crypto: stm32/cryp - remove request mutex protection

Mutex is badly used between threaded irq and driver.
This mutex must be removed as the framework must ensure
that requests must be serialized to avoid issue. Rework
req to avoid crash during finalize by fixing the NULL
pointer issue.
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/stm32/stm32-cryp.c

@@ -137,7 +137,6 @@ struct stm32_cryp {
 
 	struct crypto_engine    *engine;
 
-	struct mutex            lock; /* protects req / areq */
 	struct ablkcipher_request *req;
 	struct aead_request     *areq;
 
@@ -645,18 +644,13 @@ static void stm32_cryp_finish_req(struct stm32_cryp *cryp, int err)
 	pm_runtime_mark_last_busy(cryp->dev);
 	pm_runtime_put_autosuspend(cryp->dev);
 
-	if (is_gcm(cryp) || is_ccm(cryp)) {
+	if (is_gcm(cryp) || is_ccm(cryp))
 		crypto_finalize_aead_request(cryp->engine, cryp->areq, err);
-		cryp->areq = NULL;
-	} else {
+	else
 		crypto_finalize_ablkcipher_request(cryp->engine, cryp->req,
 						   err);
-		cryp->req = NULL;
-	}
 
 	memset(cryp->ctx->key, 0, cryp->ctx->keylen);
-
-	mutex_unlock(&cryp->lock);
 }
 
 static int stm32_cryp_cpu_start(struct stm32_cryp *cryp)
@@ -933,8 +927,6 @@ static int stm32_cryp_prepare_req(struct ablkcipher_request *req,
 	if (!cryp)
 		return -ENODEV;
 
-	mutex_lock(&cryp->lock);
-
 	rctx = req ? ablkcipher_request_ctx(req) : aead_request_ctx(areq);
 	rctx->mode &= FLG_MODE_MASK;
 
@@ -946,6 +938,7 @@ static int stm32_cryp_prepare_req(struct ablkcipher_request *req,
 
 	if (req) {
 		cryp->req = req;
+		cryp->areq = NULL;
 		cryp->total_in = req->nbytes;
 		cryp->total_out = cryp->total_in;
 	} else {
@@ -971,6 +964,7 @@ static int stm32_cryp_prepare_req(struct ablkcipher_request *req,
 		 *          <---------- total_out ----------------->
 		 */
 		cryp->areq = areq;
+		cryp->req = NULL;
 		cryp->authsize = crypto_aead_authsize(crypto_aead_reqtfm(areq));
 		cryp->total_in = areq->assoclen + areq->cryptlen;
 		if (is_encrypt(cryp))
@@ -992,19 +986,19 @@ static int stm32_cryp_prepare_req(struct ablkcipher_request *req,
 	if (cryp->in_sg_len < 0) {
 		dev_err(cryp->dev, "Cannot get in_sg_len\n");
 		ret = cryp->in_sg_len;
-		goto out;
+		return ret;
 	}
 
 	cryp->out_sg_len = sg_nents_for_len(cryp->out_sg, cryp->total_out);
 	if (cryp->out_sg_len < 0) {
 		dev_err(cryp->dev, "Cannot get out_sg_len\n");
 		ret = cryp->out_sg_len;
-		goto out;
+		return ret;
 	}
 
 	ret = stm32_cryp_copy_sgs(cryp);
 	if (ret)
-		goto out;
+		return ret;
 
 	scatterwalk_start(&cryp->in_walk, cryp->in_sg);
 	scatterwalk_start(&cryp->out_walk, cryp->out_sg);
@@ -1016,10 +1010,6 @@ static int stm32_cryp_prepare_req(struct ablkcipher_request *req,
 	}
 
 	ret = stm32_cryp_hw_init(cryp);
-out:
-	if (ret)
-		mutex_unlock(&cryp->lock);
-
 	return ret;
 }
 
@@ -1959,8 +1949,6 @@ static int stm32_cryp_probe(struct platform_device *pdev)
 
 	cryp->dev = dev;
 
-	mutex_init(&cryp->lock);
-
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	cryp->regs = devm_ioremap_resource(dev, res);
 	if (IS_ERR(cryp->regs))