linux-kernel - Re: [PATCH 5/9] crypto: engine: add enqueue_request/can_do

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Date:   Mon, 27 Jan 2020 22:58:36 +0000
From:   Iuliana Prodan <iuliana.prodan@....com>
To:     Corentin Labbe <clabbe.montjoie@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "mripard@...nel.org" <mripard@...nel.org>,
        "wens@...e.org" <wens@...e.org>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-sunxi@...glegroups.com" <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH 5/9] crypto: engine: add enqueue_request/can_do_more

On 1/22/2020 12:45 PM, Corentin Labbe wrote:
> This patchs adds two new function wrapper in crypto_engine.
> - enqueue_request() for drivers enqueuing request to hardware.
> - can_queue_more() for letting drivers to tell if they can
> enqueue/prepare more.
> 
> Since some drivers (like caam) only enqueue request without "doing"
> them, do_one_request() is now optional.
> 
> Signed-off-by: Corentin Labbe <clabbe.montjoie@...il.com>
> ---
>   crypto/crypto_engine.c  | 25 ++++++++++++++++++++++---
>   include/crypto/engine.h | 14 ++++++++------
>   2 files changed, 30 insertions(+), 9 deletions(-)
> 
> diff --git a/crypto/crypto_engine.c b/crypto/crypto_engine.c
> index 5bcb1e740fd9..4a28548c49aa 100644
> --- a/crypto/crypto_engine.c
> +++ b/crypto/crypto_engine.c
> @@ -83,6 +83,7 @@ static void crypto_pump_requests(struct crypto_engine *engine,
>   		goto out;
>   	}
>   
> +retry:
>   	/* Get the fist request from the engine queue to handle */
>   	backlog = crypto_get_backlog(&engine->queue);
>   	async_req = crypto_dequeue_request(&engine->queue);
> @@ -118,10 +119,28 @@ static void crypto_pump_requests(struct crypto_engine *engine,
>   			goto req_err2;
>   		}
>   	}
> +
> +	if (enginectx->op.enqueue_request) {
> +		ret = enginectx->op.enqueue_request(engine, async_req);
> +		if (ret) {
> +			dev_err(engine->dev, "failed to enqueue request: %d\n",
> +				ret);
> +			goto req_err;
> +		}
> +	}
> +	if (enginectx->op.can_queue_more && engine->queue.qlen > 0) {
> +		ret = enginectx->op.can_queue_more(engine, async_req);
> +		if (ret > 0) {
> +			spin_lock_irqsave(&engine->queue_lock, flags);
> +			goto retry;
> +		}
> +		if (ret < 0) {
> +			dev_err(engine->dev, "failed to call can_queue_more\n");
> +			/* TODO */
> +		}
> +	}
>   	if (!enginectx->op.do_one_request) {
> -		dev_err(engine->dev, "failed to do request\n");
> -		ret = -EINVAL;
> -		goto req_err;
> +		return;
>   	}
>   	ret = enginectx->op.do_one_request(engine, async_req);
>   	if (ret) {
> diff --git a/include/crypto/engine.h b/include/crypto/engine.h
> index 03d9f9ec1cea..8ab9d26e30fe 100644
> --- a/include/crypto/engine.h
> +++ b/include/crypto/engine.h
> @@ -63,14 +63,16 @@ struct crypto_engine {
>    * @prepare__request: do some prepare if need before handle the current request
>    * @unprepare_request: undo any work done by prepare_request()
>    * @do_one_request: do encryption for current request
> + * @enqueue_request:	Enqueue the request in the hardware
> + * @can_queue_more:	if this function return > 0, it will tell the crypto
> + * 	engine that more space are availlable for prepare/enqueue request
>    */
>   struct crypto_engine_op {
> -	int (*prepare_request)(struct crypto_engine *engine,
> -			       void *areq);
> -	int (*unprepare_request)(struct crypto_engine *engine,
> -				 void *areq);
> -	int (*do_one_request)(struct crypto_engine *engine,
> -			      void *areq);
> +	int (*prepare_request)(struct crypto_engine *engine, void *areq);
> +	int (*unprepare_request)(struct crypto_engine *engine, void *areq);
> +	int (*do_one_request)(struct crypto_engine *engine, void *areq);
> +	int (*enqueue_request)(struct crypto_engine *engine, void *areq);
> +	int (*can_queue_more)(struct crypto_engine *engine, void *areq);
>   };

As I mentioned in another thread [1], these crypto-engine patches (#1 - 
#5) imply modifications in all the drivers that use crypto-engine.
It's not backwards compatible.
Your changes imply that do_one_request executes the request & waits for 
completion and enqueue_request sends it to hardware. That means that all 
the other drivers need to be modify, to implement enqueue_request, 
instead of do_one_request. They need to be compliant with the new 
changes, new API. Otherwise, they are not using crypto-engine right, 
don't you think?

Also, do_one_request it shouldn’t be blocking. We got this confirmation 
from Herbert [2].

[1] 
https://lore.kernel.org/lkml/VI1PR04MB44455343230CBA7400D21C998C0C0@VI1PR04MB4445.eurprd04.prod.outlook.com/
[2] 
https://lore.kernel.org/lkml/20200122144134.axqpwx65j7xysyy3@gondor.apana.org.au/