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, 79 insertions, 0 deletions

diff --git a/net/sctp/stream_interleave.c b/net/sctp/stream_interleave.c
new file mode 100644
index 000000000000..397c3c1789b3
--- /dev/null
+++ b/net/sctp/stream_interleave.c
@@ -0,0 +1,79 @@
+/* SCTP kernel implementation
+ * (C) Copyright Red Hat Inc. 2017
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * These functions manipulate sctp stream queue/scheduling.
+ *
+ * This SCTP implementation is free software;
+ * you can redistribute it and/or modify it under the terms of
+ * the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This SCTP implementation is distributed in the hope that it
+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ *                 ************************
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU CC; see the file COPYING.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email addresched(es):
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *    Xin Long <lucien.xin@gmail.com>
+ */
+
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+#include <linux/sctp.h>
+
+static struct sctp_chunk *sctp_make_idatafrag_empty(
+					const struct sctp_association *asoc,
+					const struct sctp_sndrcvinfo *sinfo,
+					int len, __u8 flags, gfp_t gfp)
+{
+	struct sctp_chunk *retval;
+	struct sctp_idatahdr dp;
+
+	memset(&dp, 0, sizeof(dp));
+	dp.stream = htons(sinfo->sinfo_stream);
+
+	if (sinfo->sinfo_flags & SCTP_UNORDERED)
+		flags |= SCTP_DATA_UNORDERED;
+
+	retval = sctp_make_idata(asoc, flags, sizeof(dp) + len, gfp);
+	if (!retval)
+		return NULL;
+
+	retval->subh.idata_hdr = sctp_addto_chunk(retval, sizeof(dp), &dp);
+	memcpy(&retval->sinfo, sinfo, sizeof(struct sctp_sndrcvinfo));
+
+	return retval;
+}
+
+static struct sctp_stream_interleave sctp_stream_interleave_0 = {
+	.data_chunk_len		= sizeof(struct sctp_data_chunk),
+	/* DATA process functions */
+	.make_datafrag		= sctp_make_datafrag_empty,
+};
+
+static struct sctp_stream_interleave sctp_stream_interleave_1 = {
+	.data_chunk_len		= sizeof(struct sctp_idata_chunk),
+	/* I-DATA process functions */
+	.make_datafrag		= sctp_make_idatafrag_empty,
+};
+
+void sctp_stream_interleave_init(struct sctp_stream *stream)
+{
+	struct sctp_association *asoc;
+
+	asoc = container_of(stream, struct sctp_association, stream);
+	stream->si = asoc->intl_enable ? &sctp_stream_interleave_1
+				       : &sctp_stream_interleave_0;
+}