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uipc_mbuf.c revision 1.126
      1 /*	$NetBSD: uipc_mbuf.c,v 1.126 2008/04/09 05:11:20 thorpej Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1999, 2001 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      9  * NASA Ames Research Center.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 3. All advertising materials mentioning features or use of this software
     20  *    must display the following acknowledgement:
     21  *	This product includes software developed by the NetBSD
     22  *	Foundation, Inc. and its contributors.
     23  * 4. Neither the name of The NetBSD Foundation nor the names of its
     24  *    contributors may be used to endorse or promote products derived
     25  *    from this software without specific prior written permission.
     26  *
     27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     37  * POSSIBILITY OF SUCH DAMAGE.
     38  */
     39 
     40 /*
     41  * Copyright (c) 1982, 1986, 1988, 1991, 1993
     42  *	The Regents of the University of California.  All rights reserved.
     43  *
     44  * Redistribution and use in source and binary forms, with or without
     45  * modification, are permitted provided that the following conditions
     46  * are met:
     47  * 1. Redistributions of source code must retain the above copyright
     48  *    notice, this list of conditions and the following disclaimer.
     49  * 2. Redistributions in binary form must reproduce the above copyright
     50  *    notice, this list of conditions and the following disclaimer in the
     51  *    documentation and/or other materials provided with the distribution.
     52  * 3. Neither the name of the University nor the names of its contributors
     53  *    may be used to endorse or promote products derived from this software
     54  *    without specific prior written permission.
     55  *
     56  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     57  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     58  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     59  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     60  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     61  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     62  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     63  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     64  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     65  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     66  * SUCH DAMAGE.
     67  *
     68  *	@(#)uipc_mbuf.c	8.4 (Berkeley) 2/14/95
     69  */
     70 
     71 #include <sys/cdefs.h>
     72 __KERNEL_RCSID(0, "$NetBSD: uipc_mbuf.c,v 1.126 2008/04/09 05:11:20 thorpej Exp $");
     73 
     74 #include "opt_mbuftrace.h"
     75 #include "opt_ddb.h"
     76 
     77 #include <sys/param.h>
     78 #include <sys/systm.h>
     79 #include <sys/atomic.h>
     80 #include <sys/cpu.h>
     81 #include <sys/proc.h>
     82 #include <sys/malloc.h>
     83 #define MBTYPES
     84 #include <sys/mbuf.h>
     85 #include <sys/kernel.h>
     86 #include <sys/syslog.h>
     87 #include <sys/domain.h>
     88 #include <sys/protosw.h>
     89 #include <sys/percpu.h>
     90 #include <sys/pool.h>
     91 #include <sys/socket.h>
     92 #include <sys/sysctl.h>
     93 
     94 #include <net/if.h>
     95 
     96 #include <uvm/uvm.h>
     97 
     98 pool_cache_t mb_cache;	/* mbuf cache */
     99 pool_cache_t mcl_cache;	/* mbuf cluster cache */
    100 
    101 struct mbstat mbstat;
    102 int	max_linkhdr;
    103 int	max_protohdr;
    104 int	max_hdr;
    105 int	max_datalen;
    106 
    107 static int mb_ctor(void *, void *, int);
    108 
    109 static void	*mclpool_alloc(struct pool *, int);
    110 static void	mclpool_release(struct pool *, void *);
    111 
    112 static struct pool_allocator mclpool_allocator = {
    113 	.pa_alloc = mclpool_alloc,
    114 	.pa_free = mclpool_release,
    115 };
    116 
    117 static struct mbuf *m_copym0(struct mbuf *, int, int, int, int);
    118 static struct mbuf *m_split0(struct mbuf *, int, int, int);
    119 static int m_copyback0(struct mbuf **, int, int, const void *, int, int);
    120 
    121 /* flags for m_copyback0 */
    122 #define	M_COPYBACK0_COPYBACK	0x0001	/* copyback from cp */
    123 #define	M_COPYBACK0_PRESERVE	0x0002	/* preserve original data */
    124 #define	M_COPYBACK0_COW		0x0004	/* do copy-on-write */
    125 #define	M_COPYBACK0_EXTEND	0x0008	/* extend chain */
    126 
    127 static const char mclpool_warnmsg[] =
    128     "WARNING: mclpool limit reached; increase NMBCLUSTERS";
    129 
    130 MALLOC_DEFINE(M_MBUF, "mbuf", "mbuf");
    131 
    132 static percpu_t *mbstat_percpu;
    133 
    134 #ifdef MBUFTRACE
    135 struct mownerhead mowners = LIST_HEAD_INITIALIZER(mowners);
    136 struct mowner unknown_mowners[] = {
    137 	MOWNER_INIT("unknown", "free"),
    138 	MOWNER_INIT("unknown", "data"),
    139 	MOWNER_INIT("unknown", "header"),
    140 	MOWNER_INIT("unknown", "soname"),
    141 	MOWNER_INIT("unknown", "soopts"),
    142 	MOWNER_INIT("unknown", "ftable"),
    143 	MOWNER_INIT("unknown", "control"),
    144 	MOWNER_INIT("unknown", "oobdata"),
    145 };
    146 struct mowner revoked_mowner = MOWNER_INIT("revoked", "");
    147 #endif
    148 
    149 #define	MEXT_ISEMBEDDED(m) ((m)->m_ext_ref == (m))
    150 
    151 #define	MCLADDREFERENCE(o, n)						\
    152 do {									\
    153 	KASSERT(((o)->m_flags & M_EXT) != 0);				\
    154 	KASSERT(((n)->m_flags & M_EXT) == 0);				\
    155 	KASSERT((o)->m_ext.ext_refcnt >= 1);				\
    156 	(n)->m_flags |= ((o)->m_flags & M_EXTCOPYFLAGS);		\
    157 	atomic_inc_uint(&(o)->m_ext.ext_refcnt);			\
    158 	(n)->m_ext_ref = (o)->m_ext_ref;				\
    159 	mowner_ref((n), (n)->m_flags);					\
    160 	MCLREFDEBUGN((n), __FILE__, __LINE__);				\
    161 } while (/* CONSTCOND */ 0)
    162 
    163 /*
    164  * Initialize the mbuf allocator.
    165  */
    166 void
    167 mbinit(void)
    168 {
    169 
    170 	KASSERT(sizeof(struct _m_ext) <= MHLEN);
    171 	KASSERT(sizeof(struct mbuf) == MSIZE);
    172 
    173 	mclpool_allocator.pa_backingmap = mb_map;
    174 
    175 	mb_cache = pool_cache_init(msize, 0, 0, 0, "mbpl",
    176 	    NULL, IPL_VM, mb_ctor, NULL, NULL);
    177 	KASSERT(mb_cache != NULL);
    178 
    179 	mcl_cache = pool_cache_init(mclbytes, 0, 0, 0, "mclpl",
    180 	    &mclpool_allocator, IPL_VM, NULL, NULL, NULL);
    181 	KASSERT(mcl_cache != NULL);
    182 
    183 	pool_cache_set_drain_hook(mb_cache, m_reclaim, NULL);
    184 	pool_cache_set_drain_hook(mcl_cache, m_reclaim, NULL);
    185 
    186 	/*
    187 	 * Set the hard limit on the mclpool to the number of
    188 	 * mbuf clusters the kernel is to support.  Log the limit
    189 	 * reached message max once a minute.
    190 	 */
    191 	pool_cache_sethardlimit(mcl_cache, nmbclusters, mclpool_warnmsg, 60);
    192 
    193 	mbstat_percpu = percpu_alloc(sizeof(struct mbstat_cpu));
    194 
    195 	/*
    196 	 * Set a low water mark for both mbufs and clusters.  This should
    197 	 * help ensure that they can be allocated in a memory starvation
    198 	 * situation.  This is important for e.g. diskless systems which
    199 	 * must allocate mbufs in order for the pagedaemon to clean pages.
    200 	 */
    201 	pool_cache_setlowat(mb_cache, mblowat);
    202 	pool_cache_setlowat(mcl_cache, mcllowat);
    203 
    204 #ifdef MBUFTRACE
    205 	{
    206 		/*
    207 		 * Attach the unknown mowners.
    208 		 */
    209 		int i;
    210 		MOWNER_ATTACH(&revoked_mowner);
    211 		for (i = sizeof(unknown_mowners)/sizeof(unknown_mowners[0]);
    212 		     i-- > 0; )
    213 			MOWNER_ATTACH(&unknown_mowners[i]);
    214 	}
    215 #endif
    216 }
    217 
    218 /*
    219  * sysctl helper routine for the kern.mbuf subtree.  nmbclusters may
    220  * or may not be writable, and mblowat and mcllowat need range
    221  * checking and pool tweaking after being reset.
