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freebsd-dev/sys/kern/uipc_mbuf.c
Hiren Panchasara 86a996e6bd There are times when it would be really nice to have a record of the last few 
packets and/or state transitions from each TCP socket. That would help with
narrowing down certain problems we see in the field that are hard to reproduce
without understanding the history of how we got into a certain state. This
change provides just that.

It saves copies of the last N packets in a list in the tcpcb. When the tcpcb is
destroyed, the list is freed. I thought this was likely to be more
performance-friendly than saving copies of the tcpcb. Plus, with the packets,
you should be able to reverse-engineer what happened to the tcpcb.

To enable the feature, you will need to compile a kernel with the TCPPCAP
option. Even then, the feature defaults to being deactivated. You can activate
it by setting a positive value for the number of captured packets. You can do
that on either a global basis or on a per-socket basis (via a setsockopt call).

There is no way to get the packets out of the kernel other than using kmem or
getting a coredump. I thought that would help some of the legal/privacy concerns
regarding such a feature. However, it should be possible to add a future effort
to export them in PCAP format.

I tested this at low scale, and found that there were no mbuf leaks and the peak
mbuf usage appeared to be unchanged with and without the feature.

The main performance concern I can envision is the number of mbufs that would be
used on systems with a large number of sockets. If you save five packets per
direction per socket and have 3,000 sockets, that will consume at least 30,000
mbufs just to keep these packets. I tried to reduce the concerns associated with
this by limiting the number of clusters (not mbufs) that could be used for this
feature. Again, in my testing, that appears to work correctly.

Differential Revision:	D3100
Submitted by:		Jonathan Looney <jlooney at juniper dot net>
Reviewed by:		gnn, hiren
2015-10-14 00:35:37 +00:00

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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.
* 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_param.h"
#include "opt_mbuf_stress_test.h"
#include "opt_mbuf_profiling.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>
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
/*
* Ensure the correct size of various mbuf parameters. It could be off due
* to compiler-induced padding and alignment artifacts.
*/
CTASSERT(MSIZE - offsetof(struct mbuf, m_dat) == MLEN);
CTASSERT(MSIZE - offsetof(struct mbuf, m_pktdat) == MHLEN);
/*
* mbuf data storage should be 64-bit aligned regardless of architectural
* pointer size; check this is the case with and without a packet header.
*/
CTASSERT(offsetof(struct mbuf, m_dat) % 8 == 0);
CTASSERT(offsetof(struct mbuf, m_pktdat) % 8 == 0);
/*
* While the specific values here don't matter too much (i.e., +/- a few
* words), we do want to ensure that changes to these values are carefully
* reasoned about and properly documented. This is especially the case as
* network-protocol and device-driver modules encode these layouts, and must
* be recompiled if the structures change. Check these values at compile time
* against the ones documented in comments in mbuf.h.
*
* NB: Possibly they should be documented there via #define's and not just
* comments.
*/
#if defined(__LP64__)
CTASSERT(offsetof(struct mbuf, m_dat) == 32);
CTASSERT(sizeof(struct pkthdr) == 56);
CTASSERT(sizeof(struct m_ext) == 48);
#else
CTASSERT(offsetof(struct mbuf, m_dat) == 24);
CTASSERT(sizeof(struct pkthdr) == 48);
CTASSERT(sizeof(struct m_ext) == 28);
#endif
/*
* Assert that the queue(3) macros produce code of the same size as an old
* plain pointer does.
*/
#ifdef INVARIANTS
static struct mbuf m_assertbuf;
CTASSERT(sizeof(m_assertbuf.m_slist) == sizeof(m_assertbuf.m_next));
CTASSERT(sizeof(m_assertbuf.m_stailq) == sizeof(m_assertbuf.m_next));
CTASSERT(sizeof(m_assertbuf.m_slistpkt) == sizeof(m_assertbuf.m_nextpkt));
CTASSERT(sizeof(m_assertbuf.m_stailqpkt) == sizeof(m_assertbuf.m_nextpkt));
#endif
/*
* m_get2() allocates minimum mbuf that would fit "size" argument.
