uipc_mbuf.c

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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( );
            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;