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freebsd-nq/sys/kern/uipc_mbuf.c
Andre Oppermann 7c32173ba8 Unbreak writes of 0 bytes. Zero byte writes happen when only ancillary 
control data but no payload data is passed.

Change m_uiotombuf() to return at least one empty mbuf if the requested
length was zero.  Add comment to sosend_dgram and sosend_generic().

Diagnoses by:		jhb
Regression test by:	rwatson
Pointy hat to.		andre
2007-01-22 14:50:28 +00:00

1846 lines
45 KiB
C
Raw Blame History

/*-
* 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.
* 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
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_mac.h"
#include "opt_param.h"
#include "opt_mbuf_stress_test.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/sysctl.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/uio.h>
#include <security/mac/mac_framework.h>
int max_linkhdr;
int max_protohdr;
int max_hdr;
int max_datalen;
#ifdef MBUF_STRESS_TEST
int m_defragpackets;
int m_defragbytes;
int m_defraguseless;
int m_defragfailure;
int m_defragrandomfailures;
#endif
/*
* sysctl(8) exported objects
*/
SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RD,
&max_linkhdr, 0, "Size of largest link layer header");
SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RD,
&max_protohdr, 0, "Size of largest protocol layer header");
SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RD,
&max_hdr, 0, "Size of largest link plus protocol header");
SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RD,
&max_datalen, 0, "Minimum space left in mbuf after max_hdr");
#ifdef MBUF_STRESS_TEST
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
&m_defragpackets, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
&m_defragbytes, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
&m_defraguseless, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
&m_defragfailure, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
&m_defragrandomfailures, 0, "");
#endif
/*
* Allocate a given length worth of mbufs and/or clusters (whatever fits
* best) and return a pointer to the top of the allocated chain. If an
* existing mbuf chain is provided, then we will append the new chain
* to the existing one but still return the top of the newly allocated
* chain.
*/
struct mbuf *
m_getm2(struct mbuf *m, int len, int how, short type, int flags)
{
struct mbuf *mb, *nm = NULL, *mtail = NULL;
KASSERT(len >= 0, ("%s: len is < 0", __func__));
/* Validate flags. */
flags &= (M_PKTHDR | M_EOR);
/* Packet header mbuf must be first in chain. */
if ((flags & M_PKTHDR) && m != NULL)
flags &= ~M_PKTHDR;
/* Loop and append maximum sized mbufs to the chain tail. */
while (len > 0) {
if (len > MCLBYTES)
mb = m_getjcl(how, type, (flags & M_PKTHDR),
MJUMPAGESIZE);
else if (len >= MINCLSIZE)
mb = m_getcl(how, type, (flags & M_PKTHDR));
else if (flags & M_PKTHDR)
mb = m_gethdr(how, type);
else
mb = m_get(how, type);
/* Fail the whole operation if one mbuf can't be allocated. */
if (mb == NULL) {
if (nm != NULL)
m_freem(nm);
return (NULL);
}
/* Book keeping. */
len -= (mb->m_flags & M_EXT) ? mb->m_ext.ext_size :
((mb->m_flags & M_PKTHDR) ? MHLEN : MLEN);
if (mtail != NULL)
mtail->m_next = mb;
else
nm = mb;
mtail = mb;
flags &= ~M_PKTHDR; /* Only valid on the first mbuf. */
}
if (flags & M_EOR)
mtail->m_flags |= M_EOR; /* Only valid on the last mbuf. */
/* If mbuf was supplied, append new chain to the end of it. */
if (m != NULL) {
for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next)
;
mtail->m_next = nm;
mtail->m_flags &= ~M_EOR;
} else
m = nm;
return (m);
}
/*
* Free an entire chain of mbufs and associated external buffers, if
* applicable.
*/
void
m_freem(struct mbuf *mb)
{
while (mb != NULL)
mb = m_free(mb);
}
/*-
* Configure a provided mbuf to refer to the provided external storage
* buffer and setup a reference count for said buffer. If the setting
* up of the reference count fails, the M_EXT bit will not be set. If
* successfull, the M_EXT bit is set in the mbuf's flags.
*
* Arguments:
* mb The existing mbuf to which to attach the provided buffer.
* buf The address of the provided external storage buffer.
* size The size of the provided buffer.
* freef A pointer to a routine that is responsible for freeing the
* provided external storage buffer.
* args A pointer to an argument structure (of any type) to be passed
* to the provided freef routine (may be NULL).
* flags Any other flags to be passed to the provided mbuf.
* type The type that the external storage buffer should be
* labeled with.
*
* Returns:
* Nothing.
*/
void
m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
void (*freef)(void *, void *), void *args, int flags, int type)
{
KASSERT(type != EXT_CLUSTER, ("%s: EXT_CLUSTER not allowed", __func__));
if (type != EXT_EXTREF)
mb->m_ext.ref_cnt = (u_int *)uma_zalloc(zone_ext_refcnt, M_NOWAIT);
if (mb->m_ext.ref_cnt != NULL) {
*(mb->m_ext.ref_cnt) = 1;
mb->m_flags |= (M_EXT | flags);
mb->m_ext.ext_buf = buf;
mb->m_data = mb->m_ext.ext_buf;
mb->m_ext.ext_size = size;
mb->m_ext.ext_free = freef;
mb->m_ext.ext_args = args;
mb->m_ext.ext_type = type;
}
}
/*
* Non-directly-exported function to clean up after mbufs with M_EXT
* storage attached to them if the reference count hits 1.
