NetBSD/sys/kern/uipc_mbuf.c

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/* $NetBSD: uipc_mbuf.c,v 1.44 1999/10/27 14:23:27 itojun Exp $ */
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
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/*
* Copyright (c) 1982, 1986, 1988, 1991, 1993
* The Regents of the University of California. All rights reserved.
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*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
1998-03-01 05:20:01 +03:00
* @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
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*/
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#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/map.h>
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#define MBTYPES
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#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/pool.h>
#include <sys/socket.h>
#include <net/if.h>
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#include <vm/vm.h>
#include <vm/vm_kern.h>
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#include <uvm/uvm_extern.h>
#include <sys/sysctl.h>
struct pool mbpool; /* mbuf pool */
struct pool mclpool; /* mbuf cluster pool */
struct mbstat mbstat;
int max_linkhdr;
int max_protohdr;
int max_hdr;
int max_datalen;
void *mclpool_alloc __P((unsigned long, int, int));
void mclpool_release __P((void *, unsigned long, int));
static struct mbuf *m_copym0 __P((struct mbuf *, int, int, int, int));
const char *mclpool_warnmsg =
"WARNING: mclpool limit reached; increase NMBCLUSTERS";
/*
* Initialize the mbuf allcator.
*/
void
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mbinit()
{
pool_init(&mbpool, msize, 0, 0, 0, "mbpl", 0, NULL, NULL, 0);
pool_init(&mclpool, mclbytes, 0, 0, 0, "mclpl", 0, mclpool_alloc,
mclpool_release, 0);
/*
* Set the hard limit on the mclpool to the number of
* mbuf clusters the kernel is to support. Log the limit
* reached message max once a minute.
*/
pool_sethardlimit(&mclpool, nmbclusters, mclpool_warnmsg, 60);
/*
* Set a low water mark for both mbufs and clusters. This should
* help ensure that they can be allocated in a memory starvation
* situation. This is important for e.g. diskless systems which
* must allocate mbufs in order for the pagedaemon to clean pages.
*/
pool_setlowat(&mbpool, mblowat);
pool_setlowat(&mclpool, mcllowat);
}
int
sysctl_dombuf(name, namelen, oldp, oldlenp, newp, newlen)
int *name;
u_int namelen;
void *oldp;
size_t *oldlenp;
void *newp;
size_t newlen;
{
int error, newval;
/* All sysctl names at this level are terminal. */
if (namelen != 1)
return (ENOTDIR); /* overloaded */
switch (name[0]) {
case MBUF_MSIZE:
return (sysctl_rdint(oldp, oldlenp, newp, msize));
case MBUF_MCLBYTES:
return (sysctl_rdint(oldp, oldlenp, newp, mclbytes));
case MBUF_NMBCLUSTERS:
/*
* If we have direct-mapped pool pages, we can adjust this
* number on the fly. If not, we're limited by the size
* of mb_map, and cannot change this value.
*
* Note: we only allow the value to be increased, never
* decreased.
*/
if (mb_map == NULL) {
newval = nmbclusters;
error = sysctl_int(oldp, oldlenp, newp, newlen,
&newval);
if (error != 0)
return (error);
if (newp != NULL) {
if (newval >= nmbclusters) {
nmbclusters = newval;
pool_sethardlimit(&mclpool,
nmbclusters, mclpool_warnmsg, 60);
} else
error = EINVAL;
}
return (error);
} else
return (sysctl_rdint(oldp, oldlenp, newp, nmbclusters));
case MBUF_MBLOWAT:
case MBUF_MCLLOWAT:
/* New value must be >= 0. */
newval = (name[0] == MBUF_MBLOWAT) ? mblowat : mcllowat;
error = sysctl_int(oldp, oldlenp, newp, newlen, &newval);
if (error != 0)
return (error);
if (newp != NULL) {
if (newval >= 0) {
if (name[0] == MBUF_MBLOWAT) {
mblowat = newval;
pool_setlowat(&mbpool, newval);
} else {
mcllowat = newval;
pool_setlowat(&mclpool, newval);
}
} else
error = EINVAL;
}
return (error);
default:
return (EOPNOTSUPP);
}
/* NOTREACHED */
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}
void *
mclpool_alloc(sz, flags, mtype)
unsigned long sz;
int flags;
int mtype;
{
boolean_t waitok = (flags & PR_WAITOK) ? TRUE : FALSE;
return ((void *)uvm_km_alloc_poolpage1(mb_map, uvmexp.mb_object,
waitok));
}
void
mclpool_release(v, sz, mtype)
void *v;
unsigned long sz;
int mtype;
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{
uvm_km_free_poolpage1(mb_map, (vaddr_t)v);
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}
/*
* When MGET failes, ask protocols to free space when short of memory,
* then re-attempt to allocate an mbuf.