*/
struct mbuf *
m_get2(int size, int how, short type, int flags)
{
struct mb_args args;
struct mbuf *m, *n;
args.flags = flags;
args.type = type;
if (size <= MHLEN || (size <= MLEN && (flags & M_PKTHDR) == 0))
return (uma_zalloc_arg(zone_mbuf, &args, how));
if (size <= MCLBYTES)
return (uma_zalloc_arg(zone_pack, &args, how));
if (size > MJUMPAGESIZE)
return (NULL);
m = uma_zalloc_arg(zone_mbuf, &args, how);
if (m == NULL)
return (NULL);
n = uma_zalloc_arg(zone_jumbop, m, how);
if (n == NULL) {
uma_zfree(zone_mbuf, m);
return (NULL);
}
return (m);
}
/*
* m_getjcl() returns an mbuf with a cluster of the specified size attached.
* For size it takes MCLBYTES, MJUMPAGESIZE, MJUM9BYTES, MJUM16BYTES.
*/
struct mbuf *
m_getjcl(int how, short type, int flags, int size)
{
struct mb_args args;
struct mbuf *m, *n;
uma_zone_t zone;
if (size == MCLBYTES)
return m_getcl(how, type, flags);
args.flags = flags;
args.type = type;
m = uma_zalloc_arg(zone_mbuf, &args, how);
if (m == NULL)
return (NULL);
zone = m_getzone(size);
n = uma_zalloc_arg(zone, m, how);
if (n == NULL) {
uma_zfree(zone_mbuf, m);
return (NULL);
}
return (m);
}
/*
* 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 -= M_SIZE(mb);
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.
*/
int
m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
void (*freef)(struct mbuf *, void *, void *), void *arg1, void *arg2,
int flags, int type, int wait)
{
KASSERT(type != EXT_CLUSTER, ("%s: EXT_CLUSTER not allowed", __func__));
if (type != EXT_EXTREF)
mb->m_ext.ext_cnt = uma_zalloc(zone_ext_refcnt, wait);
if (mb->m_ext.ext_cnt == NULL)
return (ENOMEM);
*(mb->m_ext.ext_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_arg1 = arg1;
mb->m_ext.ext_arg2 = arg2;
mb->m_ext.ext_type = type;
mb->m_ext.ext_flags = 0;
return (0);
}
/*
* 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)
{
int freembuf;
KASSERT(m->m_flags & M_EXT, ("%s: M_EXT not set on %p", __func__, m));
/*
* Check if the header is embedded in the cluster.
*/
freembuf = (m->m_flags & M_NOFREE) ? 0 : 1;
switch (m->m_ext.ext_type) {
case EXT_SFBUF:
sf_ext_free(m->m_ext.ext_arg1, m->m_ext.ext_arg2);
break;
default:
KASSERT(m->m_ext.ext_cnt != NULL,
("%s: no refcounting pointer on %p", __func__, m));
/*
* Free attached storage if this mbuf is the only
* reference to it.
*/
if (*(m->m_ext.ext_cnt) != 1) {
if (atomic_fetchadd_int(m->m_ext.ext_cnt, -1) != 1)
break;
}
switch (m->m_ext.ext_type) {
case EXT_PACKET: /* The packet zone is special. */
if (*(m->m_ext.ext_cnt) == 0)
*(m->m_ext.ext_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_NET_DRV:
case EXT_MOD_TYPE:
case EXT_DISPOSABLE:
*(m->m_ext.ext_cnt) = 0;
uma_zfree(zone_ext_refcnt, __DEVOLATILE(u_int *,
m->m_ext.ext_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->m_ext.ext_arg1,
m->m_ext.ext_arg2);
break;
default:
KASSERT(m->m_ext.ext_type == 0,
("%s: unknown ext_type", __func__));
}
}
if (freembuf)
uma_zfree(zone_mbuf, m);
}
/*
* Attach the cluster from *m to *n, set up m_ext in *n
* and bump the refcount of the cluster.
