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uipc_mbuf.c
1764 lines (1513 loc) · 37.4 KB
/
uipc_mbuf.c
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/* $OpenBSD: uipc_mbuf.c,v 1.273 2019/10/22 18:45:02 bluhm Exp $ */
/* $NetBSD: uipc_mbuf.c,v 1.15.4.1 1996/06/13 17:11:44 cgd Exp $ */
/*
* 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. 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
*/
/*
* @(#)COPYRIGHT 1.1 (NRL) 17 January 1995
*
* NRL grants permission for redistribution and use in source and binary
* forms, with or without modification, of the software and documentation
* created at NRL 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 acknowledgements:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* This product includes software developed at the Information
* Technology Division, US Naval Research Laboratory.
* 4. Neither the name of the NRL nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL 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 NRL 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.
*
* The views and conclusions contained in the software and documentation
* are those of the authors and should not be interpreted as representing
* official policies, either expressed or implied, of the US Naval
* Research Laboratory (NRL).
*/
#include "pf.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/atomic.h>
#include <sys/malloc.h>
#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/percpu.h>
#include <sys/sysctl.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <net/if.h>
#include <uvm/uvm_extern.h>
#ifdef DDB
#include <machine/db_machdep.h>
#endif
#if NPF > 0
#include <net/pfvar.h>
#endif /* NPF > 0 */
/* mbuf stats */
COUNTERS_BOOT_MEMORY(mbstat_boot, MBSTAT_COUNT);
struct cpumem *mbstat = COUNTERS_BOOT_INITIALIZER(mbstat_boot);
/* mbuf pools */
struct pool mbpool;
struct pool mtagpool;
/* mbuf cluster pools */
u_int mclsizes[MCLPOOLS] = {
MCLBYTES, /* must be at slot 0 */
MCLBYTES + 2, /* ETHER_ALIGNED 2k mbufs */
4 * 1024,
8 * 1024,
9 * 1024,
12 * 1024,
16 * 1024,
64 * 1024
};
static char mclnames[MCLPOOLS][8];
struct pool mclpools[MCLPOOLS];
struct pool *m_clpool(u_int);
int max_linkhdr; /* largest link-level header */
int max_protohdr; /* largest protocol header */
int max_hdr; /* largest link+protocol header */
struct mutex m_extref_mtx = MUTEX_INITIALIZER(IPL_NET);
void m_extfree(struct mbuf *);
void m_zero(struct mbuf *);
unsigned long mbuf_mem_limit; /* how much memory can be allocated */
unsigned long mbuf_mem_alloc; /* how much memory has been allocated */
void *m_pool_alloc(struct pool *, int, int *);
void m_pool_free(struct pool *, void *);
struct pool_allocator m_pool_allocator = {
m_pool_alloc,
m_pool_free,
0 /* will be copied from pool_allocator_multi */
};
static void (*mextfree_fns[4])(caddr_t, u_int, void *);
static u_int num_extfree_fns;
#define M_DATABUF(m) ((m)->m_flags & M_EXT ? (m)->m_ext.ext_buf : \
(m)->m_flags & M_PKTHDR ? (m)->m_pktdat : (m)->m_dat)
#define M_SIZE(m) ((m)->m_flags & M_EXT ? (m)->m_ext.ext_size : \
(m)->m_flags & M_PKTHDR ? MHLEN : MLEN)
/*
* Initialize the mbuf allocator.
