net/tipc/msg.c - kernel/msm-4.9 - Gitiles

 /*
  * net/tipc/msg.c: TIPC message header routines
  *
  * Copyright (c) 2000-2006, 2014, Ericsson AB
  * Copyright (c) 2005, 2010-2011, Wind River Systems
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the names of the copyright holders nor the names of its
  *    contributors may be used to endorse or promote products derived from
  *    this software without specific prior written permission.
  *
  * Alternatively, this software may be distributed under the terms of the
  * GNU General Public License ("GPL") version 2 as published by the Free
  * Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */

 #include "core.h"
 #include "msg.h"
 #include "addr.h"
 #include "name_table.h"

 #define MAX_FORWARD_SIZE 1024

 static unsigned int align(unsigned int i)
 {
 	return (i + 3) & ~3u;
 }

 void tipc_msg_init(struct tipc_msg *m, u32 user, u32 type, u32 hsize,
 		   u32 destnode)
 {
 	memset(m, 0, hsize);
 	msg_set_version(m);
 	msg_set_user(m, user);
 	msg_set_hdr_sz(m, hsize);
 	msg_set_size(m, hsize);
 	msg_set_prevnode(m, tipc_own_addr);
 	msg_set_type(m, type);
 	if (hsize > SHORT_H_SIZE) {
 		msg_set_orignode(m, tipc_own_addr);
 		msg_set_destnode(m, destnode);
 	}
 }

 struct sk_buff *tipc_msg_create(uint user, uint type, uint hdr_sz,
 				uint data_sz, u32 dnode, u32 onode,
 				u32 dport, u32 oport, int errcode)
 {
 	struct tipc_msg *msg;
 	struct sk_buff *buf;

 	buf = tipc_buf_acquire(hdr_sz + data_sz);
 	if (unlikely(!buf))
 		return NULL;

 	msg = buf_msg(buf);
 	tipc_msg_init(msg, user, type, hdr_sz, dnode);
 	msg_set_size(msg, hdr_sz + data_sz);
 	msg_set_prevnode(msg, onode);
 	msg_set_origport(msg, oport);
 	msg_set_destport(msg, dport);
 	msg_set_errcode(msg, errcode);
 	if (hdr_sz > SHORT_H_SIZE) {
 		msg_set_orignode(msg, onode);
 		msg_set_destnode(msg, dnode);
 	}
 	return buf;
 }

 /* tipc_buf_append(): Append a buffer to the fragment list of another buffer
  * @*headbuf: in:  NULL for first frag, otherwise value returned from prev call
  *            out: set when successful non-complete reassembly, otherwise NULL
  * @*buf:     in:  the buffer to append. Always defined
  *            out: head buf after successful complete reassembly, otherwise NULL
  * Returns 1 when reassembly complete, otherwise 0
  */
 int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
 {
 	struct sk_buff *head = *headbuf;
 	struct sk_buff *frag = *buf;
 	struct sk_buff *tail;
 	struct tipc_msg *msg;
 	u32 fragid;
 	int delta;
 	bool headstolen;

 	if (!frag)
 		goto err;

 	msg = buf_msg(frag);
 	fragid = msg_type(msg);
 	frag->next = NULL;
 	skb_pull(frag, msg_hdr_sz(msg));

 	if (fragid == FIRST_FRAGMENT) {
 		if (unlikely(head))
 			goto err;
 		if (unlikely(skb_unclone(frag, GFP_ATOMIC)))
 			goto err;
 		head = *headbuf = frag;
 		skb_frag_list_init(head);
 		TIPC_SKB_CB(head)->tail = NULL;
 		*buf = NULL;
 		return 0;
 	}

 	if (!head)
 		goto err;

 	if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
 		kfree_skb_partial(frag, headstolen);
 	} else {
 		tail = TIPC_SKB_CB(head)->tail;
 		if (!skb_has_frag_list(head))
 			skb_shinfo(head)->frag_list = frag;
 		else
 			tail->next = frag;
 		head->truesize += frag->truesize;
 		head->data_len += frag->len;
 		head->len += frag->len;
 		TIPC_SKB_CB(head)->tail = frag;
 	}