*/
void
mb_free_ext(struct mbuf *m)
{
KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
/* Free attached storage if this mbuf is the only reference to it. */
if (*(m->m_ext.ref_cnt) == 1 ||
atomic_fetchadd_int(m->m_ext.ref_cnt, -1) == 1) {
switch (m->m_ext.ext_type) {
case EXT_PACKET: /* The packet zone is special. */
if (*(m->m_ext.ref_cnt) == 0)
*(m->m_ext.ref_cnt) = 1;
uma_zfree(zone_pack, m);
return; /* Job done. */
case EXT_CLUSTER:
uma_zfree(zone_clust, m->m_ext.ext_buf);
break;
case EXT_JUMBOP:
uma_zfree(zone_jumbop, m->m_ext.ext_buf);
break;
case EXT_JUMBO9:
uma_zfree(zone_jumbo9, m->m_ext.ext_buf);
break;
case EXT_JUMBO16:
uma_zfree(zone_jumbo16, m->m_ext.ext_buf);
break;
case EXT_SFBUF:
case EXT_NET_DRV:
case EXT_MOD_TYPE:
case EXT_DISPOSABLE:
*(m->m_ext.ref_cnt) = 0;
uma_zfree(zone_ext_refcnt, __DEVOLATILE(u_int *,
m->m_ext.ref_cnt));
/* FALLTHROUGH */
case EXT_EXTREF:
KASSERT(m->m_ext.ext_free != NULL,
("%s: ext_free not set", __func__));
(*(m->m_ext.ext_free))(m->m_ext.ext_buf,
m->m_ext.ext_args);
break;
default:
KASSERT(m->m_ext.ext_type == 0,
("%s: unknown ext_type", __func__));
}
}
/*
* Free this mbuf back to the mbuf zone with all m_ext
* information purged.
*/
m->m_ext.ext_buf = NULL;
m->m_ext.ext_free = NULL;
m->m_ext.ext_args = NULL;
m->m_ext.ref_cnt = NULL;
m->m_ext.ext_size = 0;
m->m_ext.ext_type = 0;
m->m_flags &= ~M_EXT;
uma_zfree(zone_mbuf, m);
}
/*
* Attach the the cluster from *m to *n, set up m_ext in *n
* and bump the refcount of the cluster.
*/
static void
mb_dupcl(struct mbuf *n, struct mbuf *m)
{
KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
KASSERT((n->m_flags & M_EXT) == 0, ("%s: M_EXT set", __func__));
if (*(m->m_ext.ref_cnt) == 1)
*(m->m_ext.ref_cnt) += 1;
else
atomic_add_int(m->m_ext.ref_cnt, 1);
n->m_ext.ext_buf = m->m_ext.ext_buf;
n->m_ext.ext_free = m->m_ext.ext_free;
n->m_ext.ext_args = m->m_ext.ext_args;
n->m_ext.ext_size = m->m_ext.ext_size;
n->m_ext.ref_cnt = m->m_ext.ref_cnt;
n->m_ext.ext_type = m->m_ext.ext_type;
n->m_flags |= M_EXT;
}
/*
* Clean up mbuf (chain) from any tags and packet headers.
* If "all" is set then the first mbuf in the chain will be
* cleaned too.
*/
void
m_demote(struct mbuf *m0, int all)
{
struct mbuf *m;
for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) {
if (m->m_flags & M_PKTHDR) {
m_tag_delete_chain(m, NULL);
m->m_flags &= ~M_PKTHDR;
bzero(&m->m_pkthdr, sizeof(struct pkthdr));
}
if (m->m_type == MT_HEADER)
m->m_type = MT_DATA;
if (m != m0 && m->m_nextpkt != NULL)
m->m_nextpkt = NULL;
m->m_flags = m->m_flags & (M_EXT|M_EOR|M_RDONLY|M_FREELIST);
}
}
/*
* Sanity checks on mbuf (chain) for use in KASSERT() and general
* debugging.
* Returns 0 or panics when bad and 1 on all tests passed.
* Sanitize, 0 to run M_SANITY_ACTION, 1 to garble things so they
* blow up later.
*/
int
m_sanity(struct mbuf *m0, int sanitize)
{
struct mbuf *m;
caddr_t a, b;
int pktlen = 0;
#define M_SANITY_ACTION(s) return (0)
/* #define M_SANITY_ACTION(s) panic("mbuf %p: " s, m) */
for (m = m0; m != NULL; m = m->m_next) {
/*
* Basic pointer checks. If any of these fails then some
* unrelated kernel memory before or after us is trashed.
* No way to recover from that.
