freebsd-dev/sys/kern/uipc_mbuf2.c

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/* $FreeBSD$ */
/* $KAME: uipc_mbuf2.c,v 1.29 2001/02/14 13:42:10 itojun Exp $ */
/* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */
/*
* Copyright (C) 1999 WIDE Project.
* 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 project 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 PROJECT 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 PROJECT 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.
*/
/*
* 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 8.4 (Berkeley) 2/14/95
*/
/*#define PULLDOWN_DEBUG*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
/* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
static struct mbuf *m_dup1 __P((struct mbuf *, int, int, int));
/*
* ensure that [off, off + len) is contiguous on the mbuf chain "m".
* packet chain before "off" is kept untouched.
* if offp == NULL, the target will start at <retval, 0> on resulting chain.
* if offp != NULL, the target will start at <retval, *offp> on resulting chain.
*
* on error return (NULL return value), original "m" will be freed.
*
* XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
*/
struct mbuf *
m_pulldown(struct mbuf *m, int off, int len, int *offp)
{
struct mbuf *n, *o;
int hlen, tlen, olen;
int writable;
/* check invalid arguments. */
if (m == NULL)
panic("m == NULL in m_pulldown()");
if (len > MCLBYTES) {
m_freem(m);
return NULL; /* impossible */
}
#ifdef PULLDOWN_DEBUG
{
struct mbuf *t;
printf("before:");
for (t = m; t; t = t->m_next)
printf(" %d", t->m_len);
printf("\n");
}
#endif
n = m;
while (n != NULL && off > 0) {
if (n->m_len > off)
break;
off -= n->m_len;
n = n->m_next;
}
/* be sure to point non-empty mbuf */
while (n != NULL && n->m_len == 0)
n = n->m_next;
if (!n) {
m_freem(m);
return NULL; /* mbuf chain too short */
}
/*
* XXX: This code is flawed because it considers a "writable" mbuf
* data region to require all of the following:
* (i) mbuf _has_ to have M_EXT set; if it is just a regular
* mbuf, it is still not considered "writable."
* (ii) since mbuf has M_EXT, the ext_type _has_ to be
* EXT_CLUSTER. Anything else makes it non-writable.
* (iii) M_WRITABLE() must evaluate true.
* Ideally, the requirement should only be (iii).
*
* If we're writable, we're sure we're writable, because the ref. count
* cannot increase from 1, as that would require posession of mbuf
* n by someone else (which is impossible). However, if we're _not_
* writable, we may eventually become writable )if the ref. count drops
* to 1), but we'll fail to notice it unless we re-evaluate
* M_WRITABLE(). For now, we only evaluate once at the beginning and
* live with this.
*/
/*
* XXX: This is dumb. If we're just a regular mbuf with no M_EXT,
* then we're not "writable," according to this code.
*/
writable = 0;
if ((n->m_flags & M_EXT) == 0 ||
(n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
writable = 1;
/*
* the target data is on <n, off>.
* if we got enough data on the mbuf "n", we're done.
*/
if ((off == 0 || offp) && len <= n->m_len - off && writable)
goto ok;
/*
* when len <= n->m_len - off and off != 0, it is a special case.
* len bytes from <n, off> sits in single mbuf, but the caller does
* not like the starting position (off).
* chop the current mbuf into two pieces, set off to 0.
*/
if (len <= n->m_len - off) {
o = m_dup1(n, off, n->m_len - off, M_DONTWAIT);
if (o == NULL) {
m_freem(m);
return NULL; /* ENOBUFS */
}
n->m_len = off;
o->m_next = n->m_next;
n->m_next = o;
n = n->m_next;
off = 0;
goto ok;
}
/*
* we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
* and construct contiguous mbuf with m_len == len.
* note that hlen + tlen == len, and tlen > 0.
*/
hlen = n->m_len - off;
tlen = len - hlen;
/*
* ensure that we have enough trailing data on mbuf chain.
* if not, we can do nothing about the chain.
*/
olen = 0;
for (o = n->m_next; o != NULL; o = o->m_next)
olen += o->m_len;
if (hlen + olen < len) {
m_freem(m);
return NULL; /* mbuf chain too short */
}
/*
* easy cases first.
* we need to use m_copydata() to get data from <n->m_next, 0>.
*/
if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
&& writable) {
m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
n->m_len += tlen;
m_adj(n->m_next, tlen);
goto ok;
}
if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
&& writable) {
n->m_next->m_data -= hlen;
n->m_next->m_len += hlen;
bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
n->m_len -= hlen;
n = n->m_next;
off = 0;
goto ok;
}
/*
* now, we need to do the hard way. don't m_copy as there's no room
* on both end.
