Re: [PATCH 9/9] crypto: qce - switch to using a mutex

[neil.armstrong@linaro.org]

On 03/12/2024 10:19, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> Having switched to workqueue from tasklet, we are no longer limited to
> atomic APIs and can now convert the spinlock to a mutex. This, along
> with the conversion from tasklet to workqueue grants us ~15% improvement
> in cryptsetup benchmarks for AES encryption.

Can you share on which platforms you did the tests and the results you got ?

> 
> While at it: use guards to simplify locking code.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
>   drivers/crypto/qce/core.c | 46 +++++++++++++++++++++-------------------------
>   drivers/crypto/qce/core.h |  3 ++-
>   2 files changed, 23 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/crypto/qce/core.c b/drivers/crypto/qce/core.c
> index 6de9f1e23e282..e95e84486d9ae 100644
> --- a/drivers/crypto/qce/core.c
> +++ b/drivers/crypto/qce/core.c
> @@ -3,6 +3,7 @@
>    * Copyright (c) 2010-2014, The Linux Foundation. All rights reserved.
>    */
>   
> +#include <linux/cleanup.h>
>   #include <linux/clk.h>
>   #include <linux/device.h>
>   #include <linux/dma-mapping.h>
> @@ -11,7 +12,6 @@
>   #include <linux/module.h>
>   #include <linux/mod_devicetable.h>
>   #include <linux/platform_device.h>
> -#include <linux/spinlock.h>
>   #include <linux/types.h>
>   #include <crypto/algapi.h>
>   #include <crypto/internal/hash.h>
> @@ -89,34 +89,28 @@ static int qce_handle_queue(struct qce_device *qce,
>   			    struct crypto_async_request *req)
>   {
>   	struct crypto_async_request *async_req, *backlog;
> -	unsigned long flags;
>   	int ret = 0, err;
>   
> -	spin_lock_irqsave(&qce->lock, flags);
> +	scoped_guard(mutex, &qce->lock) {
> +		if (req)
> +			ret = crypto_enqueue_request(&qce->queue, req);
>   
> -	if (req)
> -		ret = crypto_enqueue_request(&qce->queue, req);
> +		/* busy, do not dequeue request */
> +		if (qce->req)
> +			return ret;
>   
> -	/* busy, do not dequeue request */
> -	if (qce->req) {
> -		spin_unlock_irqrestore(&qce->lock, flags);
> -		return ret;
> +		backlog = crypto_get_backlog(&qce->queue);
> +		async_req = crypto_dequeue_request(&qce->queue);
> +		if (async_req)
> +			qce->req = async_req;
>   	}
>   
> -	backlog = crypto_get_backlog(&qce->queue);
> -	async_req = crypto_dequeue_request(&qce->queue);
> -	if (async_req)
> -		qce->req = async_req;
> -
> -	spin_unlock_irqrestore(&qce->lock, flags);
> -
>   	if (!async_req)
>   		return ret;
>   
>   	if (backlog) {
> -		spin_lock_bh(&qce->lock);
> -		crypto_request_complete(backlog, -EINPROGRESS);
> -		spin_unlock_bh(&qce->lock);
> +		scoped_guard(mutex, &qce->lock)
> +			crypto_request_complete(backlog, -EINPROGRESS);
>   	}
>   
>   	err = qce_handle_request(async_req);
> @@ -133,12 +127,11 @@ static void qce_req_done_work(struct work_struct *work)
>   	struct qce_device *qce = container_of(work, struct qce_device,
>   					      done_work);
>   	struct crypto_async_request *req;
> -	unsigned long flags;
>   
> -	spin_lock_irqsave(&qce->lock, flags);
> -	req = qce->req;
> -	qce->req = NULL;
> -	spin_unlock_irqrestore(&qce->lock, flags);
> +	scoped_guard(mutex, &qce->lock) {
> +		req = qce->req;
> +		qce->req = NULL;
> +	}
>   
>   	if (req)
>   		crypto_request_complete(req, qce->result);
> @@ -243,7 +236,10 @@ static int qce_crypto_probe(struct platform_device *pdev)
>   	if (ret)
>   		return ret;
>   
> -	spin_lock_init(&qce->lock);
> +	ret = devm_mutex_init(qce->dev, &qce->lock);
> +	if (ret)
> +		return ret;
> +
>   	INIT_WORK(&qce->done_work, qce_req_done_work);
>   	crypto_init_queue(&qce->queue, QCE_QUEUE_LENGTH);
>   
> diff --git a/drivers/crypto/qce/core.h b/drivers/crypto/qce/core.h
> index 39e75a75a4293..eb6fa7a8b64a8 100644
> --- a/drivers/crypto/qce/core.h
> +++ b/drivers/crypto/qce/core.h
> @@ -6,6 +6,7 @@
>   #ifndef _CORE_H_
>   #define _CORE_H_
>   
> +#include <linux/mutex.h>
>   #include <linux/workqueue.h>
>   
>   #include "dma.h"
> @@ -30,7 +31,7 @@
>    */
>   struct qce_device {
>   	struct crypto_queue queue;
> -	spinlock_t lock;
> +	struct mutex lock;
>   	struct work_struct done_work;
>   	struct crypto_async_request *req;
>   	int result;
> 

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>