linux-kernel - Re: [RFC][PATCH -next] make pstore/kmsg_dump run after stopping other cpus in panic path

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Message-ID: <4E9BC972.8010909@linux.intel.com>
Date:	Mon, 17 Oct 2011 14:21:38 +0800
From:	Chen Gong <gong.chen@...ux.intel.com>
To:	Seiji Aguchi <seiji.aguchi@....com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Luck, Tony" <tony.luck@...el.com>,
	Don Zickus <dzickus@...hat.com>,
	Matthew Garrett <mjg@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	"Chen, Gong" <gong.chen@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"len.brown@...el.com" <len.brown@...el.com>,
	"ying.huang@...el.com" <ying.huang@...el.com>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	"hughd@...omium.org" <hughd@...omium.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"a.p.zijlstra@...llo.nl" <a.p.zijlstra@...llo.nl>,
	"namhyung@...il.com" <namhyung@...il.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: Re: [RFC][PATCH -next] make pstore/kmsg_dump run after stopping other
 cpus in panic path

于 2011/10/15 4:53, Seiji Aguchi 写道:
> Hi,
>
>   As Don mentioned in following thread, it would be nice for pstore/kmsg_dump to serialize
>   panic path and have one cpu running because they can log messages reliably.
>
>   https://lkml.org/lkml/2011/10/13/427
>
>   For realizing this idea, we have to move kmsg_dump below smp_send_stop() and bust some locks
>   of kmsg_dump/pstore in panic path.
>
>   This patch does followings.
>
>    - moving kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop.
>    - busting logbuf_lock of kmsg_dump() in panic path for avoiding deadlock.
>    - busting psinfo->buf_lock of pstore_dump() in panic path for avoiding deadlock.
>
> Any comments are welcome.
>

Hi, Seiji

I have a stupid question: since you have serialized the process procedure via 
smp_send_stop, why still using spin_lock_xxx? Maybe preempt_disable/enable is 
enough?
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