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//==========================================================================
//
//      src/sys/kern/uipc_mbuf.c
//
//==========================================================================
//####BSDCOPYRIGHTBEGIN####
//
// -------------------------------------------
//
// Portions of this software may have been derived from OpenBSD, 
// FreeBSD or other sources, and are covered by the appropriate
// copyright disclaimers included herein.
//
// Portions created by Red Hat are
// Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
//
// -------------------------------------------
//
//####BSDCOPYRIGHTEND####
//==========================================================================
 
/*
 * Copyright (c) 1982, 1986, 1988, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94
 * $FreeBSD: src/sys/kern/uipc_mbuf.c,v 1.51.2.7 2001/07/30 23:28:00 peter Exp $
 */
 
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
 
static void mbinit __P((void *));
SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbinit, NULL)
 
struct mbuf *mbutl;
char    *mclrefcnt;
struct mbstat mbstat;
u_long  mbtypes[MT_NTYPES];
struct mbuf *mmbfree;
union mcluster *mclfree;
int     max_linkhdr;
int     max_protohdr;
int     max_hdr;
int     max_datalen;
u_int   m_mballoc_wid = 0;
u_int   m_clalloc_wid = 0;
 
int mbuf_wait = 32;  // Time in ticks to wait for mbufs to come free
 
static void     m_reclaim __P((void));
 
#ifndef NMBCLUSTERS
#define NMBCLUSTERS     (512 + maxusers * 16)
#endif
#ifndef NMBUFS
#define NMBUFS          (nmbclusters * 4)
#endif
 
 
/* "number of clusters of pages" */
#define NCL_INIT        1
 
#define NMB_INIT        16
 
/* ARGSUSED*/
static void
mbinit(dummy)
        void *dummy;
{
        int s;
 
        mmbfree = NULL; mclfree = NULL;
        mbstat.m_msize = MSIZE;
        mbstat.m_mclbytes = MCLBYTES;
        mbstat.m_minclsize = MINCLSIZE;
        mbstat.m_mlen = MLEN;
        mbstat.m_mhlen = MHLEN;
 
        s = splimp();
        if (m_mballoc(NMB_INIT, M_DONTWAIT) == 0)
                goto bad;
#if MCLBYTES <= PAGE_SIZE
        if (m_clalloc(NCL_INIT, M_DONTWAIT) == 0)
                goto bad;
#else
        /* It's OK to call contigmalloc in this context. */
        if (m_clalloc(16, M_WAIT) == 0)
                goto bad;
#endif
        splx(s);
        return;
bad:
        panic("mbinit");
}
 
/*
 * Allocate at least nmb mbufs and place on mbuf free list.
 * Must be called at splimp.
 */
/* ARGSUSED */
int
m_mballoc(nmb, how)
        register int nmb;
        int how;
{
        struct mbuf *p;
        int i;
 
        for (i = 0; i < nmb; i++) {
            p = (struct mbuf *)cyg_net_mbuf_alloc(0, 0);
            if (p != (struct mbuf *)0) {
                ((struct mbuf *)p)->m_next = mmbfree;
                mmbfree = (struct mbuf *)p;
                mbstat.m_mbufs++;
                mbtypes[MT_FREE]++;
            } else {
                // Warn - out of mbufs?
                return (0);
            }
        }
        return (1);
}
 
/*
 * Once the mb_map has been exhausted and if the call to the allocation macros
 * (or, in some cases, functions) is with M_WAIT, then it is necessary to rely
 * solely on reclaimed mbufs. Here we wait for an mbuf to be freed for a
 * designated (mbuf_wait) time.
 */
struct mbuf *
m_mballoc_wait(int caller, int type)
{
        struct mbuf *p;
        int s;
 
        s = splimp();
        m_mballoc_wid++;
        if ((tsleep(&m_mballoc_wid, PVM, "mballc", mbuf_wait)) == EWOULDBLOCK)
                m_mballoc_wid--;
        splx(s);
 