 	if (fragid == LAST_FRAGMENT) {
 		*buf = head;
 		TIPC_SKB_CB(head)->tail = NULL;
 		*headbuf = NULL;
 		return 1;
 	}
 	*buf = NULL;
 	return 0;

 err:
 	pr_warn_ratelimited("Unable to build fragment list\n");
 	kfree_skb(*buf);
 	kfree_skb(*headbuf);
 	*buf = *headbuf = NULL;
 	return 0;
 }


 /**
  * tipc_msg_build - create buffer chain containing specified header and data
  * @mhdr: Message header, to be prepended to data
  * @iov: User data
  * @offset: Posision in iov to start copying from
  * @dsz: Total length of user data
  * @pktmax: Max packet size that can be used
  * @chain: Buffer or chain of buffers to be returned to caller
  * Returns message data size or errno: -ENOMEM, -EFAULT
  */
 int tipc_msg_build(struct tipc_msg *mhdr, struct iovec const *iov,
 		   int offset, int dsz, int pktmax , struct sk_buff **chain)
 {
 	int mhsz = msg_hdr_sz(mhdr);
 	int msz = mhsz + dsz;
 	int pktno = 1;
 	int pktsz;
 	int pktrem = pktmax;
 	int drem = dsz;
 	struct tipc_msg pkthdr;
 	struct sk_buff *buf, *prev;
 	char *pktpos;
 	int rc;
 	uint chain_sz = 0;
 	msg_set_size(mhdr, msz);

 	/* No fragmentation needed? */
 	if (likely(msz <= pktmax)) {
 		buf = tipc_buf_acquire(msz);
 		*chain = buf;
 		if (unlikely(!buf))
 			return -ENOMEM;
 		skb_copy_to_linear_data(buf, mhdr, mhsz);
 		pktpos = buf->data + mhsz;
 		TIPC_SKB_CB(buf)->chain_sz = 1;
 		if (!dsz || !memcpy_fromiovecend(pktpos, iov, offset, dsz))
 			return dsz;
 		rc = -EFAULT;
 		goto error;
 	}

 	/* Prepare reusable fragment header */
 	tipc_msg_init(&pkthdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
 		      INT_H_SIZE, msg_destnode(mhdr));
 	msg_set_size(&pkthdr, pktmax);
 	msg_set_fragm_no(&pkthdr, pktno);

 	/* Prepare first fragment */
 	*chain = buf = tipc_buf_acquire(pktmax);
 	if (!buf)
 		return -ENOMEM;
 	chain_sz = 1;
 	pktpos = buf->data;
 	skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
 	pktpos += INT_H_SIZE;
 	pktrem -= INT_H_SIZE;
 	skb_copy_to_linear_data_offset(buf, INT_H_SIZE, mhdr, mhsz);
 	pktpos += mhsz;
 	pktrem -= mhsz;

 	do {
 		if (drem < pktrem)
 			pktrem = drem;

 		if (memcpy_fromiovecend(pktpos, iov, offset, pktrem)) {
 			rc = -EFAULT;
 			goto error;
 		}
 		drem -= pktrem;
 		offset += pktrem;

 		if (!drem)
 			break;

 		/* Prepare new fragment: */
 		if (drem < (pktmax - INT_H_SIZE))
 			pktsz = drem + INT_H_SIZE;
 		else
 			pktsz = pktmax;
 		prev = buf;
 		buf = tipc_buf_acquire(pktsz);
 		if (!buf) {
 			rc = -ENOMEM;
 			goto error;
 		}
 		chain_sz++;
 		prev->next = buf;
 		msg_set_type(&pkthdr, FRAGMENT);
 		msg_set_size(&pkthdr, pktsz);
 		msg_set_fragm_no(&pkthdr, ++pktno);
 		skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
 		pktpos = buf->data + INT_H_SIZE;
 		pktrem = pktsz - INT_H_SIZE;

