crypto: aead - Add common IV generation code

[deliverable/linux.git] / crypto / scatterwalk.c

diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index db920b59a6c3332fdb771a5bcc0b0c338fce3d95..2ef9cbbc5dbf326904bac71359e559402b1cd35b 100644 (file)
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -104,22 +104,18 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
                              unsigned int start, unsigned int nbytes, int out)
 {
        struct scatter_walk walk;
-       unsigned int offset = 0;
+       struct scatterlist tmp[2];
 
        if (!nbytes)
                return;
 
-       for (;;) {
-               scatterwalk_start(&walk, sg);
-
-               if (start < offset + sg->length)
-                       break;
+       sg = scatterwalk_ffwd(tmp, sg, start);
 
-               offset += sg->length;
-               sg = sg_next(sg);
-       }
+       if (sg_page(sg) == virt_to_page(buf) &&
+           sg->offset == offset_in_page(buf))
+               return;
 
-       scatterwalk_advance(&walk, start - offset);
+       scatterwalk_start(&walk, sg);
        scatterwalk_copychunks(buf, &walk, nbytes, out);
        scatterwalk_done(&walk, out, 0);
 }
@@ -162,6 +158,7 @@ struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
                src = sg_next(src);
        }
 
+       sg_init_table(dst, 2);
        sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
        scatterwalk_crypto_chain(dst, sg_next(src), 0, 2);