kern_mbuf.c

Go to the documentation of this file.

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2004, 2005,
 *      Bosko Milekic <bmilekic@FreeBSD.org>.  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 unmodified, 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include "opt_param.h"
#include "opt_kern_tls.h"
 
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/domainset.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/ktls.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/protosw.h>
#include <sys/refcount.h>
#include <sys/sf_buf.h>
#include <sys/smp.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
 
#include <net/if.h>
#include <net/if_var.h>
 
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_map.h>
#include <vm/uma.h>
#include <vm/uma_dbg.h>
 
/*
 * In FreeBSD, Mbufs and Mbuf Clusters are allocated from UMA
 * Zones.
 *
 * Mbuf Clusters (2K, contiguous) are allocated from the Cluster
 * Zone.  The Zone can be capped at kern.ipc.nmbclusters, if the
 * administrator so desires.
 *
 * Mbufs are allocated from a UMA Primary Zone called the Mbuf
 * Zone.
 *
 * Additionally, FreeBSD provides a Packet Zone, which it
 * configures as a Secondary Zone to the Mbuf Primary Zone,
 * thus sharing backend Slab kegs with the Mbuf Primary Zone.
 *
 * Thus common-case allocations and locking are simplified:
 *
 *  m_clget()                m_getcl()
 *    |                         |
 *    |   .------------>[(Packet Cache)]    m_get(), m_gethdr()
 *    |   |             [     Packet   ]            |
 *  [(Cluster Cache)]   [    Secondary ]   [ (Mbuf Cache)     ]
 *  [ Cluster Zone  ]   [     Zone     ]   [ Mbuf Primary Zone ]
 *        |                       \________         |
 *  [ Cluster Keg   ]                      \       /
 *        |                              [ Mbuf Keg   ]
 *  [ Cluster Slabs ]                         |
 *        |                              [ Mbuf Slabs ]
 *         \____________(VM)_________________/
 *
 *
 * Whenever an object is allocated with uma_zalloc() out of
 * one of the Zones its _ctor_ function is executed.  The same
 * for any deallocation through uma_zfree() the _dtor_ function
 * is executed.
 *
 * Caches are per-CPU and are filled from the Primary Zone.
 *
 * Whenever an object is allocated from the underlying global
 * memory pool it gets pre-initialized with the _zinit_ functions.
 * When the Keg's are overfull objects get decommissioned with
 * _zfini_ functions and free'd back to the global memory pool.
 *
 */
 
int nmbufs;                     /* limits number of mbufs */
int nmbclusters;                /* limits number of mbuf clusters */
int nmbjumbop;                  /* limits number of page size jumbo clusters */
int nmbjumbo9;                  /* limits number of 9k jumbo clusters */
int nmbjumbo16;                 /* limits number of 16k jumbo clusters */
 
bool mb_use_ext_pgs = false;    /* use M_EXTPG mbufs for sendfile & TLS */
 
static int
sysctl_mb_use_ext_pgs(SYSCTL_HANDLER_ARGS)
{
        int error, extpg;
 
        extpg = mb_use_ext_pgs;
        error = sysctl_handle_int(oidp, &extpg, 0, req);
        if (error == 0 && req->newptr != NULL) {
                if (extpg != 0 && !PMAP_HAS_DMAP)
                        error = EOPNOTSUPP;
                else
                        mb_use_ext_pgs = extpg != 0;
        }
        return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, mb_use_ext_pgs, CTLTYPE_INT | CTLFLAG_RW,
    &mb_use_ext_pgs, 0,
    sysctl_mb_use_ext_pgs, "IU",
    "Use unmapped mbufs for sendfile(2) and TLS offload");
 
static quad_t maxmbufmem;       /* overall real memory limit for all mbufs */
 
SYSCTL_QUAD(_kern_ipc, OID_AUTO, maxmbufmem, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxmbufmem, 0,
    "Maximum real memory allocatable to various mbuf types");
 
static counter_u64_t snd_tag_count;
SYSCTL_COUNTER_U64(_kern_ipc, OID_AUTO, num_snd_tags, CTLFLAG_RW,
    &snd_tag_count, "# of active mbuf send tags");
 
/*
 * tunable_mbinit() has to be run before any mbuf allocations are done.
 */
static void
tunable_mbinit(void *dummy)
{
        quad_t realmem;
        int extpg;
 
        /*
         * The default limit for all mbuf related memory is 1/2 of all
         * available kernel memory (physical or kmem).
         * At most it can be 3/4 of available kernel memory.
         */
        realmem = qmin((quad_t)physmem * PAGE_SIZE, vm_kmem_size);
        maxmbufmem = realmem / 2;
        TUNABLE_QUAD_FETCH("kern.ipc.maxmbufmem", &maxmbufmem);
        if (maxmbufmem > realmem / 4 * 3)
                maxmbufmem = realmem / 4 * 3;
 
        TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters);
        if (nmbclusters == 0)
                nmbclusters = maxmbufmem / MCLBYTES / 4;
 
        TUNABLE_INT_FETCH("kern.ipc.nmbjumbop", &nmbjumbop);
        if (nmbjumbop == 0)
                nmbjumbop = maxmbufmem / MJUMPAGESIZE / 4;
 
        TUNABLE_INT_FETCH("kern.ipc.nmbjumbo9", &nmbjumbo9);
        if (nmbjumbo9 == 0)
                nmbjumbo9 = maxmbufmem / MJUM9BYTES / 6;
 
        TUNABLE_INT_FETCH("kern.ipc.nmbjumbo16", &nmbjumbo16);
        if (nmbjumbo16 == 0)
                nmbjumbo16 = maxmbufmem / MJUM16BYTES / 6;
 
        /*
         * We need at least as many mbufs as we have clusters of
         * the various types added together.
         */
        TUNABLE_INT_FETCH("kern.ipc.nmbufs", &nmbufs);
        if (nmbufs < nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16)
                nmbufs = lmax(maxmbufmem / MSIZE / 5,
                    nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16);
 
        /*
         * Unmapped mbufs can only safely be used on platforms with a direct
         * map.
         */
        if (PMAP_HAS_DMAP) {
                extpg = 1;
                TUNABLE_INT_FETCH("kern.ipc.mb_use_ext_pgs", &extpg);
                mb_use_ext_pgs = extpg != 0;
        }
}
SYSINIT(tunable_mbinit, SI_SUB_KMEM, SI_ORDER_MIDDLE, tunable_mbinit, NULL);
 
static int
sysctl_nmbclusters(SYSCTL_HANDLER_ARGS)
{
        int error, newnmbclusters;
 
        newnmbclusters = nmbclusters;
        error = sysctl_handle_int(oidp, &newnmbclusters, 0, req);
        if (error == 0 && req->newptr && newnmbclusters != nmbclusters) {
                if (newnmbclusters > nmbclusters &&
                    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
                        nmbclusters = newnmbclusters;
                        nmbclusters = uma_zone_set_max(zone_clust, nmbclusters);
                        EVENTHANDLER_INVOKE(nmbclusters_change);
                } else
                        error = EINVAL;
        }
        return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbclusters,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, &nmbclusters, 0,
    sysctl_nmbclusters, "IU",
    "Maximum number of mbuf clusters allowed");
 
