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freebsd-skq/sys/kern/uipc_mbuf.c
peter 3b842d34e8 $Id$ -> $FreeBSD$
1999-08-28 01:08:13 +00:00

957 lines
20 KiB
C
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/*
* Copyright (c) 1982, 1986, 1988, 1991, 1993
* The Regents of the University of California. 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. 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.
*
* @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94
* $FreeBSD$
*/
#include "opt_param.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
static void mbinit __P((void *));
SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbinit, NULL)
struct mbuf *mbutl;
char *mclrefcnt;
struct mbstat mbstat;
struct mbuf *mmbfree;
union mcluster *mclfree;
int max_linkhdr;
int max_protohdr;
int max_hdr;
int max_datalen;
int nmbclusters;
int nmbufs;
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW,
&max_linkhdr, 0, "");
SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW,
&max_protohdr, 0, "");
SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, "");
SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW,
&max_datalen, 0, "");
SYSCTL_STRUCT(_kern_ipc, KIPC_MBSTAT, mbstat, CTLFLAG_RW, &mbstat, mbstat, "");
SYSCTL_INT(_kern_ipc, KIPC_NMBCLUSTERS, nmbclusters, CTLFLAG_RD,
&nmbclusters, 0, "Maximum number of mbuf clusters avaliable");
#ifndef NMBCLUSTERS
#define NMBCLUSTERS (512 + MAXUSERS * 16)
#endif
TUNABLE_INT_DECL("kern.ipc.nmbclusters", NMBCLUSTERS, nmbclusters);
TUNABLE_INT_DECL("kern.ipc.nmbufs", NMBCLUSTERS * 4, nmbufs); /* XXX fixup? */
static void m_reclaim __P((void));
/* "number of clusters of pages" */
#define NCL_INIT 1
#define NMB_INIT 16
/* ARGSUSED*/
static void
mbinit(dummy)
void *dummy;
{
int s;
mmbfree = NULL; mclfree = NULL;
mbstat.m_msize = MSIZE;
mbstat.m_mclbytes = MCLBYTES;
mbstat.m_minclsize = MINCLSIZE;
mbstat.m_mlen = MLEN;
mbstat.m_mhlen = MHLEN;
s = splimp();
if (m_mballoc(NMB_INIT, M_DONTWAIT) == 0)
goto bad;
#if MCLBYTES <= PAGE_SIZE
if (m_clalloc(NCL_INIT, M_DONTWAIT) == 0)
goto bad;
#else
/* It's OK to call contigmalloc in this context. */
if (m_clalloc(16, M_WAIT) == 0)
goto bad;
#endif
splx(s);
return;
bad:
panic("mbinit");
}
/*
* Allocate at least nmb mbufs and place on mbuf free list.
* Must be called at splimp.
*/
/* ARGSUSED */
int
m_mballoc(nmb, how)
register int nmb;
int how;
{
register caddr_t p;
register int i;
int nbytes;
/* Once we run out of map space, it will be impossible to get
* any more (nothing is ever freed back to the map) (XXX which
* is dumb). (however you are not dead as m_reclaim might
* still be able to free a substantial amount of space).
*/
if (mb_map_full)
return (0);
nbytes = round_page(nmb * MSIZE);
p = (caddr_t)kmem_malloc(mb_map, nbytes, M_NOWAIT);
if (p == 0 && how == M_WAIT) {
mbstat.m_wait++;
p = (caddr_t)kmem_malloc(mb_map, nbytes, M_WAITOK);
}
/*
* Either the map is now full, or `how' is M_NOWAIT and there
* are no pages left.
