[PATCH 05/12] crypto: scatterwalk - Add scatterwalk_next() to get the next scatterlist in scatter_walk

[Jerry Shih]

In some situations, we might split the `skcipher_request` into several
segments. When we try to move to next segment, we might use
`scatterwalk_ffwd()` to get the corresponding `scatterlist` iterating from
the head of `scatterlist`.

This helper function could just gather the information in `skcipher_walk`
and move to next `scatterlist` directly.

Signed-off-by: Jerry Shih <jerry.shih at sifive.com>
---
 include/crypto/scatterwalk.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h
index 32fc4473175b..b1a90afe695d 100644
--- a/include/crypto/scatterwalk.h
+++ b/include/crypto/scatterwalk.h
@@ -98,7 +98,12 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 			      unsigned int start, unsigned int nbytes, int out);
 
 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
-				     struct scatterlist *src,
-				     unsigned int len);
+				     struct scatterlist *src, unsigned int len);
+
+static inline struct scatterlist *scatterwalk_next(struct scatterlist dst[2],
+						   struct scatter_walk *src)
+{
+	return scatterwalk_ffwd(dst, src->sg, src->offset - src->sg->offset);
+}
 
 #endif  /* _CRYPTO_SCATTERWALK_H */
-- 
2.28.0