crypto: sun8i-ss - use sg_nents_for_len

When testing with some large SG list, the sun8i-ss drivers always
fallback even if it can handle it.
So use sg_nents_for_len() which permits to see less SGs than needed.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c

@@ -29,7 +29,8 @@ static bool sun8i_ss_need_fallback(struct skcipher_request *areq)
 	if (areq->cryptlen == 0 || areq->cryptlen % 16)
 		return true;
 
-	if (sg_nents(areq->src) > 8 || sg_nents(areq->dst) > 8)
+	if (sg_nents_for_len(areq->src, areq->cryptlen) > 8 ||
+		sg_nents_for_len(areq->dst, areq->cryptlen) > 8)
 		return true;
 
 	sg = areq->src;
@@ -169,6 +170,8 @@ static int sun8i_ss_cipher(struct skcipher_request *areq)
 	int nr_sgs = 0;
 	int nr_sgd = 0;
 	int err = 0;
+	int nsgs = sg_nents_for_len(areq->src, areq->cryptlen);
+	int nsgd = sg_nents_for_len(areq->dst, areq->cryptlen);
 	int i;
 
 	algt = container_of(alg, struct sun8i_ss_alg_template, alg.skcipher);
@@ -201,8 +204,7 @@ static int sun8i_ss_cipher(struct skcipher_request *areq)
 			goto theend_key;
 	}
 	if (areq->src == areq->dst) {
-		nr_sgs = dma_map_sg(ss->dev, areq->src, sg_nents(areq->src),
-				    DMA_BIDIRECTIONAL);
+		nr_sgs = dma_map_sg(ss->dev, areq->src, nsgs, DMA_BIDIRECTIONAL);
 		if (nr_sgs <= 0 || nr_sgs > 8) {
 			dev_err(ss->dev, "Invalid sg number %d\n", nr_sgs);
 			err = -EINVAL;
@@ -210,15 +212,13 @@ static int sun8i_ss_cipher(struct skcipher_request *areq)
 		}
 		nr_sgd = nr_sgs;
 	} else {
-		nr_sgs = dma_map_sg(ss->dev, areq->src, sg_nents(areq->src),
-				    DMA_TO_DEVICE);
+		nr_sgs = dma_map_sg(ss->dev, areq->src, nsgs, DMA_TO_DEVICE);
 		if (nr_sgs <= 0 || nr_sgs > 8) {
 			dev_err(ss->dev, "Invalid sg number %d\n", nr_sgs);
 			err = -EINVAL;
 			goto theend_iv;
 		}
-		nr_sgd = dma_map_sg(ss->dev, areq->dst, sg_nents(areq->dst),
-				    DMA_FROM_DEVICE);
+		nr_sgd = dma_map_sg(ss->dev, areq->dst, nsgd, DMA_FROM_DEVICE);
 		if (nr_sgd <= 0 || nr_sgd > 8) {
 			dev_err(ss->dev, "Invalid sg number %d\n", nr_sgd);
 			err = -EINVAL;
@@ -274,13 +274,10 @@ static int sun8i_ss_cipher(struct skcipher_request *areq)
 
 theend_sgs:
 	if (areq->src == areq->dst) {
-		dma_unmap_sg(ss->dev, areq->src, sg_nents(areq->src),
-			     DMA_BIDIRECTIONAL);
+		dma_unmap_sg(ss->dev, areq->src, nsgs, DMA_BIDIRECTIONAL);
 	} else {
-		dma_unmap_sg(ss->dev, areq->src, sg_nents(areq->src),
-			     DMA_TO_DEVICE);
-		dma_unmap_sg(ss->dev, areq->dst, sg_nents(areq->dst),
-			     DMA_FROM_DEVICE);
+		dma_unmap_sg(ss->dev, areq->src, nsgs, DMA_TO_DEVICE);
+		dma_unmap_sg(ss->dev, areq->dst, nsgd, DMA_FROM_DEVICE);
 	}
 
 theend_iv: