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, 7 insertions, 14 deletions

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index b969397fb773..23a7313d7972 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -721,38 +721,31 @@ nodata:
 /* Make a DATA chunk for the given association from the provided
  * parameters.  However, do not populate the data payload.
  */
-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 data_len, __u8 flags, __u16 ssn,
-					    gfp_t gfp)
+					    int len, __u8 flags, gfp_t gfp)
 {
 	struct sctp_chunk *retval;
 	struct sctp_datahdr dp;
-	int chunk_len;
 
 	/* We assign the TSN as LATE as possible, not here when
 	 * creating the chunk.
 	 */
-	dp.tsn = 0;
+	memset(&dp, 0, sizeof(dp));
+	dp.ppid = sinfo->sinfo_ppid;
 	dp.stream = htons(sinfo->sinfo_stream);
-	dp.ppid   = sinfo->sinfo_ppid;
 
 	/* Set the flags for an unordered send.  */
-	if (sinfo->sinfo_flags & SCTP_UNORDERED) {
+	if (sinfo->sinfo_flags & SCTP_UNORDERED)
 		flags |= SCTP_DATA_UNORDERED;
-		dp.ssn = 0;
-	} else
-		dp.ssn = htons(ssn);
 
-	chunk_len = sizeof(dp) + data_len;
-	retval = sctp_make_data(asoc, flags, chunk_len, gfp);
+	retval = sctp_make_data(asoc, flags, sizeof(dp) + len, gfp);
 	if (!retval)
-		goto nodata;
+		return NULL;
 
 	retval->subh.data_hdr = sctp_addto_chunk(retval, sizeof(dp), &dp);
 	memcpy(&retval->sinfo, sinfo, sizeof(struct sctp_sndrcvinfo));
 
-nodata:
 	return retval;
 }