![Jon Paul Maloy](/assets/img/avatar_default.png)
Fragmentation at message sending is currently performed in two places in link.c, depending on whether data to be transmitted is delivered in the form of an iovec or as a big sk_buff. Those functions are also tightly entangled with the send functions that are using them. We now introduce a re-entrant, standalone function, tipc_msg_build2(), that builds a packet chain directly from an iovec. Each fragment is sized according to the MTU value given by the caller, and is prepended with a correctly built fragment header, when needed. The function is independent from who is calling and where the chain will be delivered, as long as the caller is able to indicate a correct MTU. The function is tested, but not called by anybody yet. Since it is incompatible with the existing tipc_msg_build(), and we cannot yet remove that function, we have given it a temporary name. Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Reviewed-by: Erik Hugne <erik.hugne@ericsson.com> Reviewed-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
331 lines
9 KiB
C
331 lines
9 KiB
C
/*
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* net/tipc/msg.c: TIPC message header routines
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*
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* Copyright (c) 2000-2006, 2014, Ericsson AB
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* Copyright (c) 2005, 2010-2011, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "core.h"
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#include "msg.h"
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static unsigned int align(unsigned int i)
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{
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return (i + 3) & ~3u;
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}
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void tipc_msg_init(struct tipc_msg *m, u32 user, u32 type, u32 hsize,
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u32 destnode)
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{
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memset(m, 0, hsize);
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msg_set_version(m);
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msg_set_user(m, user);
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msg_set_hdr_sz(m, hsize);
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msg_set_size(m, hsize);
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msg_set_prevnode(m, tipc_own_addr);
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msg_set_type(m, type);
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msg_set_orignode(m, tipc_own_addr);
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msg_set_destnode(m, destnode);
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}
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/**
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* tipc_msg_build - create message using specified header and data
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*
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* Note: Caller must not hold any locks in case copy_from_user() is interrupted!
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*
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* Returns message data size or errno
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*/
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int tipc_msg_build(struct tipc_msg *hdr, struct iovec const *msg_sect,
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unsigned int len, int max_size, struct sk_buff **buf)
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{
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int dsz, sz, hsz;
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unsigned char *to;
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dsz = len;
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hsz = msg_hdr_sz(hdr);
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sz = hsz + dsz;
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msg_set_size(hdr, sz);
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if (unlikely(sz > max_size)) {
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*buf = NULL;
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return dsz;
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}
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*buf = tipc_buf_acquire(sz);
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if (!(*buf))
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return -ENOMEM;
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skb_copy_to_linear_data(*buf, hdr, hsz);
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to = (*buf)->data + hsz;
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if (len && memcpy_fromiovecend(to, msg_sect, 0, dsz)) {
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kfree_skb(*buf);
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*buf = NULL;
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return -EFAULT;
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}
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return dsz;
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}
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/* tipc_buf_append(): Append a buffer to the fragment list of another buffer
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* Let first buffer become head buffer
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* Returns 1 and sets *buf to headbuf if chain is complete, otherwise 0
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* Leaves headbuf pointer at NULL if failure
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*/
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int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
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{
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struct sk_buff *head = *headbuf;
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struct sk_buff *frag = *buf;
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struct sk_buff *tail;
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struct tipc_msg *msg = buf_msg(frag);
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u32 fragid = msg_type(msg);
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bool headstolen;
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int delta;
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skb_pull(frag, msg_hdr_sz(msg));
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if (fragid == FIRST_FRAGMENT) {
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if (head || skb_unclone(frag, GFP_ATOMIC))
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goto out_free;
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head = *headbuf = frag;
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skb_frag_list_init(head);
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return 0;
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}
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if (!head)
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goto out_free;
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tail = TIPC_SKB_CB(head)->tail;
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if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
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kfree_skb_partial(frag, headstolen);
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} else {
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if (!skb_has_frag_list(head))
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skb_shinfo(head)->frag_list = frag;
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else
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tail->next = frag;
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head->truesize += frag->truesize;
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head->data_len += frag->len;
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head->len += frag->len;
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TIPC_SKB_CB(head)->tail = frag;
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}
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if (fragid == LAST_FRAGMENT) {
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*buf = head;
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TIPC_SKB_CB(head)->tail = NULL;
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*headbuf = NULL;
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return 1;
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}
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*buf = NULL;
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return 0;
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out_free:
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pr_warn_ratelimited("Unable to build fragment list\n");
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kfree_skb(*buf);
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return 0;
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}
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/**
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* tipc_msg_build2 - create buffer chain containing specified header and data
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* @mhdr: Message header, to be prepended to data
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* @iov: User data
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* @offset: Posision in iov to start copying from
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* @dsz: Total length of user data
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* @pktmax: Max packet size that can be used
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* @chain: Buffer or chain of buffers to be returned to caller
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* Returns message data size or errno: -ENOMEM, -EFAULT
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*/
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int tipc_msg_build2(struct tipc_msg *mhdr, struct iovec const *iov,
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int offset, int dsz, int pktmax , struct sk_buff **chain)
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{
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int mhsz = msg_hdr_sz(mhdr);
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int msz = mhsz + dsz;
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int pktno = 1;
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int pktsz;
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int pktrem = pktmax;
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int drem = dsz;
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struct tipc_msg pkthdr;
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struct sk_buff *buf, *prev;
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char *pktpos;
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int rc;
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msg_set_size(mhdr, msz);
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/* No fragmentation needed? */