 	} while (1);
 	TIPC_SKB_CB(*chain)->chain_sz = chain_sz;
 	msg_set_type(buf_msg(buf), LAST_FRAGMENT);
 	return dsz;
 error:
 	kfree_skb_list(*chain);
 	*chain = NULL;
 	return rc;
 }

 /**
  * tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
  * @bbuf: the existing buffer ("bundle")
  * @buf:  buffer to be appended
  * @mtu:  max allowable size for the bundle buffer
  * Consumes buffer if successful
  * Returns true if bundling could be performed, otherwise false
  */
 bool tipc_msg_bundle(struct sk_buff *bbuf, struct sk_buff *buf, u32 mtu)
 {
 	struct tipc_msg *bmsg = buf_msg(bbuf);
 	struct tipc_msg *msg = buf_msg(buf);
 	unsigned int bsz = msg_size(bmsg);
 	unsigned int msz = msg_size(msg);
 	u32 start = align(bsz);
 	u32 max = mtu - INT_H_SIZE;
 	u32 pad = start - bsz;

 	if (likely(msg_user(msg) == MSG_FRAGMENTER))
 		return false;
 	if (unlikely(msg_user(msg) == CHANGEOVER_PROTOCOL))
 		return false;
 	if (unlikely(msg_user(msg) == BCAST_PROTOCOL))
 		return false;
 	if (likely(msg_user(bmsg) != MSG_BUNDLER))
 		return false;
 	if (likely(msg_type(bmsg) != BUNDLE_OPEN))
 		return false;
 	if (unlikely(skb_tailroom(bbuf) < (pad + msz)))
 		return false;
 	if (unlikely(max < (start + msz)))
 		return false;

 	skb_put(bbuf, pad + msz);
 	skb_copy_to_linear_data_offset(bbuf, start, buf->data, msz);
 	msg_set_size(bmsg, start + msz);
 	msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
 	bbuf->next = buf->next;
 	kfree_skb(buf);
 	return true;
 }

 /**
  * tipc_msg_make_bundle(): Create bundle buf and append message to its tail
  * @buf:  buffer to be appended and replaced
  * @mtu:  max allowable size for the bundle buffer, inclusive header
  * @dnode: destination node for message. (Not always present in header)
  * Replaces buffer if successful
  * Returns true if success, otherwise false
  */
 bool tipc_msg_make_bundle(struct sk_buff **buf, u32 mtu, u32 dnode)
 {
 	struct sk_buff *bbuf;
 	struct tipc_msg *bmsg;
 	struct tipc_msg *msg = buf_msg(*buf);
 	u32 msz = msg_size(msg);
 	u32 max = mtu - INT_H_SIZE;

 	if (msg_user(msg) == MSG_FRAGMENTER)
 		return false;
 	if (msg_user(msg) == CHANGEOVER_PROTOCOL)
 		return false;
 	if (msg_user(msg) == BCAST_PROTOCOL)
 		return false;
 	if (msz > (max / 2))
 		return false;

 	bbuf = tipc_buf_acquire(max);
 	if (!bbuf)
 		return false;

 	skb_trim(bbuf, INT_H_SIZE);
 	bmsg = buf_msg(bbuf);
 	tipc_msg_init(bmsg, MSG_BUNDLER, BUNDLE_OPEN, INT_H_SIZE, dnode);
 	msg_set_seqno(bmsg, msg_seqno(msg));
 	msg_set_ack(bmsg, msg_ack(msg));
 	msg_set_bcast_ack(bmsg, msg_bcast_ack(msg));
 	bbuf->next = (*buf)->next;
 	tipc_msg_bundle(bbuf, *buf, mtu);
 	*buf = bbuf;
 	return true;
 }

