sctp: implement make_datafrag for sctp_stream_interleave

To avoid hundreds of checks for the different process on I-DATA chunk,
struct sctp_stream_interleave is defined as a group of functions used
to replace the codes in some place where it needs to do different job
according to if the asoc intl_enabled is set.

With these ops, it only needs to initialize asoc->stream.si with
sctp_stream_interleave_0 for normal data if asoc intl_enable is 0,
or sctp_stream_interleave_1 for idata if asoc intl_enable is set in
sctp_stream_init.

After that, the members in asoc->stream.si can be used directly in
some special places without checking asoc intl_enable.

make_datafrag is the first member for sctp_stream_interleave, it's
used to make data or idata frags, called in sctp_datamsg_from_user.
The old function sctp_make_datafrag_empty needs to be adjust some
to fit in this ops.

Note that as idata and data chunks have different length, it also
defines data_chunk_len for sctp_stream_interleave to describe the
chunk size.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 3 deletions

diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index 5389ae034cfa..f950186aae34 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -199,10 +199,9 @@ struct sctp_chunk *sctp_make_cwr(const struct sctp_association *asoc,
 				 const struct sctp_chunk *chunk);
 struct sctp_chunk *sctp_make_idata(const struct sctp_association *asoc,
 				   __u8 flags, int paylen, gfp_t gfp);
-struct sctp_chunk *sctp_make_datafrag_empty(struct sctp_association *asoc,
+struct sctp_chunk *sctp_make_datafrag_empty(const struct sctp_association *asoc,
 					    const struct sctp_sndrcvinfo *sinfo,
-					    int len, const __u8 flags,
-					    __u16 ssn, gfp_t gfp);
+					    int len, __u8 flags, gfp_t gfp);
 struct sctp_chunk *sctp_make_ecne(const struct sctp_association *asoc,
 				  const __u32 lowest_tsn);
 struct sctp_chunk *sctp_make_sack(const struct sctp_association *asoc);