xref: /csrg-svn/sys/kern/uipc_mbuf.c (revision 41998)

/*
 * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, 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'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *	@(#)uipc_mbuf.c	7.14 (Berkeley) 05/15/90
 */

#include "param.h"
#include "user.h"
#include "proc.h"
#include "cmap.h"
#include "malloc.h"
#include "map.h"
#define MBTYPES
#include "mbuf.h"
#include "vm.h"
#include "kernel.h"
#include "syslog.h"
#include "domain.h"
#include "protosw.h"
#include "machine/pte.h"

mbinit()
{
	int s;

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

/*
 * Allocate some number of mbuf clusters
 * and place on cluster free list.
 * Must be called at splimp.
 */
/* ARGSUSED */
m_clalloc(ncl, canwait)
	register int ncl;
{
	int npg, mbx;
	register caddr_t p;
	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);
	}
	p = cltom(mbx * NBPG / MCLBYTES);
	if (memall(&Mbmap[mbx], npg, proc, CSYS) == 0) {
		rmfree(mbmap, (long)npg, (long)mbx);
		return (0);
	}
	vmaccess(&Mbmap[mbx], p, npg);
	ncl = ncl * CLBYTES / MCLBYTES;
	for (i = 0; i < ncl; i++) {
		((union mcluster *)p)->mcl_next = mclfree;
		mclfree = (union mcluster *)p;
		p += MCLBYTES;
		mbstat.m_clfree++;
	}
	mbstat.m_clusters += ncl;
	return (1);
}

/*
 * When MGET failes, 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;

	m_reclaim();
#define m_retry(i, t)	(struct mbuf *)0
	MGET(m, i, t);
#undef m_retry
	return (m);
}

/*
 * As above; retry an MGETHDR.
 */
struct mbuf *
m_retryhdr(i, t)
	int i, t;
{
	register struct mbuf *m;

	m_reclaim();
#define m_retryhdr(i, t) (struct mbuf *)0
	MGETHDR(m, i, t);
#undef m_retryhdr
	return (m);
}

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

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

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

	MGETHDR(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);
}

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

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

/*
 * 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.
 */
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 || len < 0)
		panic("m_copym");
	if (off == 0 && m->m_flags & M_PKTHDR)
		copyhdr = 1;
	while (off > 0) {
		if (m == 0)
			panic("m_copym");
		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_copym");
			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;
			mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
			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;
	}
	return (top);
nospace:
	m_freem(top);
	return (0);
}

/*
 * Copy data from an mbuf chain starting "off" bytes from the beginning,
 * continuing for "len" bytes, into the indicated buffer.
 */
m_copydata(m, off, len, cp)
	register struct mbuf *m;
	register int off;
	register int len;
	caddr_t cp;
{
	register unsigned count;

	if (off < 0 || len < 0)
		panic("m_copydata");
	while (off > 0) {
		if (m == 0)
			panic("m_copydata");
		if (off < m->m_len)
			break;
		off -= m->m_len;
		m = m->m_next;
	}
	while (len > 0) {
		if (m == 0)
			panic("m_copydata");
		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;
	}
}

/*
 * Concatenate mbuf chain n to m.
 * Both chains must be of the same type (e.g. MT_DATA).
 * Any m_pkthdr is not updated.
 */
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);
	}
}

m_adj(mp, req_len)
	struct mbuf *mp;
{
	register int len = req_len;
	register struct mbuf *m;
	register 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)->m_flags & M_PKTHDR)
				m->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->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 max_protohdr-len 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 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);
	}
	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);
	return (0);
}