Enlilghtem me with some C Code

#include <linux/err.h>
#include <linux/delay.h>
#include <crypto/engine.h>
#include <uapi/linux/sched/types.h>
#include "internal.h"

#define CRYPTO_ENGINE_MAX_QLEN 10

/**
 * crypto_finalize_request - finalize one request if the request is done
 * @engine: the hardware engine
 * @req: the request need to be finalized
 * @err: error number
 */
static void crypto_finalize_request(struct crypto_engine *engine,
			     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);
	}

	req->complete(req, err);

	kthread_queue_work(engine->kworker, &engine->pump_requests);
}

/**
 * crypto_pump_requests - dequeue one request from engine queue to process
 * @engine: the hardware engine
 * @in_kthread: true if we are in the context of the request pump thread
 *
 * This function checks if there is any request in the engine queue that
 * needs processing and if so call out to the driver to initialize hardware
 * and handle each request.
 */
static void crypto_pump_requests(struct crypto_engine *engine,
				 bool in_kthread)
{
	struct crypto_async_request *async_req, *backlog;
	unsigned long flags;
	bool was_busy = false;
	int ret;
	struct crypto_engine_ctx *enginectx;

	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);
		goto out;
	}

	/* Check if the engine queue is idle */
	if (!crypto_queue_len(&engine->queue) || !engine->running) {
		if (!engine->busy)
			goto out;

		/* Only do teardown in the thread */
		if (!in_kthread) {
			kthread_queue_work(engine->kworker,
					   &engine->pump_requests);
			goto out;
		}

		engine->busy = false;
		engine->idling = true;
		spin_unlock_irqrestore(&engine->queue_lock, flags);

		if (engine->unprepare_crypt_hardware &&
		    engine->unprepare_crypt_hardware(engine))
			dev_err(engine->dev, "failed to unprepare crypt hardware\n");

		spin_lock_irqsave(&engine->queue_lock, flags);
		engine->idling = false;
		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);

	if (engine->busy)
		was_busy = true;
	else
		engine->busy = true;

	spin_unlock_irqrestore(&engine->queue_lock, flags);

	/* Until here we get the request need to be encrypted successfully */
	if (!was_busy && engine->prepare_crypt_hardware) {
		ret = engine->prepare_crypt_hardware(engine);
		if (ret) {
			dev_err(engine->dev, "failed to prepare crypt hardware\n");
			goto req_err;
		}
	}

	enginectx = crypto_tfm_ctx(async_req->tfm);

	if (enginectx->op.prepare_request) {
		ret = enginectx->op.prepare_request(engine, async_req);
		if (ret) {
			dev_err(engine->dev, "failed to prepare request: %d\n",
				ret);
			goto req_err;
		}
		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;
	}
	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;
	}
	return;

req_err:
	crypto_finalize_request(engine, async_req, ret);
	return;

out:
	spin_unlock_irqrestore(&engine->queue_lock, flags);
}

static void crypto_pump_work(struct kthread_work *work)
{
	struct crypto_engine *engine =
		container_of(work, struct crypto_engine, pump_requests);

	crypto_pump_requests(engine, true);
}

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