*/
a = ((m->m_flags & M_EXT) ? m->m_ext.ext_buf :
((m->m_flags & M_PKTHDR) ? (caddr_t)(&m->m_pktdat) :
(caddr_t)(&m->m_dat)) );
b = (caddr_t)(a + (m->m_flags & M_EXT ? m->m_ext.ext_size :
((m->m_flags & M_PKTHDR) ? MHLEN : MLEN)));
if ((caddr_t)m->m_data < a)
M_SANITY_ACTION("m_data outside mbuf data range left");
if ((caddr_t)m->m_data > b)
M_SANITY_ACTION("m_data outside mbuf data range right");
if ((caddr_t)m->m_data + m->m_len > b)
M_SANITY_ACTION("m_data + m_len exeeds mbuf space");
if ((m->m_flags & M_PKTHDR) && m->m_pkthdr.header) {
if ((caddr_t)m->m_pkthdr.header < a ||
(caddr_t)m->m_pkthdr.header > b)
M_SANITY_ACTION("m_pkthdr.header outside mbuf data range");
}
/* m->m_nextpkt may only be set on first mbuf in chain. */
if (m != m0 && m->m_nextpkt != NULL) {
if (sanitize) {
m_freem(m->m_nextpkt);
m->m_nextpkt = (struct mbuf *)0xDEADC0DE;
} else
M_SANITY_ACTION("m->m_nextpkt on in-chain mbuf");
}
/* correct type correlations. */
if (m->m_type == MT_HEADER && !(m->m_flags & M_PKTHDR)) {
if (sanitize)
m->m_type = MT_DATA;
else
M_SANITY_ACTION("MT_HEADER set but not M_PKTHDR");
}
/* packet length (not mbuf length!) calculation */
if (m0->m_flags & M_PKTHDR)
pktlen += m->m_len;
/* m_tags may only be attached to first mbuf in chain. */
if (m != m0 && m->m_flags & M_PKTHDR &&
!SLIST_EMPTY(&m->m_pkthdr.tags)) {
if (sanitize) {
m_tag_delete_chain(m, NULL);
/* put in 0xDEADC0DE perhaps? */
} else
M_SANITY_ACTION("m_tags on in-chain mbuf");
}
/* M_PKTHDR may only be set on first mbuf in chain */
if (m != m0 && m->m_flags & M_PKTHDR) {
if (sanitize) {
bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
m->m_flags &= ~M_PKTHDR;
/* put in 0xDEADCODE and leave hdr flag in */
} else
M_SANITY_ACTION("M_PKTHDR on in-chain mbuf");
}
}
m = m0;
if (pktlen && pktlen != m->m_pkthdr.len) {
if (sanitize)
m->m_pkthdr.len = 0;
else
M_SANITY_ACTION("m_pkthdr.len != mbuf chain length");
}
return 1;
#undef M_SANITY_ACTION
}
/*
* "Move" mbuf pkthdr from "from" to "to".
* "from" must have M_PKTHDR set, and "to" must be empty.
*/
void
m_move_pkthdr(struct mbuf *to, struct mbuf *from)
{
#if 0
/* see below for why these are not enabled */
M_ASSERTPKTHDR(to);
/* Note: with MAC, this may not be a good assertion. */
KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
("m_move_pkthdr: to has tags"));
#endif
#ifdef MAC
/*
* XXXMAC: It could be this should also occur for non-MAC?
*/
if (to->m_flags & M_PKTHDR)
m_tag_delete_chain(to, NULL);
#endif
to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
if ((to->m_flags & M_EXT) == 0)
to->m_data = to->m_pktdat;
to->m_pkthdr = from->m_pkthdr; /* especially tags */
SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */
from->m_flags &= ~M_PKTHDR;
}
/*
* Duplicate "from"'s mbuf pkthdr in "to".
* "from" must have M_PKTHDR set, and "to" must be empty.
* In particular, this does a deep copy of the packet tags.
*/
int
m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
{
#if 0
/*
* The mbuf allocator only initializes the pkthdr
* when the mbuf is allocated with MGETHDR. Many users
* (e.g. m_copy*, m_prepend) use MGET and then
* smash the pkthdr as needed causing these
* assertions to trip. For now just disable them.
*/
M_ASSERTPKTHDR(to);
/* Note: with MAC, this may not be a good assertion. */
KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
#endif
MBUF_CHECKSLEEP(how);
#ifdef MAC
if (to->m_flags & M_PKTHDR)
m_tag_delete_chain(to, NULL);
#endif
to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
if ((to->m_flags & M_EXT) == 0)
to->m_data = to->m_pktdat;
to->m_pkthdr = from->m_pkthdr;
SLIST_INIT(&to->m_pkthdr.tags);
return (m_tag_copy_chain(to, from, MBTOM(how)));
}
/*
* Lesser-used path for M_PREPEND:
* allocate new mbuf to prepend to chain,
* copy junk along.
*/
struct mbuf *
m_prepend(struct mbuf *m, int len, int how)
{
struct mbuf *mn;
if (m->m_flags & M_PKTHDR)
MGETHDR(mn, how, m->m_type);
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;
if(m->m_flags & M_PKTHDR) {
if (len < MHLEN)
MH_ALIGN(m, len);
} else {
if (len < MLEN)
M_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_TRYWAIT/M_DONTWAIT from caller.
* Note that the copy is read-only, because clusters are not copied,
* only their reference counts are incremented.
*/
struct mbuf *
m_copym(struct mbuf *m, int off0, int len, int wait)
{
struct mbuf *n, **np;
int off = off0;
struct mbuf *top;
int copyhdr = 0;
KASSERT(off >= 0, ("m_copym, negative off %d", off));
KASSERT(len >= 0, ("m_copym, negative len %d", len));
MBUF_CHECKSLEEP(wait);
if (off == 0 && m->m_flags & M_PKTHDR)
copyhdr = 1;
while (off > 0) {
KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
np = &top;
top = 0;
while (len > 0) {
if (m == NULL) {
KASSERT(len == M_COPYALL,
("m_copym, length > size of mbuf chain"));
break;
}
if (copyhdr)
MGETHDR(n, wait, m->m_type);
else
MGET(n, wait, m->m_type);
*np = n;
if (n == NULL)
goto nospace;
if (copyhdr) {
if (!m_dup_pkthdr(n, m, wait))
goto nospace;
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;
mb_dupcl(n, m);
} else
bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
(u_int)n->m_len);
if (len != M_COPYALL)
len -= n->m_len;
off = 0;
m = m->m_next;
np = &n->m_next;
}
if (top == NULL)
mbstat.m_mcfail++; /* XXX: No consistency. */
return (top);
nospace:
m_freem(top);
mbstat.m_mcfail++; /* XXX: No consistency. */
return (NULL);
}
/*
* Returns mbuf chain with new head for the prepending case.