*/
void
mbinit(void)
{
int i, error;
unsigned int lowbits;
CTASSERT(MSIZE == sizeof(struct mbuf));
m_pool_allocator.pa_pagesz = pool_allocator_multi.pa_pagesz;
mbuf_mem_alloc = 0;
#if DIAGNOSTIC
if (mclsizes[0] != MCLBYTES)
panic("mbinit: the smallest cluster size != MCLBYTES");
if (mclsizes[nitems(mclsizes) - 1] != MAXMCLBYTES)
panic("mbinit: the largest cluster size != MAXMCLBYTES");
#endif
m_pool_init(&mbpool, MSIZE, 64, "mbufpl");
pool_init(&mtagpool, PACKET_TAG_MAXSIZE + sizeof(struct m_tag), 0,
IPL_NET, 0, "mtagpl", NULL);
for (i = 0; i < nitems(mclsizes); i++) {
lowbits = mclsizes[i] & ((1 << 10) - 1);
if (lowbits) {
snprintf(mclnames[i], sizeof(mclnames[0]),
"mcl%dk%u", mclsizes[i] >> 10, lowbits);
} else {
snprintf(mclnames[i], sizeof(mclnames[0]), "mcl%dk",
mclsizes[i] >> 10);
}
m_pool_init(&mclpools[i], mclsizes[i], 64, mclnames[i]);
}
error = nmbclust_update(nmbclust);
KASSERT(error == 0);
(void)mextfree_register(m_extfree_pool);
KASSERT(num_extfree_fns == 1);
}
void
mbcpuinit()
{
int i;
mbstat = counters_alloc_ncpus(mbstat, MBSTAT_COUNT);
pool_cache_init(&mbpool);
pool_cache_init(&mtagpool);
for (i = 0; i < nitems(mclsizes); i++)
pool_cache_init(&mclpools[i]);
}
int
nmbclust_update(long newval)
{
int i;
if (newval < 0 || newval > LONG_MAX / MCLBYTES)
return ERANGE;
/* update the global mbuf memory limit */
nmbclust = newval;
mbuf_mem_limit = nmbclust * MCLBYTES;
pool_wakeup(&mbpool);
for (i = 0; i < nitems(mclsizes); i++)
pool_wakeup(&mclpools[i]);
return 0;
}
/*
* Space allocation routines.
*/
struct mbuf *
m_get(int nowait, int type)
{
struct mbuf *m;
struct counters_ref cr;
uint64_t *counters;
int s;
KDASSERT(type < MT_NTYPES);
m = pool_get(&mbpool, nowait == M_WAIT ? PR_WAITOK : PR_NOWAIT);
if (m == NULL)
return (NULL);
s = splnet();
counters = counters_enter(&cr, mbstat);
counters[type]++;
counters_leave(&cr, mbstat);
splx(s);
m->m_type = type;
m->m_next = NULL;
m->m_nextpkt = NULL;
m->m_data = m->m_dat;
m->m_flags = 0;
return (m);
}
/*
* ATTN: When changing anything here check m_inithdr() and m_defrag() those
* may need to change as well.
*/
struct mbuf *
m_gethdr(int nowait, int type)
{
struct mbuf *m;
struct counters_ref cr;
uint64_t *counters;
int s;
KDASSERT(type < MT_NTYPES);
m = pool_get(&mbpool, nowait == M_WAIT ? PR_WAITOK : PR_NOWAIT);
if (m == NULL)
return (NULL);
s = splnet();
counters = counters_enter(&cr, mbstat);
counters[type]++;
counters_leave(&cr, mbstat);
splx(s);
m->m_type = type;
return (m_inithdr(m));
}
struct mbuf *
m_inithdr(struct mbuf *m)
{
/* keep in sync with m_gethdr */
m->m_next = NULL;
m->m_nextpkt = NULL;
m->m_data = m->m_pktdat;
m->m_flags = M_PKTHDR;
memset(&m->m_pkthdr, 0, sizeof(m->m_pkthdr));
m->m_pkthdr.pf.prio = IFQ_DEFPRIO;
return (m);
}
static inline void
m_clearhdr(struct mbuf *m)
{
/* delete all mbuf tags to reset the state */
m_tag_delete_chain(m);
#if NPF > 0
pf_mbuf_unlink_state_key(m);
pf_mbuf_unlink_inpcb(m);
#endif /* NPF > 0 */
memset(&m->m_pkthdr, 0, sizeof(m->m_pkthdr));
