[PATCH v2 1/2] crypto: inside_secure - Avoid dma map if size is zero

[Peter Harliman Liem <pliem@maxlinear.com>]

From commit d03c54419274 ("dma-mapping: disallow .map_sg
operations from returning zero on error"), dma_map_sg()
produces warning if size is 0. This results in visible
warnings if crypto length is zero.
To avoid that, we avoid calling dma_map_sg if size is zero.

Fixes: d03c54419274 ("dma-mapping: disallow .map_sg operations from returning zero on error")
Signed-off-by: Peter Harliman Liem <pliem@maxlinear.com>
---
v2:
 Add fixes tag

 drivers/crypto/inside-secure/safexcel_cipher.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/inside-secure/safexcel_cipher.c b/drivers/crypto/inside-secure/safexcel_cipher.c
index d68ef16650d4..3775497775e0 100644
--- a/drivers/crypto/inside-secure/safexcel_cipher.c
+++ b/drivers/crypto/inside-secure/safexcel_cipher.c
@@ -737,14 +737,17 @@ static int safexcel_send_req(struct crypto_async_request *base, int ring,
 				max(totlen_src, totlen_dst));
 			return -EINVAL;
 		}
-		dma_map_sg(priv->dev, src, sreq->nr_src, DMA_BIDIRECTIONAL);
+		if (sreq->nr_src > 0)
+			dma_map_sg(priv->dev, src, sreq->nr_src, DMA_BIDIRECTIONAL);
 	} else {
 		if (unlikely(totlen_src && (sreq->nr_src <= 0))) {
 			dev_err(priv->dev, "Source buffer not large enough (need %d bytes)!",
 				totlen_src);
 			return -EINVAL;
 		}
-		dma_map_sg(priv->dev, src, sreq->nr_src, DMA_TO_DEVICE);
+
+		if (sreq->nr_src > 0)
+			dma_map_sg(priv->dev, src, sreq->nr_src, DMA_TO_DEVICE);
 
 		if (unlikely(totlen_dst && (sreq->nr_dst <= 0))) {
 			dev_err(priv->dev, "Dest buffer not large enough (need %d bytes)!",
@@ -753,7 +756,9 @@ static int safexcel_send_req(struct crypto_async_request *base, int ring,
 				     DMA_TO_DEVICE);
 			return -EINVAL;
 		}
-		dma_map_sg(priv->dev, dst, sreq->nr_dst, DMA_FROM_DEVICE);
+
+		if (sreq->nr_dst > 0)
+			dma_map_sg(priv->dev, dst, sreq->nr_dst, DMA_FROM_DEVICE);
 	}
 
 	memcpy(ctx->base.ctxr->data, ctx->key, ctx->key_len);
-- 
2.17.1