crypto: scatterwalk - Add scatterwalk_ffwd helper

[firefly-linux-kernel-4.4.55.git] / crypto / scatterwalk.c

diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 3bd749c7bb7062d33ee694e4131d13ce7c051c31..db920b59a6c3332fdb771a5bcc0b0c338fce3d95 100644 (file)
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -146,3 +146,25 @@ int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes)
        return n;
 }
 EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen);
+
+struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
+                                    struct scatterlist *src,
+                                    unsigned int len)
+{
+       for (;;) {
+               if (!len)
+                       return src;
+
+               if (src->length > len)
+                       break;
+
+               len -= src->length;
+               src = sg_next(src);
+       }
+
+       sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
+       scatterwalk_crypto_chain(dst, sg_next(src), 0, 2);
+
+       return dst;
+}
+EXPORT_SYMBOL_GPL(scatterwalk_ffwd);