* Copies from mbuf (chain) n from off for len to mbuf (chain) m
* either prepending or appending the data.
* The resulting mbuf (chain) m is fully writeable.
* m is destination (is made writeable)
* n is source, off is offset in source, len is len from offset
* dir, 0 append, 1 prepend
* how, wait or nowait
*/
static int
m_bcopyxxx(void *s, void *t, u_int len)
{
bcopy(s, t, (size_t)len);
return 0;
}
struct mbuf *
m_copymdata(struct mbuf *m, struct mbuf *n, int off, int len,
int prep, int how)
{
struct mbuf *mm, *x, *z, *prev = NULL;
caddr_t p;
int i, nlen = 0;
caddr_t buf[MLEN];
KASSERT(m != NULL && n != NULL, ("m_copymdata, no target or source"));
KASSERT(off >= 0, ("m_copymdata, negative off %d", off));
KASSERT(len >= 0, ("m_copymdata, negative len %d", len));
KASSERT(prep == 0 || prep == 1, ("m_copymdata, unknown direction %d", prep));
mm = m;
if (!prep) {
while(mm->m_next) {
prev = mm;
mm = mm->m_next;
}
}
for (z = n; z != NULL; z = z->m_next)
nlen += z->m_len;
if (len == M_COPYALL)
len = nlen - off;
if (off + len > nlen || len < 1)
return NULL;
if (!M_WRITABLE(mm)) {
/* XXX: Use proper m_xxx function instead. */
x = m_getcl(how, MT_DATA, mm->m_flags);
if (x == NULL)
return NULL;
bcopy(mm->m_ext.ext_buf, x->m_ext.ext_buf, x->m_ext.ext_size);
p = x->m_ext.ext_buf + (mm->m_data - mm->m_ext.ext_buf);
x->m_data = p;
mm->m_next = NULL;
if (mm != m)
prev->m_next = x;
m_free(mm);
mm = x;
}
/*
* Append/prepend the data. Allocating mbufs as necessary.
*/
/* Shortcut if enough free space in first/last mbuf. */
if (!prep && M_TRAILINGSPACE(mm) >= len) {
m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t) +
mm->m_len);
mm->m_len += len;
mm->m_pkthdr.len += len;
return m;
}
if (prep && M_LEADINGSPACE(mm) >= len) {
mm->m_data = mtod(mm, caddr_t) - len;
m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t));
mm->m_len += len;
mm->m_pkthdr.len += len;
return mm;
}
/* Expand first/last mbuf to cluster if possible. */
if (!prep && !(mm->m_flags & M_EXT) && len > M_TRAILINGSPACE(mm)) {
bcopy(mm->m_data, &buf, mm->m_len);
m_clget(mm, how);
if (!(mm->m_flags & M_EXT))
return NULL;
bcopy(&buf, mm->m_ext.ext_buf, mm->m_len);
mm->m_data = mm->m_ext.ext_buf;
mm->m_pkthdr.header = NULL;
}
if (prep && !(mm->m_flags & M_EXT) && len > M_LEADINGSPACE(mm)) {
bcopy(mm->m_data, &buf, mm->m_len);
m_clget(mm, how);
if (!(mm->m_flags & M_EXT))
return NULL;
bcopy(&buf, (caddr_t *)mm->m_ext.ext_buf +
mm->m_ext.ext_size - mm->m_len, mm->m_len);
mm->m_data = (caddr_t)mm->m_ext.ext_buf +
mm->m_ext.ext_size - mm->m_len;
mm->m_pkthdr.header = NULL;
}
/* Append/prepend as many mbuf (clusters) as necessary to fit len. */
if (!prep && len > M_TRAILINGSPACE(mm)) {
if (!m_getm(mm, len - M_TRAILINGSPACE(mm), how, MT_DATA))
return NULL;
}
if (prep && len > M_LEADINGSPACE(mm)) {
if (!(z = m_getm(NULL, len - M_LEADINGSPACE(mm), how, MT_DATA)))
return NULL;
i = 0;
for (x = z; x != NULL; x = x->m_next) {
i += x->m_flags & M_EXT ? x->m_ext.ext_size :
(x->m_flags & M_PKTHDR ? MHLEN : MLEN);
if (!x->m_next)
break;
}
z->m_data += i - len;
m_move_pkthdr(mm, z);
x->m_next = mm;
mm = z;
}
/* Seek to start position in source mbuf. Optimization for long chains. */
while (off > 0) {
if (off < n->m_len)
break;
off -= n->m_len;
n = n->m_next;
}
/* Copy data into target mbuf. */
z = mm;
while (len > 0) {
KASSERT(z != NULL, ("m_copymdata, falling off target edge"));
i = M_TRAILINGSPACE(z);
m_apply(n, off, i, m_bcopyxxx, mtod(z, caddr_t) + z->m_len);
z->m_len += i;
/* fixup pkthdr.len if necessary */
if ((prep ? mm : m)->m_flags & M_PKTHDR)
(prep ? mm : m)->m_pkthdr.len += i;
off += i;
len -= i;
z = z->m_next;
}
return (prep ? mm : m);
}
/*
* Copy an entire packet, including header (which must be present).
* An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
* Note that the copy is read-only, because clusters are not copied,
* only their reference counts are incremented.
* Preserve alignment of the first mbuf so if the creator has left
* some room at the beginning (e.g. for inserting protocol headers)
* the copies still have the room available.