*/
MGET(o, M_DONTWAIT, m->m_type);
if (o && len > MLEN) {
MCLGET(o, M_DONTWAIT);
if ((o->m_flags & M_EXT) == 0) {
m_free(o);
o = NULL;
}
}
if (!o) {
m_freem(m);
return NULL; /* ENOBUFS */
}
/* get hlen from <n, off> into <o, 0> */
o->m_len = hlen;
bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
n->m_len -= hlen;
/* get tlen from <n->m_next, 0> into <o, hlen> */
m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
o->m_len += tlen;
m_adj(n->m_next, tlen);
o->m_next = n->m_next;
n->m_next = o;
n = o;
off = 0;
ok:
#ifdef PULLDOWN_DEBUG
{
struct mbuf *t;
printf("after:");
for (t = m; t; t = t->m_next)
printf("%c%d", t == n ? '*' : ' ', t->m_len);
printf(" (off=%d)\n", off);
}
#endif
if (offp)
*offp = off;
return n;
}
static struct mbuf *
m_dup1(struct mbuf *m, int off, int len, int wait)
{
struct mbuf *n;
int l;
int copyhdr;
if (len > MCLBYTES)
return NULL;
if (off == 0 && (m->m_flags & M_PKTHDR) != 0) {
copyhdr = 1;
MGETHDR(n, wait, m->m_type);
l = MHLEN;
} else {
copyhdr = 0;
MGET(n, wait, m->m_type);
l = MLEN;
}
if (n && len > l) {
MCLGET(n, wait);
if ((n->m_flags & M_EXT) == 0) {
m_free(n);
n = NULL;
}
}
if (!n)
return NULL;
if (copyhdr)
M_COPY_PKTHDR(n, m);
m_copydata(m, off, len, mtod(n, caddr_t));
return n;
}
/*
* pkthdr.aux chain manipulation.
* we don't allow clusters at this moment.
*/
struct mbuf *
m_aux_add2(struct mbuf *m, int af, int type, void *p)
{
struct mbuf *n;
struct mauxtag *t;
if ((m->m_flags & M_PKTHDR) == 0)
return NULL;
n = m_aux_find(m, af, type);
if (n)
return n;
MGET(n, M_DONTWAIT, m->m_type);
if (n == NULL)
return NULL;
t = mtod(n, struct mauxtag *);
bzero(t, sizeof(*t));
t->af = af;
t->type = type;
t->p = p;
n->m_data += sizeof(struct mauxtag);
n->m_len = 0;
n->m_next = m->m_pkthdr.aux;
m->m_pkthdr.aux = n;
return n;
}
struct mbuf *
m_aux_find2(struct mbuf *m, int af, int type, void *p)
{
struct mbuf *n;
struct mauxtag *t;
if ((m->m_flags & M_PKTHDR) == 0)
return NULL;
for (n = m->m_pkthdr.aux; n; n = n->m_next) {
t = (struct mauxtag *)n->m_dat;
if (n->m_data != ((caddr_t)t) + sizeof(struct mauxtag)) {
printf("m_aux_find: invalid m_data for mbuf=%p (%p %p)\n", n, t, n->m_data);
continue;
}
if (t->af == af && t->type == type && t->p == p)
return n;
}
return NULL;
}
struct mbuf *
m_aux_find(struct mbuf *m, int af, int type)
{
return m_aux_find2(m, af, type, NULL);
}
struct mbuf *
m_aux_add(struct mbuf *m, int af, int type)
{
return m_aux_add2(m, af, type, NULL);
}
void
m_aux_delete(struct mbuf *m, struct mbuf *victim)
{
struct mbuf *n, *prev, *next;
struct mauxtag *t;
if ((m->m_flags & M_PKTHDR) == 0)
return;
prev = NULL;
n = m->m_pkthdr.aux;
while (n) {
t = (struct mauxtag *)n->m_dat;
next = n->m_next;
if (n->m_data != ((caddr_t)t) + sizeof(struct mauxtag)) {
printf("m_aux_delete: invalid m_data for mbuf=%p (%p %p)\n", n, t, n->m_data);
prev = n;
n = next;
continue;
}
if (n == victim) {
if (prev)
prev->m_next = n->m_next;
else
m->m_pkthdr.aux = n->m_next;
n->m_next = NULL;
m_free(n);
} else
prev = n;
n = next;
}
}