static int
sysctl_nmbjumbop(SYSCTL_HANDLER_ARGS)
{
        int error, newnmbjumbop;
 
        newnmbjumbop = nmbjumbop;
        error = sysctl_handle_int(oidp, &newnmbjumbop, 0, req);
        if (error == 0 && req->newptr && newnmbjumbop != nmbjumbop) {
                if (newnmbjumbop > nmbjumbop &&
                    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
                        nmbjumbop = newnmbjumbop;
                        nmbjumbop = uma_zone_set_max(zone_jumbop, nmbjumbop);
                } else
                        error = EINVAL;
        }
        return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbjumbop,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, &nmbjumbop, 0,
    sysctl_nmbjumbop, "IU",
    "Maximum number of mbuf page size jumbo clusters allowed");
 
static int
sysctl_nmbjumbo9(SYSCTL_HANDLER_ARGS)
{
        int error, newnmbjumbo9;
 
        newnmbjumbo9 = nmbjumbo9;
        error = sysctl_handle_int(oidp, &newnmbjumbo9, 0, req);
        if (error == 0 && req->newptr && newnmbjumbo9 != nmbjumbo9) {
                if (newnmbjumbo9 > nmbjumbo9 &&
                    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
                        nmbjumbo9 = newnmbjumbo9;
                        nmbjumbo9 = uma_zone_set_max(zone_jumbo9, nmbjumbo9);
                } else
                        error = EINVAL;
        }
        return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbjumbo9,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, &nmbjumbo9, 0,
    sysctl_nmbjumbo9, "IU",
    "Maximum number of mbuf 9k jumbo clusters allowed");
 
static int
sysctl_nmbjumbo16(SYSCTL_HANDLER_ARGS)
{
        int error, newnmbjumbo16;
 
        newnmbjumbo16 = nmbjumbo16;
        error = sysctl_handle_int(oidp, &newnmbjumbo16, 0, req);
        if (error == 0 && req->newptr && newnmbjumbo16 != nmbjumbo16) {
                if (newnmbjumbo16 > nmbjumbo16 &&
                    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
                        nmbjumbo16 = newnmbjumbo16;
                        nmbjumbo16 = uma_zone_set_max(zone_jumbo16, nmbjumbo16);
                } else
                        error = EINVAL;
        }
        return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbjumbo16,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, &nmbjumbo16, 0,
    sysctl_nmbjumbo16, "IU",
    "Maximum number of mbuf 16k jumbo clusters allowed");
 
static int
sysctl_nmbufs(SYSCTL_HANDLER_ARGS)
{
        int error, newnmbufs;
 
        newnmbufs = nmbufs;
        error = sysctl_handle_int(oidp, &newnmbufs, 0, req);
        if (error == 0 && req->newptr && newnmbufs != nmbufs) {
                if (newnmbufs > nmbufs) {
                        nmbufs = newnmbufs;
                        nmbufs = uma_zone_set_max(zone_mbuf, nmbufs);
                        EVENTHANDLER_INVOKE(nmbufs_change);
                } else
                        error = EINVAL;
        }
        return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbufs,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
    &nmbufs, 0, sysctl_nmbufs, "IU",
    "Maximum number of mbufs allowed");
 
/*
 * Zones from which we allocate.
 */
uma_zone_t      zone_mbuf;
uma_zone_t      zone_clust;
uma_zone_t      zone_pack;
uma_zone_t      zone_jumbop;
uma_zone_t      zone_jumbo9;
uma_zone_t      zone_jumbo16;
 
/*
 * Local prototypes.
 */
static int      mb_ctor_mbuf(void *, int, void *, int);
static int      mb_ctor_clust(void *, int, void *, int);
static int      mb_ctor_pack(void *, int, void *, int);
static void     mb_dtor_mbuf(void *, int, void *);
static void     mb_dtor_pack(void *, int, void *);
static int      mb_zinit_pack(void *, int, int);
static void     mb_zfini_pack(void *, int);
static void     mb_reclaim(uma_zone_t, int);
 
/* Ensure that MSIZE is a power of 2. */
CTASSERT((((MSIZE - 1) ^ MSIZE) + 1) >> 1 == MSIZE);
 
_Static_assert(sizeof(struct mbuf) <= MSIZE,
    "size of mbuf exceeds MSIZE");
/*
 * Initialize FreeBSD Network buffer allocation.
 */
static void
mbuf_init(void *dummy)
{
 
        /*
         * Configure UMA zones for Mbufs, Clusters, and Packets.
         */
        zone_mbuf = uma_zcreate(MBUF_MEM_NAME, MSIZE,
            mb_ctor_mbuf, mb_dtor_mbuf, NULL, NULL,
            MSIZE - 1, UMA_ZONE_CONTIG | UMA_ZONE_MAXBUCKET);
        if (nmbufs > 0)
                nmbufs = uma_zone_set_max(zone_mbuf, nmbufs);
        uma_zone_set_warning(zone_mbuf, "kern.ipc.nmbufs limit reached");
        uma_zone_set_maxaction(zone_mbuf, mb_reclaim);
 
        zone_clust = uma_zcreate(MBUF_CLUSTER_MEM_NAME, MCLBYTES,
            mb_ctor_clust, NULL, NULL, NULL,
            UMA_ALIGN_PTR, UMA_ZONE_CONTIG);
        if (nmbclusters > 0)
                nmbclusters = uma_zone_set_max(zone_clust, nmbclusters);
        uma_zone_set_warning(zone_clust, "kern.ipc.nmbclusters limit reached");
        uma_zone_set_maxaction(zone_clust, mb_reclaim);
 
        zone_pack = uma_zsecond_create(MBUF_PACKET_MEM_NAME, mb_ctor_pack,
            mb_dtor_pack, mb_zinit_pack, mb_zfini_pack, zone_mbuf);
 
        /* Make jumbo frame zone too. Page size, 9k and 16k. */
        zone_jumbop = uma_zcreate(MBUF_JUMBOP_MEM_NAME, MJUMPAGESIZE,
            mb_ctor_clust, NULL, NULL, NULL,
            UMA_ALIGN_PTR, UMA_ZONE_CONTIG);
        if (nmbjumbop > 0)
                nmbjumbop = uma_zone_set_max(zone_jumbop, nmbjumbop);
        uma_zone_set_warning(zone_jumbop, "kern.ipc.nmbjumbop limit reached");
        uma_zone_set_maxaction(zone_jumbop, mb_reclaim);
 
        zone_jumbo9 = uma_zcreate(MBUF_JUMBO9_MEM_NAME, MJUM9BYTES,
            mb_ctor_clust, NULL, NULL, NULL,
            UMA_ALIGN_PTR, UMA_ZONE_CONTIG);
        if (nmbjumbo9 > 0)
                nmbjumbo9 = uma_zone_set_max(zone_jumbo9, nmbjumbo9);
        uma_zone_set_warning(zone_jumbo9, "kern.ipc.nmbjumbo9 limit reached");
        uma_zone_set_maxaction(zone_jumbo9, mb_reclaim);
 
        zone_jumbo16 = uma_zcreate(MBUF_JUMBO16_MEM_NAME, MJUM16BYTES,
            mb_ctor_clust, NULL, NULL, NULL,
            UMA_ALIGN_PTR, UMA_ZONE_CONTIG);
        if (nmbjumbo16 > 0)
                nmbjumbo16 = uma_zone_set_max(zone_jumbo16, nmbjumbo16);
        uma_zone_set_warning(zone_jumbo16, "kern.ipc.nmbjumbo16 limit reached");
        uma_zone_set_maxaction(zone_jumbo16, mb_reclaim);
 
