Re: [PATCH] crypto: engine - support for parallel requests

[Iuliana Prodan]

On 1/28/2020 10:58 AM, Corentin Labbe wrote:
> On Tue, Jan 28, 2020 at 12:17:05AM +0200, Iuliana Prodan wrote:
>> Added support for executing multiple requests, in parallel,
>> for crypto engine.
>> A new callback is added, can_enqueue_hardware, 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_hardware callback.
>> On crypto_pump_requests, if can_enqueue_hardware 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@xxxxxxx>
>>
>> ---
>> Changes since V0 (RFC):
>> 	- removed max_no_req and no_req, as the number of request that
>> 	  can be processed in parallel;
>> 	- added a new callback, can_enqueue_hardware, to check whether
>> 	  the hardware can process a new request.
>> ---
>>
>>   crypto/crypto_engine.c  | 105 ++++++++++++++++++++++++++++++------------------
>>   include/crypto/engine.h |  10 +++--
>>   2 files changed, 71 insertions(+), 44 deletions(-)
>>
>> diff --git a/crypto/crypto_engine.c b/crypto/crypto_engine.c
>> index eb029ff..ee3a610 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;
>> -
>>   	/* If another context is idling then defer */
>>   	if (engine->idling) {
>>   		kthread_queue_work(engine->kworker, &engine->pump_requests);
>> @@ -108,13 +90,18 @@ static void crypto_pump_requests(struct crypto_engine *engine,
>>   		goto out;
>>   	}
>>   
>> +start_request:
>> +	/* If hw is busy, do not send any request */
>> +	if (engine->can_enqueue_hardware &&
>> +	    !engine->can_enqueue_hardware(engine->dev))
>> +		goto out;
>> +
>>   	/* Get the fist request from the engine queue to handle */
>>   	backlog = crypto_get_backlog(&engine->queue);
>>   	async_req = crypto_dequeue_request(&engine->queue);
>>   	if (!async_req)
>>   		goto out;
>>   
>> -	engine->cur_req = async_req;
>>   	if (backlog)
>>   		backlog->complete(backlog, -EINPROGRESS);
>>   
>> @@ -130,7 +117,7 @@ static void crypto_pump_requests(struct crypto_engine *engine,
>>   		ret = engine->prepare_crypt_hardware(engine);
>>   		if (ret) {
>>   			dev_err(engine->dev, "failed to prepare crypt hardware\n");
>> -			goto req_err;
>> +			goto req_err_2;
>>   		}
>>   	}
>>   
>> @@ -141,26 +128,38 @@ static void crypto_pump_requests(struct crypto_engine *engine,
>>   		if (ret) {
>>   			dev_err(engine->dev, "failed to prepare request: %d\n",
>>   				ret);
>> -			goto req_err;
>> +			goto req_err_2;
>>   		}
>> -		engine->cur_req_prepared = true;
>>   	}
>>   	if (!enginectx->op.do_one_request) {
>>   		dev_err(engine->dev, "failed to do request\n");
>>   		ret = -EINVAL;
>> -		goto req_err;
>> +		goto req_err_1;
>>   	}
>> +
>>   	ret = enginectx->op.do_one_request(engine, async_req);
>>   	if (ret) {
>>   		dev_err(engine->dev, "Failed to do one request from queue: %d\n", ret);
>> -		goto req_err;
>> +		goto req_err_1;
>>   	}
>> -	return;
>>   
>> -req_err:
>> -	crypto_finalize_request(engine, async_req, ret);
>> -	return;
>> +	goto retry;
>> +
>> +req_err_1:
>> +	if (enginectx->op.unprepare_request) {
>> +		ret = enginectx->op.unprepare_request(engine, async_req);
>> +		if (ret)
>> +			dev_err(engine->dev, "failed to unprepare request\n");
>> +	}
>> +req_err_2:
>> +	async_req->complete(async_req, ret);
>>   
>> +retry:
>> +	if (engine->can_enqueue_hardware) {
>> +		spin_lock_irqsave(&engine->queue_lock, flags);
>> +		goto start_request;
>> +	}
>> +	return;
>>   out:
>>   	spin_unlock_irqrestore(&engine->queue_lock, flags);
>>   }
>> @@ -386,15 +385,25 @@ int crypto_engine_stop(struct crypto_engine *engine)
>>   EXPORT_SYMBOL_GPL(crypto_engine_stop);
>>   
>>   /**
>> - * crypto_engine_alloc_init - allocate crypto hardware engine structure and
>> - * initialize it.
>> + * crypto_engine_alloc_init_and_set - allocate crypto hardware engine structure
>> + * and initialize it by setting the maximum number of entries in the software
>> + * crypto-engine queue.
>>    * @dev: the device attached with one hardware engine
>> + * @cbk: pointer to a callback function to be invoked when pumping requests
>> + *       to check whether the hardware can process a new request.
>> + *       This has the form:
>> + *       callback(struct device *dev)
>> + *       where:
>> + *       @dev: contains the device that processed this response.
>>    * @rt: whether this queue is set to run as a realtime task
>> + * @qlen: maximum size of the crypto-engine queue
>>    *
>>    * This must be called from context that can sleep.
>>    * Return: the crypto engine structure on success, else NULL.
>>    */
>> -struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt)
>> +struct crypto_engine *crypto_engine_alloc_init_and_set(struct device *dev,
>> +						       bool (*cbk)(struct device *dev),
>> +						       bool rt, int qlen)
>>   {
>>   	struct sched_param param = { .sched_priority = MAX_RT_PRIO / 2 };
>>   	struct crypto_engine *engine;
>> @@ -411,12 +420,12 @@ struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt)
>>   	engine->running = false;
>>   	engine->busy = false;
>>   	engine->idling = false;
