crypto: nx - use the new scatterwalk functions

- In nx_walk_and_build(), use scatterwalk_start_at_pos() instead of a
  more complex way to achieve the same result.

- Also in nx_walk_and_build(), use the new functions scatterwalk_next()
  which consolidates scatterwalk_clamp() and scatterwalk_map(), and use
  scatterwalk_done_src() which consolidates scatterwalk_unmap(),
  scatterwalk_advance(), and scatterwalk_done().  Remove unnecessary
  code that seemed to be intended to advance to the next sg entry, which
  is already handled by the scatterwalk functions.

  Note that nx_walk_and_build() does not actually read or write the
  mapped virtual address, and thus it is misusing the scatter_walk API.
  It really should just access the scatterlist directly.  This patch
  does not try to address this existing issue.

- In nx_gca(), use memcpy_from_sglist() instead of a more complex way to
  achieve the same result.

- In various functions, replace calls to scatterwalk_map_and_copy() with
  memcpy_from_sglist() or memcpy_to_sglist() as appropriate.  Note that
  this eliminates the confusing 'out' argument (which this driver had
  tried to work around by defining the missing constants for it...)

Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 5 insertions, 26 deletions

diff --git a/drivers/crypto/nx/nx.c b/drivers/crypto/nx/nx.c
index 010e87d9da36..dd95e5361d88 100644
--- a/drivers/crypto/nx/nx.c
+++ b/drivers/crypto/nx/nx.c
@@ -153,40 +153,19 @@ struct nx_sg *nx_walk_and_build(struct nx_sg       *nx_dst,
 {
 	struct scatter_walk walk;
 	struct nx_sg *nx_sg = nx_dst;
-	unsigned int n, offset = 0, len = *src_len;
+	unsigned int n, len = *src_len;
 	char *dst;
 
 	/* we need to fast forward through @start bytes first */
-	for (;;) {
-		scatterwalk_start(&walk, sg_src);
-
-		if (start < offset + sg_src->length)
-			break;
-
-		offset += sg_src->length;
-		sg_src = sg_next(sg_src);
-	}
-
-	/* start - offset is the number of bytes to advance in the scatterlist
-	 * element we're currently looking at */
-	scatterwalk_advance(&walk, start - offset);
+	scatterwalk_start_at_pos(&walk, sg_src, start);
 
 	while (len && (nx_sg - nx_dst) < sglen) {
-		n = scatterwalk_clamp(&walk, len);
-		if (!n) {
-			/* In cases where we have scatterlist chain sg_next
-			 * handles with it properly */
-			scatterwalk_start(&walk, sg_next(walk.sg));
-			n = scatterwalk_clamp(&walk, len);
-		}
-		dst = scatterwalk_map(&walk);
+		dst = scatterwalk_next(&walk, len, &n);
 
 		nx_sg = nx_build_sg_list(nx_sg, dst, &n, sglen - (nx_sg - nx_dst));
-		len -= n;
 
-		scatterwalk_unmap(dst);
-		scatterwalk_advance(&walk, n);
-		scatterwalk_done(&walk, SCATTERWALK_FROM_SG, len);
+		scatterwalk_done_src(&walk, dst, n);
+		len -= n;
 	}
 	/* update to_process */
 	*src_len -= len;