        /*
         * Hook event handler for low-memory situation, used to
         * drain protocols and push data back to the caches (UMA
         * later pushes it back to VM).
         */
        EVENTHANDLER_REGISTER(vm_lowmem, mb_reclaim, NULL,
            EVENTHANDLER_PRI_FIRST);
 
        snd_tag_count = counter_u64_alloc(M_WAITOK);
}
SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbuf_init, NULL);
 
#ifdef DEBUGNET
/*
 * debugnet makes use of a pre-allocated pool of mbufs and clusters.  When
 * debugnet is configured, we initialize a set of UMA cache zones which return
 * items from this pool.  At panic-time, the regular UMA zone pointers are
 * overwritten with those of the cache zones so that drivers may allocate and
 * free mbufs and clusters without attempting to allocate physical memory.
 *
 * We keep mbufs and clusters in a pair of mbuf queues.  In particular, for
 * the purpose of caching clusters, we treat them as mbufs.
 */
static struct mbufq dn_mbufq =
    { STAILQ_HEAD_INITIALIZER(dn_mbufq.mq_head), 0, INT_MAX };
static struct mbufq dn_clustq =
    { STAILQ_HEAD_INITIALIZER(dn_clustq.mq_head), 0, INT_MAX };
 
static int dn_clsize;
static uma_zone_t dn_zone_mbuf;
static uma_zone_t dn_zone_clust;
static uma_zone_t dn_zone_pack;
 
static struct debugnet_saved_zones {
        uma_zone_t dsz_mbuf;
        uma_zone_t dsz_clust;
        uma_zone_t dsz_pack;
        uma_zone_t dsz_jumbop;
        uma_zone_t dsz_jumbo9;
        uma_zone_t dsz_jumbo16;
        bool dsz_debugnet_zones_enabled;
} dn_saved_zones;
 
static int
dn_buf_import(void *arg, void **store, int count, int domain __unused,
    int flags)
{
        struct mbufq *q;
        struct mbuf *m;
        int i;
 
        q = arg;
 
        for (i = 0; i < count; i++) {
                m = mbufq_dequeue(q);
                if (m == NULL)
                        break;
                trash_init(m, q == &dn_mbufq ? MSIZE : dn_clsize, flags);
                store[i] = m;
        }
        KASSERT((flags & M_WAITOK) == 0 || i == count,
            ("%s: ran out of pre-allocated mbufs", __func__));
        return (i);
}
 
static void
dn_buf_release(void *arg, void **store, int count)
{
        struct mbufq *q;
        struct mbuf *m;
        int i;
 
        q = arg;
 
        for (i = 0; i < count; i++) {
                m = store[i];
                (void)mbufq_enqueue(q, m);
        }
}
 
static int
dn_pack_import(void *arg __unused, void **store, int count, int domain __unused,
    int flags __unused)
{
        struct mbuf *m;
        void *clust;
        int i;
 
        for (i = 0; i < count; i++) {
                m = m_get(MT_DATA, M_NOWAIT);
                if (m == NULL)
                        break;
                clust = uma_zalloc(dn_zone_clust, M_NOWAIT);
                if (clust == NULL) {
                        m_free(m);
                        break;
                }
                mb_ctor_clust(clust, dn_clsize, m, 0);
                store[i] = m;
        }
        KASSERT((flags & M_WAITOK) == 0 || i == count,
            ("%s: ran out of pre-allocated mbufs", __func__));
        return (i);
}
 
static void
dn_pack_release(void *arg __unused, void **store, int count)
{
        struct mbuf *m;
        void *clust;
        int i;
 
        for (i = 0; i < count; i++) {
                m = store[i];
                clust = m->m_ext.ext_buf;
                uma_zfree(dn_zone_clust, clust);
                uma_zfree(dn_zone_mbuf, m);
        }
}
 
/*
 * Free the pre-allocated mbufs and clusters reserved for debugnet, and destroy
 * the corresponding UMA cache zones.
 */
void
debugnet_mbuf_drain(void)
{
        struct mbuf *m;
        void *item;
 
        if (dn_zone_mbuf != NULL) {
                uma_zdestroy(dn_zone_mbuf);
                dn_zone_mbuf = NULL;
        }
        if (dn_zone_clust != NULL) {
                uma_zdestroy(dn_zone_clust);
                dn_zone_clust = NULL;
        }
        if (dn_zone_pack != NULL) {
                uma_zdestroy(dn_zone_pack);
                dn_zone_pack = NULL;
        }
 
        while ((m = mbufq_dequeue(&dn_mbufq)) != NULL)
                m_free(m);
        while ((item = mbufq_dequeue(&dn_clustq)) != NULL)
                uma_zfree(m_getzone(dn_clsize), item);
}
 
/*
 * Callback invoked immediately prior to starting a debugnet connection.
 */
void
debugnet_mbuf_start(void)
{
 
        MPASS(!dn_saved_zones.dsz_debugnet_zones_enabled);
 
        /* Save the old zone pointers to restore when debugnet is closed. */
        dn_saved_zones = (struct debugnet_saved_zones) {
                .dsz_debugnet_zones_enabled = true,
                .dsz_mbuf = zone_mbuf,
                .dsz_clust = zone_clust,
                .dsz_pack = zone_pack,
                .dsz_jumbop = zone_jumbop,
                .dsz_jumbo9 = zone_jumbo9,
                .dsz_jumbo16 = zone_jumbo16,
        };
 
        /*
         * All cluster zones return buffers of the size requested by the
         * drivers.  It's up to the driver to reinitialize the zones if the
         * MTU of a debugnet-enabled interface changes.
         */
        printf("debugnet: overwriting mbuf zone pointers\n");
        zone_mbuf = dn_zone_mbuf;
        zone_clust = dn_zone_clust;
        zone_pack = dn_zone_pack;
        zone_jumbop = dn_zone_clust;
        zone_jumbo9 = dn_zone_clust;
        zone_jumbo16 = dn_zone_clust;
}
 
/*
 * Callback invoked when a debugnet connection is closed/finished.
 */
void
debugnet_mbuf_finish(void)
{
 
