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Date: Tue, 19 Jul 2011 20:40:36 +0100
From: Matthew Garrett <mjg@redhat.com>
To: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: "kexec@lists.infradead.org" <kexec@lists.infradead.org>,
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Subject: Re: [RFC][PATCH -mmotm 1/4] Add static function calls of pstore to
 kexec path
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On Tue, Jul 19, 2011 at 08:27:54PM +0100, Matthew Garrett wrote:
> 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.

I'm sorry, you're right, this is a trylock so we won't hang in this 
case. We should probably document that in the pstore documentation to 
ensure that any future backends have the same behaviour.

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