    222  */
    223 static int
    224 sysctl_kern_mbuf(SYSCTLFN_ARGS)
    225 {
    226 	int error, newval;
    227 	struct sysctlnode node;
    228 
    229 	node = *rnode;
    230 	node.sysctl_data = &newval;
    231 	switch (rnode->sysctl_num) {
    232 	case MBUF_NMBCLUSTERS:
    233 		if (mb_map != NULL) {
    234 			node.sysctl_flags &= ~CTLFLAG_READWRITE;
    235 			node.sysctl_flags |= CTLFLAG_READONLY;
    236 		}
    237 		/* FALLTHROUGH */
    238 	case MBUF_MBLOWAT:
    239 	case MBUF_MCLLOWAT:
    240 		newval = *(int*)rnode->sysctl_data;
    241 		break;
    242 	default:
    243 		return (EOPNOTSUPP);
    244 	}
    245 
    246 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
    247 	if (error || newp == NULL)
    248 		return (error);
    249 	if (newval < 0)
    250 		return (EINVAL);
    251 
    252 	switch (node.sysctl_num) {
    253 	case MBUF_NMBCLUSTERS:
    254 		if (newval < nmbclusters)
    255 			return (EINVAL);
    256 		nmbclusters = newval;
    257 		pool_cache_sethardlimit(mcl_cache, nmbclusters,
    258 		    mclpool_warnmsg, 60);
    259 		break;
    260 	case MBUF_MBLOWAT:
    261 		mblowat = newval;
    262 		pool_cache_setlowat(mb_cache, mblowat);
    263 		break;
    264 	case MBUF_MCLLOWAT:
    265 		mcllowat = newval;
    266 		pool_cache_setlowat(mcl_cache, mcllowat);
    267 		break;
    268 	}
    269 
    270 	return (0);
    271 }
    272 
    273 #ifdef MBUFTRACE
    274 static void
    275 mowner_conver_to_user_cb(void *v1, void *v2, struct cpu_info *ci)
    276 {
    277 	struct mowner_counter *mc = v1;
    278 	struct mowner_user *mo_user = v2;
    279 	int i;
    280 
    281 	for (i = 0; i < MOWNER_COUNTER_NCOUNTERS; i++) {
    282 		mo_user->mo_counter[i] += mc->mc_counter[i];
    283 	}
    284 }
    285 
    286 static void
    287 mowner_convert_to_user(struct mowner *mo, struct mowner_user *mo_user)
    288 {
    289 
    290 	memset(mo_user, 0, sizeof(*mo_user));
    291 	KASSERT(sizeof(mo_user->mo_name) == sizeof(mo->mo_name));
    292 	KASSERT(sizeof(mo_user->mo_descr) == sizeof(mo->mo_descr));
    293 	memcpy(mo_user->mo_name, mo->mo_name, sizeof(mo->mo_name));
    294 	memcpy(mo_user->mo_descr, mo->mo_descr, sizeof(mo->mo_descr));
    295 	percpu_foreach(mo->mo_counters, mowner_conver_to_user_cb, mo_user);
    296 }
    297 
    298 static int
    299 sysctl_kern_mbuf_mowners(SYSCTLFN_ARGS)
    300 {
    301 	struct mowner *mo;
    302 	size_t len = 0;
    303 	int error = 0;
    304 
    305 	if (namelen != 0)
    306 		return (EINVAL);
    307 	if (newp != NULL)
    308 		return (EPERM);
    309 
    310 	LIST_FOREACH(mo, &mowners, mo_link) {
    311 		struct mowner_user mo_user;
    312 
    313 		mowner_convert_to_user(mo, &mo_user);
    314 
    315 		if (oldp != NULL) {
    316 			if (*oldlenp - len < sizeof(mo_user)) {
    317 				error = ENOMEM;
    318 				break;
    319 			}
    320 			error = copyout(&mo_user, (char *)oldp + len,
    321 			    sizeof(mo_user));
    322 			if (error)
    323 				break;
    324 		}
    325 		len += sizeof(mo_user);
    326 	}
    327 
    328 	if (error == 0)
    329 		*oldlenp = len;
    330 
    331 	return (error);
    332 }
    333 #endif /* MBUFTRACE */
    334 
    335 static void
    336 mbstat_conver_to_user_cb(void *v1, void *v2, struct cpu_info *ci)
    337 {
    338 	struct mbstat_cpu *mbsc = v1;
    339 	struct mbstat *mbs = v2;
    340 	int i;
    341 
    342 	for (i = 0; i < __arraycount(mbs->m_mtypes); i++) {
    343 		mbs->m_mtypes[i] += mbsc->m_mtypes[i];
    344 	}
    345 }
    346 
    347 static void
    348 mbstat_convert_to_user(struct mbstat *mbs)
    349 {
    350 
    351 	memset(mbs, 0, sizeof(*mbs));
    352 	mbs->m_drain = mbstat.m_drain;
    353 	percpu_foreach(mbstat_percpu, mbstat_conver_to_user_cb, mbs);
    354 }
    355 
    356 static int
    357 sysctl_kern_mbuf_stats(SYSCTLFN_ARGS)
    358 {
    359 	struct sysctlnode node;
    360 	struct mbstat mbs;
    361 
    362 	mbstat_convert_to_user(&mbs);
    363 	node = *rnode;
    364 	node.sysctl_data = &mbs;
    365 	node.sysctl_size = sizeof(mbs);
    366 	return sysctl_lookup(SYSCTLFN_CALL(&node));
    367 }
    368 
    369 SYSCTL_SETUP(sysctl_kern_mbuf_setup, "sysctl kern.mbuf subtree setup")
    370 {
    371 
    372 	sysctl_createv(clog, 0, NULL, NULL,
    373 		       CTLFLAG_PERMANENT,
    374 		       CTLTYPE_NODE, "kern", NULL,
    375 		       NULL, 0, NULL, 0,
    376 		       CTL_KERN, CTL_EOL);
    377 	sysctl_createv(clog, 0, NULL, NULL,
    378 		       CTLFLAG_PERMANENT,
    379 		       CTLTYPE_NODE, "mbuf",
    380 		       SYSCTL_DESCR("mbuf control variables"),
    381 		       NULL, 0, NULL, 0,
    382 		       CTL_KERN, KERN_MBUF, CTL_EOL);
    383 
    384 	sysctl_createv(clog, 0, NULL, NULL,
    385 		       CTLFLAG_PERMANENT|CTLFLAG_IMMEDIATE,
    386 		       CTLTYPE_INT, "msize",
    387 		       SYSCTL_DESCR("mbuf base size"),
    388 		       NULL, msize, NULL, 0,
    389 		       CTL_KERN, KERN_MBUF, MBUF_MSIZE, CTL_EOL);
    390 	sysctl_createv(clog, 0, NULL, NULL,
    391 		       CTLFLAG_PERMANENT|CTLFLAG_IMMEDIATE,
    392 		       CTLTYPE_INT, "mclbytes",
    393 		       SYSCTL_DESCR("mbuf cluster size"),
    394 		       NULL, mclbytes, NULL, 0,
    395 		       CTL_KERN, KERN_MBUF, MBUF_MCLBYTES, CTL_EOL);
    396 	sysctl_createv(clog, 0, NULL, NULL,
    397 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    398 		       CTLTYPE_INT, "nmbclusters",
    399 		       SYSCTL_DESCR("Limit on the number of mbuf clusters"),
    400 		       sysctl_kern_mbuf, 0, &nmbclusters, 0,
    401 		       CTL_KERN, KERN_MBUF, MBUF_NMBCLUSTERS, CTL_EOL);
    402 	sysctl_createv(clog, 0, NULL, NULL,
    403 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    404 		       CTLTYPE_INT, "mblowat",
    405 		       SYSCTL_DESCR("mbuf low water mark"),
    406 		       sysctl_kern_mbuf, 0, &mblowat, 0,
    407 		       CTL_KERN, KERN_MBUF, MBUF_MBLOWAT, CTL_EOL);
    408 	sysctl_createv(clog, 0, NULL, NULL,
    409 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    410 		       CTLTYPE_INT, "mcllowat",
    411 		       SYSCTL_DESCR("mbuf cluster low water mark"),
    412 		       sysctl_kern_mbuf, 0, &mcllowat, 0,
    413 		       CTL_KERN, KERN_MBUF, MBUF_MCLLOWAT, CTL_EOL);
    414 	sysctl_createv(clog, 0, NULL, NULL,
    415 		       CTLFLAG_PERMANENT,
    416 		       CTLTYPE_STRUCT, "stats",
    417 		       SYSCTL_DESCR("mbuf allocation statistics"),
    418 		       sysctl_kern_mbuf_stats, 0, NULL, 0,
    419 		       CTL_KERN, KERN_MBUF, MBUF_STATS, CTL_EOL);
    420 #ifdef MBUFTRACE
    421 	sysctl_createv(clog, 0, NULL, NULL,
    422 		       CTLFLAG_PERMANENT,