*/
struct mbuf *
m_retry(i, t)
int i, t;
{
struct mbuf *m;
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m_reclaim(i);
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#define m_retry(i, t) (struct mbuf *)0
MGET(m, i, t);
#undef m_retry
if (m != NULL)
mbstat.m_wait++;
else
mbstat.m_drops++;
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return (m);
}
/*
* As above; retry an MGETHDR.
*/
struct mbuf *
m_retryhdr(i, t)
int i, t;
{
struct mbuf *m;
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m_reclaim(i);
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#define m_retryhdr(i, t) (struct mbuf *)0
MGETHDR(m, i, t);
#undef m_retryhdr
if (m != NULL)
mbstat.m_wait++;
else
mbstat.m_drops++;
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return (m);
}
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void
m_reclaim(how)
int how;
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{
struct domain *dp;
struct protosw *pr;
struct ifnet *ifp;
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int s = splimp();
for (dp = domains; dp; dp = dp->dom_next)
for (pr = dp->dom_protosw;
pr < dp->dom_protoswNPROTOSW; pr++)
if (pr->pr_drain)
(*pr->pr_drain)();
for (ifp = TAILQ_FIRST(&ifnet); ifp; ifp = TAILQ_NEXT(ifp, if_list))
if (ifp->if_drain)
(*ifp->if_drain)(ifp);
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splx(s);
mbstat.m_drain++;
}
/*
* Space allocation routines.
* These are also available as macros
* for critical paths.
*/
struct mbuf *
m_get(nowait, type)
int nowait, type;
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{
struct mbuf *m;
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MGET(m, nowait, type);
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return (m);
}
struct mbuf *
m_gethdr(nowait, type)
int nowait, type;
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{
struct mbuf *m;
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MGETHDR(m, nowait, type);
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return (m);
}
struct mbuf *
m_getclr(nowait, type)
int nowait, type;
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{
struct mbuf *m;
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MGET(m, nowait, type);
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if (m == 0)
return (0);
memset(mtod(m, caddr_t), 0, MLEN);
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return (m);
}
struct mbuf *
m_free(m)
struct mbuf *m;
{
struct mbuf *n;
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MFREE(m, n);
return (n);
}
void
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m_freem(m)
struct mbuf *m;
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{
struct mbuf *n;
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if (m == NULL)
return;
do {
MFREE(m, n);
m = n;
} while (m);
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}
/*
* Mbuffer utility routines.
*/
/*
* Lesser-used path for M_PREPEND:
* allocate new mbuf to prepend to chain,
* copy junk along.
*/
struct mbuf *
m_prepend(m, len, how)
struct mbuf *m;
int len, how;
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{
struct mbuf *mn;
MGET(mn, how, m->m_type);
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if (mn == (struct mbuf *)NULL) {
m_freem(m);
return ((struct mbuf *)NULL);
}
if (m->m_flags & M_PKTHDR) {
M_COPY_PKTHDR(mn, m);
m->m_flags &= ~M_PKTHDR;
}
mn->m_next = m;
m = mn;
if (len < MHLEN)
MH_ALIGN(m, len);
m->m_len = len;
return (m);
}
/*
* Make a copy of an mbuf chain starting "off0" bytes from the beginning,
* continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf.
* The wait parameter is a choice of M_WAIT/M_DONTWAIT from caller.