}
void
m_removehdr(struct mbuf *m)
{
KASSERT(m->m_flags & M_PKTHDR);
m_clearhdr(m);
m->m_flags &= ~M_PKTHDR;
}
void
m_resethdr(struct mbuf *m)
{
int len = m->m_pkthdr.len;
u_int8_t loopcnt = m->m_pkthdr.ph_loopcnt;
KASSERT(m->m_flags & M_PKTHDR);
m->m_flags &= (M_EXT|M_PKTHDR|M_EOR|M_EXTWR|M_ZEROIZE);
m_clearhdr(m);
/* like m_inithdr(), but keep any associated data and mbufs */
m->m_pkthdr.pf.prio = IFQ_DEFPRIO;
m->m_pkthdr.len = len;
m->m_pkthdr.ph_loopcnt = loopcnt;
}
void
m_calchdrlen(struct mbuf *m)
{
struct mbuf *n;
int plen = 0;
KASSERT(m->m_flags & M_PKTHDR);
for (n = m; n; n = n->m_next)
plen += n->m_len;
m->m_pkthdr.len = plen;
}
struct mbuf *
m_getclr(int nowait, int type)
{
struct mbuf *m;
MGET(m, nowait, type);
if (m == NULL)
return (NULL);
memset(mtod(m, caddr_t), 0, MLEN);
return (m);
}
struct pool *
m_clpool(u_int pktlen)
{
struct pool *pp;
int pi;
for (pi = 0; pi < nitems(mclpools); pi++) {
pp = &mclpools[pi];
if (pktlen <= pp->pr_size)
return (pp);
}
return (NULL);
}
struct mbuf *
m_clget(struct mbuf *m, int how, u_int pktlen)
{
struct mbuf *m0 = NULL;
struct pool *pp;
caddr_t buf;
pp = m_clpool(pktlen);
#ifdef DIAGNOSTIC
if (pp == NULL)
panic("m_clget: request for %u byte cluster", pktlen);
#endif
if (m == NULL) {
m0 = m_gethdr(how, MT_DATA);
if (m0 == NULL)
return (NULL);
m = m0;
}
buf = pool_get(pp, how == M_WAIT ? PR_WAITOK : PR_NOWAIT);
if (buf == NULL) {
m_freem(m0);
return (NULL);
}
MEXTADD(m, buf, pp->pr_size, M_EXTWR, MEXTFREE_POOL, pp);
return (m);
}
void
m_extfree_pool(caddr_t buf, u_int size, void *pp)
{
pool_put(pp, buf);
}
struct mbuf *
m_free(struct mbuf *m)
{
struct mbuf *n;
struct counters_ref cr;
uint64_t *counters;
int s;
if (m == NULL)
return (NULL);
s = splnet();
counters = counters_enter(&cr, mbstat);
counters[m->m_type]--;
counters_leave(&cr, mbstat);
splx(s);
n = m->m_next;
if (m->m_flags & M_ZEROIZE) {
m_zero(m);
/* propagate M_ZEROIZE to the next mbuf in the chain */
if (n)
n->m_flags |= M_ZEROIZE;
}
if (m->m_flags & M_PKTHDR) {
m_tag_delete_chain(m);
#if NPF > 0
pf_mbuf_unlink_state_key(m);
pf_mbuf_unlink_inpcb(m);
#endif /* NPF > 0 */
}
if (m->m_flags & M_EXT)
m_extfree(m);
pool_put(&mbpool, m);
return (n);
}
void
m_extref(struct mbuf *o, struct mbuf *n)
{
int refs = MCLISREFERENCED(o);
n->m_flags |= o->m_flags & (M_EXT|M_EXTWR);
if (refs)
mtx_enter(&m_extref_mtx);
n->m_ext.ext_nextref = o->m_ext.ext_nextref;
n->m_ext.ext_prevref = o;
o->m_ext.ext_nextref = n;
n->m_ext.ext_nextref->m_ext.ext_prevref = n;
if (refs)
mtx_leave(&m_extref_mtx);
MCLREFDEBUGN((n), __FILE__, __LINE__);
}
static inline u_int
m_extunref(struct mbuf *m)
{
int refs = 0;
if (!MCLISREFERENCED(m))
return (0);
mtx_enter(&m_extref_mtx);
if (MCLISREFERENCED(m)) {
m->m_ext.ext_nextref->m_ext.ext_prevref =
m->m_ext.ext_prevref;
m->m_ext.ext_prevref->m_ext.ext_nextref =
m->m_ext.ext_nextref;
refs = 1;
}
mtx_leave(&m_extref_mtx);
return (refs);
}
/*
* Returns a number for use with MEXTADD.