*/
void
mb_dupcl(struct mbuf *n, const struct mbuf *m)
{
KASSERT(m->m_flags & M_EXT, ("%s: M_EXT not set on %p", __func__, m));
KASSERT(!(n->m_flags & M_EXT), ("%s: M_EXT set on %p", __func__, n));
switch (m->m_ext.ext_type) {
case EXT_SFBUF:
sf_ext_ref(m->m_ext.ext_arg1, m->m_ext.ext_arg2);
break;
default:
KASSERT(m->m_ext.ext_cnt != NULL,
("%s: no refcounting pointer on %p", __func__, m));
if (*(m->m_ext.ext_cnt) == 1)
*(m->m_ext.ext_cnt) += 1;
else
atomic_add_int(m->m_ext.ext_cnt, 1);
}
n->m_ext = m->m_ext;
n->m_flags |= M_EXT;
n->m_flags |= m->m_flags & M_RDONLY;
}
void
m_demote_pkthdr(struct mbuf *m)
{
M_ASSERTPKTHDR(m);
m_tag_delete_chain(m, NULL);
m->m_flags &= ~M_PKTHDR;
bzero(&m->m_pkthdr, sizeof(struct pkthdr));
}
/*
* 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, int flags)
{
struct mbuf *m;
for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) {
KASSERT(m->m_nextpkt == NULL, ("%s: m_nextpkt in m %p, m0 %p",
__func__, m, m0));
if (m->m_flags & M_PKTHDR)
m_demote_pkthdr(m);
m->m_flags = m->m_flags & (M_EXT | M_RDONLY | M_NOFREE | flags);
}
}
/*
* 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;
#ifdef INVARIANTS
#define M_SANITY_ACTION(s) panic("mbuf %p: " s, m)
#else
#define M_SANITY_ACTION(s) printf("mbuf %p: " s, m)
#endif
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_START(m);
b = a + M_SIZE(m);
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");
/* 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");
}
/* 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, const struct mbuf *from, int how)
{
#if 0
/*
* The mbuf allocator only initializes the pkthdr
* when the mbuf is allocated with m_gethdr(). Many users
* (e.g. m_copy*, m_prepend) use m_get() 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, 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)
mn = m_gethdr(how, m->m_type);
else
mn = m_get(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 (len < M_SIZE(m))
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_WAITOK/M_NOWAIT from caller.
* Note that the copy is read-only, because clusters are not copied,
* only their reference counts are incremented.
*/
struct mbuf *
m_copym(const 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)
n = m_gethdr(wait, m->m_type);
else
n = m_get(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;
}
return (top);
nospace:
m_freem(top);
return (NULL);
}
/*
* 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);
n = m_get(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) {
o = m_get(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);
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(const 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_flags &= ~M_RDONLY;
}
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);
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_WRITABLE(m) ||
M_TRAILINGSPACE(m) < n->m_len) {
/* 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);
}
}
/*
* Concatenate two pkthdr mbuf chains.
*/
void
m_catpkt(struct mbuf *m, struct mbuf *n)
{
M_ASSERTPKTHDR(m);
M_ASSERTPKTHDR(n);
m->m_pkthdr.len += n->m_pkthdr.len;
m_demote(n, 1, 0);
m_cat(m, 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;
}
}
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;
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 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;
m = m_get(M_NOWAIT, n->m_type);
if (m == NULL)
goto bad;
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);
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).
*/
struct mbuf *
m_copyup(struct mbuf *n, int len, int dstoff)
{
struct mbuf *m;
int count, space;
if (len > (MHLEN - dstoff))
goto bad;
m = m_get(M_NOWAIT, n->m_type);
if (m == NULL)
goto bad;
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);
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 && remain == 0) {
n = m_gethdr(wait, m0->m_type);
if (n == NULL)
return (NULL);
n->m_next = m->m_next;
m->m_next = NULL;
n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
n->m_pkthdr.len = m0->m_pkthdr.len - len0;
m0->m_pkthdr.len = len0;
return (n);
} else if (m0->m_flags & M_PKTHDR) {
n = m_gethdr(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 */
M_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
M_ALIGN(n, remain);
} else if (remain == 0) {
n = m->m_next;
m->m_next = NULL;
return (n);
} else {
n = m_get(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_NOWAIT, MT_DATA, M_PKTHDR);
len = MCLBYTES;
} else {
m = m_gethdr(M_NOWAIT, 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_NOWAIT, MT_DATA, 0);
len = MCLBYTES;
} else {
m = m_get(M_NOWAIT, 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_NOWAIT, 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) {
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);
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_NOWAIT, 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_NOWAIT, 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 == NULL) {
printf("mbuf: %p\n", m);
return;
}
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);
}
/*
* Defragment an mbuf chain, returning at most maxfrags separate
* mbufs+clusters. If this is not possible NULL is returned and
* the original mbuf chain is left in it's present (potentially
* modified) state. We use two techniques: collapsing consecutive
* mbufs and replacing consecutive mbufs by a cluster.