 /**
  * tipc_msg_reverse(): swap source and destination addresses and add error code
  * @buf:  buffer containing message to be reversed
  * @dnode: return value: node where to send message after reversal
  * @err:  error code to be set in message
  * Consumes buffer if failure
  * Returns true if success, otherwise false
  */
 bool tipc_msg_reverse(struct sk_buff *buf, u32 *dnode, int err)
 {
 	struct tipc_msg *msg = buf_msg(buf);
 	uint imp = msg_importance(msg);
 	struct tipc_msg ohdr;
 	uint rdsz = min_t(uint, msg_data_sz(msg), MAX_FORWARD_SIZE);

 	if (skb_linearize(buf))
 		goto exit;
 	if (msg_dest_droppable(msg))
 		goto exit;
 	if (msg_errcode(msg))
 		goto exit;

 	memcpy(&ohdr, msg, msg_hdr_sz(msg));
 	imp = min_t(uint, imp + 1, TIPC_CRITICAL_IMPORTANCE);
 	if (msg_isdata(msg))
 		msg_set_importance(msg, imp);
 	msg_set_errcode(msg, err);
 	msg_set_origport(msg, msg_destport(&ohdr));
 	msg_set_destport(msg, msg_origport(&ohdr));
 	msg_set_prevnode(msg, tipc_own_addr);
 	if (!msg_short(msg)) {
 		msg_set_orignode(msg, msg_destnode(&ohdr));
 		msg_set_destnode(msg, msg_orignode(&ohdr));
 	}
 	msg_set_size(msg, msg_hdr_sz(msg) + rdsz);
 	skb_trim(buf, msg_size(msg));
 	skb_orphan(buf);
 	*dnode = msg_orignode(&ohdr);
 	return true;
 exit:
 	kfree_skb(buf);
 	return false;
 }

 /**
  * tipc_msg_eval: determine fate of message that found no destination
  * @buf: the buffer containing the message.
  * @dnode: return value: next-hop node, if message to be forwarded
  * @err: error code to use, if message to be rejected
  *
  * Does not consume buffer
  * Returns 0 (TIPC_OK) if message ok and we can try again, -TIPC error
  * code if message to be rejected
  */
 int tipc_msg_eval(struct sk_buff *buf, u32 *dnode)
 {
 	struct tipc_msg *msg = buf_msg(buf);
 	u32 dport;

 	if (msg_type(msg) != TIPC_NAMED_MSG)
 		return -TIPC_ERR_NO_PORT;
 	if (skb_linearize(buf))
 		return -TIPC_ERR_NO_NAME;
 	if (msg_data_sz(msg) > MAX_FORWARD_SIZE)
 		return -TIPC_ERR_NO_NAME;
 	if (msg_reroute_cnt(msg) > 0)
 		return -TIPC_ERR_NO_NAME;

 	*dnode = addr_domain(msg_lookup_scope(msg));
 	dport = tipc_nametbl_translate(msg_nametype(msg),
 				       msg_nameinst(msg),
 				       dnode);
 	if (!dport)
 		return -TIPC_ERR_NO_NAME;
 	msg_incr_reroute_cnt(msg);
 	msg_set_destnode(msg, *dnode);
 	msg_set_destport(msg, dport);
 	return TIPC_OK;
 }

 /* tipc_msg_reassemble() - clone a buffer chain of fragments and
  *                         reassemble the clones into one message
  */
 struct sk_buff *tipc_msg_reassemble(struct sk_buff *chain)
 {
 	struct sk_buff *buf = chain;
 	struct sk_buff *frag = buf;
 	struct sk_buff *head = NULL;
 	int hdr_sz;

 	/* Copy header if single buffer */
 	if (!buf->next) {
 		hdr_sz = skb_headroom(buf) + msg_hdr_sz(buf_msg(buf));
 		return __pskb_copy(buf, hdr_sz, GFP_ATOMIC);
 	}