        /*
         * Now that we (think) that we've got something, we will redo an
         * MGET, but avoid getting into another instance of m_mballoc_wait()
         * XXX: We retry to fetch _even_ if the sleep timed out. This is left
         *      this way, purposely, in the [unlikely] case that an mbuf was
         *      freed but the sleep was not awakened in time.
         */
        p = NULL;
        switch (caller) {
        case MGET_C:
                MGET(p, M_DONTWAIT, type);
                break;
        case MGETHDR_C:
                MGETHDR(p, M_DONTWAIT, type);
                break;
        default:
                panic("m_mballoc_wait: invalid caller (%d)", caller);
        }
 
        s = splimp();
        if (p != NULL) {                /* We waited and got something... */
                mbstat.m_wait++;
                /* Wake up another if we have more free. */
                if (mmbfree != NULL)
                        MMBWAKEUP();
        }
        splx(s);
        return (p);
}
 
#if MCLBYTES > PAGE_SIZE
static int i_want_my_mcl;
 
static void
kproc_mclalloc(void)
{
        int status;
 
        while (1) {
                tsleep(&i_want_my_mcl, PVM, "mclalloc", 0);
 
                for (; i_want_my_mcl; i_want_my_mcl--) {
                        if (m_clalloc(1, M_WAIT) == 0)
                                printf("m_clalloc failed even in process context!\n");
                }
        }
}
 
static struct proc *mclallocproc;
static struct kproc_desc mclalloc_kp = {
        "mclalloc",
        kproc_mclalloc,
        &mclallocproc
};
SYSINIT(mclallocproc, SI_SUB_KTHREAD_UPDATE, SI_ORDER_ANY, kproc_start,
           &mclalloc_kp);
#endif
 
/*
 * Allocate some number of mbuf clusters
 * and place on cluster free list.
 * Must be called at splimp.
 */
/* ARGSUSED */
int
m_clalloc(ncl, how)
        register int ncl;
        int how;
{
        union mcluster *p;
        int i;
 
        for (i = 0; i < ncl; i++) {
            p = (union mcluster *)cyg_net_cluster_alloc();
            if (p != (union mcluster *)0) {
                ((union mcluster *)p)->mcl_next = mclfree;
                mclfree = (union mcluster *)p;
                mbstat.m_clfree++;
                mbstat.m_clusters++;
            } else {
                // Warn - no more clusters?
                return (0);
            }
        }
        return (1);
}
 
/*
 * Once the mb_map submap has been exhausted and the allocation is called with
 * M_WAIT, we rely on the mclfree union pointers. If nothing is free, we will
 * sleep for a designated amount of time (mbuf_wait) or until we're woken up
 * due to sudden mcluster availability.
 */
caddr_t
m_clalloc_wait(void)
{
        caddr_t p;
        int s;
 
        /* Sleep until something's available or until we expire. */
        m_clalloc_wid++;
        if ((tsleep(&m_clalloc_wid, PVM, "mclalc", mbuf_wait)) == EWOULDBLOCK)
                m_clalloc_wid--;
 
        /*
         * Now that we (think) that we've got something, we will redo and
         * MGET, but avoid getting into another instance of m_clalloc_wait()
         */
        p = NULL;
        MCLALLOC(p, M_DONTWAIT);
 
        s = splimp();
        if (p != NULL) {        /* We waited and got something... */
                mbstat.m_wait++;
                /* Wake up another if we have more free. */
                if (mclfree != NULL)
                        MCLWAKEUP();
        }
 
        splx(s);
        return (p);
}
 
/*
 * When MGET fails, ask protocols to free space when short of memory,
 * then re-attempt to allocate an mbuf.
 */
struct mbuf *
m_retry(i, t)
        int i, t;
{
        register struct mbuf *m;
 
        /*
         * Must only do the reclaim if not in an interrupt context.
         */
        if (i == M_WAIT) {
                m_reclaim();
        }
 