        MPASS(dn_saved_zones.dsz_debugnet_zones_enabled);
 
        printf("debugnet: restoring mbuf zone pointers\n");
        zone_mbuf = dn_saved_zones.dsz_mbuf;
        zone_clust = dn_saved_zones.dsz_clust;
        zone_pack = dn_saved_zones.dsz_pack;
        zone_jumbop = dn_saved_zones.dsz_jumbop;
        zone_jumbo9 = dn_saved_zones.dsz_jumbo9;
        zone_jumbo16 = dn_saved_zones.dsz_jumbo16;
 
        memset(&dn_saved_zones, 0, sizeof(dn_saved_zones));
}
 
/*
 * Reinitialize the debugnet mbuf+cluster pool and cache zones.
 */
void
debugnet_mbuf_reinit(int nmbuf, int nclust, int clsize)
{
        struct mbuf *m;
        void *item;
 
        debugnet_mbuf_drain();
 
        dn_clsize = clsize;
 
        dn_zone_mbuf = uma_zcache_create("debugnet_" MBUF_MEM_NAME,
            MSIZE, mb_ctor_mbuf, mb_dtor_mbuf, NULL, NULL,
            dn_buf_import, dn_buf_release,
            &dn_mbufq, UMA_ZONE_NOBUCKET);
 
        dn_zone_clust = uma_zcache_create("debugnet_" MBUF_CLUSTER_MEM_NAME,
            clsize, mb_ctor_clust, NULL, NULL, NULL,
            dn_buf_import, dn_buf_release,
            &dn_clustq, UMA_ZONE_NOBUCKET);
 
        dn_zone_pack = uma_zcache_create("debugnet_" MBUF_PACKET_MEM_NAME,
            MCLBYTES, mb_ctor_pack, mb_dtor_pack, NULL, NULL,
            dn_pack_import, dn_pack_release,
            NULL, UMA_ZONE_NOBUCKET);
 
        while (nmbuf-- > 0) {
                m = m_get(MT_DATA, M_WAITOK);
                uma_zfree(dn_zone_mbuf, m);
        }
        while (nclust-- > 0) {
                item = uma_zalloc(m_getzone(dn_clsize), M_WAITOK);
                uma_zfree(dn_zone_clust, item);
        }
}
#endif /* DEBUGNET */
 
/*
 * Constructor for Mbuf primary zone.
 *
 * The 'arg' pointer points to a mb_args structure which
 * contains call-specific information required to support the
 * mbuf allocation API.  See mbuf.h.
 */
static int
mb_ctor_mbuf(void *mem, int size, void *arg, int how)
{
        struct mbuf *m;
        struct mb_args *args;
        int error;
        int flags;
        short type;
 
        args = (struct mb_args *)arg;
        type = args->type;
 
        /*
         * The mbuf is initialized later.  The caller has the
         * responsibility to set up any MAC labels too.
         */
        if (type == MT_NOINIT)
                return (0);
 
        m = (struct mbuf *)mem;
        flags = args->flags;
        MPASS((flags & M_NOFREE) == 0);
 
        error = m_init(m, how, type, flags);
 
        return (error);
}
 
/*
 * The Mbuf primary zone destructor.
 */
static void
mb_dtor_mbuf(void *mem, int size, void *arg)
{
        struct mbuf *m;
        unsigned long flags __diagused;
 
        m = (struct mbuf *)mem;
        flags = (unsigned long)arg;
 
        KASSERT((m->m_flags & M_NOFREE) == 0, ("%s: M_NOFREE set", __func__));
        KASSERT((flags & 0x1) == 0, ("%s: obsolete MB_DTOR_SKIP passed", __func__));
        if ((m->m_flags & M_PKTHDR) && !SLIST_EMPTY(&m->m_pkthdr.tags))
                m_tag_delete_chain(m, NULL);
}
 
/*
 * The Mbuf Packet zone destructor.
 */
static void
mb_dtor_pack(void *mem, int size, void *arg)
{
        struct mbuf *m;
 
        m = (struct mbuf *)mem;
        if ((m->m_flags & M_PKTHDR) != 0)
                m_tag_delete_chain(m, NULL);
 
        /* Make sure we've got a clean cluster back. */
        KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
        KASSERT(m->m_ext.ext_buf != NULL, ("%s: ext_buf == NULL", __func__));
        KASSERT(m->m_ext.ext_free == NULL, ("%s: ext_free != NULL", __func__));
        KASSERT(m->m_ext.ext_arg1 == NULL, ("%s: ext_arg1 != NULL", __func__));
        KASSERT(m->m_ext.ext_arg2 == NULL, ("%s: ext_arg2 != NULL", __func__));
        KASSERT(m->m_ext.ext_size == MCLBYTES, ("%s: ext_size != MCLBYTES", __func__));
        KASSERT(m->m_ext.ext_type == EXT_PACKET, ("%s: ext_type != EXT_PACKET", __func__));
#if defined(INVARIANTS) && !defined(KMSAN)
        trash_dtor(m->m_ext.ext_buf, MCLBYTES, arg);
#endif
        /*
         * If there are processes blocked on zone_clust, waiting for pages
         * to be freed up, cause them to be woken up by draining the
         * packet zone.  We are exposed to a race here (in the check for
         * the UMA_ZFLAG_FULL) where we might miss the flag set, but that
         * is deliberate. We don't want to acquire the zone lock for every
         * mbuf free.
         */
        if (uma_zone_exhausted(zone_clust))
                uma_zone_reclaim(zone_pack, UMA_RECLAIM_DRAIN);
}
 
/*
 * The Cluster and Jumbo[PAGESIZE|9|16] zone constructor.
 *
 * Here the 'arg' pointer points to the Mbuf which we
 * are configuring cluster storage for.  If 'arg' is
 * empty we allocate just the cluster without setting
 * the mbuf to it.  See mbuf.h.
 */
static int
mb_ctor_clust(void *mem, int size, void *arg, int how)
{
        struct mbuf *m;
 
        m = (struct mbuf *)arg;
        if (m != NULL) {
                m->m_ext.ext_buf = (char *)mem;
                m->m_data = m->m_ext.ext_buf;
                m->m_flags |= M_EXT;
                m->m_ext.ext_free = NULL;
                m->m_ext.ext_arg1 = NULL;
                m->m_ext.ext_arg2 = NULL;
                m->m_ext.ext_size = size;
                m->m_ext.ext_type = m_gettype(size);
                m->m_ext.ext_flags = EXT_FLAG_EMBREF;
                m->m_ext.ext_count = 1;
        }
 
        return (0);
}
 
/*
 * The Packet secondary zone's init routine, executed on the
 * object's transition from mbuf keg slab to zone cache.
 */
static int
mb_zinit_pack(void *mem, int size, int how)
{
        struct mbuf *m;
 
        m = (struct mbuf *)mem;         /* m is virgin. */
        if (uma_zalloc_arg(zone_clust, m, how) == NULL ||
            m->m_ext.ext_buf == NULL)
                return (ENOMEM);
        m->m_ext.ext_type = EXT_PACKET; /* Override. */
#if defined(INVARIANTS) && !defined(KMSAN)
        trash_init(m->m_ext.ext_buf, MCLBYTES, how);
#endif
        return (0);
}
 