    423 		       CTLTYPE_STRUCT, "mowners",
    424 		       SYSCTL_DESCR("Information about mbuf owners"),
    425 		       sysctl_kern_mbuf_mowners, 0, NULL, 0,
    426 		       CTL_KERN, KERN_MBUF, MBUF_MOWNERS, CTL_EOL);
    427 #endif /* MBUFTRACE */
    428 }
    429 
    430 static void *
    431 mclpool_alloc(struct pool *pp, int flags)
    432 {
    433 	bool waitok = (flags & PR_WAITOK) ? true : false;
    434 
    435 	return ((void *)uvm_km_alloc_poolpage(mb_map, waitok));
    436 }
    437 
    438 static void
    439 mclpool_release(struct pool *pp, void *v)
    440 {
    441 
    442 	uvm_km_free_poolpage(mb_map, (vaddr_t)v);
    443 }
    444 
    445 /*ARGSUSED*/
    446 static int
    447 mb_ctor(void *arg, void *object, int flags)
    448 {
    449 	struct mbuf *m = object;
    450 
    451 #ifdef POOL_VTOPHYS
    452 	m->m_paddr = POOL_VTOPHYS(m);
    453 #else
    454 	m->m_paddr = M_PADDR_INVALID;
    455 #endif
    456 	return (0);
    457 }
    458 
    459 void
    460 m_reclaim(void *arg, int flags)
    461 {
    462 	struct domain *dp;
    463 	const struct protosw *pr;
    464 	struct ifnet *ifp;
    465 	int s;
    466 
    467 	KERNEL_LOCK(1, NULL);
    468 	s = splvm();
    469 	DOMAIN_FOREACH(dp) {
    470 		for (pr = dp->dom_protosw;
    471 		     pr < dp->dom_protoswNPROTOSW; pr++)
    472 			if (pr->pr_drain)
    473 				(*pr->pr_drain)();
    474 	}
    475 	IFNET_FOREACH(ifp) {
    476 		if (ifp->if_drain)
    477 			(*ifp->if_drain)(ifp);
    478 	}
    479 	splx(s);
    480 	mbstat.m_drain++;
    481 	KERNEL_UNLOCK_ONE(NULL);
    482 }
    483 
    484 /*
    485  * Space allocation routines.
    486  * These are also available as macros
    487  * for critical paths.
    488  */
    489 struct mbuf *
    490 m_get(int nowait, int type)
    491 {
    492 	struct mbuf *m;
    493 
    494 	m = pool_cache_get(mb_cache,
    495 	    nowait == M_WAIT ? PR_WAITOK|PR_LIMITFAIL : 0);
    496 	if (m == NULL)
    497 		return NULL;
    498 
    499 	mbstat_type_add(type, 1);
    500 	mowner_init(m, type);
    501 	m->m_ext_ref = m;
    502 	m->m_type = type;
    503 	m->m_next = NULL;
    504 	m->m_nextpkt = NULL;
    505 	m->m_data = m->m_dat;
    506 	m->m_flags = 0;
    507 
    508 	return m;
    509 }
    510 
    511 struct mbuf *
    512 m_gethdr(int nowait, int type)
    513 {
    514 	struct mbuf *m;
    515 
    516 	m = m_get(nowait, type);
    517 	if (m == NULL)
    518 		return NULL;
    519 
    520 	m->m_data = m->m_pktdat;
    521 	m->m_flags = M_PKTHDR;
    522 	m->m_pkthdr.rcvif = NULL;
    523 	m->m_pkthdr.csum_flags = 0;
    524 	m->m_pkthdr.csum_data = 0;
    525 	SLIST_INIT(&m->m_pkthdr.tags);
    526 
    527 	return m;
    528 }
    529 
    530 struct mbuf *
    531 m_getclr(int nowait, int type)
    532 {
    533 	struct mbuf *m;
    534 
    535 	MGET(m, nowait, type);
    536 	if (m == 0)
    537 		return (NULL);
    538 	memset(mtod(m, void *), 0, MLEN);
    539 	return (m);
    540 }
    541 
    542 void
    543 m_clget(struct mbuf *m, int nowait)
    544 {
    545 
    546 	MCLGET(m, nowait);
    547 }
    548 
    549 struct mbuf *
    550 m_free(struct mbuf *m)
    551 {
    552 	struct mbuf *n;
    553 
    554 	MFREE(m, n);
    555 	return (n);
    556 }
    557 
    558 void
    559 m_freem(struct mbuf *m)
    560 {
    561 	struct mbuf *n;
    562 
    563 	if (m == NULL)
    564 		return;
    565 	do {
    566 		MFREE(m, n);
    567 		m = n;
    568 	} while (m);
    569 }
    570 
    571 #ifdef MBUFTRACE
    572 /*
    573  * Walk a chain of mbufs, claiming ownership of each mbuf in the chain.
    574  */
    575 void
    576 m_claimm(struct mbuf *m, struct mowner *mo)
    577 {
    578 
    579 	for (; m != NULL; m = m->m_next)
    580 		MCLAIM(m, mo);
    581 }
    582 #endif
    583 
    584 /*
    585  * Mbuffer utility routines.
    586  */
    587 
    588 /*
    589  * Lesser-used path for M_PREPEND:
    590  * allocate new mbuf to prepend to chain,
    591  * copy junk along.
    592  */
    593 struct mbuf *
    594 m_prepend(struct mbuf *m, int len, int how)
    595 {
    596 	struct mbuf *mn;
    597 
    598 	MGET(mn, how, m->m_type);
    599 	if (mn == (struct mbuf *)NULL) {
    600 		m_freem(m);
    601 		return ((struct mbuf *)NULL);
    602 	}
    603 	if (m->m_flags & M_PKTHDR) {
    604 		M_MOVE_PKTHDR(mn, m);
    605 	} else {
    606 		MCLAIM(mn, m->m_owner);
    607 	}
    608 	mn->m_next = m;
    609 	m = mn;
    610 	if (len < MHLEN)
    611 		MH_ALIGN(m, len);
    612 	m->m_len = len;
    613 	return (m);
    614 }
    615 
    616 /*
    617  * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
    618  * continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
    619  * The wait parameter is a choice of M_WAIT/M_DONTWAIT from caller.
    620  */
    621 int MCFail;
    622 
    623 struct mbuf *
    624 m_copym(struct mbuf *m, int off0, int len, int wait)
    625 {
    626 
    627 	return m_copym0(m, off0, len, wait, 0);	/* shallow copy on M_EXT */
    628 }
    629 
    630 struct mbuf *
    631 m_dup(struct mbuf *m, int off0, int len, int wait)
    632 {
    633 
    634 	return m_copym0(m, off0, len, wait, 1);	/* deep copy */
    635 }
    636 
    637 static struct mbuf *
    638 m_copym0(struct mbuf *m, int off0, int len, int wait, int deep)
    639 {
    640 	struct mbuf *n, **np;
    641 	int off = off0;
    642 	struct mbuf *top;
    643 	int copyhdr = 0;
    644 
    645 	if (off < 0 || len < 0)
    646 		panic("m_copym: off %d, len %d", off, len);
    647 	if (off == 0 && m->m_flags & M_PKTHDR)
    648 		copyhdr = 1;
    649 	while (off > 0) {
    650 		if (m == 0)
    651 			panic("m_copym: m == 0, off %d", off);
    652 		if (off < m->m_len)
    653 			break;
    654 		off -= m->m_len;
    655 		m = m->m_next;
    656 	}
    657 	np = &top;
    658 	top = 0;
    659 	while (len > 0) {
    660 		if (m == 0) {
    661 			if (len != M_COPYALL)
    662 				panic("m_copym: m == 0, len %d [!COPYALL]",
    663 				    len);
    664 			break;
    665 		}
    666 		MGET(n, wait, m->m_type);
    667 		*np = n;
    668 		if (n == 0)
    669 			goto nospace;
    670 		MCLAIM(n, m->m_owner);
    671 		if (copyhdr) {
    672 			M_COPY_PKTHDR(n, m);
    673 			if (len == M_COPYALL)
    674 				n->m_pkthdr.len -= off0;
    675 			else
    676 				n->m_pkthdr.len = len;
    677 			copyhdr = 0;
    678 		}
    679 		n->m_len = min(len, m->m_len - off);
    680 		if (m->m_flags & M_EXT) {
    681 			if (!deep) {
    682 				n->m_data = m->m_data + off;
    683 				MCLADDREFERENCE(m, n);
    684 			} else {
    685 				/*
    686 				 * we are unsure about the way m was allocated.