*/
int MCFail;
struct mbuf *
m_copym(m, off0, len, wait)
struct mbuf *m;
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int off0, wait;
int len;
{
return m_copym0(m, off0, len, wait, 0); /* shallow copy on M_EXT */
}
struct mbuf *
m_dup(m, off0, len, wait)
struct mbuf *m;
int off0, wait;
int len;
{
return m_copym0(m, off0, len, wait, 1); /* deep copy */
}
static struct mbuf *
m_copym0(m, off0, len, wait, deep)
struct mbuf *m;
int off0, wait;
int len;
int deep; /* deep copy */
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{
struct mbuf *n, **np;
int off = off0;
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struct mbuf *top;
int copyhdr = 0;
if (off < 0 || len < 0)
panic("m_copym: off %d, len %d", off, len);
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if (off == 0 && m->m_flags & M_PKTHDR)
copyhdr = 1;
while (off > 0) {
if (m == 0)
panic("m_copym: m == 0");
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if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
np = &top;
top = 0;
while (len > 0) {
if (m == 0) {
if (len != M_COPYALL)
panic("m_copym: m == 0 and not COPYALL");
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break;
}
MGET(n, wait, m->m_type);
*np = n;
if (n == 0)
goto nospace;
if (copyhdr) {
M_COPY_PKTHDR(n, m);
if (len == M_COPYALL)
n->m_pkthdr.len -= off0;
else
n->m_pkthdr.len = len;
copyhdr = 0;
}
n->m_len = min(len, m->m_len - off);
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if (m->m_flags & M_EXT) {
if (!deep) {
n->m_data = m->m_data + off;
n->m_ext = m->m_ext;
MCLADDREFERENCE(m, n);
} else {
MCLGET(n, wait);
memcpy(mtod(n, caddr_t), mtod(m, caddr_t)+off,
(unsigned)n->m_len);
}
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} else
memcpy(mtod(n, caddr_t), mtod(m, caddr_t)+off,
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(unsigned)n->m_len);
if (len != M_COPYALL)
len -= n->m_len;
off = 0;
m = m->m_next;
np = &n->m_next;
}
if (top == 0)
MCFail++;
return (top);
nospace:
m_freem(top);
MCFail++;
return (0);
}
/*
* Copy an entire packet, including header (which must be present).
* An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
*/
struct mbuf *
m_copypacket(m, how)
struct mbuf *m;
int how;
{
struct mbuf *top, *n, *o;
MGET(n, how, m->m_type);
top = n;
if (!n)
goto nospace;
M_COPY_PKTHDR(n, m);
n->m_len = m->m_len;
if (m->m_flags & M_EXT) {
n->m_data = m->m_data;
n->m_ext = m->m_ext;
MCLADDREFERENCE(m, n);
} else {
memcpy(mtod(n, char *), mtod(m, char *), n->m_len);
}
m = m->m_next;
while (m) {
MGET(o, how, m->m_type);
if (!o)
goto nospace;
n->m_next = o;
n = n->m_next;
n->m_len = m->m_len;
if (m->m_flags & M_EXT) {
n->m_data = m->m_data;
n->m_ext = m->m_ext;
MCLADDREFERENCE(m, n);
} else {
memcpy(mtod(n, char *), mtod(m, char *), n->m_len);
}
m = m->m_next;
}
return top;
nospace:
m_freem(top);
MCFail++;
return 0;
}
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/*
* Copy data from an mbuf chain starting "off" bytes from the beginning,
* continuing for "len" bytes, into the indicated buffer.
*/
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void
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m_copydata(m, off, len, cp)
struct mbuf *m;
int off;
int len;
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caddr_t cp;
{
unsigned count;
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if (off < 0 || len < 0)
panic("m_copydata");
while (off > 0) {
if (m == 0)
panic("m_copydata");
if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
while (len > 0) {
if (m == 0)
panic("m_copydata");
count = min(m->m_len - off, len);
memcpy(cp, mtod(m, caddr_t) + off, count);
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len -= count;
cp += count;
off = 0;
m = m->m_next;
}
}
/*
* Concatenate mbuf chain n to m.
* Both chains must be of the same type (e.g. MT_DATA).
* Any m_pkthdr is not updated.