* Should only be called once per function.
* Drivers can be assured that the index will be non zero.
*/
u_int
mextfree_register(void (*fn)(caddr_t, u_int, void *))
{
KASSERT(num_extfree_fns < nitems(mextfree_fns));
mextfree_fns[num_extfree_fns] = fn;
return num_extfree_fns++;
}
void
m_extfree(struct mbuf *m)
{
if (m_extunref(m) == 0) {
KASSERT(m->m_ext.ext_free_fn < num_extfree_fns);
mextfree_fns[m->m_ext.ext_free_fn](m->m_ext.ext_buf,
m->m_ext.ext_size, m->m_ext.ext_arg);
}
m->m_flags &= ~(M_EXT|M_EXTWR);
}
struct mbuf *
m_freem(struct mbuf *m)
{
struct mbuf *n;
if (m == NULL)
return (NULL);
n = m->m_nextpkt;
do
m = m_free(m);
while (m != NULL);
return (n);
}
void
m_purge(struct mbuf *m)
{
while (m != NULL)
m = m_freem(m);
}
/*
* mbuf chain defragmenter. This function uses some evil tricks to defragment
* an mbuf chain into a single buffer without changing the mbuf pointer.
* This needs to know a lot of the mbuf internals to make this work.
*/
int
m_defrag(struct mbuf *m, int how)
{
struct mbuf *m0;
if (m->m_next == NULL)
return (0);
KASSERT(m->m_flags & M_PKTHDR);
if ((m0 = m_gethdr(how, m->m_type)) == NULL)
return (ENOBUFS);
if (m->m_pkthdr.len > MHLEN) {
MCLGETI(m0, how, NULL, m->m_pkthdr.len);
if (!(m0->m_flags & M_EXT)) {
m_free(m0);
return (ENOBUFS);
}
}
m_copydata(m, 0, m->m_pkthdr.len, mtod(m0, caddr_t));
m0->m_pkthdr.len = m0->m_len = m->m_pkthdr.len;
/* free chain behind and possible ext buf on the first mbuf */
m_freem(m->m_next);
m->m_next = NULL;
if (m->m_flags & M_EXT)
m_extfree(m);
/*
* Bounce copy mbuf over to the original mbuf and set everything up.
* This needs to reset or clear all pointers that may go into the
* original mbuf chain.
*/
if (m0->m_flags & M_EXT) {
memcpy(&m->m_ext, &m0->m_ext, sizeof(struct mbuf_ext));
MCLINITREFERENCE(m);
m->m_flags |= m0->m_flags & (M_EXT|M_EXTWR);
m->m_data = m->m_ext.ext_buf;
} else {
m->m_data = m->m_pktdat;
memcpy(m->m_data, m0->m_data, m0->m_len);
}
m->m_pkthdr.len = m->m_len = m0->m_len;
m0->m_flags &= ~(M_EXT|M_EXTWR); /* cluster is gone */
m_free(m0);
return (0);
}
/*
* Mbuffer utility routines.
*/
/*
* Ensure len bytes of contiguous space at the beginning of the mbuf chain
*/
struct mbuf *
m_prepend(struct mbuf *m, int len, int how)
{
struct mbuf *mn;
if (len > MHLEN)
panic("mbuf prepend length too big");
if (m_leadingspace(m) >= len) {
m->m_data -= len;
m->m_len += len;
} else {
MGET(mn, how, m->m_type);
if (mn == NULL) {
m_freem(m);
return (NULL);
}
if (m->m_flags & M_PKTHDR)
M_MOVE_PKTHDR(mn, m);
mn->m_next = m;
m = mn;
m_align(m, len);
m->m_len = len;
}
if (m->m_flags & M_PKTHDR)
m->m_pkthdr.len += len;
return (m);
}
/*
* Make a copy of an mbuf chain starting "off" 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.