        /*
         * Both m_mballoc_wait and m_retry must be nulled because
         * when the MGET macro is run from here, we deffinately do _not_
         * want to enter an instance of m_mballoc_wait() or m_retry() (again!)
         */
#undef m_retry
#undef m_mballoc_wait
#define m_mballoc_wait(caller,type)    (struct mbuf *)0
#define m_retry(i, t)   (struct mbuf *)0
        MGET(m, i, t);
#undef m_retry
#undef m_mballoc_wait
#define m_retry cyg_m_retry
#define m_retryhdr cyg_m_retryhdr
#define m_mballoc_wait cyg_m_mballoc_wait
 
        if (m != NULL)
                mbstat.m_wait++;
        else
                mbstat.m_drops++;
 
        return (m);
}
 
/*
 * As above; retry an MGETHDR.
 */
struct mbuf *
m_retryhdr(i, t)
        int i, t;
{
        register struct mbuf *m;
 
        /*
         * Must only do the reclaim if not in an interrupt context.
         */
        if (i == M_WAIT) {
                m_reclaim();
        }
 
#undef m_retryhdr
#undef m_mballoc_wait
#define m_mballoc_wait(caller,type)    (struct mbuf *)0
#define m_retryhdr(i, t) (struct mbuf *)0
        MGETHDR(m, i, t);
#undef m_retryhdr
#undef m_mballoc_wait
#define m_retry cyg_m_retry
#define m_retryhdr cyg_m_retryhdr
#define m_mballoc_wait cyg_m_mballoc_wait
 
        if (m != NULL)
                mbstat.m_wait++;
        else
                mbstat.m_drops++;
 
        return (m);
}
 
static void
m_reclaim()
{
        register struct domain *dp;
        register struct protosw *pr;
        int s = splimp();
 
        for (dp = domains; dp; dp = dp->dom_next)
                for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
                        if (pr->pr_drain)
                                (*pr->pr_drain)();
        splx(s);
        mbstat.m_drain++;
}
 
/*
 * Space allocation routines.
 * These are also available as macros
 * for critical paths.
 */
struct mbuf *
m_get(how, type)
        int how, type;
{
        register struct mbuf *m;
 
        MGET(m, how, type);
        return (m);
}
 
struct mbuf *
m_gethdr(how, type)
        int how, type;
{
        register struct mbuf *m;
 
        MGETHDR(m, how, type);
        return (m);
}
 
struct mbuf *
m_getclr(how, type)
        int how, type;
{
        register struct mbuf *m;
 
        MGET(m, how, type);
        if (m == 0)
                return (0);
        bzero(mtod(m, caddr_t), MLEN);
        return (m);
}
 
/*
 * struct mbuf *
 * m_getm(m, len, how, type)
 *
 * This will allocate len-worth of mbufs and/or mbuf clusters (whatever fits
 * best) and return a pointer to the top of the allocated chain. If m is
 * non-null, then we assume that it is a single mbuf or an mbuf chain to
 * which we want len bytes worth of mbufs and/or clusters attached, and so
 * if we succeed in allocating it, we will just return a pointer to m.
 *
 * If we happen to fail at any point during the allocation, we will free
 * up everything we have already allocated and return NULL.
 *
 */
struct mbuf *
m_getm(struct mbuf *m, int len, int how, int type)
{
        struct mbuf *top, *tail, *mp, *mtail = NULL;
 
        MGET(mp, how, type);
        if (mp == NULL)
                return (NULL);
        else if (len > MINCLSIZE) {
                MCLGET(mp, how);
                if ((mp->m_flags & M_EXT) == 0) {
                        m_free(mp);
                        return (NULL);
                }
        }
        mp->m_len = 0;
        len -= M_TRAILINGSPACE(mp);
 
        if (m != NULL)
                for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next);
        else
                m = mp;
 
        top = tail = mp;
        while (len > 0) {
                MGET(mp, how, type);
                if (mp == NULL)
                        goto failed;
 
                tail->m_next = mp;
                tail = mp;
                if (len > MINCLSIZE) {
                        MCLGET(mp, how);
                        if ((mp->m_flags & M_EXT) == 0)
                                goto failed;
                }
 
                mp->m_len = 0;
                len -= M_TRAILINGSPACE(mp);
        }
 
        if (mtail != NULL)
                mtail->m_next = top;
        return (m);
 
failed:
        m_freem(top);
        return (NULL);
}
 
struct mbuf *
m_free(m)
        struct mbuf *m;
{
        register struct mbuf *n;
 
