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[unix-history] / usr / src / sys / kern / uipc_mbuf.c

/*
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that this notice is preserved and that due credit is given
* to the University of California at Berkeley. The name of the University
* may not be used to endorse or promote products derived from this
* software without specific prior written permission. This software
* is provided ``as is'' without express or implied warranty.
*
*      @(#)uipc_mbuf.c 7.6 (Berkeley) %G%
*/

#include "../machine/pte.h"

#include "param.h"
#include "dir.h"
#include "user.h"
#include "proc.h"
#include "cmap.h"
#include "map.h"
#include "mbuf.h"
#include "vm.h"
#include "kernel.h"
#include "syslog.h"
#include "domain.h"
#include "protosw.h"

mbinit()
{
       int s;

#if CLBYTES < 4096
#define NCL_INIT        (4096/CLBYTES)
#else
#define NCL_INIT        1
#endif
       s = splimp();
       if (m_clalloc(NCL_INIT, MPG_MBUFS, M_DONTWAIT) == 0)
               goto bad;
       if (m_clalloc(NCL_INIT, MPG_CLUSTERS, M_DONTWAIT) == 0)
               goto bad;
       splx(s);
       return;
bad:
       panic("mbinit");
}

/*
* Must be called at splimp.
*/
/* ARGSUSED */
caddr_t
m_clalloc(ncl, how, canwait)
       register int ncl;
       int how;
{
       int npg, mbx;
       register struct mbuf *m;
       register int i;
       static int logged;

       npg = ncl * CLSIZE;
       mbx = rmalloc(mbmap, (long)npg);
       if (mbx == 0) {
               if (logged == 0) {
                       logged++;
                       log(LOG_ERR, "mbuf map full\n");
               }
               return (0);
       }
       m = cltom(mbx * NBPG / MCLBYTES);
       if (memall(&Mbmap[mbx], npg, proc, CSYS) == 0) {
               rmfree(mbmap, (long)npg, (long)mbx);
               return (0);
       }
       vmaccess(&Mbmap[mbx], (caddr_t)m, npg);
       switch (how) {

       case MPG_CLUSTERS:
               ncl = ncl * CLBYTES / MCLBYTES;
               for (i = 0; i < ncl; i++) {
                       m->m_off = 0;
                       m->m_next = mclfree;
                       mclfree = m;
                       m += MCLBYTES / sizeof (*m);
                       mbstat.m_clfree++;
               }
               mbstat.m_clusters += ncl;
               break;

       case MPG_MBUFS:
               for (i = ncl * CLBYTES / sizeof (*m); i > 0; i--) {
                       m->m_off = 0;
                       m->m_type = MT_DATA;
                       mbstat.m_mtypes[MT_DATA]++;
                       mbstat.m_mbufs++;
                       (void) m_free(m);
                       m++;
               }
               break;
       }
       return ((caddr_t)m);
}

m_pgfree(addr, n)
       caddr_t addr;
       int n;
{

#ifdef lint
       addr = addr; n = n;
#endif
}

/*
* Must be called at splimp.
*/
m_expand(canwait)
       int canwait;
{
       register struct domain *dp;
       register struct protosw *pr;
       int tries;

       for (tries = 0;; ) {
               if (m_clalloc(1, MPG_MBUFS, canwait))
                       return (1);
               if (canwait == 0 || tries++)
                       return (0);

               /* ask protocols to free space */
               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)();
               mbstat.m_drain++;
       }
}

/* NEED SOME WAY TO RELEASE SPACE */

/*
* Space allocation routines.
* These are also available as macros
* for critical paths.
*/
struct mbuf *
m_get(canwait, type)
       int canwait, type;
{
       register struct mbuf *m;

       MGET(m, canwait, type);
       return (m);
}

struct mbuf *
m_getclr(canwait, type)
       int canwait, type;
{
       register struct mbuf *m;

       MGET(m, canwait, type);
       if (m == 0)
               return (0);
       bzero(mtod(m, caddr_t), MLEN);
       return (m);
}

struct mbuf *
m_free(m)
       struct mbuf *m;
{
       register struct mbuf *n;