/*
 * The Packet secondary zone's fini routine, executed on the
 * object's transition from zone cache to keg slab.
 */
static void
mb_zfini_pack(void *mem, int size)
{
        struct mbuf *m;
 
        m = (struct mbuf *)mem;
#if defined(INVARIANTS) && !defined(KMSAN)
        trash_fini(m->m_ext.ext_buf, MCLBYTES);
#endif
        uma_zfree_arg(zone_clust, m->m_ext.ext_buf, NULL);
#if defined(INVARIANTS) && !defined(KMSAN)
        trash_dtor(mem, size, NULL);
#endif
}
 
/*
 * The "packet" keg constructor.
 */
static int
mb_ctor_pack(void *mem, int size, void *arg, int how)
{
        struct mbuf *m;
        struct mb_args *args;
        int error, flags;
        short type;
 
        m = (struct mbuf *)mem;
        args = (struct mb_args *)arg;
        flags = args->flags;
        type = args->type;
        MPASS((flags & M_NOFREE) == 0);
 
#if defined(INVARIANTS) && !defined(KMSAN)
        trash_ctor(m->m_ext.ext_buf, MCLBYTES, arg, how);
#endif
 
        error = m_init(m, how, type, flags);
 
        /* m_ext is already initialized. */
        m->m_data = m->m_ext.ext_buf;
        m->m_flags = (flags | M_EXT);
 
        return (error);
}
 
/*
 * This is the protocol drain routine.  Called by UMA whenever any of the
 * mbuf zones is closed to its limit.
 *
 * No locks should be held when this is called.  The drain routines have to
 * presently acquire some locks which raises the possibility of lock order
 * reversal.
 */
static void
mb_reclaim(uma_zone_t zone __unused, int pending __unused)
{
        struct epoch_tracker et;
        struct domain *dp;
        struct protosw *pr;
 
        WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK | WARN_PANIC, NULL, __func__);
 
        NET_EPOCH_ENTER(et);
        for (dp = domains; dp != NULL; dp = dp->dom_next)
                for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
                        if (pr->pr_drain != NULL)
                                (*pr->pr_drain)();
        NET_EPOCH_EXIT(et);
}
 
/*
 * Free "count" units of I/O from an mbuf chain.  They could be held
 * in M_EXTPG or just as a normal mbuf.  This code is intended to be
 * called in an error path (I/O error, closed connection, etc).
 */
void
mb_free_notready(struct mbuf *m, int count)
{
        int i;
 
        for (i = 0; i < count && m != NULL; i++) {
                if ((m->m_flags & M_EXTPG) != 0) {
                        m->m_epg_nrdy--;
                        if (m->m_epg_nrdy != 0)
                                continue;
                }
                m = m_free(m);
        }
        KASSERT(i == count, ("Removed only %d items from %p", i, m));
}
 
/*
 * Compress an unmapped mbuf into a simple mbuf when it holds a small
 * amount of data.  This is used as a DOS defense to avoid having
 * small packets tie up wired pages, an ext_pgs structure, and an
 * mbuf.  Since this converts the existing mbuf in place, it can only
 * be used if there are no other references to 'm'.
 */
int
mb_unmapped_compress(struct mbuf *m)
{
        volatile u_int *refcnt;
        char buf[MLEN];
 
        /*
         * Assert that 'm' does not have a packet header.  If 'm' had
         * a packet header, it would only be able to hold MHLEN bytes
         * and m_data would have to be initialized differently.
         */
        KASSERT((m->m_flags & M_PKTHDR) == 0 && (m->m_flags & M_EXTPG),
            ("%s: m %p !M_EXTPG or M_PKTHDR", __func__, m));
        KASSERT(m->m_len <= MLEN, ("m_len too large %p", m));
 
        if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) {
                refcnt = &m->m_ext.ext_count;
        } else {
                KASSERT(m->m_ext.ext_cnt != NULL,
                    ("%s: no refcounting pointer on %p", __func__, m));
                refcnt = m->m_ext.ext_cnt;
        }
 
        if (*refcnt != 1)
                return (EBUSY);
 
        m_copydata(m, 0, m->m_len, buf);
 
        /* Free the backing pages. */
        m->m_ext.ext_free(m);
 
        /* Turn 'm' into a "normal" mbuf. */
        m->m_flags &= ~(M_EXT | M_RDONLY | M_EXTPG);
        m->m_data = m->m_dat;
 
        /* Copy data back into m. */
        bcopy(buf, mtod(m, char *), m->m_len);
 
        return (0);
}
 
/*
 * These next few routines are used to permit downgrading an unmapped
 * mbuf to a chain of mapped mbufs.  This is used when an interface
 * doesn't supported unmapped mbufs or if checksums need to be
 * computed in software.
 *
 * Each unmapped mbuf is converted to a chain of mbufs.  First, any
 * TLS header data is stored in a regular mbuf.  Second, each page of
 * unmapped data is stored in an mbuf with an EXT_SFBUF external
 * cluster.  These mbufs use an sf_buf to provide a valid KVA for the
 * associated physical page.  They also hold a reference on the
 * original M_EXTPG mbuf to ensure the physical page doesn't go away.
 * Finally, any TLS trailer data is stored in a regular mbuf.
 *
 * mb_unmapped_free_mext() is the ext_free handler for the EXT_SFBUF
 * mbufs.  It frees the associated sf_buf and releases its reference
 * on the original M_EXTPG mbuf.
 *
 * _mb_unmapped_to_ext() is a helper function that converts a single
 * unmapped mbuf into a chain of mbufs.
 *
 * mb_unmapped_to_ext() is the public function that walks an mbuf
 * chain converting any unmapped mbufs to mapped mbufs.  It returns
 * the new chain of unmapped mbufs on success.  On failure it frees
 * the original mbuf chain and returns NULL.
 */
static void
mb_unmapped_free_mext(struct mbuf *m)
{
        struct sf_buf *sf;
        struct mbuf *old_m;
 
        sf = m->m_ext.ext_arg1;
        sf_buf_free(sf);
 
        /* Drop the reference on the backing M_EXTPG mbuf. */
        old_m = m->m_ext.ext_arg2;
        mb_free_extpg(old_m);
}
 
static struct mbuf *
_mb_unmapped_to_ext(struct mbuf *m)
{
        struct mbuf *m_new, *top, *prev, *mref;
        struct sf_buf *sf;
        vm_page_t pg;
        int i, len, off, pglen, pgoff, seglen, segoff;
        volatile u_int *refcnt;
        u_int ref_inc = 0;
 
        M_ASSERTEXTPG(m);
        len = m->m_len;
        KASSERT(m->m_epg_tls == NULL, ("%s: can't convert TLS mbuf %p",
            __func__, m));
 
        /* See if this is the mbuf that holds the embedded refcount. */
        if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) {
                refcnt = &m->m_ext.ext_count;
                mref = m;
        } else {
                KASSERT(m->m_ext.ext_cnt != NULL,
                    ("%s: no refcounting pointer on %p", __func__, m));
                refcnt = m->m_ext.ext_cnt;
                mref = __containerof(refcnt, struct mbuf, m_ext.ext_count);
        }
 