*/
struct mbuf *
m_copypacket(struct mbuf *m, int how)
{
struct mbuf *top, *n, *o;
MBUF_CHECKSLEEP(how);
MGET(n, how, m->m_type);
top = n;
if (n == NULL)
goto nospace;
if (!m_dup_pkthdr(n, m, how))
goto nospace;
n->m_len = m->m_len;
if (m->m_flags & M_EXT) {
n->m_data = m->m_data;
mb_dupcl(n, m);
} else {
n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
}
m = m->m_next;
while (m) {
MGET(o, how, m->m_type);
if (o == NULL)
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;
mb_dupcl(n, m);
} else {
bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
}
m = m->m_next;
}
return top;
nospace:
m_freem(top);
mbstat.m_mcfail++; /* XXX: No consistency. */
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(const struct mbuf *m, int off, int len, caddr_t cp)
{
u_int count;
KASSERT(off >= 0, ("m_copydata, negative off %d", off));
KASSERT(len >= 0, ("m_copydata, negative len %d", len));
while (off > 0) {
KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
while (len > 0) {
KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
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;
}
}
/*
* Copy a packet header mbuf chain into a completely new chain, including
* copying any mbuf clusters. Use this instead of m_copypacket() when
* you need a writable copy of an mbuf chain.
*/
struct mbuf *
m_dup(struct mbuf *m, int how)
{
struct mbuf **p, *top = NULL;
int remain, moff, nsize;
MBUF_CHECKSLEEP(how);
/* Sanity check */
if (m == NULL)
return (NULL);
M_ASSERTPKTHDR(m);
/* While there's more data, get a new mbuf, tack it on, and fill it */
remain = m->m_pkthdr.len;
moff = 0;
p = &top;
while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */
struct mbuf *n;
/* Get the next new mbuf */
if (remain >= MINCLSIZE) {
n = m_getcl(how, m->m_type, 0);
nsize = MCLBYTES;
} else {
n = m_get(how, m->m_type);
nsize = MLEN;
}
if (n == NULL)
goto nospace;
if (top == NULL) { /* First one, must be PKTHDR */
if (!m_dup_pkthdr(n, m, how)) {
m_free(n);
goto nospace;
}
if ((n->m_flags & M_EXT) == 0)
nsize = MHLEN;
}
n->m_len = 0;
/* Link it into the new chain */
*p = n;
p = &n->m_next;
/* Copy data from original mbuf(s) into new mbuf */
while (n->m_len < nsize && m != NULL) {
int chunk = min(nsize - n->m_len, m->m_len - moff);
bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
moff += chunk;
n->m_len += chunk;
remain -= chunk;
if (moff == m->m_len) {
m = m->m_next;
moff = 0;
}
}
/* Check correct total mbuf length */
KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
("%s: bogus m_pkthdr.len", __func__));
}
return (top);
nospace:
m_freem(top);
mbstat.m_mcfail++; /* XXX: No consistency. */
return (NULL);
}
/*
* 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(struct mbuf *m, struct mbuf *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(struct mbuf *mp, int req_len)
{
int len = req_len;
struct mbuf *m;
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;
if (m->m_next != NULL) {
m_freem(m->m_next);
m->m_next = NULL;
}
break;
}
count -= m->m_len;
}
}
}
/*
* 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.
*/
struct mbuf *
m_pullup(struct mbuf *n, int len)
{
struct mbuf *m;
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 == NULL)
goto bad;
m->m_len = 0;
if (n->m_flags & M_PKTHDR)
M_MOVE_PKTHDR(m, n);
}
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,
(u_int)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);
mbstat.m_mpfail++; /* XXX: No consistency. */
return (NULL);
}
/*
* Like m_pullup(), except a new mbuf is always allocated, and we allow
* the amount of empty space before the data in the new mbuf to be specified
* (in the event that the caller expects to prepend later).
*/
int MSFail;
struct mbuf *
m_copyup(struct mbuf *n, int len, int dstoff)
{
struct mbuf *m;
int count, space;
if (len > (MHLEN - dstoff))
goto bad;
MGET(m, M_DONTWAIT, n->m_type);
if (m == NULL)
goto bad;
m->m_len = 0;
if (n->m_flags & M_PKTHDR)
M_MOVE_PKTHDR(m, n);
m->m_data += dstoff;
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),
(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);
MSFail++;
return (NULL);
}
/*
* 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.
*
* Note that the resulting mbufs might be read-only, because the new
* mbuf can end up sharing an mbuf cluster with the original mbuf if
* the "breaking point" happens to lie within a cluster mbuf. Use the
* M_WRITABLE() macro to check for this case.
*/
struct mbuf *
m_split(struct mbuf *m0, int len0, int wait)
{
struct mbuf *m, *n;
u_int len = len0, remain;
MBUF_CHECKSLEEP(wait);
for (m = m0; m && len > m->m_len; m = m->m_next)
len -= m->m_len;
if (m == NULL)
return (NULL);
remain = m->m_len - len;
if (m0->m_flags & M_PKTHDR) {
MGETHDR(n, wait, m0->m_type);
if (n == NULL)
return (NULL);
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 == NULL) {
(void) m_free(n);
return (NULL);
} else {
n->m_len = 0;
return (n);
}
} else
MH_ALIGN(n, remain);
} else if (remain == 0) {
n = m->m_next;
m->m_next = NULL;
return (n);
} else {
MGET(n, wait, m->m_type);
if (n == NULL)
return (NULL);
M_ALIGN(n, remain);
}
extpacket:
if (m->m_flags & M_EXT) {
n->m_data = m->m_data + len;
mb_dupcl(n, m);
} 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 = NULL;
return (n);
}
/*
* Routine to copy from device local memory into mbufs.