 	/* Clone all fragments and reassemble */
 	while (buf) {
 		frag = skb_clone(buf, GFP_ATOMIC);
 		if (!frag)
 			goto error;
 		frag->next = NULL;
 		if (tipc_buf_append(&head, &frag))
 			break;
 		if (!head)
 			goto error;
 		buf = buf->next;
 	}
 	return frag;
 error:
 	pr_warn("Failed do clone local mcast rcv buffer\n");
 	kfree_skb(head);
 	return NULL;
 }
	/*
	* net/tipc/msg.c: TIPC message header routines
	*
	* Copyright (c) 2000-2006, 2014, Ericsson AB
	* Copyright (c) 2005, 2010-2011, Wind River Systems
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the names of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* Alternatively, this software may be distributed under the terms of the
	* GNU General Public License ("GPL") version 2 as published by the Free
	* Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	* POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "core.h"
	#include "msg.h"
	#include "addr.h"
	#include "name_table.h"

	#define MAX_FORWARD_SIZE 1024

	static unsigned int align(unsigned int i)
	{
	return (i + 3) & ~3u;
	}

	void tipc_msg_init(struct tipc_msg *m, u32 user, u32 type, u32 hsize,
	u32 destnode)
	{
	memset(m, 0, hsize);
	msg_set_version(m);
	msg_set_user(m, user);
	msg_set_hdr_sz(m, hsize);
	msg_set_size(m, hsize);
	msg_set_prevnode(m, tipc_own_addr);
	msg_set_type(m, type);
	if (hsize > SHORT_H_SIZE) {
	msg_set_orignode(m, tipc_own_addr);
	msg_set_destnode(m, destnode);
	}
	}

	struct sk_buff *tipc_msg_create(uint user, uint type, uint hdr_sz,
	uint data_sz, u32 dnode, u32 onode,
	u32 dport, u32 oport, int errcode)
	{
	struct tipc_msg *msg;
	struct sk_buff *buf;

	buf = tipc_buf_acquire(hdr_sz + data_sz);
	if (unlikely(!buf))
	return NULL;

	msg = buf_msg(buf);
	tipc_msg_init(msg, user, type, hdr_sz, dnode);
	msg_set_size(msg, hdr_sz + data_sz);
	msg_set_prevnode(msg, onode);
	msg_set_origport(msg, oport);
	msg_set_destport(msg, dport);
	msg_set_errcode(msg, errcode);
	if (hdr_sz > SHORT_H_SIZE) {
	msg_set_orignode(msg, onode);
	msg_set_destnode(msg, dnode);
	}
	return buf;
	}

	/* tipc_buf_append(): Append a buffer to the fragment list of another buffer
	* @*headbuf: in: NULL for first frag, otherwise value returned from prev call
	* out: set when successful non-complete reassembly, otherwise NULL
	* @*buf: in: the buffer to append. Always defined
	* out: head buf after successful complete reassembly, otherwise NULL
	* Returns 1 when reassembly complete, otherwise 0
	*/
	int tipc_buf_append(struct sk_buff headbuf, struct sk_buff buf)
	{
	struct sk_buff head = headbuf;
	struct sk_buff frag = buf;
	struct sk_buff *tail;
	struct tipc_msg *msg;
	u32 fragid;
	int delta;
	bool headstolen;

	if (!frag)
	goto err;

	msg = buf_msg(frag);
	fragid = msg_type(msg);
	frag->next = NULL;
	skb_pull(frag, msg_hdr_sz(msg));

	if (fragid == FIRST_FRAGMENT) {
	if (unlikely(head))
	goto err;
	if (unlikely(skb_unclone(frag, GFP_ATOMIC)))
	goto err;
	head = *headbuf = frag;
	skb_frag_list_init(head);
	TIPC_SKB_CB(head)->tail = NULL;
	*buf = NULL;
	return 0;
	}

	if (!head)
	goto err;