        /* Skip over any data removed from the front. */
        off = mtod(m, vm_offset_t);
 
        top = NULL;
        if (m->m_epg_hdrlen != 0) {
                if (off >= m->m_epg_hdrlen) {
                        off -= m->m_epg_hdrlen;
                } else {
                        seglen = m->m_epg_hdrlen - off;
                        segoff = off;
                        seglen = min(seglen, len);
                        off = 0;
                        len -= seglen;
                        m_new = m_get(M_NOWAIT, MT_DATA);
                        if (m_new == NULL)
                                goto fail;
                        m_new->m_len = seglen;
                        prev = top = m_new;
                        memcpy(mtod(m_new, void *), &m->m_epg_hdr[segoff],
                            seglen);
                }
        }
        pgoff = m->m_epg_1st_off;
        for (i = 0; i < m->m_epg_npgs && len > 0; i++) {
                pglen = m_epg_pagelen(m, i, pgoff);
                if (off >= pglen) {
                        off -= pglen;
                        pgoff = 0;
                        continue;
                }
                seglen = pglen - off;
                segoff = pgoff + off;
                off = 0;
                seglen = min(seglen, len);
                len -= seglen;
 
                pg = PHYS_TO_VM_PAGE(m->m_epg_pa[i]);
                m_new = m_get(M_NOWAIT, MT_DATA);
                if (m_new == NULL)
                        goto fail;
                if (top == NULL) {
                        top = prev = m_new;
                } else {
                        prev->m_next = m_new;
                        prev = m_new;
                }
                sf = sf_buf_alloc(pg, SFB_NOWAIT);
                if (sf == NULL)
                        goto fail;
 
                ref_inc++;
                m_extadd(m_new, (char *)sf_buf_kva(sf), PAGE_SIZE,
                    mb_unmapped_free_mext, sf, mref, M_RDONLY, EXT_SFBUF);
                m_new->m_data += segoff;
                m_new->m_len = seglen;
 
                pgoff = 0;
        };
        if (len != 0) {
                KASSERT((off + len) <= m->m_epg_trllen,
                    ("off + len > trail (%d + %d > %d)", off, len,
                    m->m_epg_trllen));
                m_new = m_get(M_NOWAIT, MT_DATA);
                if (m_new == NULL)
                        goto fail;
                if (top == NULL)
                        top = m_new;
                else
                        prev->m_next = m_new;
                m_new->m_len = len;
                memcpy(mtod(m_new, void *), &m->m_epg_trail[off], len);
        }
 
        if (ref_inc != 0) {
                /*
                 * Obtain an additional reference on the old mbuf for
                 * each created EXT_SFBUF mbuf.  They will be dropped
                 * in mb_unmapped_free_mext().
                 */
                if (*refcnt == 1)
                        *refcnt += ref_inc;
                else
                        atomic_add_int(refcnt, ref_inc);
        }
        m_free(m);
        return (top);
 
fail:
        if (ref_inc != 0) {
                /*
                 * Obtain an additional reference on the old mbuf for
                 * each created EXT_SFBUF mbuf.  They will be
                 * immediately dropped when these mbufs are freed
                 * below.
                 */
                if (*refcnt == 1)
                        *refcnt += ref_inc;
                else
                        atomic_add_int(refcnt, ref_inc);
        }
        m_free(m);
        m_freem(top);
        return (NULL);
}
 
struct mbuf *
mb_unmapped_to_ext(struct mbuf *top)
{
        struct mbuf *m, *next, *prev = NULL;
 
        prev = NULL;
        for (m = top; m != NULL; m = next) {
                /* m might be freed, so cache the next pointer. */
                next = m->m_next;
                if (m->m_flags & M_EXTPG) {
                        if (prev != NULL) {
                                /*
                                 * Remove 'm' from the new chain so
                                 * that the 'top' chain terminates
                                 * before 'm' in case 'top' is freed
                                 * due to an error.
                                 */
                                prev->m_next = NULL;
                        }
                        m = _mb_unmapped_to_ext(m);
                        if (m == NULL) {
                                m_freem(top);
                                m_freem(next);
                                return (NULL);
                        }
                        if (prev == NULL) {
                                top = m;
                        } else {
                                prev->m_next = m;
                        }
 
                        /*
                         * Replaced one mbuf with a chain, so we must
                         * find the end of chain.
                         */
                        prev = m_last(m);
                } else {
                        if (prev != NULL) {
                                prev->m_next = m;
                        }
                        prev = m;
                }
        }
        return (top);
}
 
/*
 * Allocate an empty M_EXTPG mbuf.  The ext_free routine is
 * responsible for freeing any pages backing this mbuf when it is
 * freed.
 */
struct mbuf *
mb_alloc_ext_pgs(int how, m_ext_free_t ext_free)
{
        struct mbuf *m;
 
        m = m_get(how, MT_DATA);
        if (m == NULL)
                return (NULL);
 
        m->m_epg_npgs = 0;
        m->m_epg_nrdy = 0;
        m->m_epg_1st_off = 0;
        m->m_epg_last_len = 0;
        m->m_epg_flags = 0;
        m->m_epg_hdrlen = 0;
        m->m_epg_trllen = 0;
        m->m_epg_tls = NULL;
        m->m_epg_so = NULL;
        m->m_data = NULL;
        m->m_flags |= (M_EXT | M_RDONLY | M_EXTPG);
        m->m_ext.ext_flags = EXT_FLAG_EMBREF;
        m->m_ext.ext_count = 1;
        m->m_ext.ext_size = 0;
        m->m_ext.ext_free = ext_free;
        return (m);
}
 
/*
 * Clean up after mbufs with M_EXT storage attached to them if the
 * reference count hits 1.
 */
void
mb_free_ext(struct mbuf *m)
{
        volatile u_int *refcnt;
        struct mbuf *mref;
        int freembuf;
 
        KASSERT(m->m_flags & M_EXT, ("%s: M_EXT not set on %p", __func__, m));
 
        /* See if this is the mbuf that holds the embedded refcount. */
        if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) {
                refcnt = &m->m_ext.ext_count;
                mref = m;
        } else {
                KASSERT(m->m_ext.ext_cnt != NULL,
                    ("%s: no refcounting pointer on %p", __func__, m));
                refcnt = m->m_ext.ext_cnt;
                mref = __containerof(refcnt, struct mbuf, m_ext.ext_count);
        }
 
        /*
         * Check if the header is embedded in the cluster.  It is
         * important that we can't touch any of the mbuf fields
         * after we have freed the external storage, since mbuf
         * could have been embedded in it.  For now, the mbufs
         * embedded into the cluster are always of type EXT_EXTREF,
         * and for this type we won't free the mref.
         */
        if (m->m_flags & M_NOFREE) {
                freembuf = 0;
                KASSERT(m->m_ext.ext_type == EXT_EXTREF ||
                    m->m_ext.ext_type == EXT_RXRING,
                    ("%s: no-free mbuf %p has wrong type", __func__, m));
        } else
                freembuf = 1;
 