*/
struct mbuf *
m_copym(struct mbuf *m0, int off, int len, int wait)
{
struct mbuf *m, *n, **np;
struct mbuf *top;
int copyhdr = 0;
if (off < 0 || len < 0)
panic("m_copym0: off %d, len %d", off, len);
if (off == 0 && m0->m_flags & M_PKTHDR)
copyhdr = 1;
if ((m = m_getptr(m0, off, &off)) == NULL)
panic("m_copym0: short mbuf chain");
np = ⊤
top = NULL;
while (len > 0) {
if (m == NULL) {
if (len != M_COPYALL)
panic("m_copym0: m == NULL and not COPYALL");
break;
}
MGET(n, wait, m->m_type);
*np = n;
if (n == NULL)
goto nospace;
if (copyhdr) {
if (m_dup_pkthdr(n, m0, wait))
goto nospace;
if (len != M_COPYALL)
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;
n->m_ext = m->m_ext;
MCLADDREFERENCE(m, n);
} else {
n->m_data += m->m_data -
(m->m_flags & M_PKTHDR ? m->m_pktdat : m->m_dat);
n->m_data += off;
memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off,
n->m_len);
}
if (len != M_COPYALL)
len -= n->m_len;
off += n->m_len;
#ifdef DIAGNOSTIC
if (off > m->m_len)
panic("m_copym0 overrun");
#endif
if (off == m->m_len) {
m = m->m_next;
off = 0;
}
np = &n->m_next;
}
return (top);
nospace:
m_freem(top);
return (NULL);
}
/*
* Copy data from an mbuf chain starting "off" bytes from the beginning,
* continuing for "len" bytes, into the indicated buffer.
*/
void
m_copydata(struct mbuf *m, int off, int len, caddr_t cp)
{
unsigned count;
if (off < 0)
panic("m_copydata: off %d < 0", off);
if (len < 0)
panic("m_copydata: len %d < 0", len);
if ((m = m_getptr(m, off, &off)) == NULL)
panic("m_copydata: short mbuf chain");
while (len > 0) {
if (m == NULL)
panic("m_copydata: null mbuf");
count = min(m->m_len - off, len);
memmove(cp, mtod(m, caddr_t) + off, count);
len -= count;
cp += count;
off = 0;
m = m->m_next;
}
}
/*
* Copy data from a buffer back into the indicated mbuf chain,
* starting "off" bytes from the beginning, extending the mbuf
* chain if necessary. The mbuf needs to be properly initialized
* including the setting of m_len.
*/
int
m_copyback(struct mbuf *m0, int off, int len, const void *_cp, int wait)
{
int mlen, totlen = 0;
struct mbuf *m = m0, *n;
caddr_t cp = (caddr_t)_cp;
int error = 0;
if (m0 == NULL)
return (0);
while (off > (mlen = m->m_len)) {
off -= mlen;
totlen += mlen;
if (m->m_next == NULL) {
if ((n = m_get(wait, m->m_type)) == NULL) {
error = ENOBUFS;
goto out;
}
if (off + len > MLEN) {
MCLGETI(n, wait, NULL, off + len);
if (!(n->m_flags & M_EXT)) {
m_free(n);
error = ENOBUFS;
goto out;
}
}
memset(mtod(n, caddr_t), 0, off);
n->m_len = len + off;
m->m_next = n;
}
m = m->m_next;
}
while (len > 0) {
/* extend last packet to be filled fully */
if (m->m_next == NULL && (len > m->m_len - off))
m->m_len += min(len - (m->m_len - off),
m_trailingspace(m));
mlen = min(m->m_len - off, len);
memmove(mtod(m, caddr_t) + off, cp, mlen);
cp += mlen;
len -= mlen;
totlen += mlen + off;
if (len == 0)
break;
off = 0;
if (m->m_next == NULL) {
if ((n = m_get(wait, m->m_type)) == NULL) {
error = ENOBUFS;
goto out;
}
if (len > MLEN) {
MCLGETI(n, wait, NULL, len);
if (!(n->m_flags & M_EXT)) {
m_free(n);
error = ENOBUFS;
goto out;
}
}
n->m_len = 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;
return (error);
}
/*
* Concatenate mbuf chain n to m.
