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SubjectRe: Remaining crypto API regressions with CONFIG_VMAP_STACK
On Tue, Dec 13, 2016 at 09:06:31AM -0800, Andy Lutomirski wrote:
>
> > Having 0 as type and CRYPTO_ALG_ASYNC as mask in general means
> > that we're requesting a sync algorithm (i.e., ASYNC bit off).
> >
> > However, it is completely unnecessary for shash as they can never
> > be async. So this could be changed to just ("michael_mic", 0, 0).
>
> I'm confused by a bunch of this.
>
> 1. Is it really the case that crypto_alloc_xyz(..., CRYPTO_ALG_ASYNC)
> means to allocate a *synchronous* transform? That's not what I
> expected.

crypto_alloc_xyz(name, 0, CRYPTO_ALG_ASYNC) allocates a sync tfm
and crypto_alloc_xyz(name, CRYPTO_ALG_ASYNC, CRYPTO_ALG_ASYNC)
allocates an async tfm while crypto_alloc_xyz(name, 0, 0) does
not care whether the allocated tfm is sync or asnc.

> 2. What guarantees that an async request is never allocated on the
> stack? If it's just convention, could an assertion be added
> somewhere?

Sure we can add an assertion.

Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

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