    687 				 * copy into multiple MCLBYTES cluster mbufs.
    688 				 */
    689 				MCLGET(n, wait);
    690 				n->m_len = 0;
    691 				n->m_len = M_TRAILINGSPACE(n);
    692 				n->m_len = min(n->m_len, len);
    693 				n->m_len = min(n->m_len, m->m_len - off);
    694 				memcpy(mtod(n, void *), mtod(m, char *) + off,
    695 				    (unsigned)n->m_len);
    696 			}
    697 		} else
    698 			memcpy(mtod(n, void *), mtod(m, char *) + off,
    699 			    (unsigned)n->m_len);
    700 		if (len != M_COPYALL)
    701 			len -= n->m_len;
    702 		off += n->m_len;
    703 #ifdef DIAGNOSTIC
    704 		if (off > m->m_len)
    705 			panic("m_copym0 overrun");
    706 #endif
    707 		if (off == m->m_len) {
    708 			m = m->m_next;
    709 			off = 0;
    710 		}
    711 		np = &n->m_next;
    712 	}
    713 	if (top == 0)
    714 		MCFail++;
    715 	return (top);
    716 nospace:
    717 	m_freem(top);
    718 	MCFail++;
    719 	return (NULL);
    720 }
    721 
    722 /*
    723  * Copy an entire packet, including header (which must be present).
    724  * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
    725  */
    726 struct mbuf *
    727 m_copypacket(struct mbuf *m, int how)
    728 {
    729 	struct mbuf *top, *n, *o;
    730 
    731 	MGET(n, how, m->m_type);
    732 	top = n;
    733 	if (!n)
    734 		goto nospace;
    735 
    736 	MCLAIM(n, m->m_owner);
    737 	M_COPY_PKTHDR(n, m);
    738 	n->m_len = m->m_len;
    739 	if (m->m_flags & M_EXT) {
    740 		n->m_data = m->m_data;
    741 		MCLADDREFERENCE(m, n);
    742 	} else {
    743 		memcpy(mtod(n, char *), mtod(m, char *), n->m_len);
    744 	}
    745 
    746 	m = m->m_next;
    747 	while (m) {
    748 		MGET(o, how, m->m_type);
    749 		if (!o)
    750 			goto nospace;
    751 
    752 		MCLAIM(o, m->m_owner);
    753 		n->m_next = o;
    754 		n = n->m_next;
    755 
    756 		n->m_len = m->m_len;
    757 		if (m->m_flags & M_EXT) {
    758 			n->m_data = m->m_data;
    759 			MCLADDREFERENCE(m, n);
    760 		} else {
    761 			memcpy(mtod(n, char *), mtod(m, char *), n->m_len);
    762 		}
    763 
    764 		m = m->m_next;
    765 	}
    766 	return top;
    767 nospace:
    768 	m_freem(top);
    769 	MCFail++;
    770 	return NULL;
    771 }
    772 
    773 /*
    774  * Copy data from an mbuf chain starting "off" bytes from the beginning,
    775  * continuing for "len" bytes, into the indicated buffer.
    776  */
    777 void
    778 m_copydata(struct mbuf *m, int off, int len, void *vp)
    779 {
    780 	unsigned	count;
    781 	void *		cp = vp;
    782 
    783 	if (off < 0 || len < 0)
    784 		panic("m_copydata: off %d, len %d", off, len);
    785 	while (off > 0) {
    786 		if (m == NULL)
    787 			panic("m_copydata: m == NULL, off %d", off);
    788 		if (off < m->m_len)
    789 			break;
    790 		off -= m->m_len;
    791 		m = m->m_next;
    792 	}
    793 	while (len > 0) {
    794 		if (m == NULL)
    795 			panic("m_copydata: m == NULL, len %d", len);
    796 		count = min(m->m_len - off, len);
    797 		memcpy(cp, mtod(m, char *) + off, count);
    798 		len -= count;
    799 		cp = (char *)cp + count;
    800 		off = 0;
    801 		m = m->m_next;
    802 	}
    803 }
    804 
    805 /*
    806  * Concatenate mbuf chain n to m.
    807  * n might be copied into m (when n->m_len is small), therefore data portion of
    808  * n could be copied into an mbuf of different mbuf type.
    809  * Any m_pkthdr is not updated.
    810  */
    811 void
    812 m_cat(struct mbuf *m, struct mbuf *n)
    813 {
    814 
    815 	while (m->m_next)
    816 		m = m->m_next;
    817 	while (n) {
    818 		if (M_READONLY(m) || n->m_len > M_TRAILINGSPACE(m)) {
    819 			/* just join the two chains */
    820 			m->m_next = n;
    821 			return;
    822 		}
    823 		/* splat the data from one into the other */
    824 		memcpy(mtod(m, char *) + m->m_len, mtod(n, void *),
    825 		    (u_int)n->m_len);
    826 		m->m_len += n->m_len;
    827 		n = m_free(n);
    828 	}
    829 }
    830 
    831 void
    832 m_adj(struct mbuf *mp, int req_len)
    833 {
    834 	int len = req_len;
    835 	struct mbuf *m;
    836 	int count;
    837 
    838 	if ((m = mp) == NULL)
    839 		return;
    840 	if (len >= 0) {
    841 		/*
    842 		 * Trim from head.
    843 		 */
    844 		while (m != NULL && len > 0) {
    845 			if (m->m_len <= len) {
    846 				len -= m->m_len;
    847 				m->m_len = 0;
    848 				m = m->m_next;
    849 			} else {
    850 				m->m_len -= len;
    851 				m->m_data += len;
    852 				len = 0;
    853 			}
    854 		}
    855 		m = mp;
    856 		if (mp->m_flags & M_PKTHDR)
    857 			m->m_pkthdr.len -= (req_len - len);
    858 	} else {
    859 		/*
    860 		 * Trim from tail.  Scan the mbuf chain,
    861 		 * calculating its length and finding the last mbuf.
    862 		 * If the adjustment only affects this mbuf, then just
    863 		 * adjust and return.  Otherwise, rescan and truncate
    864 		 * after the remaining size.
    865 		 */
    866 		len = -len;
    867 		count = 0;
    868 		for (;;) {
    869 			count += m->m_len;
    870 			if (m->m_next == (struct mbuf *)0)
    871 				break;
    872 			m = m->m_next;
    873 		}
    874 		if (m->m_len >= len) {
    875 			m->m_len -= len;
    876 			if (mp->m_flags & M_PKTHDR)
    877 				mp->m_pkthdr.len -= len;
    878 			return;
    879 		}
    880 		count -= len;
    881 		if (count < 0)
    882 			count = 0;
    883 		/*
    884 		 * Correct length for chain is "count".
    885 		 * Find the mbuf with last data, adjust its length,
    886 		 * and toss data from remaining mbufs on chain.
    887 		 */
    888 		m = mp;
    889 		if (m->m_flags & M_PKTHDR)
    890 			m->m_pkthdr.len = count;
    891 		for (; m; m = m->m_next) {
    892 			if (m->m_len >= count) {
    893 				m->m_len = count;
    894 				break;
    895 			}
    896 			count -= m->m_len;
    897 		}
    898 		if (m)
    899 			while (m->m_next)
    900 				(m = m->m_next)->m_len = 0;
    901 	}
    902 }
    903 
    904 /*
    905  * Rearrange an mbuf chain so that len bytes are contiguous
    906  * and in the data area of an mbuf (so that mtod and dtom
    907  * will work for a structure of size len).  Returns the resulting
    908  * mbuf chain on success, frees it and returns null on failure.