       MFREE(m, n);
       return (n);
}

/*
* Get more mbufs; called from MGET macro if mfree list is empty.
* Must be called at splimp.
*/
/*ARGSUSED*/
struct mbuf *
m_more(canwait, type)
       int canwait, type;
{
       register struct mbuf *m;

       while (m_expand(canwait) == 0) {
               if (canwait == M_WAIT) {
                       mbstat.m_wait++;
                       m_want++;
                       sleep((caddr_t)&mfree, PZERO - 1);
               } else {
                       mbstat.m_drops++;
                       return (NULL);
               }
       }
#define m_more(x,y) (panic("m_more"), (struct mbuf *)0)
       MGET(m, canwait, type);
#undef m_more
       return (m);
}

m_freem(m)
       register struct mbuf *m;
{
       register struct mbuf *n;
       register int s;

       if (m == NULL)
               return;
       s = splimp();
       do {
               MFREE(m, n);
       } while (m = n);
       splx(s);
}

/*
* Mbuffer utility routines.
*/

/*
* Make a copy of an mbuf chain starting "off" bytes from the beginning,
* continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
* Should get M_WAIT/M_DONTWAIT from caller.
*/
struct mbuf *
m_copy(m, off, len)
       register struct mbuf *m;
       int off;
       register int len;
{
       register struct mbuf *n, **np;
       struct mbuf *top, *p;

       if (len == 0)
               return (0);
       if (off < 0 || len < 0)
               panic("m_copy");
       while (off > 0) {
               if (m == 0)
                       panic("m_copy");
               if (off < m->m_len)
                       break;
               off -= m->m_len;
               m = m->m_next;
       }
       np = &top;
       top = 0;
       while (len > 0) {
               if (m == 0) {
                       if (len != M_COPYALL)
                               panic("m_copy");
                       break;
               }
               MGET(n, M_DONTWAIT, m->m_type);
               *np = n;
               if (n == 0)
                       goto nospace;
               n->m_len = MIN(len, m->m_len - off);
               if (m->m_off > MMAXOFF) {
                       p = mtod(m, struct mbuf *);
                       n->m_off = ((int)p - (int)n) + off;
                       mclrefcnt[mtocl(p)]++;
               } 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;
       }
       return (top);
nospace:
       m_freem(top);
       return (0);
}

m_cat(m, n)
       register struct mbuf *m, *n;
{
       while (m->m_next)
               m = m->m_next;
       while (n) {
               if (m->m_off >= MMAXOFF ||
                   m->m_off + m->m_len + n->m_len > MMAXOFF) {
                       /* 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);
       }
}

m_adj(mp, len)
       struct mbuf *mp;
       register int len;
{
       register struct mbuf *m;
       register count;

       if ((m = mp) == NULL)
               return;
       if (len >= 0) {
               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_off += len;
                               break;
                       }
               }
       } 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;
                       return;
               }
               count -= len;
               /*
                * Correct length for chain is "count".
                * Find the mbuf with last data, adjust its length,
                * and toss data from remaining mbufs on chain.
                */
               for (m = mp; m; m = m->m_next) {
                       if (m->m_len >= count) {
                               m->m_len = count;
                               break;
                       }
                       count -= m->m_len;
               }
               while (m = m->m_next)
                       m->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 MPULL_EXTRA bytes to the
* contiguous region in an attempt to avoid being called next time.
*/
struct mbuf *
m_pullup(n, len)
       register struct mbuf *n;
       int len;
{
       register struct mbuf *m;
       register int count;
       int space;

       if (n->m_off + len <= MMAXOFF && n->m_next) {
               m = n;
               n = n->m_next;
               len -= m->m_len;
       } else {
               if (len > MLEN)
                       goto bad;
               MGET(m, M_DONTWAIT, n->m_type);
               if (m == 0)
                       goto bad;
               m->m_len = 0;
       }
       space = MMAXOFF - m->m_off;
       do {
               count = MIN(MIN(space - m->m_len, len + MPULL_EXTRA), 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;
               if (n->m_len)
                       n->m_off += count;
               else
                       n = m_free(n);
       } while (len > 0 && n);
       if (len > 0) {
               (void) m_free(m);
               goto bad;
       }
       m->m_next = n;
       return (m);
bad:
       m_freem(n);
       return (0);
}