From de4aee2e0a376fb272f44139150115a6dec1da95 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Tue, 25 Feb 2014 17:21:08 -0500 Subject: rpc: Allow xdr_buf_subsegment to operate in-place Allow xdr_buf_subsegment(&buf, &buf, base, len) to modify an xdr_buf in-place. Also, none of the callers need the iov_base of head or tail to be zeroed out. Also add documentation. (As it turns out, I'm not really using this new guarantee, but it seems a simple way to make this function a bit more robust.) Signed-off-by: J. Bruce Fields --- net/sunrpc/xdr.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) (limited to 'net/sunrpc') diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 1504bb11e4f3..dd97ba3c4456 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -833,8 +833,20 @@ xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf) } EXPORT_SYMBOL_GPL(xdr_buf_from_iov); -/* Sets subbuf to the portion of buf of length len beginning base bytes - * from the start of buf. Returns -1 if base of length are out of bounds. */ +/** + * xdr_buf_subsegment - set subbuf to a portion of buf + * @buf: an xdr buffer + * @subbuf: the result buffer + * @base: beginning of range in bytes + * @len: length of range in bytes + * + * sets @subbuf to an xdr buffer representing the portion of @buf of + * length @len starting at offset @base. + * + * @buf and @subbuf may be pointers to the same struct xdr_buf. + * + * Returns -1 if base of length are out of bounds. + */ int xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf, unsigned int base, unsigned int len) @@ -847,9 +859,8 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf, len -= subbuf->head[0].iov_len; base = 0; } else { - subbuf->head[0].iov_base = NULL; - subbuf->head[0].iov_len = 0; base -= buf->head[0].iov_len; + subbuf->head[0].iov_len = 0; } if (base < buf->page_len) { @@ -871,9 +882,8 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf, len -= subbuf->tail[0].iov_len; base = 0; } else { - subbuf->tail[0].iov_base = NULL; - subbuf->tail[0].iov_len = 0; base -= buf->tail[0].iov_len; + subbuf->tail[0].iov_len = 0; } if (base || len) -- cgit v1.2.3