*/
if (p == NULL)
return (0);
nmb = nbytes / MSIZE;
for (i = 0; i < nmb; i++) {
((struct mbuf *)p)->m_next = mmbfree;
mmbfree = (struct mbuf *)p;
p += MSIZE;
}
mbstat.m_mbufs += nmb;
return (1);
}
#if MCLBYTES > PAGE_SIZE
static int i_want_my_mcl;
static void
kproc_mclalloc(void)
{
int status;
while (1) {
tsleep(&i_want_my_mcl, PVM, "mclalloc", 0);
for (; i_want_my_mcl; i_want_my_mcl--) {
if (m_clalloc(1, M_WAIT) == 0)
printf("m_clalloc failed even in process context!\n");
}
}
}
static struct proc *mclallocproc;
static struct kproc_desc mclalloc_kp = {
"mclalloc",
kproc_mclalloc,
&mclallocproc
};
SYSINIT(mclallocproc, SI_SUB_KTHREAD_UPDATE, SI_ORDER_ANY, kproc_start,
&mclalloc_kp);
#endif
/*
* Allocate some number of mbuf clusters
* and place on cluster free list.
* Must be called at splimp.
*/
/* ARGSUSED */
int
m_clalloc(ncl, how)
register int ncl;
int how;
{
register caddr_t p;
register int i;
int npg;
/*
* Once we run out of map space, it will be impossible
* to get any more (nothing is ever freed back to the
* map).
*/
if (mb_map_full) {
mbstat.m_drops++;
return (0);
}
#if MCLBYTES > PAGE_SIZE
if (how != M_WAIT) {
i_want_my_mcl += ncl;
wakeup(&i_want_my_mcl);
mbstat.m_wait++;
p = 0;
} else {
p = contigmalloc1(MCLBYTES * ncl, M_DEVBUF, M_WAITOK, 0ul,
~0ul, PAGE_SIZE, 0, mb_map);
}
#else
npg = ncl;
p = (caddr_t)kmem_malloc(mb_map, ctob(npg),
how != M_WAIT ? M_NOWAIT : M_WAITOK);
ncl = ncl * PAGE_SIZE / MCLBYTES;
#endif
/*
* Either the map is now full, or `how' is M_NOWAIT and there
* are no pages left.
*/
if (p == NULL) {
mbstat.m_drops++;
return (0);
}
for (i = 0; i < ncl; i++) {
((union mcluster *)p)->mcl_next = mclfree;
mclfree = (union mcluster *)p;
p += MCLBYTES;
mbstat.m_clfree++;
}
mbstat.m_clusters += ncl;
return (1);
}
/*
* When MGET fails, 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;
{
register struct mbuf *m;
/*
* Must only do the reclaim if not in an interrupt context.
*/
if (i == M_WAIT)
m_reclaim();
#define m_retry(i, t) (struct mbuf *)0
MGET(m, i, t);
#undef m_retry
if (m != NULL) {
mbstat.m_wait++;
} else {
if (i == M_DONTWAIT)
mbstat.m_drops++;
else
panic("Out of mbuf clusters");
}
return (m);
}
/*
* As above; retry an MGETHDR.
*/
struct mbuf *
m_retryhdr(i, t)
int i, t;
{
register struct mbuf *m;
/*
* Must only do the reclaim if not in an interrupt context.
*/
if (i == M_WAIT)
m_reclaim();
#define m_retryhdr(i, t) (struct mbuf *)0
MGETHDR(m, i, t);
#undef m_retryhdr
if (m != NULL) {
mbstat.m_wait++;
} else {
if (i == M_DONTWAIT)
mbstat.m_drops++;
else
panic("Out of mbuf clusters");
}
return (m);
}
static void
m_reclaim()
{
register struct domain *dp;
register struct protosw *pr;
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)();
splx(s);
mbstat.m_drain++;
}
/*
* Space allocation routines.
* These are also available as macros
* for critical paths.
*/
struct mbuf *
m_get(how, type)
int how, type;
{
register struct mbuf *m;
MGET(m, how, type);
return (m);
}
struct mbuf *
m_gethdr(how, type)
int how, type;
{
register struct mbuf *m;
MGETHDR(m, how, type);
return (m);
}
struct mbuf *
m_getclr(how, type)
int how, type;
{
register struct mbuf *m;
MGET(m, how, type);
if (m == 0)
return (0);
bzero(mtod(m, caddr_t), MLEN);
return (m);
}
struct mbuf *
m_free(m)
struct mbuf *m;
{
register struct mbuf *n;
MFREE(m, n);
return (n);
}
void
m_freem(m)
register struct mbuf *m;
{
register struct mbuf *n;
if (m == NULL)
return;
do {
MFREE(m, n);
m = n;
} while (m);
}
/*
* 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)
register struct mbuf *m;
int len, how;
{
struct mbuf *mn;
MGET(mn, how, m->m_type);
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.