        MFREE(m, n);
        return (n);
}
 
void
m_freem(m)
        register struct mbuf *m;
{
        register struct mbuf *n;
        struct mbuf *orig = m;
 
        if (m == NULL)
                return;
        do {
                MFREE(m, n);
                m = n;
                if (m == orig) {
                    diag_printf("DEBUG: Circular MBUF %p!\n", orig);
                    return;
                }
        } while (m);
}
 
/*
 * Mbuffer utility routines.
 */
 
/*
 * Lesser-used path for M_PREPEND:
 * allocate new mbuf to prepend to chain,
 * copy junk along.
 */
struct mbuf *
m_prepend(m, len, how)
        register struct mbuf *m;
        int len, how;
{
        struct mbuf *mn;
 
        MGET(mn, how, m->m_type);
        if (mn == (struct mbuf *)NULL) {
                m_freem(m);
                return ((struct mbuf *)NULL);
        }
        if (m->m_flags & M_PKTHDR) {
                M_COPY_PKTHDR(mn, m);
                m->m_flags &= ~M_PKTHDR;
        }
        mn->m_next = m;
        m = mn;
        if (len < MHLEN)
                MH_ALIGN(m, len);
        m->m_len = len;
        return (m);
}
 
/*
 * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
 * continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
 * The wait parameter is a choice of M_WAIT/M_DONTWAIT from caller.
 * Note that the copy is read-only, because clusters are not copied,
 * only their reference counts are incremented.
 */
#define MCFail (mbstat.m_mcfail)
 
struct mbuf *
m_copym(m, off0, len, wait)
        register struct mbuf *m;
        int off0, wait;
        register int len;
{
        register struct mbuf *n, **np;
        register int off = off0;
        struct mbuf *top;
        int copyhdr = 0;
 
        if (off == 0 && m->m_flags & M_PKTHDR)
                copyhdr = 1;
        while (off > 0) {
                if (off < m->m_len)
                        break;
                off -= m->m_len;
                m = m->m_next;
        }
        np = &top;
        top = 0;
        while (len > 0) {
                if (m == 0) {
                        break;
                }
                MGET(n, wait, m->m_type);
                *np = n;
                if (n == 0)
                        goto nospace;
                if (copyhdr) {
                        M_COPY_PKTHDR(n, m);
                        if (len == M_COPYALL)
                                n->m_pkthdr.len -= off0;
                        else
                                n->m_pkthdr.len = len;
                        copyhdr = 0;
                }
                n->m_len = min(len, m->m_len - off);
                if (m->m_flags & M_EXT) {
                        n->m_data = m->m_data + off;
                        if(!m->m_ext.ext_ref)
                                mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
                        else
                                (*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
                                                        m->m_ext.ext_size);
                        n->m_ext = m->m_ext;
                        n->m_flags |= M_EXT;
                } else
                        bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
                            (unsigned)n->m_len);
                if (len != M_COPYALL)
                        len -= n->m_len;
                off = 0;
                m = m->m_next;
                np = &n->m_next;
        }
        if (top == 0)
                MCFail++;
        return (top);
nospace:
        m_freem(top);
        MCFail++;
        return (0);
}
 
/*
 * Copy an entire packet, including header (which must be present).
 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
 * Note that the copy is read-only, because clusters are not copied,
 * only their reference counts are incremented.
 */
struct mbuf *
m_copypacket(m, how)
        struct mbuf *m;
        int how;
{
        struct mbuf *top, *n, *o;
 