    909  * If there is room, it will add up to max_protohdr-len extra bytes to the
    910  * contiguous region in an attempt to avoid being called next time.
    911  */
    912 int MPFail;
    913 
    914 struct mbuf *
    915 m_pullup(struct mbuf *n, int len)
    916 {
    917 	struct mbuf *m;
    918 	int count;
    919 	int space;
    920 
    921 	/*
    922 	 * If first mbuf has no cluster, and has room for len bytes
    923 	 * without shifting current data, pullup into it,
    924 	 * otherwise allocate a new mbuf to prepend to the chain.
    925 	 */
    926 	if ((n->m_flags & M_EXT) == 0 &&
    927 	    n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
    928 		if (n->m_len >= len)
    929 			return (n);
    930 		m = n;
    931 		n = n->m_next;
    932 		len -= m->m_len;
    933 	} else {
    934 		if (len > MHLEN)
    935 			goto bad;
    936 		MGET(m, M_DONTWAIT, n->m_type);
    937 		if (m == 0)
    938 			goto bad;
    939 		MCLAIM(m, n->m_owner);
    940 		m->m_len = 0;
    941 		if (n->m_flags & M_PKTHDR) {
    942 			M_MOVE_PKTHDR(m, n);
    943 		}
    944 	}
    945 	space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
    946 	do {
    947 		count = min(min(max(len, max_protohdr), space), n->m_len);
    948 		memcpy(mtod(m, char *) + m->m_len, mtod(n, void *),
    949 		  (unsigned)count);
    950 		len -= count;
    951 		m->m_len += count;
    952 		n->m_len -= count;
    953 		space -= count;
    954 		if (n->m_len)
    955 			n->m_data += count;
    956 		else
    957 			n = m_free(n);
    958 	} while (len > 0 && n);
    959 	if (len > 0) {
    960 		(void) m_free(m);
    961 		goto bad;
    962 	}
    963 	m->m_next = n;
    964 	return (m);
    965 bad:
    966 	m_freem(n);
    967 	MPFail++;
    968 	return (NULL);
    969 }
    970 
    971 /*
    972  * Like m_pullup(), except a new mbuf is always allocated, and we allow
    973  * the amount of empty space before the data in the new mbuf to be specified
    974  * (in the event that the caller expects to prepend later).
    975  */
    976 int MSFail;
    977 
    978 struct mbuf *
    979 m_copyup(struct mbuf *n, int len, int dstoff)
    980 {
    981 	struct mbuf *m;
    982 	int count, space;
    983 
    984 	if (len > (MHLEN - dstoff))
    985 		goto bad;
    986 	MGET(m, M_DONTWAIT, n->m_type);
    987 	if (m == NULL)
    988 		goto bad;
    989 	MCLAIM(m, n->m_owner);
    990 	m->m_len = 0;
    991 	if (n->m_flags & M_PKTHDR) {
    992 		M_MOVE_PKTHDR(m, n);
    993 	}
    994 	m->m_data += dstoff;
    995 	space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
    996 	do {
    997 		count = min(min(max(len, max_protohdr), space), n->m_len);
    998 		memcpy(mtod(m, char *) + m->m_len, mtod(n, void *),
    999 		    (unsigned)count);
   1000 		len -= count;
   1001 		m->m_len += count;
   1002 		n->m_len -= count;
   1003 		space -= count;
   1004 		if (n->m_len)
   1005 			n->m_data += count;
   1006 		else
   1007 			n = m_free(n);
   1008 	} while (len > 0 && n);
   1009 	if (len > 0) {
   1010 		(void) m_free(m);
   1011 		goto bad;
   1012 	}
   1013 	m->m_next = n;
   1014 	return (m);
   1015  bad:
   1016 	m_freem(n);
   1017 	MSFail++;
   1018 	return (NULL);
   1019 }
   1020 
   1021 /*
   1022  * Partition an mbuf chain in two pieces, returning the tail --
   1023  * all but the first len0 bytes.  In case of failure, it returns NULL and
   1024  * attempts to restore the chain to its original state.
   1025  */
   1026 struct mbuf *
   1027 m_split(struct mbuf *m0, int len0, int wait)
   1028 {
   1029 
   1030 	return m_split0(m0, len0, wait, 1);
   1031 }
   1032 
   1033 static struct mbuf *
   1034 m_split0(struct mbuf *m0, int len0, int wait, int copyhdr)
   1035 {
   1036 	struct mbuf *m, *n;
   1037 	unsigned len = len0, remain, len_save;
   1038 
   1039 	for (m = m0; m && len > m->m_len; m = m->m_next)
   1040 		len -= m->m_len;
   1041 	if (m == 0)
   1042 		return (NULL);
   1043 	remain = m->m_len - len;
   1044 	if (copyhdr && (m0->m_flags & M_PKTHDR)) {
   1045 		MGETHDR(n, wait, m0->m_type);
   1046 		if (n == 0)
   1047 			return (NULL);
   1048 		MCLAIM(n, m0->m_owner);
   1049 		n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
   1050 		n->m_pkthdr.len = m0->m_pkthdr.len - len0;
   1051 		len_save = m0->m_pkthdr.len;
   1052 		m0->m_pkthdr.len = len0;
   1053 		if (m->m_flags & M_EXT)
   1054 			goto extpacket;
   1055 		if (remain > MHLEN) {
   1056 			/* m can't be the lead packet */
   1057 			MH_ALIGN(n, 0);
   1058 			n->m_next = m_split(m, len, wait);
   1059 			if (n->m_next == 0) {
   1060 				(void) m_free(n);
   1061 				m0->m_pkthdr.len = len_save;
   1062 				return (NULL);
   1063 			} else
   1064 				return (n);
   1065 		} else
   1066 			MH_ALIGN(n, remain);
   1067 	} else if (remain == 0) {
   1068 		n = m->m_next;
   1069 		m->m_next = 0;
   1070 		return (n);
   1071 	} else {
   1072 		MGET(n, wait, m->m_type);
   1073 		if (n == 0)
   1074 			return (NULL);
   1075 		MCLAIM(n, m->m_owner);
   1076 		M_ALIGN(n, remain);
   1077 	}
   1078 extpacket:
   1079 	if (m->m_flags & M_EXT) {
   1080 		n->m_data = m->m_data + len;
   1081 		MCLADDREFERENCE(m, n);
   1082 	} else {
   1083 		memcpy(mtod(n, void *), mtod(m, char *) + len, remain);
   1084 	}
   1085 	n->m_len = remain;
   1086 	m->m_len = len;
   1087 	n->m_next = m->m_next;
   1088 	m->m_next = 0;
   1089 	return (n);
   1090 }
   1091 /*
   1092  * Routine to copy from device local memory into mbufs.
   1093  */
   1094 struct mbuf *
   1095 m_devget(char *buf, int totlen, int off0, struct ifnet *ifp,
   1096     void (*copy)(const void *from, void *to, size_t len))
   1097 {
   1098 	struct mbuf *m;
   1099 	struct mbuf *top = 0, **mp = &top;
   1100 	int off = off0, len;
   1101 	char *cp;
   1102 	char *epkt;
   1103 
   1104 	cp = buf;
   1105 	epkt = cp + totlen;
   1106 	if (off) {
   1107 		/*
   1108 		 * If 'off' is non-zero, packet is trailer-encapsulated,
   1109 		 * so we have to skip the type and length fields.
   1110 		 */
   1111 		cp += off + 2 * sizeof(uint16_t);
   1112 		totlen -= 2 * sizeof(uint16_t);
   1113 	}
   1114 	MGETHDR(m, M_DONTWAIT, MT_DATA);
   1115 	if (m == 0)
   1116 		return (NULL);
   1117 	m->m_pkthdr.rcvif = ifp;
   1118 	m->m_pkthdr.len = totlen;
   1119 	m->m_len = MHLEN;
   1120 
   1121 	while (totlen > 0) {
   1122 		if (top) {
   1123 			MGET(m, M_DONTWAIT, MT_DATA);
   1124 			if (m == 0) {
   1125 				m_freem(top);
   1126 				return (NULL);
   1127 			}
   1128 			m->m_len = MLEN;
   1129 		}
   1130 		len = min(totlen, epkt - cp);
   1131 		if (len >= MINCLSIZE) {
   1132 			MCLGET(m, M_DONTWAIT);
   1133 			if ((m->m_flags & M_EXT) == 0) {
   1134 				m_free(m);
   1135 				m_freem(top);
   1136 				return (NULL);
   1137 			}
   1138 			m->m_len = len = min(len, MCLBYTES);
   1139 		} else {
   1140 			/*
   1141 			 * Place initial small packet/header at end of mbuf.