        /* Free attached storage if this mbuf is the only reference to it. */
        if (*refcnt == 1 || atomic_fetchadd_int(refcnt, -1) == 1) {
                switch (m->m_ext.ext_type) {
                case EXT_PACKET:
                        /* The packet zone is special. */
                        if (*refcnt == 0)
                                *refcnt = 1;
                        uma_zfree(zone_pack, mref);
                        break;
                case EXT_CLUSTER:
                        uma_zfree(zone_clust, m->m_ext.ext_buf);
                        m_free_raw(mref);
                        break;
                case EXT_JUMBOP:
                        uma_zfree(zone_jumbop, m->m_ext.ext_buf);
                        m_free_raw(mref);
                        break;
                case EXT_JUMBO9:
                        uma_zfree(zone_jumbo9, m->m_ext.ext_buf);
                        m_free_raw(mref);
                        break;
                case EXT_JUMBO16:
                        uma_zfree(zone_jumbo16, m->m_ext.ext_buf);
                        m_free_raw(mref);
                        break;
                case EXT_SFBUF:
                case EXT_NET_DRV:
                case EXT_MOD_TYPE:
                case EXT_DISPOSABLE:
                        KASSERT(mref->m_ext.ext_free != NULL,
                            ("%s: ext_free not set", __func__));
                        mref->m_ext.ext_free(mref);
                        m_free_raw(mref);
                        break;
                case EXT_EXTREF:
                        KASSERT(m->m_ext.ext_free != NULL,
                            ("%s: ext_free not set", __func__));
                        m->m_ext.ext_free(m);
                        break;
                case EXT_RXRING:
                        KASSERT(m->m_ext.ext_free == NULL,
                            ("%s: ext_free is set", __func__));
                        break;
                default:
                        KASSERT(m->m_ext.ext_type == 0,
                            ("%s: unknown ext_type", __func__));
                }
        }
 
        if (freembuf && m != mref)
                m_free_raw(m);
}
 
/*
 * Clean up after mbufs with M_EXTPG storage attached to them if the
 * reference count hits 1.
 */
void
mb_free_extpg(struct mbuf *m)
{
        volatile u_int *refcnt;
        struct mbuf *mref;
 
        M_ASSERTEXTPG(m);
 
        /* See if this is the mbuf that holds the embedded refcount. */
        if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) {
                refcnt = &m->m_ext.ext_count;
                mref = m;
        } else {
                KASSERT(m->m_ext.ext_cnt != NULL,
                    ("%s: no refcounting pointer on %p", __func__, m));
                refcnt = m->m_ext.ext_cnt;
                mref = __containerof(refcnt, struct mbuf, m_ext.ext_count);
        }
 
        /* Free attached storage if this mbuf is the only reference to it. */
        if (*refcnt == 1 || atomic_fetchadd_int(refcnt, -1) == 1) {
                KASSERT(mref->m_ext.ext_free != NULL,
                    ("%s: ext_free not set", __func__));
 
                mref->m_ext.ext_free(mref);
#ifdef KERN_TLS
                if (mref->m_epg_tls != NULL &&
                    !refcount_release_if_not_last(&mref->m_epg_tls->refcount))
                        ktls_enqueue_to_free(mref);
                else
#endif
                        m_free_raw(mref);
        }
 
        if (m != mref)
                m_free_raw(m);
}
 
/*
 * Official mbuf(9) allocation KPI for stack and drivers:
 *
 * m_get()      - a single mbuf without any attachments, sys/mbuf.h.
 * m_gethdr()   - a single mbuf initialized as M_PKTHDR, sys/mbuf.h.
 * m_getcl()    - an mbuf + 2k cluster, sys/mbuf.h.
 * m_clget()    - attach cluster to already allocated mbuf.
 * m_cljget()   - attach jumbo cluster to already allocated mbuf.
 * m_get2()     - allocate minimum mbuf that would fit size argument.
 * m_getm2()    - allocate a chain of mbufs/clusters.
 * m_extadd()   - attach external cluster to mbuf.
 *
 * m_free()     - free single mbuf with its tags and ext, sys/mbuf.h.
 * m_freem()    - free chain of mbufs.
 */
 
int
m_clget(struct mbuf *m, int how)
{
 
        KASSERT((m->m_flags & M_EXT) == 0, ("%s: mbuf %p has M_EXT",
            __func__, m));
        m->m_ext.ext_buf = (char *)NULL;
        uma_zalloc_arg(zone_clust, m, how);
        /*
         * On a cluster allocation failure, drain the packet zone and retry,
         * we might be able to loosen a few clusters up on the drain.
         */
        if ((how & M_NOWAIT) && (m->m_ext.ext_buf == NULL)) {
                uma_zone_reclaim(zone_pack, UMA_RECLAIM_DRAIN);
                uma_zalloc_arg(zone_clust, m, how);
        }
        MBUF_PROBE2(m__clget, m, how);
        return (m->m_flags & M_EXT);
}
 
/*
 * m_cljget() is different from m_clget() as it can allocate clusters without
 * attaching them to an mbuf.  In that case the return value is the pointer
 * to the cluster of the requested size.  If an mbuf was specified, it gets
 * the cluster attached to it and the return value can be safely ignored.
 * For size it takes MCLBYTES, MJUMPAGESIZE, MJUM9BYTES, MJUM16BYTES.
 */
void *
m_cljget(struct mbuf *m, int how, int size)
{
        uma_zone_t zone;
        void *retval;
 
        if (m != NULL) {
                KASSERT((m->m_flags & M_EXT) == 0, ("%s: mbuf %p has M_EXT",
                    __func__, m));
                m->m_ext.ext_buf = NULL;
        }
 
        zone = m_getzone(size);
        retval = uma_zalloc_arg(zone, m, how);
 
        MBUF_PROBE4(m__cljget, m, how, size, retval);
 
        return (retval);
}
 
/*
 * 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) {
                m_free_raw(m);
                return (NULL);
        }
 
        return (m);
}
 
/*
 * m_get3() allocates minimum mbuf that would fit "size" argument.
 * Unlike m_get2() it can allocate clusters up to MJUM16BYTES.
 */
struct mbuf *
m_get3(int size, int how, short type, int flags)
{
        struct mb_args args;
        struct mbuf *m, *n;
        uma_zone_t zone;
 
        if (size <= MJUMPAGESIZE)
                return (m_get2(size, how, type, flags));
 
        if (size > MJUM16BYTES)
                return (NULL);
 
        args.flags = flags;
        args.type = type;
 
        m = uma_zalloc_arg(zone_mbuf, &args, how);
        if (m == NULL)
                return (NULL);
 
        if (size <= MJUM9BYTES)
                zone = zone_jumbo9;
        else
                zone = zone_jumbo16;
 
        n = uma_zalloc_arg(zone, m, how);
        if (n == NULL) {
                m_free_raw(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) {
                m_free_raw(m);
                return (NULL);
        }
        MBUF_PROBE5(m__getjcl, how, type, flags, size, m);
        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 and return a pointer to the provided mbuf.
 */
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) {
                mb = NULL;
                if (len > MCLBYTES) {
                        mb = m_getjcl(M_NOWAIT, type, (flags & M_PKTHDR),
                            MJUMPAGESIZE);
                }
                if (mb == NULL) {
                        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) {
                                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);
}
 