* Note that `off' argument is offset into first mbuf of target chain from
* which to begin copying the data to.
*/
struct mbuf *
m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
void (*copy)(char *from, caddr_t to, u_int len))
{
struct mbuf *m;
struct mbuf *top = NULL, **mp = &top;
int len;
if (off < 0 || off > MHLEN)
return (NULL);
while (totlen > 0) {
if (top == NULL) { /* First one, must be PKTHDR */
if (totlen + off >= MINCLSIZE) {
m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
len = MCLBYTES;
} else {
m = m_gethdr(M_DONTWAIT, MT_DATA);
len = MHLEN;
/* Place initial small packet/header at end of mbuf */
if (m && totlen + off + max_linkhdr <= MLEN) {
m->m_data += max_linkhdr;
len -= max_linkhdr;
}
}
if (m == NULL)
return NULL;
m->m_pkthdr.rcvif = ifp;
m->m_pkthdr.len = totlen;
} else {
if (totlen + off >= MINCLSIZE) {
m = m_getcl(M_DONTWAIT, MT_DATA, 0);
len = MCLBYTES;
} else {
m = m_get(M_DONTWAIT, MT_DATA);
len = MLEN;
}
if (m == NULL) {
m_freem(top);
return NULL;
}
}
if (off) {
m->m_data += off;
len -= off;
off = 0;
}
m->m_len = len = min(totlen, len);
if (copy)
copy(buf, mtod(m, caddr_t), (u_int)len);
else
bcopy(buf, mtod(m, caddr_t), (u_int)len);
buf += len;
*mp = m;
mp = &m->m_next;
totlen -= len;
}
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(struct mbuf *m0, int off, int len, c_caddr_t cp)
{
int mlen;
struct mbuf *m = m0, *n;
int totlen = 0;
if (m0 == NULL)
return;
while (off > (mlen = m->m_len)) {
off -= mlen;
totlen += mlen;
if (m->m_next == NULL) {
n = m_get(M_DONTWAIT, m->m_type);
if (n == NULL)
goto out;
bzero(mtod(n, caddr_t), MLEN);
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), (u_int)mlen);
cp += mlen;
len -= mlen;
mlen += off;
off = 0;
totlen += mlen;
if (len == 0)
break;
if (m->m_next == NULL) {
n = m_get(M_DONTWAIT, m->m_type);
if (n == NULL)
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;
}
/*
* Append the specified data to the indicated mbuf chain,
* Extend the mbuf chain if the new data does not fit in
* existing space.
*
* Return 1 if able to complete the job; otherwise 0.
*/
int
m_append(struct mbuf *m0, int len, c_caddr_t cp)
{
struct mbuf *m, *n;
int remainder, space;
for (m = m0; m->m_next != NULL; m = m->m_next)
;
remainder = len;
space = M_TRAILINGSPACE(m);
if (space > 0) {
/*
* Copy into available space.
*/
if (space > remainder)
space = remainder;
bcopy(cp, mtod(m, caddr_t) + m->m_len, space);
m->m_len += space;
cp += space, remainder -= space;
}
while (remainder > 0) {
/*
* Allocate a new mbuf; could check space
* and allocate a cluster instead.
*/
n = m_get(M_DONTWAIT, m->m_type);
if (n == NULL)
break;
n->m_len = min(MLEN, remainder);
bcopy(cp, mtod(n, caddr_t), n->m_len);
cp += n->m_len, remainder -= n->m_len;
m->m_next = n;
m = n;
}
if (m0->m_flags & M_PKTHDR)
m0->m_pkthdr.len += len - remainder;
return (remainder == 0);
}
/*
* Apply function f to the data in an mbuf chain starting "off" bytes from
* the beginning, continuing for "len" bytes.
*/
int
m_apply(struct mbuf *m, int off, int len,
int (*f)(void *, void *, u_int), void *arg)
{
u_int count;
int rval;
KASSERT(off >= 0, ("m_apply, negative off %d", off));
KASSERT(len >= 0, ("m_apply, negative len %d", len));
while (off > 0) {
KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
while (len > 0) {
KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
count = min(m->m_len - off, len);
rval = (*f)(arg, mtod(m, caddr_t) + off, count);
if (rval)
return (rval);
len -= count;
off = 0;
m = m->m_next;
}
return (0);
}
/*
* Return a pointer to mbuf/offset of location in mbuf chain.
*/
struct mbuf *
m_getptr(struct mbuf *m, int loc, int *off)
{
while (loc >= 0) {
/* Normal end of search. */
if (m->m_len > loc) {
*off = loc;
return (m);
} else {
loc -= m->m_len;
if (m->m_next == NULL) {
if (loc == 0) {
/* Point at the end of valid data. */
*off = m->m_len;
return (m);
}
return (NULL);
}
m = m->m_next;
}
}
return (NULL);
}
void
m_print(const struct mbuf *m, int maxlen)
{
int len;
int pdata;
const struct mbuf *m2;
if (m->m_flags & M_PKTHDR)
len = m->m_pkthdr.len;
else
len = -1;
m2 = m;
while (m2 != NULL && (len == -1 || len)) {
pdata = m2->m_len;
if (maxlen != -1 && pdata > maxlen)
pdata = maxlen;
printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
m2->m_next, m2->m_flags, "\20\20freelist\17skipfw"
"\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
"\3eor\2pkthdr\1ext", pdata ? "" : "\n");
if (pdata)
printf(", %*D\n", pdata, (u_char *)m2->m_data, "-");
if (len != -1)
len -= m2->m_len;
m2 = m2->m_next;
}
if (len > 0)
printf("%d bytes unaccounted for.\n", len);
return;
}
u_int
m_fixhdr(struct mbuf *m0)
{
u_int len;
len = m_length(m0, NULL);
m0->m_pkthdr.len = len;
return (len);
}
u_int
m_length(struct mbuf *m0, struct mbuf **last)
{
struct mbuf *m;
u_int len;
len = 0;
for (m = m0; m != NULL; m = m->m_next) {
len += m->m_len;
if (m->m_next == NULL)
break;
}
if (last != NULL)
*last = m;
return (len);
}
/*
* Defragment a mbuf chain, returning the shortest possible
* chain of mbufs and clusters. If allocation fails and
* this cannot be completed, NULL will be returned, but
* the passed in chain will be unchanged. Upon success,
* the original chain will be freed, and the new chain
* will be returned.
