crypto: sahara - do not resize req->src when doing hash operations

When testing sahara sha256 speed performance with tcrypt (mode=404) on
imx53-qsrb board, multiple "Invalid numbers of src SG." errors are
reported. This was traced to sahara_walk_and_recalc() resizing req->src
and causing the subsequent dma_map_sg() call to fail.

Now that the previous commit fixed sahara_sha_hw_links_create() to take
into account the actual request size, rather than relying on sg->length
values, the resize operation is no longer necessary.

Therefore, remove sahara_walk_and_recalc() and simplify associated logic.

Fixes: 5a2bb93 ("crypto: sahara - add support for SHA1/256")
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Author: opanait-wr

drivers/crypto/sahara.c

@@ -884,24 +884,6 @@ static int sahara_sha_hw_context_descriptor_create(struct sahara_dev *dev,
 	return 0;
 }
 
-static int sahara_walk_and_recalc(struct scatterlist *sg, unsigned int nbytes)
-{
-	if (!sg || !sg->length)
-		return nbytes;
-
-	while (nbytes && sg) {
-		if (nbytes <= sg->length) {
-			sg->length = nbytes;
-			sg_mark_end(sg);
-			break;
-		}
-		nbytes -= sg->length;
-		sg = sg_next(sg);
-	}
-
-	return nbytes;
-}
-
 static int sahara_sha_prepare_request(struct ahash_request *req)
 {
 	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
@@ -938,36 +920,20 @@ static int sahara_sha_prepare_request(struct ahash_request *req)
 					hash_later, 0);
 	}
 
-	/* nbytes should now be multiple of blocksize */
-	req->nbytes = req->nbytes - hash_later;
-
-	sahara_walk_and_recalc(req->src, req->nbytes);
-
+	rctx->total = len - hash_later;
 	/* have data from previous operation and current */
 	if (rctx->buf_cnt && req->nbytes) {
 		sg_init_table(rctx->in_sg_chain, 2);
 		sg_set_buf(rctx->in_sg_chain, rctx->rembuf, rctx->buf_cnt);
-
 		sg_chain(rctx->in_sg_chain, 2, req->src);
-
-		rctx->total = req->nbytes + rctx->buf_cnt;
 		rctx->in_sg = rctx->in_sg_chain;
-
-		req->src = rctx->in_sg_chain;
 	/* only data from previous operation */
 	} else if (rctx->buf_cnt) {
-		if (req->src)
-			rctx->in_sg = req->src;
-		else
-			rctx->in_sg = rctx->in_sg_chain;
-		/* buf was copied into rembuf above */
+		rctx->in_sg = rctx->in_sg_chain;
 		sg_init_one(rctx->in_sg, rctx->rembuf, rctx->buf_cnt);
-		rctx->total = rctx->buf_cnt;
 	/* no data from previous operation */
 	} else {
 		rctx->in_sg = req->src;
-		rctx->total = req->nbytes;
-		req->src = rctx->in_sg;
 	}
 
 	/* on next call, we only have the remaining data in the buffer */