        MGET(n, how, m->m_type);
        top = n;
        if (!n)
                goto nospace;
 
        M_COPY_PKTHDR(n, m);
        n->m_len = m->m_len;
        if (m->m_flags & M_EXT) {
                n->m_data = m->m_data;
                if(!m->m_ext.ext_ref)
                        mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
                else
                        (*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
                                                m->m_ext.ext_size);
                n->m_ext = m->m_ext;
                n->m_flags |= M_EXT;
        } else {
                bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
        }
 
        m = m->m_next;
        while (m) {
                MGET(o, how, m->m_type);
                if (!o)
                        goto nospace;
 
                n->m_next = o;
                n = n->m_next;
 
                n->m_len = m->m_len;
                if (m->m_flags & M_EXT) {
                        n->m_data = m->m_data;
                        if(!m->m_ext.ext_ref)
                                mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
                        else
                                (*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
                                                        m->m_ext.ext_size);
                        n->m_ext = m->m_ext;
                        n->m_flags |= M_EXT;
                } else {
                        bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
                }
 
                m = m->m_next;
        }
        return top;
nospace:
        m_freem(top);
        MCFail++;
        return 0;
}
 
/*
 * Copy data from an mbuf chain starting "off" bytes from the beginning,
 * continuing for "len" bytes, into the indicated buffer.
 */
void
m_copydata(m, off, len, cp)
        register struct mbuf *m;
        register int off;
        register int len;
        caddr_t cp;
{
        register unsigned count;
 
        while (off > 0) {
                if (off < m->m_len)
                        break;
                off -= m->m_len;
                m = m->m_next;
        }
        while (len > 0) {
                count = min(m->m_len - off, len);
                bcopy(mtod(m, caddr_t) + off, cp, count);
                len -= count;
                cp += count;
                off = 0;
                m = m->m_next;
        }
}
 
/*
 * Copy a packet header mbuf chain into a completely new chain, including
 * copying any mbuf clusters.  Use this instead of m_copypacket() when
 * you need a writable copy of an mbuf chain.
 */
struct mbuf *
m_dup(m, how)
        struct mbuf *m;
        int how;
{
        struct mbuf **p, *top = NULL;
        int remain, moff, nsize;
 
        /* Sanity check */
        if (m == NULL)
                return (0);
 
        /* While there's more data, get a new mbuf, tack it on, and fill it */
        remain = m->m_pkthdr.len;
        moff = 0;
        p = &top;
        while (remain > 0 || top == NULL) {      /* allow m->m_pkthdr.len == 0 */
                struct mbuf *n;
 
                /* Get the next new mbuf */
                MGET(n, how, m->m_type);
                if (n == NULL)
                        goto nospace;
                if (top == NULL) {              /* first one, must be PKTHDR */
                        M_COPY_PKTHDR(n, m);
                        nsize = MHLEN;
                } else                          /* not the first one */
                        nsize = MLEN;
                if (remain >= MINCLSIZE) {
                        MCLGET(n, how);
                        if ((n->m_flags & M_EXT) == 0) {
                                (void)m_free(n);
                                goto nospace;
                        }
                        nsize = MCLBYTES;
                }
                n->m_len = 0;
 
                /* Link it into the new chain */
                *p = n;
                p = &n->m_next;
 
                /* Copy data from original mbuf(s) into new mbuf */
                while (n->m_len < nsize && m != NULL) {
                        int chunk = min(nsize - n->m_len, m->m_len - moff);
 