*/
#define MCFail (mbstat.m_mcfail)
struct mbuf *
m_copym(m, off0, len, wait)
register struct mbuf *m;
int off0, wait;
register int len;
{
register struct mbuf *n, **np;
register int off = off0;
struct mbuf *top;
int copyhdr = 0;
if (off < 0 || len < 0)
panic("m_copym");
if (off == 0 && m->m_flags & M_PKTHDR)
copyhdr = 1;
while (off > 0) {
if (m == 0)
panic("m_copym");
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");
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);
if (m->m_flags & M_EXT) {
n->m_data = m->m_data + off;
if(!m->m_ext.ext_ref)
mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
else
(*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
m->m_ext.ext_size);
n->m_ext = m->m_ext;
n->m_flags |= M_EXT;
} else
bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
(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;
if(!m->m_ext.ext_ref)
mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
else
(*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
m->m_ext.ext_size);
n->m_ext = m->m_ext;
n->m_flags |= M_EXT;
} else {
bcopy(mtod(m, char *), mtod(n, 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;
if(!m->m_ext.ext_ref)
mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
else
(*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
m->m_ext.ext_size);
n->m_ext = m->m_ext;
n->m_flags |= M_EXT;
} else {
bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
}
m = m->m_next;
}
return top;
nospace:
m_freem(top);
MCFail++;
return 0;
}
/*
* Copy data from an mbuf chain starting "off" bytes from the beginning,
* continuing for "len" bytes, into the indicated buffer.
*/
void
m_copydata(m, off, len, cp)
register struct mbuf *m;
register int off;
register int len;
caddr_t cp;
{
register unsigned count;
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);
bcopy(mtod(m, caddr_t) + off, cp, count);
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.
*/
void
m_cat(m, n)
register struct mbuf *m, *n;
{
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 */
bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
(u_int)n->m_len);
m->m_len += n->m_len;
n = m_free(n);
}
}
void
m_adj(mp, req_len)
struct mbuf *mp;
int req_len;
{
register int len = req_len;
register struct mbuf *m;
register int count;
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;
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;
}
}
/*
* 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.
*/
#define MPFail (mbstat.m_mpfail)
struct mbuf *
m_pullup(n, len)
register struct mbuf *n;
int len;
{
register struct mbuf *m;
register int count;
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);
bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
(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)
register struct mbuf *m0;
int len0, wait;
{
register struct mbuf *m, *n;
unsigned len = len0, remain;
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;
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);
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_flags |= M_EXT;
n->m_ext = m->m_ext;
if(!m->m_ext.ext_ref)
mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
else
(*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
m->m_ext.ext_size);
m->m_ext.ext_size = 0; /* For Accounting XXXXXX danger */
n->m_data = m->m_data + len;
} else {
bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), 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((char *from, caddr_t to, u_int len));
{
register struct mbuf *m;
struct mbuf *top = 0, **mp = &top;
register int off = off0, len;
register char *cp;
char *epkt;
cp = buf;
epkt = cp + totlen;
if (off) {
cp += off + 2 * sizeof(u_short);
totlen -= 2 * sizeof(u_short);
}
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)
m->m_len = len = min(len, MCLBYTES);
else
len = m->m_len;
} 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)
copy(cp, mtod(m, caddr_t), (unsigned)len);
else
bcopy(cp, mtod(m, caddr_t), (unsigned)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;
register int off;
register int len;
caddr_t cp;
{
register int mlen;
register 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);
bcopy(cp, off + mtod(m, caddr_t), (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;
}
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