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From:   Iuliana Prodan <iuliana.prodan@nxp.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>
CC:     Baolin Wang <baolin.wang@linaro.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Corentin Labbe <clabbe.montjoie@gmail.com>,
        Horia Geanta <horia.geanta@nxp.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
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        Maxime Ripard <mripard@kernel.org>,
        Aymen Sghaier <aymen.sghaier@nxp.com>,
        "David S. Miller" <davem@davemloft.net>,
        Silvano Di Ninno <silvano.dininno@nxp.com>,
        Franck Lenormand <franck.lenormand@nxp.com>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH v5 2/3] crypto: engine - support for parallel requests
 based on retry mechanism
Thread-Topic: [PATCH v5 2/3] crypto: engine - support for parallel requests
 based on retry mechanism
Thread-Index: AQHWE2Qot8PxFDaTpUuNLpWYBZnAxA==
Date:   Fri, 24 Apr 2020 14:34:57 +0000
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On 4/23/2020 2:47 PM, Herbert Xu wrote:=0A=
> On Wed, Apr 15, 2020 at 11:26:14PM +0300, Iuliana Prodan wrote:=0A=
>> Added support for executing multiple requests, in parallel,=0A=
>> for crypto engine based on a retry mechanism.=0A=
>> If hardware was unable to execute a backlog request, enqueue it=0A=
>> back in front of crypto-engine queue, to keep the order=0A=
>> of requests.=0A=
>>=0A=
>> A new variable is added, retry_support (this is to keep the=0A=
>> backward compatibility of crypto-engine) , which keeps track=0A=
>> whether the hardware has support for retry mechanism and,=0A=
>> also, if can run multiple requests.=0A=
>>=0A=
>> If do_one_request() returns:=0A=
>>> =3D 0: hardware executed the request successfully;=0A=
>> < 0: this is the old error path. If hardware has support for retry=0A=
>> mechanism, the request is put back in front of crypto-engine queue.=0A=
>> For backwards compatibility, if the retry support is not available,=0A=
>> the crypto-engine will work as before.=0A=
>> Only MAY_BACKLOG requests are enqueued back into=0A=
>> crypto-engine's queue, since the others can be dropped.=0A=
> =0A=
> This looks a lot nicer!=0A=
> =0A=
> However, I do have one little issue with the error case.  I think=0A=
> we should not lump all errors together.  For queueing errors, we=0A=
> should requeue regardless of MAY_BACKLOG.  After all, we don't=0A=
> want to have random packet loss just becayse the queue was full.=0A=
> =0A=
> For other errors (e.g., a kmalloc error), we should requeue the=0A=
> MAY_BACKLOG requests and drop everythin else.=0A=
> =0A=
=0A=
Do you refer to the error codes returned by do_one_request (which sends =0A=
the req to hw for execution)?=0A=
=0A=
If this returns:=0A=
1. 0, success;=0A=
2. -ENOSPC, I'll requeue it regardless of MAY_BACKLOG;=0A=
3. any other error (-EIO, -EINVAL, -ENOMEM, etc), I'll requeue only =0A=
MAY_BACKLOG requests.=0A=
=0A=
Thanks,=0A=
Iulia=0A=