*
* If a non-packet header is passed in, the original
* mbuf (chain?) will be returned unharmed.
*/
struct mbuf *
m_defrag(struct mbuf *m0, int how)
{
struct mbuf *m_new = NULL, *m_final = NULL;
int progress = 0, length;
MBUF_CHECKSLEEP(how);
if (!(m0->m_flags & M_PKTHDR))
return (m0);
m_fixhdr(m0); /* Needed sanity check */
#ifdef MBUF_STRESS_TEST
if (m_defragrandomfailures) {
int temp = arc4random() & 0xff;
if (temp == 0xba)
goto nospace;
}
#endif
if (m0->m_pkthdr.len > MHLEN)
m_final = m_getcl(how, MT_DATA, M_PKTHDR);
else
m_final = m_gethdr(how, MT_DATA);
if (m_final == NULL)
goto nospace;
if (m_dup_pkthdr(m_final, m0, how) == 0)
goto nospace;
m_new = m_final;
while (progress < m0->m_pkthdr.len) {
length = m0->m_pkthdr.len - progress;
if (length > MCLBYTES)
length = MCLBYTES;
if (m_new == NULL) {
if (length > MLEN)
m_new = m_getcl(how, MT_DATA, 0);
else
m_new = m_get(how, MT_DATA);
if (m_new == NULL)
goto nospace;
}
m_copydata(m0, progress, length, mtod(m_new, caddr_t));
progress += length;
m_new->m_len = length;
if (m_new != m_final)
m_cat(m_final, m_new);
m_new = NULL;
}
#ifdef MBUF_STRESS_TEST
if (m0->m_next == NULL)
m_defraguseless++;
#endif
m_freem(m0);
m0 = m_final;
#ifdef MBUF_STRESS_TEST
m_defragpackets++;
m_defragbytes += m0->m_pkthdr.len;
#endif
return (m0);
nospace:
#ifdef MBUF_STRESS_TEST
m_defragfailure++;
#endif
if (m_final)
m_freem(m_final);
return (NULL);
}
#ifdef MBUF_STRESS_TEST
/*
* Fragment an mbuf chain. There's no reason you'd ever want to do
* this in normal usage, but it's great for stress testing various
* mbuf consumers.
*
* If fragmentation is not possible, the original chain will be
* returned.
*
* Possible length values:
* 0 no fragmentation will occur
* > 0 each fragment will be of the specified length
* -1 each fragment will be the same random value in length
* -2 each fragment's length will be entirely random
* (Random values range from 1 to 256)
*/
struct mbuf *
m_fragment(struct mbuf *m0, int how, int length)
{
struct mbuf *m_new = NULL, *m_final = NULL;
int progress = 0;
if (!(m0->m_flags & M_PKTHDR))
return (m0);
if ((length == 0) || (length < -2))
return (m0);
m_fixhdr(m0); /* Needed sanity check */
m_final = m_getcl(how, MT_DATA, M_PKTHDR);
if (m_final == NULL)
goto nospace;
if (m_dup_pkthdr(m_final, m0, how) == 0)
goto nospace;
m_new = m_final;
if (length == -1)
length = 1 + (arc4random() & 255);
while (progress < m0->m_pkthdr.len) {
int fraglen;
if (length > 0)
fraglen = length;
else
fraglen = 1 + (arc4random() & 255);
if (fraglen > m0->m_pkthdr.len - progress)
fraglen = m0->m_pkthdr.len - progress;
if (fraglen > MCLBYTES)
fraglen = MCLBYTES;
if (m_new == NULL) {
m_new = m_getcl(how, MT_DATA, 0);
if (m_new == NULL)
goto nospace;
}
m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t));
progress += fraglen;
m_new->m_len = fraglen;
if (m_new != m_final)
m_cat(m_final, m_new);
m_new = NULL;
}
m_freem(m0);
m0 = m_final;
return (m0);
nospace:
if (m_final)
m_freem(m_final);
/* Return the original chain on failure */
return (m0);
}
#endif
/*
* Copy the contents of uio into a properly sized mbuf chain.
*/
struct mbuf *
m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
{
struct mbuf *m, *mb;
int error, length, total;
int progress = 0;
/*
* len can be zero or an arbitrary large value bound by
* the total data supplied by the uio.
*/
if (len > 0)
total = min(uio->uio_resid, len);
else
total = uio->uio_resid;
/*
* The smallest unit returned by m_getm2() is a single mbuf
* with pkthdr. We can't align past it. Align align itself.
*/
if (align)
align &= ~(sizeof(long) - 1);
if (align >= MHLEN)
return (NULL);
/*
* Give us the full allocation or nothing.
* If len is zero return the smallest empty mbuf.
