kern_mbuf.c

/*-
 * Copyright (c) 2004
 * 	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.
 * 3. Neither the name of the author nor the names of contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * 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_mac.h"
#include "opt_param.h"

#include <sys/param.h>
#include <sys/mac.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/protosw.h>
#include <sys/smp.h>
#include <sys/sysctl.h>

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/uma.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 Master Zone called the Mbuf
 * Zone.
 *
 * Additionally, FreeBSD provides a Packet Zone, which it
 * configures as a Secondary Zone to the Mbuf Master Zone,
 * thus sharing backend Slab kegs with the Mbuf Master 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 Master Zone ]
 *        |                       \________         |
 *  [ Cluster Keg   ]                      \       /
 *        |    	                         [ Mbuf Keg   ] 
 *  [ Cluster Slabs ]                         |
 *        |                              [ Mbuf Slabs ]
 *         \____________(VM)_________________/
 */

int nmbclusters;
struct mbstat mbstat;

static void
tunable_mbinit(void *dummy)
{

	/* This has to be done before VM init. */
	nmbclusters = 1024 + maxusers * 64;
	TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters);
}
SYSINIT(tunable_mbinit, SI_SUB_TUNABLES, SI_ORDER_ANY, tunable_mbinit, NULL);

SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, OID_AUTO, nmbclusters, CTLFLAG_RW, &nmbclusters, 0,
    "Maximum number of mbuf clusters allowed");
SYSCTL_STRUCT(_kern_ipc, OID_AUTO, mbstat, CTLFLAG_RD, &mbstat, mbstat,
    "Mbuf general information and statistics");

/*
 * Zones from which we allocate.
 */
uma_zone_t	zone_mbuf;
uma_zone_t	zone_clust;
uma_zone_t	zone_pack;

/*
 * 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_clust(void *, int, void *);	/* XXX */
static void	mb_dtor_pack(void *, int, void *);	/* XXX */
static int	mb_init_pack(void *, int, int);
static void	mb_fini_pack(void *, int);

static void	mb_reclaim(void *);
static void	mbuf_init(void *);

/*
 * Initialize FreeBSD Network buffer allocation.
 */
SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbuf_init, NULL)
static void
mbuf_init(void *dummy)
{

	/*
	 * Configure UMA zones for Mbufs, Clusters, and Packets.
	 */
	zone_mbuf = uma_zcreate("Mbuf", MSIZE, mb_ctor_mbuf, mb_dtor_mbuf,
	    NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_MAXBUCKET);
	zone_clust = uma_zcreate("MbufClust", MCLBYTES, mb_ctor_clust,
	    mb_dtor_clust, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_REFCNT);
	if (nmbclusters > 0)
		uma_zone_set_max(zone_clust, nmbclusters);
	zone_pack = uma_zsecond_create("Packet", mb_ctor_pack, mb_dtor_pack,
	    mb_init_pack, mb_fini_pack, zone_mbuf);

	/* uma_prealloc() goes here */

	/*
	 * 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);

	/*
	 * [Re]set counters and local statistics knobs.
	 * XXX Some of these should go and be replaced, but UMA stat
	 * gathering needs to be revised.
	 */
	mbstat.m_mbufs = 0;
	mbstat.m_mclusts = 0;
	mbstat.m_drain = 0;
	mbstat.m_msize = MSIZE;
	mbstat.m_mclbytes = MCLBYTES;
	mbstat.m_minclsize = MINCLSIZE;
	mbstat.m_mlen = MLEN;
	mbstat.m_mhlen = MHLEN;
	mbstat.m_numtypes = MT_NTYPES;

	mbstat.m_mcfail = mbstat.m_mpfail = 0;
	mbstat.sf_iocnt = 0;
	mbstat.sf_allocwait = mbstat.sf_allocfail = 0;
}

/*
 * Constructor for Mbuf master zone.
 *
 * The 'arg' pointer points to a mb_args structure which
 * contains call-specific information required to support the
 * mbuf allocation API.
 */
static int
mb_ctor_mbuf(void *mem, int size, void *arg, int how)
{
	struct mbuf *m;
	struct mb_args *args;
#ifdef MAC
	int error;
#endif
	int flags;
	short type;

	m = (struct mbuf *)mem;
	args = (struct mb_args *)arg;
	flags = args->flags;
	type = args->type;

	m->m_type = type;
	m->m_next = NULL;
	m->m_nextpkt = NULL;
	m->m_flags = flags;
	if (flags & M_PKTHDR) {
		m->m_data = m->m_pktdat;
		m->m_pkthdr.rcvif = NULL;
		m->m_pkthdr.csum_flags = 0;
		SLIST_INIT(&m->m_pkthdr.tags);
#ifdef MAC
		/* If the label init fails, fail the alloc */
		error = mac_init_mbuf(m, how);
		if (error)
			return (error);
#endif
	} else
		m->m_data = m->m_dat;
	mbstat.m_mbufs += 1;	/* XXX */
	return (0);
}

