[3/5] [CRYPTO] Split src/dst handling out from crypt()

[Herbert Xu]

Hi:

Move src/dst handling from crypt() into the helpers prepare_src,
prepare_dst, complete_src and complete_dst.  complete_src doesn't
actually do anything at the moment but is included for completeness.

This sets the stage for further optimisations down the track without
polluting crypt() itself.

These helpers don't belong in scatterwalk.[ch] since they only help
the particular way that crypt() is walking the scatter lists.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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diff -Nru a/crypto/cipher.c b/crypto/cipher.c
--- a/crypto/cipher.c	2005-03-21 18:44:09 +11:00
+++ b/crypto/cipher.c	2005-03-21 18:44:09 +11:00
@@ -38,7 +38,38 @@
 	((u32 *)a)[2] ^= ((u32 *)b)[2];
 	((u32 *)a)[3] ^= ((u32 *)b)[3];
 }
+ 
+static inline void *prepare_src(struct scatter_walk *walk, int bsize,
+				void *tmp, int in_place)
+{
+	void *src = walk->data;
+
+	if (unlikely(scatterwalk_across_pages(walk, bsize)))
+		src = tmp;
+	scatterwalk_copychunks(src, walk, bsize, 0);
+	return src;
+}
 
+static inline void *prepare_dst(struct scatter_walk *walk, int bsize,
+				void *tmp, int in_place)
+{
+	void *dst = walk->data;
+
+	if (unlikely(scatterwalk_across_pages(walk, bsize)) || in_place)
+		dst = tmp;
+	return dst;
+}
+
+static inline void complete_src(struct scatter_walk *walk, int bsize,
+				void *src, int in_place)
+{
+}
+
+static inline void complete_dst(struct scatter_walk *walk, int bsize,
+				void *dst, int in_place)
+{
+	scatterwalk_copychunks(dst, walk, bsize, 1);
+}
 
 /* 
  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
@@ -76,24 +107,17 @@
 
 		in_place = scatterwalk_samebuf(&walk_in, &walk_out);
 
-		src_p = walk_in.data;
-		if (unlikely(scatterwalk_across_pages(&walk_in, bsize)))
-			src_p = tmp_src;
-
-		dst_p = walk_out.data;
-		if (unlikely(scatterwalk_across_pages(&walk_out, bsize)) ||
-		    in_place)
-			dst_p = tmp_dst;
+		src_p = prepare_src(&walk_in, bsize, tmp_src, in_place);
+		dst_p = prepare_dst(&walk_out, bsize, tmp_dst, in_place);
 
 		nbytes -= bsize;
 
-		scatterwalk_copychunks(src_p, &walk_in, bsize, 0);
-
 		prfn(tfm, dst_p, src_p, crfn, enc, info);
 
+		complete_src(&walk_in, bsize, src_p, in_place);
 		scatterwalk_done(&walk_in, 0, nbytes);
 
-		scatterwalk_copychunks(dst_p, &walk_out, bsize, 1);
+		complete_dst(&walk_out, bsize, dst_p, in_place);
 		scatterwalk_done(&walk_out, 1, nbytes);
 
 		if (!nbytes)