linux-kernel - Re: [PATCH 1/2] efi: Provide a non-blocking SetVariable() operation

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Message-ID: <20141001161151.GD14343@console-pimps.org>
Date:	Wed, 1 Oct 2014 17:11:51 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH 1/2] efi: Provide a non-blocking SetVariable() operation

On Wed, 01 Oct, at 05:26:24PM, Peter Zijlstra wrote:
> 
> If you want to have this usable from NMI context, you need to convert
> efi_runtime_lock to a raw_spinlock_t.
 
Hmm.. I note that none of the spinlocks in the pstore code path that we
execute to get here are raw_spinlock_t. And that's the only code path
that calls this function.

They need to be raw_spinlock_t for -rt?

> Also, it would probably be a good idea to have some selftest like thing
> that actually calls this from NMI context, right?

Yeah probably, although that'd need to be a core pstore test since
there's nothing really interesting going on in
virt_efi_set_variable_nonblocking(), and it would be good to test it out
in the larger pstore context.

-- 
Matt Fleming, Intel Open Source Technology Center
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