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, 12 insertions, 0 deletions

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 7026a8039367..96cc898787f1 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -89,6 +89,7 @@ struct sctp_stream;
 #include <net/sctp/tsnmap.h>
 #include <net/sctp/ulpevent.h>
 #include <net/sctp/ulpqueue.h>
+#include <net/sctp/stream_interleave.h>
 
 /* Structures useful for managing bind/connect. */
 
@@ -1389,11 +1390,22 @@ struct sctp_stream {
 			struct sctp_stream_out_ext *rr_next;
 		};
 	};
+	struct sctp_stream_interleave *si;
 };
 
 #define SCTP_STREAM_CLOSED		0x00
 #define SCTP_STREAM_OPEN		0x01
 
+static inline __u16 sctp_datachk_len(const struct sctp_stream *stream)
+{
+	return stream->si->data_chunk_len;
+}
+
+static inline __u16 sctp_datahdr_len(const struct sctp_stream *stream)
+{
+	return stream->si->data_chunk_len - sizeof(struct sctp_chunkhdr);
+}
+
 /* SCTP_GET_ASSOC_STATS counters */
 struct sctp_priv_assoc_stats {
 	/* Maximum observed rto in the association during subsequent