*
* NB: this should really be named m_defrag but that name is taken
*/
struct mbuf *
m_collapse(struct mbuf *m0, int how, int maxfrags)
{
struct mbuf *m, *n, *n2, **prev;
u_int curfrags;
/*
* Calculate the current number of frags.
*/
curfrags = 0;
for (m = m0; m != NULL; m = m->m_next)
curfrags++;
/*
* First, try to collapse mbufs. Note that we always collapse
* towards the front so we don't need to deal with moving the
* pkthdr. This may be suboptimal if the first mbuf has much
* less data than the following.
*/
m = m0;
again:
for (;;) {
n = m->m_next;
if (n == NULL)
break;
if (M_WRITABLE(m) &&
n->m_len < M_TRAILINGSPACE(m)) {
bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
n->m_len);
m->m_len += n->m_len;
m->m_next = n->m_next;
m_free(n);
if (--curfrags <= maxfrags)
return m0;
} else
m = n;
}
KASSERT(maxfrags > 1,
("maxfrags %u, but normal collapse failed", maxfrags));
/*
* Collapse consecutive mbufs to a cluster.
*/
prev = &m0->m_next; /* NB: not the first mbuf */
while ((n = *prev) != NULL) {
if ((n2 = n->m_next) != NULL &&
n->m_len + n2->m_len < MCLBYTES) {
m = m_getcl(how, MT_DATA, 0);
if (m == NULL)
goto bad;
bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
n2->m_len);
m->m_len = n->m_len + n2->m_len;
m->m_next = n2->m_next;
*prev = m;
m_free(n);
m_free(n2);
if (--curfrags <= maxfrags) /* +1 cl -2 mbufs */
return m0;
/*
* Still not there, try the normal collapse
* again before we allocate another cluster.
*/
goto again;
}
prev = &n->m_next;
}
/*
* No place where we can collapse to a cluster; punt.
* This can occur if, for example, you request 2 frags
* but the packet requires that both be clusters (we
* never reallocate the first mbuf to avoid moving the
* packet header).
*/
bad:
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;
ssize_t 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.
*/
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);
}
/*
* Copy an mbuf chain into a uio limited by len if set.
*/
int
m_mbuftouio(struct uio *uio, struct mbuf *m, int len)
{
int error, length, total;
int progress = 0;
if (len > 0)
total = min(uio->uio_resid, len);
else
total = uio->uio_resid;
/* Fill the uio with data from the mbufs. */
for (; m != NULL; m = m->m_next) {
length = min(m->m_len, total - progress);
error = uiomove(mtod(m, void *), length, uio);
if (error)
return (error);
progress += length;
}
return (0);
}
/*
* 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 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.
