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Commit fc42bcba authored by Herbert Xu's avatar Herbert Xu
Browse files

crypto: scatterwalk - Add scatterwalk_ffwd helper 



This patch adds the scatterwalk_ffwd helper which can create an
SG list that starts in the middle of an existing SG list.  The
new list may either be part of the existing list or be a chain
that latches onto part of the existing list.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 66d948e7

crypto/scatterwalk.c

+22 −0
Original line number Diff line number Diff line
@@ -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);

include/crypto/scatterwalk.h

+4 −0
Original line number Diff line number Diff line
@@ -102,4 +102,8 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 


int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes);



struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],

				     struct scatterlist *src,

				     unsigned int len);



#endif  /* _CRYPTO_SCATTERWALK_H */