*/
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void
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m_cat(m, n)
struct mbuf *m, *n;
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{
while (m->m_next)
m = m->m_next;
while (n) {
if (m->m_flags & M_EXT ||
m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) {
/* just join the two chains */
m->m_next = n;
return;
}
/* splat the data from one into the other */
memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t),
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(u_int)n->m_len);
m->m_len += n->m_len;
n = m_free(n);
}
}
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void
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m_adj(mp, req_len)
struct mbuf *mp;
int req_len;
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{
int len = req_len;
struct mbuf *m;
int count;
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if ((m = mp) == NULL)
return;
if (len >= 0) {
/*
* Trim from head.
*/
while (m != NULL && len > 0) {
if (m->m_len <= len) {
len -= m->m_len;
m->m_len = 0;
m = m->m_next;
} else {
m->m_len -= len;
m->m_data += len;
len = 0;
}
}
m = mp;
if (mp->m_flags & M_PKTHDR)
m->m_pkthdr.len -= (req_len - len);
} else {
/*
* Trim from tail. Scan the mbuf chain,
* calculating its length and finding the last mbuf.
* If the adjustment only affects this mbuf, then just
* adjust and return. Otherwise, rescan and truncate
* after the remaining size.
*/
len = -len;
count = 0;
for (;;) {
count += m->m_len;
if (m->m_next == (struct mbuf *)0)
break;
m = m->m_next;
}
if (m->m_len >= len) {
m->m_len -= len;
if (mp->m_flags & M_PKTHDR)
mp->m_pkthdr.len -= len;
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return;
}
count -= len;
if (count < 0)
count = 0;
/*
* Correct length for chain is "count".
* Find the mbuf with last data, adjust its length,
* and toss data from remaining mbufs on chain.
*/
m = mp;
if (m->m_flags & M_PKTHDR)
m->m_pkthdr.len = count;
for (; m; m = m->m_next) {
if (m->m_len >= count) {
m->m_len = count;
break;
}
count -= m->m_len;
}
while (m->m_next)
(m = m->m_next) ->m_len = 0;
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}
}
/*
* Rearange an mbuf chain so that len bytes are contiguous
* and in the data area of an mbuf (so that mtod and dtom
* will work for a structure of size len). Returns the resulting
* mbuf chain on success, frees it and returns null on failure.
* If there is room, it will add up to max_protohdr-len extra bytes to the
* contiguous region in an attempt to avoid being called next time.
*/
int MPFail;
struct mbuf *
m_pullup(n, len)
struct mbuf *n;
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int len;
{
struct mbuf *m;
int count;
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int space;
/*
* If first mbuf has no cluster, and has room for len bytes
* without shifting current data, pullup into it,
* otherwise allocate a new mbuf to prepend to the chain.
*/
if ((n->m_flags & M_EXT) == 0 &&
n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
if (n->m_len >= len)
return (n);
m = n;
n = n->m_next;
len -= m->m_len;
} else {
if (len > MHLEN)
goto bad;
MGET(m, M_DONTWAIT, n->m_type);
if (m == 0)
goto bad;
m->m_len = 0;
if (n->m_flags & M_PKTHDR) {
M_COPY_PKTHDR(m, n);
n->m_flags &= ~M_PKTHDR;
}
}
space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
do {
count = min(min(max(len, max_protohdr), space), n->m_len);
memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t),
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(unsigned)count);
len -= count;
m->m_len += count;
n->m_len -= count;
space -= count;
if (n->m_len)
n->m_data += count;
else
n = m_free(n);
} while (len > 0 && n);
if (len > 0) {
(void) m_free(m);
goto bad;
}
m->m_next = n;
return (m);
bad:
m_freem(n);
MPFail++;
return (0);
}
/*
* Partition an mbuf chain in two pieces, returning the tail --
* all but the first len0 bytes. In case of failure, it returns NULL and
* attempts to restore the chain to its original state.
