[CRYPTO] digest: Added user API for new hash type

The existing digest user interface is inadequate for support asynchronous
operations.  For one it doesn't return a value to indicate success or
failure, nor does it take a per-operation descriptor which is essential
for the issuing of requests while other requests are still outstanding.

This patch is the first in a series of steps to remodel the interface
for asynchronous operations.

For the ease of transition the new interface will be known as "hash"
while the old one will remain as "digest".

This patch also changes sg_next to allow chaining.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 1 insertions, 3 deletions

diff --git a/crypto/scatterwalk.h b/crypto/scatterwalk.h
index ace595a2e119..f1592cc2d0f4 100644
--- a/crypto/scatterwalk.h
+++ b/crypto/scatterwalk.h
@@ -20,11 +20,9 @@
 
 #include "internal.h"
 
-/* Define sg_next is an inline routine now in case we want to change
-   scatterlist to a linked list later. */
 static inline struct scatterlist *sg_next(struct scatterlist *sg)
 {
-        return sg + 1;
+        return (++sg)->length ? sg : (void *)sg->page;
 }
 
 static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,