linux-kernel - Re: [PATCH v3 01/28] crypto: change backlog return code to -EIOCBQUEUED

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Date:   Mon, 3 Jul 2017 20:35:15 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Gilad Ben-Yossef <gilad@...yossef.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jonathan Corbet <corbet@....net>,
        David Howells <dhowells@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Gary Hook <gary.hook@....com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Arnaud Ebalard <arno@...isbad.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        Shaohua Li <shli@...nel.org>, Steve French <sfrench@...ba.org>,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <james.l.morris@...cle.com>,
        "Serge E. Hallyn" <serge@...lyn.com>, linux-crypto@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        keyrings@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-raid@...r.kernel.org,
        linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
        linux-fscrypt@...r.kernel.org,
        linux-ima-devel@...ts.sourceforge.net,
        linux-ima-user@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org,
        Ofir Drang <ofir.drang@....com>
Subject: Re: [PATCH v3 01/28] crypto: change backlog return code to
 -EIOCBQUEUED

On Sun, Jul 02, 2017 at 05:41:43PM +0300, Gilad Ben-Yossef wrote:
> The crypto API was using the -EBUSY return value to indicate
> both a hard failure to submit a crypto operation into a
> transformation provider when the latter was busy and the backlog
> mechanism was not enabled as well as a notification that the operation
> was queued into the backlog when the backlog mechanism was enabled.
> 
> Having the same return code indicate two very different conditions
> depending on a flag is both error prone and requires extra runtime
> check like the following to discern between the cases:
> 
> 	if (err == -EINPROGRESS ||
> 	    (err == -EBUSY && (ahash_request_flags(req) &
> 			       CRYPTO_TFM_REQ_MAY_BACKLOG)))
> 
> This patch changes the return code used to indicate a crypto op
> was queued in the backlog to -EIOCBQUEUED, thus resolving both
> issues.
> 
> Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>

So you're changing the success case from EBUSY to EIOCBQUEUED.
This results in a lot of churn as you have to change every single
driver and caller.

How about changing the error case to use something other than
EBUSY instead?

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