	if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
	kfree_skb_partial(frag, headstolen);
	} else {
	tail = TIPC_SKB_CB(head)->tail;
	if (!skb_has_frag_list(head))
	skb_shinfo(head)->frag_list = frag;
	else
	tail->next = frag;
	head->truesize += frag->truesize;
	head->data_len += frag->len;
	head->len += frag->len;
	TIPC_SKB_CB(head)->tail = frag;
	}

	if (fragid == LAST_FRAGMENT) {
	*buf = head;
	TIPC_SKB_CB(head)->tail = NULL;
	*headbuf = NULL;
	return 1;
	}
	*buf = NULL;
	return 0;

	err:
	pr_warn_ratelimited("Unable to build fragment list\n");
	kfree_skb(*buf);
	kfree_skb(*headbuf);
	buf = headbuf = NULL;
	return 0;
	}


	/**
	* tipc_msg_build - create buffer chain containing specified header and data
	* @mhdr: Message header, to be prepended to data
	* @iov: User data
	* @offset: Posision in iov to start copying from
	* @dsz: Total length of user data
	* @pktmax: Max packet size that can be used
	* @chain: Buffer or chain of buffers to be returned to caller
	* Returns message data size or errno: -ENOMEM, -EFAULT
	*/
	int tipc_msg_build(struct tipc_msg mhdr, struct iovec const iov,
	int offset, int dsz, int pktmax , struct sk_buff **chain)
	{
	int mhsz = msg_hdr_sz(mhdr);
	int msz = mhsz + dsz;
	int pktno = 1;
	int pktsz;
	int pktrem = pktmax;
	int drem = dsz;
	struct tipc_msg pkthdr;
	struct sk_buff buf, prev;
	char *pktpos;
	int rc;
	uint chain_sz = 0;
	msg_set_size(mhdr, msz);

	/* No fragmentation needed? */
	if (likely(msz <= pktmax)) {
	buf = tipc_buf_acquire(msz);
	*chain = buf;
	if (unlikely(!buf))
	return -ENOMEM;
	skb_copy_to_linear_data(buf, mhdr, mhsz);
	pktpos = buf->data + mhsz;
	TIPC_SKB_CB(buf)->chain_sz = 1;
	if (!dsz \|\| !memcpy_fromiovecend(pktpos, iov, offset, dsz))
	return dsz;
	rc = -EFAULT;
	goto error;
	}

	/* Prepare reusable fragment header */
	tipc_msg_init(&pkthdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
	INT_H_SIZE, msg_destnode(mhdr));
	msg_set_size(&pkthdr, pktmax);
	msg_set_fragm_no(&pkthdr, pktno);

	/* Prepare first fragment */
	*chain = buf = tipc_buf_acquire(pktmax);
	if (!buf)
	return -ENOMEM;
	chain_sz = 1;
	pktpos = buf->data;
	skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
	pktpos += INT_H_SIZE;
	pktrem -= INT_H_SIZE;
	skb_copy_to_linear_data_offset(buf, INT_H_SIZE, mhdr, mhsz);
	pktpos += mhsz;
	pktrem -= mhsz;

	do {
	if (drem < pktrem)
	pktrem = drem;

	if (memcpy_fromiovecend(pktpos, iov, offset, pktrem)) {
	rc = -EFAULT;
	goto error;
	}
	drem -= pktrem;
	offset += pktrem;

	if (!drem)
	break;

	/* Prepare new fragment: */
	if (drem < (pktmax - INT_H_SIZE))
	pktsz = drem + INT_H_SIZE;
	else
	pktsz = pktmax;
	prev = buf;
	buf = tipc_buf_acquire(pktsz);
	if (!buf) {
	rc = -ENOMEM;
	goto error;
	}
	chain_sz++;
	prev->next = buf;
	msg_set_type(&pkthdr, FRAGMENT);
	msg_set_size(&pkthdr, pktsz);
	msg_set_fragm_no(&pkthdr, ++pktno);
	skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
	pktpos = buf->data + INT_H_SIZE;
	pktrem = pktsz - INT_H_SIZE;