   1142 			 */
   1143 			if (len < m->m_len) {
   1144 				if (top == 0 && len + max_linkhdr <= m->m_len)
   1145 					m->m_data += max_linkhdr;
   1146 				m->m_len = len;
   1147 			} else
   1148 				len = m->m_len;
   1149 		}
   1150 		if (copy)
   1151 			copy(cp, mtod(m, void *), (size_t)len);
   1152 		else
   1153 			memcpy(mtod(m, void *), cp, (size_t)len);
   1154 		cp += len;
   1155 		*mp = m;
   1156 		mp = &m->m_next;
   1157 		totlen -= len;
   1158 		if (cp == epkt)
   1159 			cp = buf;
   1160 	}
   1161 	return (top);
   1162 }
   1163 
   1164 /*
   1165  * Copy data from a buffer back into the indicated mbuf chain,
   1166  * starting "off" bytes from the beginning, extending the mbuf
   1167  * chain if necessary.
   1168  */
   1169 void
   1170 m_copyback(struct mbuf *m0, int off, int len, const void *cp)
   1171 {
   1172 #if defined(DEBUG)
   1173 	struct mbuf *origm = m0;
   1174 	int error;
   1175 #endif /* defined(DEBUG) */
   1176 
   1177 	if (m0 == NULL)
   1178 		return;
   1179 
   1180 #if defined(DEBUG)
   1181 	error =
   1182 #endif /* defined(DEBUG) */
   1183 	m_copyback0(&m0, off, len, cp,
   1184 	    M_COPYBACK0_COPYBACK|M_COPYBACK0_EXTEND, M_DONTWAIT);
   1185 
   1186 #if defined(DEBUG)
   1187 	if (error != 0 || (m0 != NULL && origm != m0))
   1188 		panic("m_copyback");
   1189 #endif /* defined(DEBUG) */
   1190 }
   1191 
   1192 struct mbuf *
   1193 m_copyback_cow(struct mbuf *m0, int off, int len, const void *cp, int how)
   1194 {
   1195 	int error;
   1196 
   1197 	/* don't support chain expansion */
   1198 	KDASSERT(off + len <= m_length(m0));
   1199 
   1200 	error = m_copyback0(&m0, off, len, cp,
   1201 	    M_COPYBACK0_COPYBACK|M_COPYBACK0_COW, how);
   1202 	if (error) {
   1203 		/*
   1204 		 * no way to recover from partial success.
   1205 		 * just free the chain.
   1206 		 */
   1207 		m_freem(m0);
   1208 		return NULL;
   1209 	}
   1210 	return m0;
   1211 }
   1212 
   1213 /*
   1214  * m_makewritable: ensure the specified range writable.
   1215  */
   1216 int
   1217 m_makewritable(struct mbuf **mp, int off, int len, int how)
   1218 {
   1219 	int error;
   1220 #if defined(DEBUG)
   1221 	struct mbuf *n;
   1222 	int origlen, reslen;
   1223 
   1224 	origlen = m_length(*mp);
   1225 #endif /* defined(DEBUG) */
   1226 
   1227 #if 0 /* M_COPYALL is large enough */
   1228 	if (len == M_COPYALL)
   1229 		len = m_length(*mp) - off; /* XXX */
   1230 #endif
   1231 
   1232 	error = m_copyback0(mp, off, len, NULL,
   1233 	    M_COPYBACK0_PRESERVE|M_COPYBACK0_COW, how);
   1234 
   1235 #if defined(DEBUG)
   1236 	reslen = 0;
   1237 	for (n = *mp; n; n = n->m_next)
   1238 		reslen += n->m_len;
   1239 	if (origlen != reslen)
   1240 		panic("m_makewritable: length changed");
   1241 	if (((*mp)->m_flags & M_PKTHDR) != 0 && reslen != (*mp)->m_pkthdr.len)
   1242 		panic("m_makewritable: inconsist");
   1243 #endif /* defined(DEBUG) */
   1244 
   1245 	return error;
   1246 }
   1247 
   1248 int
   1249 m_copyback0(struct mbuf **mp0, int off, int len, const void *vp, int flags,
   1250     int how)
   1251 {
   1252 	int mlen;
   1253 	struct mbuf *m, *n;
   1254 	struct mbuf **mp;
   1255 	int totlen = 0;
   1256 	const char *cp = vp;
   1257 
   1258 	KASSERT(mp0 != NULL);
   1259 	KASSERT(*mp0 != NULL);
   1260 	KASSERT((flags & M_COPYBACK0_PRESERVE) == 0 || cp == NULL);
   1261 	KASSERT((flags & M_COPYBACK0_COPYBACK) == 0 || cp != NULL);
   1262 
   1263 	/*
   1264 	 * we don't bother to update "totlen" in the case of M_COPYBACK0_COW,
   1265 	 * assuming that M_COPYBACK0_EXTEND and M_COPYBACK0_COW are exclusive.
   1266 	 */
   1267 
   1268 	KASSERT((~flags & (M_COPYBACK0_EXTEND|M_COPYBACK0_COW)) != 0);
   1269 
   1270 	mp = mp0;
   1271 	m = *mp;
   1272 	while (off > (mlen = m->m_len)) {
   1273 		off -= mlen;
   1274 		totlen += mlen;
   1275 		if (m->m_next == NULL) {
   1276 			int tspace;
   1277 extend:
   1278 			if ((flags & M_COPYBACK0_EXTEND) == 0)
   1279 				goto out;
   1280 
   1281 			/*
   1282 			 * try to make some space at the end of "m".
   1283 			 */
   1284 
   1285 			mlen = m->m_len;
   1286 			if (off + len >= MINCLSIZE &&
   1287 			    (m->m_flags & M_EXT) == 0 && m->m_len == 0) {
   1288 				MCLGET(m, how);
   1289 			}
   1290 			tspace = M_TRAILINGSPACE(m);
   1291 			if (tspace > 0) {
   1292 				tspace = min(tspace, off + len);
   1293 				KASSERT(tspace > 0);
   1294 				memset(mtod(m, char *) + m->m_len, 0,
   1295 				    min(off, tspace));
   1296 				m->m_len += tspace;
   1297 				off += mlen;
   1298 				totlen -= mlen;
   1299 				continue;
   1300 			}
   1301 
   1302 			/*
   1303 			 * need to allocate an mbuf.
   1304 			 */
   1305 
   1306 			if (off + len >= MINCLSIZE) {
   1307 				n = m_getcl(how, m->m_type, 0);
   1308 			} else {
   1309 				n = m_get(how, m->m_type);
   1310 			}
   1311 			if (n == NULL) {
   1312 				goto out;
   1313 			}
   1314 			n->m_len = 0;
   1315 			n->m_len = min(M_TRAILINGSPACE(n), off + len);
   1316 			memset(mtod(n, char *), 0, min(n->m_len, off));
   1317 			m->m_next = n;
   1318 		}
   1319 		mp = &m->m_next;
   1320 		m = m->m_next;
   1321 	}
   1322 	while (len > 0) {
   1323 		mlen = m->m_len - off;
   1324 		if (mlen != 0 && M_READONLY(m)) {
   1325 			char *datap;
   1326 			int eatlen;
   1327 
   1328 			/*
   1329 			 * this mbuf is read-only.
   1330 			 * allocate a new writable mbuf and try again.
   1331 			 */
   1332 
   1333 #if defined(DIAGNOSTIC)
   1334 			if ((flags & M_COPYBACK0_COW) == 0)
   1335 				panic("m_copyback0: read-only");
   1336 #endif /* defined(DIAGNOSTIC) */
   1337 
   1338 			/*
   1339 			 * if we're going to write into the middle of
   1340 			 * a mbuf, split it first.
   1341 			 */
   1342 			if (off > 0 && len < mlen) {
   1343 				n = m_split0(m, off, how, 0);
   1344 				if (n == NULL)
   1345 					goto enobufs;
   1346 				m->m_next = n;
   1347 				mp = &m->m_next;
   1348 				m = n;
   1349 				off = 0;
   1350 				continue;
   1351 			}
   1352 
   1353 			/*
   1354 			 * XXX TODO coalesce into the trailingspace of
   1355 			 * the previous mbuf when possible.
   1356 			 */
   1357 
   1358 			/*
   1359 			 * allocate a new mbuf.  copy packet header if needed.
