linux-kernel - Re: [RFC][PATCH -mmotm 1/4] Add static function calls of pstore to kexec path

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Date:	Tue, 19 Jul 2011 20:27:54 +0100
From:	Matthew Garrett <mjg@...hat.com>
To:	Seiji Aguchi <seiji.aguchi@....com>
Cc:	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Americo Wang <xiyou.wangcong@...il.com>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jarod Wilson <jwilson@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: Re: [RFC][PATCH -mmotm 1/4] Add static function calls of pstore to
 kexec path

On Tue, Jul 19, 2011 at 03:14:22PM -0400, Seiji Aguchi wrote:
> 
> >And how does that handle the case where we're halfway through a pstore
> >access when the NMI arrives? ERST, at least, has a complex state
> >machine. You can't guarantee what starting one transaction without
> >completing one that was in process will do.
> 
> As for ERST, write access is protected by raw_spin_trylock_irqsave(&erst_lock).
> Are there anything I'm missing?

If there's already locking involved, what benefit does removing the lock 
in the pstore code give? You'll just hang when you hit the erst code 
instead of the pstore code.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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