linux-kernel - Re: [BUGFIX 2/3] crypto: Remove CRYPTO_TFM_REQ_MAY_SLEEP flag in AES-NI accelerated ecb/cbc mode

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Date:	Fri, 19 Jun 2009 08:55:20 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
Subject: Re: [BUGFIX 2/3] crypto: Remove CRYPTO_TFM_REQ_MAY_SLEEP flag in
 AES-NI accelerated ecb/cbc mode

On Thu, 2009-06-18 at 19:40 +0800, Herbert Xu wrote:
> On Mon, Jun 15, 2009 at 05:04:57PM +0800, Huang Ying wrote:
> > Because AES-NI instructions will touch XMM state, corresponding code
> > must be enclosed within kernel_fpu_begin/end, which used
> > preempt_disable/enable. So sleep should be prevented between
> > kernel_fpu_begin/end.
> > 
> > Signed-off-by: Huang Ying <ying.huang@...el.com>
> 
> I'll apply this for now.  But it would be much better to allow
> sleeping in this case.
> 
> Couldn't we simply move the kernel_fpu_begin/end inside the loop?
> It shouldn't be too expensive when it runs the 2nd time since it
> doesn't have to save anything, right?

I will test the performance difference.

Best Regards,
Huang Ying


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