                        bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
                        moff += chunk;
                        n->m_len += chunk;
                        remain -= chunk;
                        if (moff == m->m_len) {
                                m = m->m_next;
                                moff = 0;
                        }
                }
        }
        return (top);
 
nospace:
        m_freem(top);
        MCFail++;
        return (0);
}
 
/*
 * Concatenate mbuf chain n to m.
 * Both chains must be of the same type (e.g. MT_DATA).
 * Any m_pkthdr is not updated.
 */
void
m_cat(m, n)
        register struct mbuf *m, *n;
{
        while (m->m_next)
                m = m->m_next;
        while (n) {
                if (m->m_flags & M_EXT ||
                    m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) {
                        /* just join the two chains */
                        m->m_next = n;
                        return;
                }
                /* splat the data from one into the other */
                bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
                    (u_int)n->m_len);
                m->m_len += n->m_len;
                n = m_free(n);
        }
}
 
void
m_adj(mp, req_len)
        struct mbuf *mp;
        int req_len;
{
        register int len = req_len;
        register struct mbuf *m;
        register int count;
 
        if ((m = mp) == NULL)
                return;
        if (len >= 0) {
                /*
                 * Trim from head.
                 */
                while (m != NULL && len > 0) {
                        if (m->m_len <= len) {
                                len -= m->m_len;
                                m->m_len = 0;
                                m = m->m_next;
                        } else {
                                m->m_len -= len;
                                m->m_data += len;
                                len = 0;
                        }
                }
                m = mp;
                if (mp->m_flags & M_PKTHDR)
                        m->m_pkthdr.len -= (req_len - len);
        } else {
                /*
                 * Trim from tail.  Scan the mbuf chain,
                 * calculating its length and finding the last mbuf.
                 * If the adjustment only affects this mbuf, then just
                 * adjust and return.  Otherwise, rescan and truncate
                 * after the remaining size.
                 */
                len = -len;
                count = 0;
                for (;;) {
                        count += m->m_len;
                        if (m->m_next == (struct mbuf *)0)
                                break;
                        m = m->m_next;
                }
                if (m->m_len >= len) {
                        m->m_len -= len;
                        if (mp->m_flags & M_PKTHDR)
                                mp->m_pkthdr.len -= len;
                        return;
                }
                count -= len;
                if (count < 0)
                        count = 0;
                /*
                 * Correct length for chain is "count".
                 * Find the mbuf with last data, adjust its length,
                 * and toss data from remaining mbufs on chain.
                 */
                m = mp;
                if (m->m_flags & M_PKTHDR)
                        m->m_pkthdr.len = count;
                for (; m; m = m->m_next) {
                        if (m->m_len >= count) {
                                m->m_len = count;
                                break;
                        }
                        count -= m->m_len;
                }
                while (m->m_next)
                        (m = m->m_next) ->m_len = 0;
        }
}
 
/*
 * Rearange an mbuf chain so that len bytes are contiguous
 * and in the data area of an mbuf (so that mtod and dtom
 * will work for a structure of size len).  Returns the resulting
 * mbuf chain on success, frees it and returns null on failure.
 * If there is room, it will add up to max_protohdr-len extra bytes to the
 * contiguous region in an attempt to avoid being called next time.
 */
#define MPFail (mbstat.m_mpfail)
 
struct mbuf *
m_pullup(n, len)
        register struct mbuf *n;
        int len;
{
        register struct mbuf *m;
        register int count;
        int space;
 
        /*
         * If first mbuf has no cluster, and has room for len bytes
         * without shifting current data, pullup into it,
         * otherwise allocate a new mbuf to prepend to the chain.
         */
        if ((n->m_flags & M_EXT) == 0 &&
            n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
                if (n->m_len >= len)
                        return (n);
                m = n;
                n = n->m_next;
                len -= m->m_len;
        } else {
                if (len > MHLEN)
                        goto bad;
                MGET(m, M_DONTWAIT, n->m_type);
                if (m == 0)
                        goto bad;
                m->m_len = 0;
                if (n->m_flags & M_PKTHDR) {
                        M_COPY_PKTHDR(m, n);
                        n->m_flags &= ~M_PKTHDR;
                }
        }
        space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
        do {
                count = min(min(max(len, max_protohdr), space), n->m_len);
                bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
                  (unsigned)count);
                len -= count;
                m->m_len += count;
                n->m_len -= count;
                space -= count;
                if (n->m_len)
                        n->m_data += count;
                else
                        n = m_free(n);
        } while (len > 0 && n);
        if (len > 0) {
                (void) m_free(m);
                goto bad;
        }
        m->m_next = n;
        return (m);
bad:
        m_freem(n);
        MPFail++;
        return (0);
}
 
