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>

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);

include/net/sctp/stream_interleave.h

+/* SCTP kernel implementation
+ * (C) Copyright Red Hat Inc. 2017
+ *
+ * These are definitions used by the stream schedulers, defined in RFC
+ * draft ndata (https://tools.ietf.org/html/draft-ietf-tsvwg-sctp-ndata-11)
+ *
+ * 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 addresses:
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *   Xin Long <lucien.xin@gmail.com>
+ */
+
+#ifndef __sctp_stream_interleave_h__
+#define __sctp_stream_interleave_h__
+
+struct sctp_stream_interleave {
+	__u16	data_chunk_len;
+	/* (I-)DATA process */
+	struct sctp_chunk *(*make_datafrag)(const struct sctp_association *asoc,
+					    const struct sctp_sndrcvinfo *sinfo,
+					    int len, __u8 flags, gfp_t gfp);
+};
+
+void sctp_stream_interleave_init(struct sctp_stream *stream);
+
+#endif /* __sctp_stream_interleave_h__ */

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

net/sctp/Makefile

@@ -14,7 +14,7 @@ sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
 	  output.o input.o debug.o stream.o auth.o \
 	  offload.o stream_sched.o stream_sched_prio.o \
-	  stream_sched_rr.o
+	  stream_sched_rr.o stream_interleave.o
 
 sctp_probe-y := probe.o
 

net/sctp/chunk.c

@@ -191,7 +191,7 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 	 */
 	max_data = asoc->pathmtu -
 		   sctp_sk(asoc->base.sk)->pf->af->net_header_len -
-		   sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk);
+		   sizeof(struct sctphdr) - sctp_datachk_len(&asoc->stream);
 	max_data = SCTP_TRUNC4(max_data);
 
 	/* If the the peer requested that we authenticate DATA chunks
@@ -264,8 +264,8 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 				frag |= SCTP_DATA_SACK_IMM;
 		}
 
-		chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag,
-						 0, GFP_KERNEL);
+		chunk = asoc->stream.si->make_datafrag(asoc, sinfo, len, frag,
+						       GFP_KERNEL);
 		if (!chunk) {
 			err = -ENOMEM;
 			goto errout;

net/sctp/sm_make_chunk.c

@@ -721,38 +721,31 @@ struct sctp_chunk *sctp_make_ecne(const struct sctp_association *asoc,
 /* 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;
 }
 

net/sctp/stream.c

@@ -167,6 +167,7 @@ int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
 	sched->init(stream);
 
 in:
+	sctp_stream_interleave_init(stream);
 	if (!incnt)
 		goto out;
 

net/sctp/stream_interleave.c

+/* 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;
+}