	} while (1);
	TIPC_SKB_CB(*chain)->chain_sz = chain_sz;
	msg_set_type(buf_msg(buf), LAST_FRAGMENT);
	return dsz;
	error:
	kfree_skb_list(*chain);
	*chain = NULL;
	return rc;
	}

	/**
	* tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
	* @bbuf: the existing buffer ("bundle")
	* @buf: buffer to be appended
	* @mtu: max allowable size for the bundle buffer
	* Consumes buffer if successful
	* Returns true if bundling could be performed, otherwise false
	*/
	bool tipc_msg_bundle(struct sk_buff bbuf, struct sk_buff buf, u32 mtu)
	{
	struct tipc_msg *bmsg = buf_msg(bbuf);
	struct tipc_msg *msg = buf_msg(buf);
	unsigned int bsz = msg_size(bmsg);
	unsigned int msz = msg_size(msg);
	u32 start = align(bsz);
	u32 max = mtu - INT_H_SIZE;
	u32 pad = start - bsz;

	if (likely(msg_user(msg) == MSG_FRAGMENTER))
	return false;
	if (unlikely(msg_user(msg) == CHANGEOVER_PROTOCOL))
	return false;
	if (unlikely(msg_user(msg) == BCAST_PROTOCOL))
	return false;
	if (likely(msg_user(bmsg) != MSG_BUNDLER))
	return false;
	if (likely(msg_type(bmsg) != BUNDLE_OPEN))
	return false;
	if (unlikely(skb_tailroom(bbuf) < (pad + msz)))
	return false;
	if (unlikely(max < (start + msz)))
	return false;

	skb_put(bbuf, pad + msz);
	skb_copy_to_linear_data_offset(bbuf, start, buf->data, msz);
	msg_set_size(bmsg, start + msz);
	msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
	bbuf->next = buf->next;
	kfree_skb(buf);
	return true;
	}

	/**
	* tipc_msg_make_bundle(): Create bundle buf and append message to its tail
	* @buf: buffer to be appended and replaced
	* @mtu: max allowable size for the bundle buffer, inclusive header
	* @dnode: destination node for message. (Not always present in header)
	* Replaces buffer if successful
	* Returns true if success, otherwise false
	*/
	bool tipc_msg_make_bundle(struct sk_buff **buf, u32 mtu, u32 dnode)
	{
	struct sk_buff *bbuf;
	struct tipc_msg *bmsg;
	struct tipc_msg msg = buf_msg(buf);
	u32 msz = msg_size(msg);
	u32 max = mtu - INT_H_SIZE;

	if (msg_user(msg) == MSG_FRAGMENTER)
	return false;
	if (msg_user(msg) == CHANGEOVER_PROTOCOL)
	return false;
	if (msg_user(msg) == BCAST_PROTOCOL)
	return false;
	if (msz > (max / 2))
	return false;

	bbuf = tipc_buf_acquire(max);
	if (!bbuf)
	return false;

	skb_trim(bbuf, INT_H_SIZE);
	bmsg = buf_msg(bbuf);
	tipc_msg_init(bmsg, MSG_BUNDLER, BUNDLE_OPEN, INT_H_SIZE, dnode);
	msg_set_seqno(bmsg, msg_seqno(msg));
	msg_set_ack(bmsg, msg_ack(msg));
	msg_set_bcast_ack(bmsg, msg_bcast_ack(msg));
	bbuf->next = (*buf)->next;
	tipc_msg_bundle(bbuf, *buf, mtu);
	*buf = bbuf;
	return true;
	}