>> -	engine->cur_req_prepared = false;
>>   	engine->priv_data = dev;
>> +	engine->can_enqueue_hardware = cbk;
>>   	snprintf(engine->name, sizeof(engine->name),
>>   		 "%s-engine", dev_name(dev));
>>   
>> -	crypto_init_queue(&engine->queue, CRYPTO_ENGINE_MAX_QLEN);
>> +	crypto_init_queue(&engine->queue, qlen);
>>   	spin_lock_init(&engine->queue_lock);
>>   
>>   	engine->kworker = kthread_create_worker(0, "%s", engine->name);
>> @@ -433,6 +442,22 @@ struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt)
>>   
>>   	return engine;
>>   }
>> +EXPORT_SYMBOL_GPL(crypto_engine_alloc_init_and_set);
>> +
>> +/**
>> + * crypto_engine_alloc_init - allocate crypto hardware engine structure and
>> + * initialize it.
>> + * @dev: the device attached with one hardware engine
>> + * @rt: whether this queue is set to run as a realtime task
>> + *
>> + * This must be called from context that can sleep.
>> + * Return: the crypto engine structure on success, else NULL.
>> + */
>> +struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt)
>> +{
>> +	return crypto_engine_alloc_init_and_set(dev, NULL, rt,
>> +						CRYPTO_ENGINE_MAX_QLEN);
>> +}
>>   EXPORT_SYMBOL_GPL(crypto_engine_alloc_init);
>>   
>>   /**
>> diff --git a/include/crypto/engine.h b/include/crypto/engine.h
>> index e29cd67..15d1150 100644
>> --- a/include/crypto/engine.h
>> +++ b/include/crypto/engine.h
>> @@ -24,7 +24,6 @@
>>    * @idling: the engine is entering idle state
>>    * @busy: request pump is busy
>>    * @running: the engine is on working
>> - * @cur_req_prepared: current request is prepared
>>    * @list: link with the global crypto engine list
>>    * @queue_lock: spinlock to syncronise access to request queue
>>    * @queue: the crypto queue of the engine
>> @@ -35,17 +34,17 @@
>>    * @unprepare_crypt_hardware: there are currently no more requests on the
>>    * queue so the subsystem notifies the driver that it may relax the
>>    * hardware by issuing this call
>> + * @can_enqueue_hardware: callback to check whether the hardware can process
>> + * a new request
>>    * @kworker: kthread worker struct for request pump
>>    * @pump_requests: work struct for scheduling work to the request pump
>>    * @priv_data: the engine private data
>> - * @cur_req: the current request which is on processing
>>    */
>>   struct crypto_engine {
>>   	char			name[ENGINE_NAME_LEN];
>>   	bool			idling;
>>   	bool			busy;
>>   	bool			running;
>> -	bool			cur_req_prepared;
>>   
>>   	struct list_head	list;
>>   	spinlock_t		queue_lock;
>> @@ -56,12 +55,12 @@ struct crypto_engine {
>>   
>>   	int (*prepare_crypt_hardware)(struct crypto_engine *engine);
>>   	int (*unprepare_crypt_hardware)(struct crypto_engine *engine);
>> +	bool (*can_enqueue_hardware)(struct device *dev);
>>   
>>   	struct kthread_worker           *kworker;
>>   	struct kthread_work             pump_requests;
>>   
>>   	void				*priv_data;
>> -	struct crypto_async_request	*cur_req;
>>   };
>>   
>>   /*
>> @@ -102,6 +101,9 @@ void crypto_finalize_skcipher_request(struct crypto_engine *engine,
>>   int crypto_engine_start(struct crypto_engine *engine);
>>   int crypto_engine_stop(struct crypto_engine *engine);
>>   struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt);
>> +struct crypto_engine *crypto_engine_alloc_init_and_set(struct device *dev,
>> +						       bool (*cbk)(struct device *dev),
>> +						       bool rt, int qlen);
>>   int crypto_engine_exit(struct crypto_engine *engine);
>>   
>>   #endif /* _CRYPTO_ENGINE_H */
>> -- 
>> 2.1.0
>>
> 
> 
> Hello
> 
> For someone which said "I'm planning to improve crypto-engine incrementally", this is lot of change in one.
> You could have used my first 4 patchs which clean crypto_engine (for getting rid of cur_req_prepared/cur_req for example).
> 

The number of patches is something debatable!
Your first patches were already in my RFC!
This patch adds support for independent requests by adding a check for 
hardware availability. Removing current request (cur_req) means we need 
to add something else to break from the loop we have in pump_requests(). 
I didn't see how I could split it in several commits, but I don't see 
this as a big deal.
We can split it any way we/Herbert agree on.

> Furthermore, the callback should not be registred at init, but should be part of the struct crypto_engine_op.

We need to check if we can enqueue a new request before dequeuing the 
request from crypto-engine's queue.

> And the callback need to have the crypto engine itself as parameter, in case the driver own more than one crypto engine.
I can add crypto-engine as argument if you consider it useful.

> In my serie I added also the current request for giving more hint on the current state and let the driver do the right decision.
> 
If you refer to linked requests, this is something specific for your 
case/driver. I'm not handling this case, here.
But, for sure, is not correct to do do_one_request, only on the first 
request. This breaks the current API and doesn't scale to supporting 
multiple independent requests.