   1360 			 */
   1361 			MGET(n, how, m->m_type);
   1362 			if (n == NULL)
   1363 				goto enobufs;
   1364 			MCLAIM(n, m->m_owner);
   1365 			if (off == 0 && (m->m_flags & M_PKTHDR) != 0) {
   1366 				M_MOVE_PKTHDR(n, m);
   1367 				n->m_len = MHLEN;
   1368 			} else {
   1369 				if (len >= MINCLSIZE)
   1370 					MCLGET(n, M_DONTWAIT);
   1371 				n->m_len =
   1372 				    (n->m_flags & M_EXT) ? MCLBYTES : MLEN;
   1373 			}
   1374 			if (n->m_len > len)
   1375 				n->m_len = len;
   1376 
   1377 			/*
   1378 			 * free the region which has been overwritten.
   1379 			 * copying data from old mbufs if requested.
   1380 			 */
   1381 			if (flags & M_COPYBACK0_PRESERVE)
   1382 				datap = mtod(n, char *);
   1383 			else
   1384 				datap = NULL;
   1385 			eatlen = n->m_len;
   1386 			KDASSERT(off == 0 || eatlen >= mlen);
   1387 			if (off > 0) {
   1388 				KDASSERT(len >= mlen);
   1389 				m->m_len = off;
   1390 				m->m_next = n;
   1391 				if (datap) {
   1392 					m_copydata(m, off, mlen, datap);
   1393 					datap += mlen;
   1394 				}
   1395 				eatlen -= mlen;
   1396 				mp = &m->m_next;
   1397 				m = m->m_next;
   1398 			}
   1399 			while (m != NULL && M_READONLY(m) &&
   1400 			    n->m_type == m->m_type && eatlen > 0) {
   1401 				mlen = min(eatlen, m->m_len);
   1402 				if (datap) {
   1403 					m_copydata(m, 0, mlen, datap);
   1404 					datap += mlen;
   1405 				}
   1406 				m->m_data += mlen;
   1407 				m->m_len -= mlen;
   1408 				eatlen -= mlen;
   1409 				if (m->m_len == 0)
   1410 					*mp = m = m_free(m);
   1411 			}
   1412 			if (eatlen > 0)
   1413 				n->m_len -= eatlen;
   1414 			n->m_next = m;
   1415 			*mp = m = n;
   1416 			continue;
   1417 		}
   1418 		mlen = min(mlen, len);
   1419 		if (flags & M_COPYBACK0_COPYBACK) {
   1420 			memcpy(mtod(m, char *) + off, cp, (unsigned)mlen);
   1421 			cp += mlen;
   1422 		}
   1423 		len -= mlen;
   1424 		mlen += off;
   1425 		off = 0;
   1426 		totlen += mlen;
   1427 		if (len == 0)
   1428 			break;
   1429 		if (m->m_next == NULL) {
   1430 			goto extend;
   1431 		}
   1432 		mp = &m->m_next;
   1433 		m = m->m_next;
   1434 	}
   1435 out:	if (((m = *mp0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) {
   1436 		KASSERT((flags & M_COPYBACK0_EXTEND) != 0);
   1437 		m->m_pkthdr.len = totlen;
   1438 	}
   1439 
   1440 	return 0;
   1441 
   1442 enobufs:
   1443 	return ENOBUFS;
   1444 }
   1445 
   1446 void
   1447 m_move_pkthdr(struct mbuf *to, struct mbuf *from)
   1448 {
   1449 
   1450 	KASSERT((to->m_flags & M_EXT) == 0);
   1451 	KASSERT((to->m_flags & M_PKTHDR) == 0 || m_tag_first(to) == NULL);
   1452 	KASSERT((from->m_flags & M_PKTHDR) != 0);
   1453 
   1454 	to->m_pkthdr = from->m_pkthdr;
   1455 	to->m_flags = from->m_flags & M_COPYFLAGS;
   1456 	to->m_data = to->m_pktdat;
   1457 
   1458 	from->m_flags &= ~M_PKTHDR;
   1459 }
   1460 
   1461 /*
   1462  * Apply function f to the data in an mbuf chain starting "off" bytes from the
   1463  * beginning, continuing for "len" bytes.
   1464  */
   1465 int
   1466 m_apply(struct mbuf *m, int off, int len,
   1467     int (*f)(void *, void *, unsigned int), void *arg)
   1468 {
   1469 	unsigned int count;
   1470 	int rval;
   1471 
   1472 	KASSERT(len >= 0);
   1473 	KASSERT(off >= 0);
   1474 
   1475 	while (off > 0) {
   1476 		KASSERT(m != NULL);
   1477 		if (off < m->m_len)
   1478 			break;
   1479 		off -= m->m_len;
   1480 		m = m->m_next;
   1481 	}
   1482 	while (len > 0) {
   1483 		KASSERT(m != NULL);
   1484 		count = min(m->m_len - off, len);
   1485 
   1486 		rval = (*f)(arg, mtod(m, char *) + off, count);
   1487 		if (rval)
   1488 			return (rval);
   1489 
   1490 		len -= count;
   1491 		off = 0;
   1492 		m = m->m_next;
   1493 	}
   1494 
   1495 	return (0);
   1496 }
   1497 
   1498 /*
   1499  * Return a pointer to mbuf/offset of location in mbuf chain.
   1500  */
   1501 struct mbuf *
   1502 m_getptr(struct mbuf *m, int loc, int *off)
   1503 {
   1504 
   1505 	while (loc >= 0) {
   1506 		/* Normal end of search */
   1507 		if (m->m_len > loc) {
   1508 	    		*off = loc;
   1509 	    		return (m);
   1510 		} else {
   1511 	    		loc -= m->m_len;
   1512 
   1513 	    		if (m->m_next == NULL) {
   1514 				if (loc == 0) {
   1515  					/* Point at the end of valid data */
   1516 		    			*off = m->m_len;
   1517 		    			return (m);
   1518 				} else
   1519 		  			return (NULL);
   1520 	    		} else
   1521 	      			m = m->m_next;
   1522 		}
   1523     	}
   1524 
   1525 	return (NULL);
   1526 }
   1527 
   1528 /*
   1529  * m_ext_free: release a reference to the mbuf external storage.
   1530  *
   1531  * => free the mbuf m itsself as well.
   1532  */
   1533 
   1534 void
   1535 m_ext_free(struct mbuf *m)
   1536 {
   1537 	bool embedded = MEXT_ISEMBEDDED(m);
   1538 	bool dofree = true;
   1539 	u_int refcnt;
   1540 
   1541 	KASSERT((m->m_flags & M_EXT) != 0);
   1542 	KASSERT(MEXT_ISEMBEDDED(m->m_ext_ref));
   1543 	KASSERT((m->m_ext_ref->m_flags & M_EXT) != 0);
   1544 	KASSERT((m->m_flags & M_EXT_CLUSTER) ==
   1545 	    (m->m_ext_ref->m_flags & M_EXT_CLUSTER));
   1546 
   1547 	if (__predict_true(m->m_ext.ext_refcnt == 1)) {
   1548 		refcnt = m->m_ext.ext_refcnt = 0;
   1549 	} else {
   1550 		refcnt = atomic_dec_uint_nv(&m->m_ext.ext_refcnt);
   1551 	}
   1552 	if (refcnt > 0) {
   1553 		if (embedded) {
   1554 			/*
   1555 			 * other mbuf's m_ext_ref still points to us.
   1556 			 */
   1557 			dofree = false;
   1558 		} else {
   1559 			m->m_ext_ref = m;
   1560 		}
   1561 	} else {
   1562 		/*
   1563 		 * dropping the last reference
   1564 		 */
   1565 		if (!embedded) {
   1566 			m->m_ext.ext_refcnt++; /* XXX */
   1567 			m_ext_free(m->m_ext_ref);
   1568 			m->m_ext_ref = m;
   1569 		} else if ((m->m_flags & M_EXT_CLUSTER) != 0) {
   1570 			pool_cache_put_paddr((struct pool_cache *)
   1571 			    m->m_ext.ext_arg,
   1572 			    m->m_ext.ext_buf, m->m_ext.ext_paddr);
   1573 		} else if (m->m_ext.ext_free) {
   1574 			(*m->m_ext.ext_free)(m,
   1575 			    m->m_ext.ext_buf, m->m_ext.ext_size,
   1576 			    m->m_ext.ext_arg);
   1577 			/*
   1578 			 * 'm' is already freed by the ext_free callback.