/*-
 * Configure a provided mbuf to refer to the provided external storage
 * buffer and setup a reference count for said buffer.
 *
 * Arguments:
 *    mb     The existing mbuf to which to attach the provided buffer.
 *    buf    The address of the provided external storage buffer.
 *    size   The size of the provided buffer.
 *    freef  A pointer to a routine that is responsible for freeing the
 *           provided external storage buffer.
 *    args   A pointer to an argument structure (of any type) to be passed
 *           to the provided freef routine (may be NULL).
 *    flags  Any other flags to be passed to the provided mbuf.
 *    type   The type that the external storage buffer should be
 *           labeled with.
 *
 * Returns:
 *    Nothing.
 */
void
m_extadd(struct mbuf *mb, char *buf, u_int size, m_ext_free_t freef,
    void *arg1, void *arg2, int flags, int type)
{
 
        KASSERT(type != EXT_CLUSTER, ("%s: EXT_CLUSTER not allowed", __func__));
 
        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;
 
        if (type != EXT_EXTREF) {
                mb->m_ext.ext_count = 1;
                mb->m_ext.ext_flags = EXT_FLAG_EMBREF;
        } else
                mb->m_ext.ext_flags = 0;
}
 
/*
 * Free an entire chain of mbufs and associated external buffers, if
 * applicable.
 */
void
m_freem(struct mbuf *mb)
{
 
        MBUF_PROBE1(m__freem, mb);
        while (mb != NULL)
                mb = m_free(mb);
}
 
/*
 * Temporary primitive to allow freeing without going through m_free.
 */
void
m_free_raw(struct mbuf *mb)
{
 
        uma_zfree(zone_mbuf, mb);
}
 
int
m_snd_tag_alloc(struct ifnet *ifp, union if_snd_tag_alloc_params *params,
    struct m_snd_tag **mstp)
{
 
        if (ifp->if_snd_tag_alloc == NULL)
                return (EOPNOTSUPP);
        return (ifp->if_snd_tag_alloc(ifp, params, mstp));
}
 
void
m_snd_tag_init(struct m_snd_tag *mst, struct ifnet *ifp,
    const struct if_snd_tag_sw *sw)
{
 
        if_ref(ifp);
        mst->ifp = ifp;
        refcount_init(&mst->refcount, 1);
        mst->sw = sw;
        counter_u64_add(snd_tag_count, 1);
}
 
void
m_snd_tag_destroy(struct m_snd_tag *mst)
{
        struct ifnet *ifp;
 
        ifp = mst->ifp;
        mst->sw->snd_tag_free(mst);
        if_rele(ifp);
        counter_u64_add(snd_tag_count, -1);
}
 
void
m_rcvif_serialize(struct mbuf *m)
{
        u_short idx, gen;
 
        M_ASSERTPKTHDR(m);
        idx = m->m_pkthdr.rcvif->if_index;
        gen = m->m_pkthdr.rcvif->if_idxgen;
        m->m_pkthdr.rcvidx = idx;
        m->m_pkthdr.rcvgen = gen;
}
 
struct ifnet *
m_rcvif_restore(struct mbuf *m)
{
        struct ifnet *ifp;
 
        M_ASSERTPKTHDR(m);
        NET_EPOCH_ASSERT();
 
        ifp = ifnet_byindexgen(m->m_pkthdr.rcvidx, m->m_pkthdr.rcvgen);
        if (ifp == NULL || (ifp->if_flags & IFF_DYING))
                return (NULL);
 
        return (m->m_pkthdr.rcvif = ifp);
}
 
/*
 * Allocate an mbuf with anonymous external pages.
 */
struct mbuf *
mb_alloc_ext_plus_pages(int len, int how)
{
        struct mbuf *m;
        vm_page_t pg;
        int i, npgs;
 
        m = mb_alloc_ext_pgs(how, mb_free_mext_pgs);
        if (m == NULL)
                return (NULL);
        m->m_epg_flags |= EPG_FLAG_ANON;
        npgs = howmany(len, PAGE_SIZE);
        for (i = 0; i < npgs; i++) {
                do {
                        pg = vm_page_alloc_noobj(VM_ALLOC_NODUMP |
                            VM_ALLOC_WIRED);
                        if (pg == NULL) {
                                if (how == M_NOWAIT) {
                                        m->m_epg_npgs = i;
                                        m_free(m);
                                        return (NULL);
                                }
                                vm_wait(NULL);
                        }
                } while (pg == NULL);
                m->m_epg_pa[i] = VM_PAGE_TO_PHYS(pg);
        }
        m->m_epg_npgs = npgs;
        return (m);
}
 
/*
 * Copy the data in the mbuf chain to a chain of mbufs with anonymous external
 * unmapped pages.
 * len is the length of data in the input mbuf chain.
 * mlen is the maximum number of bytes put into each ext_page mbuf.
 */
struct mbuf *
mb_mapped_to_unmapped(struct mbuf *mp, int len, int mlen, int how,
    struct mbuf **mlast)
{
        struct mbuf *m, *mout;
        char *pgpos, *mbpos;
        int i, mblen, mbufsiz, pglen, xfer;
 
        if (len == 0)
                return (NULL);
        mbufsiz = min(mlen, len);
        m = mout = mb_alloc_ext_plus_pages(mbufsiz, how);
        if (m == NULL)
                return (m);
        pgpos = (char *)(void *)PHYS_TO_DMAP(m->m_epg_pa[0]);
        pglen = PAGE_SIZE;
        mblen = 0;
        i = 0;
        do {
                if (pglen == 0) {
                        if (++i == m->m_epg_npgs) {
                                m->m_epg_last_len = PAGE_SIZE;
                                mbufsiz = min(mlen, len);
                                m->m_next = mb_alloc_ext_plus_pages(mbufsiz,
                                    how);
                                m = m->m_next;
                                if (m == NULL) {
                                        m_freem(mout);
                                        return (m);
                                }
                                i = 0;
                        }
                        pgpos = (char *)(void *)PHYS_TO_DMAP(m->m_epg_pa[i]);
                        pglen = PAGE_SIZE;
                }
                while (mblen == 0) {
                        if (mp == NULL) {
                                m_freem(mout);
                                return (NULL);
                        }
                        KASSERT((mp->m_flags & M_EXTPG) == 0,
                            ("mb_copym_ext_pgs: ext_pgs input mbuf"));
                        mbpos = mtod(mp, char *);
                        mblen = mp->m_len;
                        mp = mp->m_next;
                }
                xfer = min(mblen, pglen);
                memcpy(pgpos, mbpos, xfer);
                pgpos += xfer;
                mbpos += xfer;
                pglen -= xfer;
                mblen -= xfer;
                len -= xfer;
                m->m_len += xfer;
        } while (len > 0);
        m->m_epg_last_len = PAGE_SIZE - pglen;
        if (mlast != NULL)
                *mlast = m;
        return (mout);
}