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authorHerbert Xu <herbert@gondor.apana.org.au>2015-05-21 15:10:59 +0800
committerHerbert Xu <herbert@gondor.apana.org.au>2015-05-22 11:25:50 +0800
commitfc42bcba97bae738f905b83741134a63af7e6c02 (patch)
tree8ace4b3690395cd811f3cd63a96b77e066e4cb5f /crypto/scatterwalk.c
parent66d948e732f665c905678d810833d4f0a5071537 (diff)
downloadlinux-fc42bcba97bae738f905b83741134a63af7e6c02.tar.bz2
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: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/scatterwalk.c')
-rw-r--r--crypto/scatterwalk.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 3bd749c7bb70..db920b59a6c3 100644
--- 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);