	/**
	* tipc_msg_reverse(): swap source and destination addresses and add error code
	* @buf: buffer containing message to be reversed
	* @dnode: return value: node where to send message after reversal
	* @err: error code to be set in message
	* Consumes buffer if failure
	* Returns true if success, otherwise false
	*/
	bool tipc_msg_reverse(struct sk_buff buf, u32 dnode, int err)
	{
	struct tipc_msg *msg = buf_msg(buf);
	uint imp = msg_importance(msg);
	struct tipc_msg ohdr;
	uint rdsz = min_t(uint, msg_data_sz(msg), MAX_FORWARD_SIZE);

	if (skb_linearize(buf))
	goto exit;
	if (msg_dest_droppable(msg))
	goto exit;
	if (msg_errcode(msg))
	goto exit;

	memcpy(&ohdr, msg, msg_hdr_sz(msg));
	imp = min_t(uint, imp + 1, TIPC_CRITICAL_IMPORTANCE);
	if (msg_isdata(msg))
	msg_set_importance(msg, imp);
	msg_set_errcode(msg, err);
	msg_set_origport(msg, msg_destport(&ohdr));
	msg_set_destport(msg, msg_origport(&ohdr));
	msg_set_prevnode(msg, tipc_own_addr);
	if (!msg_short(msg)) {
	msg_set_orignode(msg, msg_destnode(&ohdr));
	msg_set_destnode(msg, msg_orignode(&ohdr));
	}
	msg_set_size(msg, msg_hdr_sz(msg) + rdsz);
	skb_trim(buf, msg_size(msg));
	skb_orphan(buf);
	*dnode = msg_orignode(&ohdr);
	return true;
	exit:
	kfree_skb(buf);
	return false;
	}

	/**
	* tipc_msg_eval: determine fate of message that found no destination
	* @buf: the buffer containing the message.
	* @dnode: return value: next-hop node, if message to be forwarded
	* @err: error code to use, if message to be rejected
	*
	* Does not consume buffer
	* Returns 0 (TIPC_OK) if message ok and we can try again, -TIPC error
	* code if message to be rejected
	*/
	int tipc_msg_eval(struct sk_buff buf, u32 dnode)
	{
	struct tipc_msg *msg = buf_msg(buf);
	u32 dport;

	if (msg_type(msg) != TIPC_NAMED_MSG)
	return -TIPC_ERR_NO_PORT;
	if (skb_linearize(buf))
	return -TIPC_ERR_NO_NAME;
	if (msg_data_sz(msg) > MAX_FORWARD_SIZE)
	return -TIPC_ERR_NO_NAME;
	if (msg_reroute_cnt(msg) > 0)
	return -TIPC_ERR_NO_NAME;

	*dnode = addr_domain(msg_lookup_scope(msg));
	dport = tipc_nametbl_translate(msg_nametype(msg),
	msg_nameinst(msg),
	dnode);
	if (!dport)
	return -TIPC_ERR_NO_NAME;
	msg_incr_reroute_cnt(msg);
	msg_set_destnode(msg, *dnode);
	msg_set_destport(msg, dport);
	return TIPC_OK;
	}

	/* tipc_msg_reassemble() - clone a buffer chain of fragments and
	* reassemble the clones into one message
	*/
	struct sk_buff tipc_msg_reassemble(struct sk_buff chain)
	{
	struct sk_buff *buf = chain;
	struct sk_buff *frag = buf;
	struct sk_buff *head = NULL;
	int hdr_sz;

	/* Copy header if single buffer */
	if (!buf->next) {
	hdr_sz = skb_headroom(buf) + msg_hdr_sz(buf_msg(buf));
	return __pskb_copy(buf, hdr_sz, GFP_ATOMIC);
	}

	/* Clone all fragments and reassemble */
	while (buf) {
	frag = skb_clone(buf, GFP_ATOMIC);
	if (!frag)
	goto error;
	frag->next = NULL;
	if (tipc_buf_append(&head, &frag))
	break;
	if (!head)
	goto error;
	buf = buf->next;
	}
	return frag;
	error:
	pr_warn("Failed do clone local mcast rcv buffer\n");
	kfree_skb(head);
	return NULL;
	}