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if (likely(msz <= pktmax)) {
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buf = tipc_buf_acquire(msz);
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*chain = buf;
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if (unlikely(!buf))
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return -ENOMEM;
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skb_copy_to_linear_data(buf, mhdr, mhsz);
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pktpos = buf->data + mhsz;
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if (!dsz || !memcpy_fromiovecend(pktpos, iov, offset, dsz))
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return dsz;
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rc = -EFAULT;
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goto error;
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}
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/* Prepare reusable fragment header */
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tipc_msg_init(&pkthdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
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INT_H_SIZE, msg_destnode(mhdr));
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msg_set_size(&pkthdr, pktmax);
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msg_set_fragm_no(&pkthdr, pktno);
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/* Prepare first fragment */
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*chain = buf = tipc_buf_acquire(pktmax);
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if (!buf)
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return -ENOMEM;
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pktpos = buf->data;
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skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
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pktpos += INT_H_SIZE;
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pktrem -= INT_H_SIZE;
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skb_copy_to_linear_data_offset(buf, INT_H_SIZE, mhdr, mhsz);
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pktpos += mhsz;
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pktrem -= mhsz;
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do {
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if (drem < pktrem)
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pktrem = drem;
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if (memcpy_fromiovecend(pktpos, iov, offset, pktrem)) {
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rc = -EFAULT;
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goto error;
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}
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drem -= pktrem;
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offset += pktrem;
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if (!drem)
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break;
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/* Prepare new fragment: */
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if (drem < (pktmax - INT_H_SIZE))
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pktsz = drem + INT_H_SIZE;
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else
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pktsz = pktmax;
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prev = buf;
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buf = tipc_buf_acquire(pktsz);
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if (!buf) {
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rc = -ENOMEM;
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goto error;
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}
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prev->next = buf;
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msg_set_type(&pkthdr, FRAGMENT);
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msg_set_size(&pkthdr, pktsz);
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msg_set_fragm_no(&pkthdr, ++pktno);
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skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
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pktpos = buf->data + INT_H_SIZE;
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pktrem = pktsz - INT_H_SIZE;
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} while (1);
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msg_set_type(buf_msg(buf), LAST_FRAGMENT);
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return dsz;
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error:
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kfree_skb_list(*chain);
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*chain = NULL;
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return rc;
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}
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/**
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* tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
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* @bbuf: the existing buffer ("bundle")
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* @buf: buffer to be appended
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* @mtu: max allowable size for the bundle buffer
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* Consumes buffer if successful
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* Returns true if bundling could be performed, otherwise false
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*/
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bool tipc_msg_bundle(struct sk_buff *bbuf, struct sk_buff *buf, u32 mtu)
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{
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struct tipc_msg *bmsg = buf_msg(bbuf);
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struct tipc_msg *msg = buf_msg(buf);
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unsigned int bsz = msg_size(bmsg);
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unsigned int msz = msg_size(msg);
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u32 start = align(bsz);
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u32 max = mtu - INT_H_SIZE;
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u32 pad = start - bsz;
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if (likely(msg_user(msg) == MSG_FRAGMENTER))
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return false;
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if (unlikely(msg_user(msg) == CHANGEOVER_PROTOCOL))
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return false;
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if (unlikely(msg_user(msg) == BCAST_PROTOCOL))
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return false;
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if (likely(msg_user(bmsg) != MSG_BUNDLER))
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return false;
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if (likely(msg_type(bmsg) != BUNDLE_OPEN))
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return false;
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if (unlikely(skb_tailroom(bbuf) < (pad + msz)))
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return false;
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if (unlikely(max < (start + msz)))
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return false;
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skb_put(bbuf, pad + msz);
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skb_copy_to_linear_data_offset(bbuf, start, buf->data, msz);
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msg_set_size(bmsg, start + msz);
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msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
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bbuf->next = buf->next;
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kfree_skb(buf);
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return true;
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}
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/**
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* tipc_msg_make_bundle(): Create bundle buf and append message to its tail
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* @buf: buffer to be appended and replaced
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* @mtu: max allowable size for the bundle buffer, inclusive header
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* @dnode: destination node for message. (Not always present in header)
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* Replaces buffer if successful
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* Returns true if sucess, otherwise false
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*/
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bool tipc_msg_make_bundle(struct sk_buff **buf, u32 mtu, u32 dnode)
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{
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struct sk_buff *bbuf;
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struct tipc_msg *bmsg;
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struct tipc_msg *msg = buf_msg(*buf);
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u32 msz = msg_size(msg);
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u32 max = mtu - INT_H_SIZE;
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if (msg_user(msg) == MSG_FRAGMENTER)
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return false;
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if (msg_user(msg) == CHANGEOVER_PROTOCOL)
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return false;
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if (msg_user(msg) == BCAST_PROTOCOL)
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return false;
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if (msz > (max / 2))
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return false;
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bbuf = tipc_buf_acquire(max);
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if (!bbuf)
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return false;
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skb_trim(bbuf, INT_H_SIZE);
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bmsg = buf_msg(bbuf);
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tipc_msg_init(bmsg, MSG_BUNDLER, BUNDLE_OPEN, INT_H_SIZE, dnode);
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msg_set_seqno(bmsg, msg_seqno(msg));
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msg_set_ack(bmsg, msg_ack(msg));
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msg_set_bcast_ack(bmsg, msg_bcast_ack(msg));
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bbuf->next = (*buf)->next;
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tipc_msg_bundle(bbuf, *buf, mtu);
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*buf = bbuf;
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return true;
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}
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