/*
 * Partition an mbuf chain in two pieces, returning the tail --
 * all but the first len0 bytes.  In case of failure, it returns NULL and
 * attempts to restore the chain to its original state.
 */
struct mbuf *
m_split(m0, len0, wait)
        register struct mbuf *m0;
        int len0, wait;
{
        register struct mbuf *m, *n;
        unsigned len = len0, remain;
 
        for (m = m0; m && len > m->m_len; m = m->m_next)
                len -= m->m_len;
        if (m == 0)
                return (0);
        remain = m->m_len - len;
        if (m0->m_flags & M_PKTHDR) {
                MGETHDR(n, wait, m0->m_type);
                if (n == 0)
                        return (0);
                n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
                n->m_pkthdr.len = m0->m_pkthdr.len - len0;
                m0->m_pkthdr.len = len0;
                if (m->m_flags & M_EXT)
                        goto extpacket;
                if (remain > MHLEN) {
                        /* m can't be the lead packet */
                        MH_ALIGN(n, 0);
                        n->m_next = m_split(m, len, wait);
                        if (n->m_next == 0) {
                                (void) m_free(n);
                                return (0);
                        } else
                                return (n);
                } else
                        MH_ALIGN(n, remain);
        } else if (remain == 0) {
                n = m->m_next;
                m->m_next = 0;
                return (n);
        } else {
                MGET(n, wait, m->m_type);
                if (n == 0)
                        return (0);
                M_ALIGN(n, remain);
        }
extpacket:
        if (m->m_flags & M_EXT) {
                n->m_flags |= M_EXT;
                n->m_ext = m->m_ext;
                if(!m->m_ext.ext_ref)
                        mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
                else
                        (*(m->m_ext.ext_ref))(m->m_ext.ext_buf,
                                                m->m_ext.ext_size);
                m->m_ext.ext_size = 0; /* For Accounting XXXXXX danger */
                n->m_data = m->m_data + len;
        } else {
                bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
        }
        n->m_len = remain;
        m->m_len = len;
        n->m_next = m->m_next;
        m->m_next = 0;
        return (n);
}
/*
 * Routine to copy from device local memory into mbufs.
 */
struct mbuf *
m_devget(buf, totlen, off0, ifp, copy)
        char *buf;
        int totlen, off0;
        struct ifnet *ifp;
        void (*copy) __P((char *from, caddr_t to, u_int len));
{
        register struct mbuf *m;
        struct mbuf *top = 0, **mp = &top;
        register int off = off0, len;
        register char *cp;
        char *epkt;
 
        cp = buf;
        epkt = cp + totlen;
        if (off) {
                cp += off + 2 * sizeof(u_short);
                totlen -= 2 * sizeof(u_short);
        }
        MGETHDR(m, M_DONTWAIT, MT_DATA);
        if (m == 0)
                return (0);
        m->m_pkthdr.rcvif = ifp;
        m->m_pkthdr.len = totlen;
        m->m_len = MHLEN;
 
        while (totlen > 0) {
                if (top) {
                        MGET(m, M_DONTWAIT, MT_DATA);
                        if (m == 0) {
                                m_freem(top);
                                return (0);
                        }
                        m->m_len = MLEN;
                }
                len = min(totlen, epkt - cp);
                if (len >= MINCLSIZE) {
                        MCLGET(m, M_DONTWAIT);
                        if (m->m_flags & M_EXT)
                                m->m_len = len = min(len, MCLBYTES);
                        else
                                len = m->m_len;
                } else {
                        /*
                         * Place initial small packet/header at end of mbuf.
                         */
                        if (len < m->m_len) {
                                if (top == 0 && len + max_linkhdr <= m->m_len)
                                        m->m_data += max_linkhdr;
                                m->m_len = len;
                        } else
                                len = m->m_len;
                }
                if (copy)
                        copy(cp, mtod(m, caddr_t), (unsigned)len);
                else
                        bcopy(cp, mtod(m, caddr_t), (unsigned)len);
                cp += len;
                *mp = m;
                mp = &m->m_next;
                totlen -= len;
                if (cp == epkt)
                        cp = buf;
        }
        return (top);
}
 