* n might be copied into m (when n->m_len is small), therefore data portion of
* n could be copied into an mbuf of different mbuf type.
* Therefore both chains should be of the same type (e.g. MT_DATA).
* Any m_pkthdr is not updated.
*/
void
m_cat(struct mbuf *m, struct mbuf *n)
{
while (m->m_next)
m = m->m_next;
while (n) {
if (M_READONLY(m) || n->m_len > m_trailingspace(m)) {
/* 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),
n->m_len);
m->m_len += n->m_len;
n = m_free(n);
}
}
void
m_adj(struct mbuf *mp, int req_len)
{
int len = req_len;
struct mbuf *m;
int count;
if (mp == NULL)
return;
if (len >= 0) {
/*
* Trim from head.
*/
m = mp;
while (m != NULL && len > 0) {
if (m->m_len <= len) {
len -= m->m_len;
m->m_data += m->m_len;
m->m_len = 0;
m = m->m_next;
} else {
m->m_data += len;
m->m_len -= len;
len = 0;
}
}
if (mp->m_flags & M_PKTHDR)
mp->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;
m = mp;
for (;;) {
count += m->m_len;
if (m->m_next == NULL)
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.
*/
if (mp->m_flags & M_PKTHDR)
mp->m_pkthdr.len = count;
m = mp;
for (;;) {
if (m->m_len >= count) {
m->m_len = count;
break;
}
count -= m->m_len;
m = m->m_next;
}
while ((m = m->m_next) != NULL)
m->m_len = 0;
}
}
/*
* Rearrange an mbuf chain so that len bytes are contiguous
* and in the data area of an mbuf (so that mtod will work
* for a structure of size len). Returns the resulting
* mbuf chain on success, frees it and returns null on failure.
*/
struct mbuf *
m_pullup(struct mbuf *m0, int len)
{
struct mbuf *m;
unsigned int adj;
caddr_t head, tail;
unsigned int space;
/* if len is already contig in m0, then don't do any work */
if (len <= m0->m_len)
return (m0);
/* look for some data */
m = m0->m_next;
if (m == NULL)
goto freem0;
head = M_DATABUF(m0);
if (m0->m_len == 0) {
m0->m_data = head;
while (m->m_len == 0) {
m = m_free(m);
if (m == NULL)
goto freem0;
}
adj = mtod(m, unsigned long) & ALIGNBYTES;
} else
adj = mtod(m0, unsigned long) & ALIGNBYTES;
tail = head + M_SIZE(m0);
head += adj;
if (len <= tail - head) {
/* there's enough space in the first mbuf */
if (len > tail - mtod(m0, caddr_t)) {
/* need to memmove to make space at the end */
memmove(head, mtod(m0, caddr_t), m0->m_len);
m0->m_data = head;
}
len -= m0->m_len;
} else {
/* the first mbuf is too small so make a new one */
space = adj + len;
if (space > MAXMCLBYTES)
goto bad;
m0->m_next = m;
m = m0;
MGET(m0, M_DONTWAIT, m->m_type);
if (m0 == NULL)
goto bad;
if (space > MHLEN) {
MCLGETI(m0, M_DONTWAIT, NULL, space);
if ((m0->m_flags & M_EXT) == 0)
goto bad;
}
if (m->m_flags & M_PKTHDR)
M_MOVE_PKTHDR(m0, m);
m0->m_len = 0;
m0->m_data += adj;
}
KDASSERT(m_trailingspace(m0) >= len);
for (;;) {
space = min(len, m->m_len);
memcpy(mtod(m0, caddr_t) + m0->m_len, mtod(m, caddr_t), space);
len -= space;
m0->m_len += space;
m->m_len -= space;