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To:     Eric Biggers <ebiggers@kernel.org>
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Subject: RE: :Re: [PATCH v2 04/19] crypto: x86/sha - limit FPU preemption
Thread-Topic: :Re: [PATCH v2 04/19] crypto: x86/sha - limit FPU preemption
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Date:   Thu, 13 Oct 2022 22:41:58 +0000
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> > diff --git a/arch/x86/crypto/sha1_ssse3_glue.c
...
> > +	do {
> > +		unsigned int chunk =3D min(len, FPU_BYTES);
> > +
> > +		if (chunk) {
> > +			kernel_fpu_begin();
> > +			sha1_base_do_update(desc, data, chunk, sha1_xform);
> > +			kernel_fpu_end();
> > +		}
> > +
> > +		len -=3D chunk;
> > +		data +=3D chunk;
> > +	} while (len);
>=20
> 'len' can't be 0 at the beginning of this loop, so the 'if (chunk)' check
> isn't needed.  And it wouldn't make sense even if 'len' could be 0, since
> a while loop could just be used in that case.

Thanks, I'll remove that if from all the sha functions, since they do
have that protective check upfront. I'll review the 0 byte handling in
all of them.