   1579 			 */
   1580 			dofree = false;
   1581 		} else {
   1582 			free(m->m_ext.ext_buf, m->m_ext.ext_type);
   1583 		}
   1584 	}
   1585 	if (dofree) {
   1586 		pool_cache_put(mb_cache, m);
   1587 	}
   1588 }
   1589 
   1590 #if defined(DDB)
   1591 void
   1592 m_print(const struct mbuf *m, const char *modif, void (*pr)(const char *, ...))
   1593 {
   1594 	char ch;
   1595 	bool opt_c = false;
   1596 	char buf[512];
   1597 
   1598 	while ((ch = *(modif++)) != '\0') {
   1599 		switch (ch) {
   1600 		case 'c':
   1601 			opt_c = true;
   1602 			break;
   1603 		}
   1604 	}
   1605 
   1606 nextchain:
   1607 	(*pr)("MBUF %p\n", m);
   1608 	bitmask_snprintf((u_int)m->m_flags, M_FLAGS_BITS, buf, sizeof(buf));
   1609 	(*pr)("  data=%p, len=%d, type=%d, flags=0x%s\n",
   1610 	    m->m_data, m->m_len, m->m_type, buf);
   1611 	(*pr)("  owner=%p, next=%p, nextpkt=%p\n", m->m_owner, m->m_next,
   1612 	    m->m_nextpkt);
   1613 	(*pr)("  leadingspace=%u, trailingspace=%u, readonly=%u\n",
   1614 	    (int)M_LEADINGSPACE(m), (int)M_TRAILINGSPACE(m),
   1615 	    (int)M_READONLY(m));
   1616 	if ((m->m_flags & M_PKTHDR) != 0) {
   1617 		bitmask_snprintf(m->m_pkthdr.csum_flags, M_CSUM_BITS, buf,
   1618 		    sizeof(buf));
   1619 		(*pr)("  pktlen=%d, rcvif=%p, csum_flags=0x%s, csum_data=0x%"
   1620 		    PRIx32 ", segsz=%u\n",
   1621 		    m->m_pkthdr.len, m->m_pkthdr.rcvif,
   1622 		    buf, m->m_pkthdr.csum_data, m->m_pkthdr.segsz);
   1623 	}
   1624 	if ((m->m_flags & M_EXT)) {
   1625 		(*pr)("  ext_refcnt=%u, ext_buf=%p, ext_size=%zd, "
   1626 		    "ext_free=%p, ext_arg=%p\n",
   1627 		    m->m_ext.ext_refcnt,
   1628 		    m->m_ext.ext_buf, m->m_ext.ext_size,
   1629 		    m->m_ext.ext_free, m->m_ext.ext_arg);
   1630 	}
   1631 	if ((~m->m_flags & (M_EXT|M_EXT_PAGES)) == 0) {
   1632 		vaddr_t sva = (vaddr_t)m->m_ext.ext_buf;
   1633 		vaddr_t eva = sva + m->m_ext.ext_size;
   1634 		int n = (round_page(eva) - trunc_page(sva)) >> PAGE_SHIFT;
   1635 		int i;
   1636 
   1637 		(*pr)("  pages:");
   1638 		for (i = 0; i < n; i ++) {
   1639 			(*pr)(" %p", m->m_ext.ext_pgs[i]);
   1640 		}
   1641 		(*pr)("\n");
   1642 	}
   1643 
   1644 	if (opt_c) {
   1645 		m = m->m_next;
   1646 		if (m != NULL) {
   1647 			goto nextchain;
   1648 		}
   1649 	}
   1650 }
   1651 #endif /* defined(DDB) */
   1652 
   1653 void
   1654 mbstat_type_add(int type, int diff)
   1655 {
   1656 	struct mbstat_cpu *mb;
   1657 	int s;
   1658 
   1659 	s = splvm();
   1660 	mb = percpu_getref(mbstat_percpu);
   1661 	mb->m_mtypes[type] += diff;
   1662 	percpu_putref(mbstat_percpu);
   1663 	splx(s);
   1664 }
   1665 
   1666 #if defined(MBUFTRACE)
   1667 void
   1668 mowner_attach(struct mowner *mo)
   1669 {
   1670 
   1671 	KASSERT(mo->mo_counters == NULL);
   1672 	mo->mo_counters = percpu_alloc(sizeof(struct mowner_counter));
   1673 
   1674 	/* XXX lock */
   1675 	LIST_INSERT_HEAD(&mowners, mo, mo_link);
   1676 }
   1677 
   1678 void
   1679 mowner_detach(struct mowner *mo)
   1680 {
   1681 
   1682 	KASSERT(mo->mo_counters != NULL);
   1683 
   1684 	/* XXX lock */
   1685 	LIST_REMOVE(mo, mo_link);
   1686 
   1687 	percpu_free(mo->mo_counters, sizeof(struct mowner_counter));
   1688 	mo->mo_counters = NULL;
   1689 }
   1690 
   1691 void
   1692 mowner_init(struct mbuf *m, int type)
   1693 {
   1694 	struct mowner_counter *mc;
   1695 	struct mowner *mo;
   1696 	int s;
   1697 
   1698 	m->m_owner = mo = &unknown_mowners[type];
   1699 	s = splvm();
   1700 	mc = percpu_getref(mo->mo_counters);
   1701 	mc->mc_counter[MOWNER_COUNTER_CLAIMS]++;
   1702 	percpu_putref(mo->mo_counters);
   1703 	splx(s);
   1704 }
   1705 
   1706 void
   1707 mowner_ref(struct mbuf *m, int flags)
   1708 {
   1709 	struct mowner *mo = m->m_owner;
   1710 	struct mowner_counter *mc;
   1711 	int s;
   1712 
   1713 	s = splvm();
   1714 	mc = percpu_getref(mo->mo_counters);
   1715 	if ((flags & M_EXT) != 0)
   1716 		mc->mc_counter[MOWNER_COUNTER_EXT_CLAIMS]++;
   1717 	if ((flags & M_CLUSTER) != 0)
   1718 		mc->mc_counter[MOWNER_COUNTER_CLUSTER_CLAIMS]++;
   1719 	percpu_putref(mo->mo_counters);
   1720 	splx(s);
   1721 }
   1722 
   1723 void
   1724 mowner_revoke(struct mbuf *m, bool all, int flags)
   1725 {
   1726 	struct mowner *mo = m->m_owner;
   1727 	struct mowner_counter *mc;
   1728 	int s;
   1729 
   1730 	s = splvm();
   1731 	mc = percpu_getref(mo->mo_counters);
   1732 	if ((flags & M_EXT) != 0)
   1733 		mc->mc_counter[MOWNER_COUNTER_EXT_RELEASES]++;
   1734 	if ((flags & M_CLUSTER) != 0)
   1735 		mc->mc_counter[MOWNER_COUNTER_CLUSTER_RELEASES]++;
   1736 	if (all)
   1737 		mc->mc_counter[MOWNER_COUNTER_RELEASES]++;
   1738 	percpu_putref(mo->mo_counters);
   1739 	splx(s);
   1740 	if (all)
   1741 		m->m_owner = &revoked_mowner;
   1742 }
   1743 
   1744 static void
   1745 mowner_claim(struct mbuf *m, struct mowner *mo)
   1746 {
   1747 	struct mowner_counter *mc;
   1748 	int flags = m->m_flags;
   1749 	int s;
   1750 
   1751 	s = splvm();
   1752 	mc = percpu_getref(mo->mo_counters);
   1753 	mc->mc_counter[MOWNER_COUNTER_CLAIMS]++;
   1754 	if ((flags & M_EXT) != 0)
   1755 		mc->mc_counter[MOWNER_COUNTER_EXT_CLAIMS]++;
   1756 	if ((flags & M_CLUSTER) != 0)
   1757 		mc->mc_counter[MOWNER_COUNTER_CLUSTER_CLAIMS]++;
   1758 	percpu_putref(mo->mo_counters);
   1759 	splx(s);
   1760 	m->m_owner = mo;
   1761 }
   1762 
   1763 void
   1764 m_claim(struct mbuf *m, struct mowner *mo)
   1765 {
   1766 
   1767 	if (m->m_owner == mo || mo == NULL)
   1768 		return;
   1769 
   1770 	mowner_revoke(m, true, m->m_flags);
   1771 	mowner_claim(m, mo);
   1772 }
   1773 #endif /* defined(MBUFTRACE) */
   1774