*/
n = m_getcl(how, m->m_type, m->m_flags);
if (n == NULL) {
m_freem(m0);
return (NULL);
}
if (m->m_flags & M_PKTHDR) {
KASSERT(mprev == NULL, ("%s: m0 %p, m %p has M_PKTHDR",
__func__, m0, m));
m_move_pkthdr(n, m);
}
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);
}
#ifdef MBUF_PROFILING
#define MP_BUCKETS 32 /* don't just change this as things may overflow.*/
struct mbufprofile {
uintmax_t wasted[MP_BUCKETS];
uintmax_t used[MP_BUCKETS];
uintmax_t segments[MP_BUCKETS];
} mbprof;
#define MP_MAXDIGITS 21 /* strlen("16,000,000,000,000,000,000") == 21 */
#define MP_NUMLINES 6
#define MP_NUMSPERLINE 16
#define MP_EXTRABYTES 64 /* > strlen("used:\nwasted:\nsegments:\n") */
/* work out max space needed and add a bit of spare space too */
#define MP_MAXLINE ((MP_MAXDIGITS+1) * MP_NUMSPERLINE)
#define MP_BUFSIZE ((MP_MAXLINE * MP_NUMLINES) + 1 + MP_EXTRABYTES)
char mbprofbuf[MP_BUFSIZE];
void
m_profile(struct mbuf *m)
{
int segments = 0;
int used = 0;
int wasted = 0;
while (m) {
segments++;
used += m->m_len;
if (m->m_flags & M_EXT) {
wasted += MHLEN - sizeof(m->m_ext) +
m->m_ext.ext_size - m->m_len;
} else {
if (m->m_flags & M_PKTHDR)
wasted += MHLEN - m->m_len;
else
wasted += MLEN - m->m_len;
}
m = m->m_next;
}
/* be paranoid.. it helps */
if (segments > MP_BUCKETS - 1)
segments = MP_BUCKETS - 1;
if (used > 100000)
used = 100000;
if (wasted > 100000)
wasted = 100000;
/* store in the appropriate bucket */
/* don't bother locking. if it's slightly off, so what? */
mbprof.segments[segments]++;
mbprof.used[fls(used)]++;
mbprof.wasted[fls(wasted)]++;
}
static void
mbprof_textify(void)
{
int offset;
char *c;
uint64_t *p;
p = &mbprof.wasted[0];
c = mbprofbuf;
offset = snprintf(c, MP_MAXLINE + 10,
"wasted:\n"
"%ju %ju %ju %ju %ju %ju %ju %ju "
"%ju %ju %ju %ju %ju %ju %ju %ju\n",
p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
#ifdef BIG_ARRAY
p = &mbprof.wasted[16];
c += offset;
offset = snprintf(c, MP_MAXLINE,
"%ju %ju %ju %ju %ju %ju %ju %ju "
"%ju %ju %ju %ju %ju %ju %ju %ju\n",
p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
#endif
p = &mbprof.used[0];
c += offset;
offset = snprintf(c, MP_MAXLINE + 10,
"used:\n"
"%ju %ju %ju %ju %ju %ju %ju %ju "
"%ju %ju %ju %ju %ju %ju %ju %ju\n",
p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
#ifdef BIG_ARRAY
p = &mbprof.used[16];
c += offset;
offset = snprintf(c, MP_MAXLINE,
"%ju %ju %ju %ju %ju %ju %ju %ju "
"%ju %ju %ju %ju %ju %ju %ju %ju\n",
p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
#endif
p = &mbprof.segments[0];
c += offset;
offset = snprintf(c, MP_MAXLINE + 10,
"segments:\n"
"%ju %ju %ju %ju %ju %ju %ju %ju "
"%ju %ju %ju %ju %ju %ju %ju %ju\n",
p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
#ifdef BIG_ARRAY
p = &mbprof.segments[16];
c += offset;
offset = snprintf(c, MP_MAXLINE,
"%ju %ju %ju %ju %ju %ju %ju %ju "
"%ju %ju %ju %ju %ju %ju %ju %jju",
p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
#endif
}
static int
mbprof_handler(SYSCTL_HANDLER_ARGS)
{
int error;
mbprof_textify();
error = SYSCTL_OUT(req, mbprofbuf, strlen(mbprofbuf) + 1);
return (error);
}
static int
mbprof_clr_handler(SYSCTL_HANDLER_ARGS)
{
int clear, error;
clear = 0;
error = sysctl_handle_int(oidp, &clear, 0, req);
if (error || !req->newptr)
return (error);
if (clear) {
bzero(&mbprof, sizeof(mbprof));
}
return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofile, CTLTYPE_STRING|CTLFLAG_RD,
NULL, 0, mbprof_handler, "A", "mbuf profiling statistics");
SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofileclr, CTLTYPE_INT|CTLFLAG_RW,
NULL, 0, mbprof_clr_handler, "I", "clear mbuf profiling statistics");
#endif
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