*/
m = m_getm2(NULL, max(total + align, 1), how, MT_DATA, flags);
if (m == NULL)
return (NULL);
m->m_data += align;
/* Fill all mbufs with uio data and update header information. */
for (mb = m; mb != NULL; mb = mb->m_next) {
length = min(M_TRAILINGSPACE(mb), total - progress);
error = uiomove(mtod(mb, void *), length, uio);
if (error) {
m_freem(m);
return (NULL);
}
mb->m_len = length;
progress += length;
if (flags & M_PKTHDR)
m->m_pkthdr.len += length;
}
KASSERT(progress == total, ("%s: progress != total", __func__));
return (m);
}
/*
* Set the m_data pointer of a newly-allocated mbuf
* to place an object of the specified size at the
* end of the mbuf, longword aligned.
*/
void
m_align(struct mbuf *m, int len)
{
int adjust;
if (m->m_flags & M_EXT)
adjust = m->m_ext.ext_size - len;
else if (m->m_flags & M_PKTHDR)
adjust = MHLEN - len;
else
adjust = MLEN - len;
m->m_data += adjust &~ (sizeof(long)-1);
}
/*
* Create a writable copy of the mbuf chain. While doing this
* we compact the chain with a goal of producing a chain with
* at most two mbufs. The second mbuf in this chain is likely
* to be a cluster. The primary purpose of this work is to create
* a writable packet for encryption, compression, etc. The
* secondary goal is to linearize the data so the data can be
* passed to crypto hardware in the most efficient manner possible.
*/
struct mbuf *
m_unshare(struct mbuf *m0, int how)
{
struct mbuf *m, *mprev;
struct mbuf *n, *mfirst, *mlast;
int len, off;
mprev = NULL;
for (m = m0; m != NULL; m = mprev->m_next) {
/*
* Regular mbufs are ignored unless there's a cluster
* in front of it that we can use to coalesce. We do
* the latter mainly so later clusters can be coalesced
* also w/o having to handle them specially (i.e. convert
* mbuf+cluster -> cluster). This optimization is heavily
* influenced by the assumption that we're running over
* Ethernet where MCLBYTES is large enough that the max
* packet size will permit lots of coalescing into a
* single cluster. This in turn permits efficient
* crypto operations, especially when using hardware.
*/
if ((m->m_flags & M_EXT) == 0) {
if (mprev && (mprev->m_flags & M_EXT) &&
m->m_len <= M_TRAILINGSPACE(mprev)) {
/* XXX: this ignores mbuf types */
memcpy(mtod(mprev, caddr_t) + mprev->m_len,
mtod(m, caddr_t), m->m_len);
mprev->m_len += m->m_len;
mprev->m_next = m->m_next; /* unlink from chain */
m_free(m); /* reclaim mbuf */
#if 0
newipsecstat.ips_mbcoalesced++;
#endif
} else {
mprev = m;
}
continue;
}
/*
* Writable mbufs are left alone (for now).
*/
if (M_WRITABLE(m)) {
mprev = m;
continue;
}
/*
* Not writable, replace with a copy or coalesce with
* the previous mbuf if possible (since we have to copy
* it anyway, we try to reduce the number of mbufs and
* clusters so that future work is easier).
*/
KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags));
/* NB: we only coalesce into a cluster or larger */
if (mprev != NULL && (mprev->m_flags & M_EXT) &&
m->m_len <= M_TRAILINGSPACE(mprev)) {
/* XXX: this ignores mbuf types */
memcpy(mtod(mprev, caddr_t) + mprev->m_len,
mtod(m, caddr_t), m->m_len);
mprev->m_len += m->m_len;
mprev->m_next = m->m_next; /* unlink from chain */
m_free(m); /* reclaim mbuf */
#if 0
newipsecstat.ips_clcoalesced++;
#endif
continue;
}
/*
* Allocate new space to hold the copy...
*/
/* XXX why can M_PKTHDR be set past the first mbuf? */
if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
/*
* NB: if a packet header is present we must
* allocate the mbuf separately from any cluster
* because M_MOVE_PKTHDR will smash the data
* pointer and drop the M_EXT marker.
*/
MGETHDR(n, how, m->m_type);
if (n == NULL) {
m_freem(m0);
return (NULL);
}
M_MOVE_PKTHDR(n, m);
MCLGET(n, how);
if ((n->m_flags & M_EXT) == 0) {
m_free(n);
m_freem(m0);
return (NULL);
}
} else {
n = m_getcl(how, m->m_type, m->m_flags);
if (n == NULL) {
m_freem(m0);
return (NULL);
}
}
/*
* ... and copy the data. We deal with jumbo mbufs
* (i.e. m_len > MCLBYTES) by splitting them into
* clusters. We could just malloc a buffer and make
* it external but too many device drivers don't know
* how to break up the non-contiguous memory when
* doing DMA.
*/
len = m->m_len;
off = 0;
mfirst = n;
mlast = NULL;
for (;;) {
int cc = min(len, MCLBYTES);
memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
n->m_len = cc;
if (mlast != NULL)
mlast->m_next = n;
mlast = n;
#if 0
newipsecstat.ips_clcopied++;
#endif
len -= cc;
if (len <= 0)
break;
off += cc;
n = m_getcl(how, m->m_type, m->m_flags);
if (n == NULL) {
m_freem(mfirst);
m_freem(m0);
return (NULL);
}
}
n->m_next = m->m_next;
if (mprev == NULL)
m0 = mfirst; /* new head of chain */
else
mprev->m_next = mfirst; /* replace old mbuf */
m_free(m); /* release old mbuf */
mprev = mfirst;
}
return (m0);
}
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