/*
 * The Mbuf master zone and Packet secondary zone destructor.
 */
static void
mb_dtor_mbuf(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);
	mbstat.m_mbufs -= 1;	/* XXX */
}

/* XXX Only because of stats */
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);
	mbstat.m_mbufs -= 1;	/* XXX */
	mbstat.m_mclusts -= 1;	/* XXX */
}

/*
 * The Cluster zone constructor.
 *
 * Here the 'arg' pointer points to the Mbuf which we
 * are configuring cluster storage for.
 */
static int
mb_ctor_clust(void *mem, int size, void *arg, int how)
{
	struct mbuf *m;

	m = (struct mbuf *)arg;
	m->m_ext.ext_buf = (caddr_t)mem;
	m->m_data = m->m_ext.ext_buf;
	m->m_flags |= M_EXT;
	m->m_ext.ext_free = NULL;
	m->m_ext.ext_args = NULL;
	m->m_ext.ext_size = MCLBYTES;
	m->m_ext.ext_type = EXT_CLUSTER;
	m->m_ext.ref_cnt = (u_int *)uma_find_refcnt(zone_clust,
	    m->m_ext.ext_buf);
	*(m->m_ext.ref_cnt) = 1;
	mbstat.m_mclusts += 1;	/* XXX */
	return (0);
}

/* XXX */
static void
mb_dtor_clust(void *mem, int size, void *arg)
{
	mbstat.m_mclusts -= 1;	/* XXX */
}

/*
 * The Packet secondary zone's init routine, executed on the
 * object's transition from keg slab to zone cache.
 */
static int
mb_init_pack(void *mem, int size, int how)
{
	struct mbuf *m;

	m = (struct mbuf *)mem;
	m->m_ext.ext_buf = NULL;
	uma_zalloc_arg(zone_clust, m, how);
	if (m->m_ext.ext_buf == NULL)
		return (ENOMEM);
	mbstat.m_mclusts -= 1;	/* XXX */
	return (0);
}

/*
 * The Packet secondary zone's fini routine, executed on the
 * object's transition from zone cache to keg slab.
 */
static void
mb_fini_pack(void *mem, int size)
{
	struct mbuf *m;

	m = (struct mbuf *)mem;
	uma_zfree_arg(zone_clust, m->m_ext.ext_buf, NULL);
	m->m_ext.ext_buf = NULL;
	mbstat.m_mclusts += 1;	/* XXX */
}

/*
 * The "packet" keg constructor.
 */
static int
mb_ctor_pack(void *mem, int size, void *arg, int how)
{
	struct mbuf *m;
	struct mb_args *args;
#ifdef MAC
	int error;
#endif
	int flags;
	short type;

	m = (struct mbuf *)mem;
	args = (struct mb_args *)arg;
	flags = args->flags;
	type = args->type;

	m->m_type = type;
	m->m_next = NULL;
	m->m_nextpkt = NULL;
	m->m_data = m->m_ext.ext_buf;
	m->m_flags = flags|M_EXT;
	m->m_ext.ext_free = NULL;
	m->m_ext.ext_args = NULL;
	m->m_ext.ext_size = MCLBYTES;
	m->m_ext.ext_type = EXT_PACKET;
	*(m->m_ext.ref_cnt) = 1;

	if (flags & M_PKTHDR) {
		m->m_pkthdr.rcvif = NULL;
		m->m_pkthdr.csum_flags = 0;
		SLIST_INIT(&m->m_pkthdr.tags);
#ifdef MAC
		/* If the label init fails, fail the alloc */
		error = mac_init_mbuf(m, how);
		if (error)
			return (error);
#endif
	}
	mbstat.m_mbufs += 1;	/* XXX */
	mbstat.m_mclusts += 1;	/* XXX */
	return (0);
}

/*
 * This is the protocol drain routine.
 *
 * 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(void *junk)
{
	struct domain *dp;
	struct protosw *pr;

	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK | WARN_PANIC, NULL,
	    "mb_reclaim()");

	mbstat.m_drain++;
	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)();
}