*/
struct mbuf *
m_split(m0, len0, wait)
struct mbuf *m0;
int len0, wait;
{
struct mbuf *m, *n;
unsigned len = len0, remain, len_save;
for (m = m0; m && len > m->m_len; m = m->m_next)
len -= m->m_len;
if (m == 0)
return (0);
remain = m->m_len - len;
if (m0->m_flags & M_PKTHDR) {
MGETHDR(n, wait, m0->m_type);
if (n == 0)
return (0);
n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
n->m_pkthdr.len = m0->m_pkthdr.len - len0;
len_save = m0->m_pkthdr.len;
m0->m_pkthdr.len = len0;
if (m->m_flags & M_EXT)
goto extpacket;
if (remain > MHLEN) {
/* m can't be the lead packet */
MH_ALIGN(n, 0);
n->m_next = m_split(m, len, wait);
if (n->m_next == 0) {
(void) m_free(n);
m0->m_pkthdr.len = len_save;
return (0);
} else
return (n);
} else
MH_ALIGN(n, remain);
} else if (remain == 0) {
n = m->m_next;
m->m_next = 0;
return (n);
} else {
MGET(n, wait, m->m_type);
if (n == 0)
return (0);
M_ALIGN(n, remain);
}
extpacket:
if (m->m_flags & M_EXT) {
n->m_ext = m->m_ext;
MCLADDREFERENCE(m, n);
n->m_data = m->m_data + len;
} else {
memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + len, remain);
}
n->m_len = remain;
m->m_len = len;
n->m_next = m->m_next;
m->m_next = 0;
return (n);
}
/*
* Routine to copy from device local memory into mbufs.
*/
struct mbuf *
m_devget(buf, totlen, off0, ifp, copy)
char *buf;
int totlen, off0;
struct ifnet *ifp;
void (*copy) __P((const void *from, void *to, size_t len));
{
struct mbuf *m;
struct mbuf *top = 0, **mp = &top;
int off = off0, len;
char *cp;
char *epkt;
cp = buf;
epkt = cp + totlen;
if (off) {
/*
* If 'off' is non-zero, packet is trailer-encapsulated,
* so we have to skip the type and length fields.
*/
cp += off + 2 * sizeof(u_int16_t);
totlen -= 2 * sizeof(u_int16_t);
}
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == 0)
return (0);
m->m_pkthdr.rcvif = ifp;
m->m_pkthdr.len = totlen;
m->m_len = MHLEN;
while (totlen > 0) {
if (top) {
MGET(m, M_DONTWAIT, MT_DATA);
if (m == 0) {
m_freem(top);
return (0);
}
m->m_len = MLEN;
}
len = min(totlen, epkt - cp);
if (len >= MINCLSIZE) {
MCLGET(m, M_DONTWAIT);
if ((m->m_flags & M_EXT) == 0) {
m_free(m);
m_freem(top);
return (0);
}
m->m_len = len = min(len, MCLBYTES);
} else {
/*
* Place initial small packet/header at end of mbuf.
*/
if (len < m->m_len) {
if (top == 0 && len + max_linkhdr <= m->m_len)
m->m_data += max_linkhdr;
m->m_len = len;
} else
len = m->m_len;
}
if (copy)
1996-02-04 05:17:43 +03:00
copy(cp, mtod(m, caddr_t), (size_t)len);
else
memcpy(mtod(m, caddr_t), cp, (size_t)len);
cp += len;
*mp = m;
mp = &m->m_next;
totlen -= len;
if (cp == epkt)
cp = buf;
}
return (top);
}
/*
* Copy data from a buffer back into the indicated mbuf chain,
* starting "off" bytes from the beginning, extending the mbuf
* chain if necessary.
*/
void
m_copyback(m0, off, len, cp)
struct mbuf *m0;
int off;
int len;
caddr_t cp;
{
int mlen;
struct mbuf *m = m0, *n;
int totlen = 0;
if (m0 == 0)
return;
while (off > (mlen = m->m_len)) {
off -= mlen;
totlen += mlen;
if (m->m_next == 0) {
n = m_getclr(M_DONTWAIT, m->m_type);
if (n == 0)
goto out;
n->m_len = min(MLEN, len + off);
m->m_next = n;
}
m = m->m_next;
}
while (len > 0) {
mlen = min (m->m_len - off, len);
memcpy(mtod(m, caddr_t) + off, cp, (unsigned)mlen);
cp += mlen;
len -= mlen;
mlen += off;
off = 0;
totlen += mlen;
if (len == 0)
break;
if (m->m_next == 0) {
n = m_get(M_DONTWAIT, m->m_type);
if (n == 0)
break;
n->m_len = min(MLEN, len);
m->m_next = n;
}
m = m->m_next;
}
out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
m->m_pkthdr.len = totlen;
}