linux-kernel - Re: [PATCH v2 1/2] crypto: engine

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Message-ID: <20200207121723.GB10979@Red>
Date:   Fri, 7 Feb 2020 13:17:23 +0100
From:   Corentin Labbe <clabbe.montjoie@...il.com>
To:     Iuliana Prodan <iuliana.prodan@....com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        Baolin Wang <baolin.wang@...aro.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Horia Geanta <horia.geanta@....com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Ripard <mripard@...nel.org>,
        Aymen Sghaier <aymen.sghaier@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Silvano Di Ninno <silvano.dininno@....com>,
        Franck Lenormand <franck.lenormand@....com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH v2 1/2] crypto: engine - support for parallel requests

On Fri, Feb 07, 2020 at 11:26:38AM +0000, Iuliana Prodan wrote:
> On 2/5/2020 9:11 PM, Corentin Labbe wrote:
> > On Tue, Feb 04, 2020 at 02:34:19PM +0200, Iuliana Prodan wrote:
> >> Added support for executing multiple requests, in parallel,
> >> for crypto engine.
> >> A new callback is added, can_enqueue_more, which asks the
> >> driver if the hardware has free space, to enqueue a new request.
> >> The new crypto_engine_alloc_init_and_set function, initialize
> >> crypto-engine, sets the maximum size for crypto-engine software
> >> queue (not hardcoded anymore) and the can_enqueue_more callback.
> >> On crypto_pump_requests, if can_enqueue_more callback returns true,
> >> a new request is send to hardware, until there is no space and the
> >> callback returns false.
> >>
> >> Signed-off-by: Iuliana Prodan <iuliana.prodan@....com>
> >> ---
> >>   crypto/crypto_engine.c  | 106 ++++++++++++++++++++++++++++++------------------
> >>   include/crypto/engine.h |  10 +++--
> >>   2 files changed, 72 insertions(+), 44 deletions(-)
> >>
> >> diff --git a/crypto/crypto_engine.c b/crypto/crypto_engine.c
> >> index eb029ff..aba934f 100644
> >> --- a/crypto/crypto_engine.c
> >> +++ b/crypto/crypto_engine.c
> >> @@ -22,32 +22,18 @@
> >>    * @err: error number
> >>    */
> >>   static void crypto_finalize_request(struct crypto_engine *engine,
> >> -			     struct crypto_async_request *req, int err)
> >> +				    struct crypto_async_request *req, int err)
> >>   {
> >> -	unsigned long flags;
> >> -	bool finalize_cur_req = false;
> >>   	int ret;
> >>   	struct crypto_engine_ctx *enginectx;
> >>   
> >> -	spin_lock_irqsave(&engine->queue_lock, flags);
> >> -	if (engine->cur_req == req)
> >> -		finalize_cur_req = true;
> >> -	spin_unlock_irqrestore(&engine->queue_lock, flags);
> >> -
> >> -	if (finalize_cur_req) {
> >> -		enginectx = crypto_tfm_ctx(req->tfm);
> >> -		if (engine->cur_req_prepared &&
> >> -		    enginectx->op.unprepare_request) {
> >> -			ret = enginectx->op.unprepare_request(engine, req);
> >> -			if (ret)
> >> -				dev_err(engine->dev, "failed to unprepare request\n");
> >> -		}
> >> -		spin_lock_irqsave(&engine->queue_lock, flags);
> >> -		engine->cur_req = NULL;
> >> -		engine->cur_req_prepared = false;
> >> -		spin_unlock_irqrestore(&engine->queue_lock, flags);
> >> +	enginectx = crypto_tfm_ctx(req->tfm);
> >> +	if (enginectx->op.prepare_request &&
> >> +	    enginectx->op.unprepare_request) {
> >> +		ret = enginectx->op.unprepare_request(engine, req);
> >> +		if (ret)
> >> +			dev_err(engine->dev, "failed to unprepare request\n");
> >>   	}
> >> -
> >>   	req->complete(req, err);
> >>   
> >>   	kthread_queue_work(engine->kworker, &engine->pump_requests);
> >> @@ -73,10 +59,6 @@ static void crypto_pump_requests(struct crypto_engine *engine,
> >>   
> >>   	spin_lock_irqsave(&engine->queue_lock, flags);
> >>   
> >> -	/* Make sure we are not already running a request */
> >> -	if (engine->cur_req)
> >> -		goto out;
> >> -
> > 
> > Hello
> > 
> > Your patch has the same problem than mine reported by Horia.
> > If a queue has more than one request, a first crypto_pump_requests() will send a request and for drivers which do not block on do_one_request() crypto_pump_requests() will end.
> > Then another crypto_pump_requests() will fire sending a second request while the driver does not support that.
> 
> > So we need to replace engine->cur_req by another locking mechanism.
> > Perhaps the cleaner is to add a "request count" (increased when do_one_request, decreased in crypto_finalize_request)
> > I know that the early version have that and it was removed, but I do not see any better way.
> > 
> 
> The "request count" I've change it to can_enqueue_more, so the hw can 
> "answer" if it can enqueue or not.
> 
> I'll (re)add the cur_req in crypto-engine.
> If the new callback, can_enqueue_more, is not implemented the crypto- 
> engine will work as before - will send requests to hardware, one-by-one, 
> on crypto_pump_requests, and complete it, on crypto_finalize_request, 
> and so on.
> 

But if the crypto_engine use can_enqueue_more, cur_req is a lie, so the name should be changed (or this fact need to be heavy documented on each of its occurence).