/*
 * Copy data from a buffer back into the indicated mbuf chain,
 * starting "off" bytes from the beginning, extending the mbuf
 * chain if necessary.
 */
void
m_copyback(m0, off, len, cp)
        struct  mbuf *m0;
        register int off;
        register int len;
        caddr_t cp;
{
        register int mlen;
        register struct mbuf *m = m0, *n;
        int totlen = 0;
 
        if (m0 == 0)
                return;
        while (off > (mlen = m->m_len)) {
                off -= mlen;
                totlen += mlen;
                if (m->m_next == 0) {
                        n = m_getclr(M_DONTWAIT, m->m_type);
                        if (n == 0)
                                goto out;
                        n->m_len = min(MLEN, len + off);
                        m->m_next = n;
                }
                m = m->m_next;
        }
        while (len > 0) {
                mlen = min (m->m_len - off, len);
                bcopy(cp, off + mtod(m, caddr_t), (unsigned)mlen);
                cp += mlen;
                len -= mlen;
                mlen += off;
                off = 0;
                totlen += mlen;
                if (len == 0)
                        break;
                if (m->m_next == 0) {
                        n = m_get(M_DONTWAIT, m->m_type);
                        if (n == 0)
                                break;
                        n->m_len = min(MLEN, len);
                        m->m_next = n;
                }
                m = m->m_next;
        }
out:    if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
                m->m_pkthdr.len = totlen;
}
 
#ifndef __ECOS
void
m_print(const struct mbuf *m)
{
        int len;
        const struct mbuf *m2;
 
        len = m->m_pkthdr.len;
        m2 = m;
        while (len) {
                printf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-");
                len -= m2->m_len;
                m2 = m2->m_next;
        }
        return;
}
#endif
 
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Line No.	Rev	Author	Line
1	27	unneback	`//==========================================================================`
2			`//`
3			`// src/sys/kern/uipc_mbuf.c`
4			`//`
5			`//==========================================================================`
6			`//####BSDCOPYRIGHTBEGIN####`
7			`//`
8			`// -------------------------------------------`
9			`//`
10			`// Portions of this software may have been derived from OpenBSD,`
11			`// FreeBSD or other sources, and are covered by the appropriate`
12			`// copyright disclaimers included herein.`
13			`//`
14			`// Portions created by Red Hat are`
15			`// Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.`
16			`//`
17			`// -------------------------------------------`
18			`//`
19			`//####BSDCOPYRIGHTEND####`
20			`//==========================================================================`
21
22			`/*`
23			`* Copyright (c) 1982, 1986, 1988, 1991, 1993`
24			`* The Regents of the University of California. All rights reserved.`
25			`*`
26			`* Redistribution and use in source and binary forms, with or without`
27			`* modification, are permitted provided that the following conditions`
28			`* are met:`
29			`* 1. Redistributions of source code must retain the above copyright`
30			`* notice, this list of conditions and the following disclaimer.`
31			`* 2. Redistributions in binary form must reproduce the above copyright`
32			`* notice, this list of conditions and the following disclaimer in the`
33			`* documentation and/or other materials provided with the distribution.`
34			`* 3. All advertising materials mentioning features or use of this software`
35			`* must display the following acknowledgement:`
36			`* This product includes software developed by the University of`
37			`* California, Berkeley and its contributors.`
38			`* 4. Neither the name of the University nor the names of its contributors`
39			`* may be used to endorse or promote products derived from this software`
40			`* without specific prior written permission.`