linux-kernel - Re: [PATCH 03/13] crypto: x86/sha - yield FPU context during long loops

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Date:   Thu, 12 Jan 2023 10:46:42 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Robert Elliott <elliott@....com>, davem@...emloft.net,
        Jason@...c4.com, ardb@...nel.org, ap420073@...il.com,
        David.Laight@...lab.com, tim.c.chen@...ux.intel.com,
        peter@...jl.ca, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, linux-crypto@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/13] crypto: x86/sha - yield FPU context during long
 loops

On Thu, Jan 12, 2023 at 04:05:55PM +0800, Herbert Xu wrote:
> On Mon, Dec 19, 2022 at 04:02:13PM -0600, Robert Elliott wrote:
> >
> > @@ -41,9 +41,7 @@ static int sha1_update(struct shash_desc *desc, const u8 *data,
> 
> I just realised a show-stopper with this patch-set.  We don't
> have a desc->flags field that tells us whether we can sleep or
> not.
> 
> I'm currently doing a patch-set for per-request keys and I will
> add a flags field to shash_desc so we could use that for your
> patch-set too.
> 

Right, this used to exist, but it didn't actually do anything, and it had
suffered heavily from bitrot.  For example, some callers specified MAY_SLEEP
when actually they couldn't sleep.  IIRC, some callers also didn't even bother
initializing the flags, so they were passing uninitialized memory.  So I removed
it in commit 877b5691f27a ("crypto: shash - remove shash_desc::flags").

Has there been any consideration of just adding the crypto_shash_update_large()
helper function that I had mentioned in the commit message of 877b5691f27a?

- Eric