch@lst.de>, Masami Hiramatsu <mhiramat@redhat.com>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com>,
        Andi Kleen <andi@firstfloor.org>, Roland McGrath <roland@redhat.com>,
        Amerigo Wang <amwang@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [Patch 16/21] Wait for threads to freeze
Message-ID: <20101214164203.GI11400@redhat.com>
References: <20101214152259.67896960@suzukikp> <20101214154900.2d7a643c@suzukikp>
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On 12/14, Suzuki K. Poulose wrote:
>
> + * zero_thread_state :
> + * For threads, which are not frozen, we cannot capture the register state.

Indeed, but

> +		if (!tinfo->frozen)
> +			zero_thread_state(tinfo);

Again, we can race with TASK_STOPPED/SIGCONT. And
is_task_frozen_enough() thins task_is_stopped_or_traced() is fine.

Oleg.

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