Add support for MP-safe network interface statistics by maintaining them
in per-cpu storage, and collecting them for export in an if_data structure
when user-space wants them.

The new if_stat API is structured to make a gradual transition to the
new way in network drivers possible, and per-cpu stats are currently
disabled (thus there is no kernel ABI change).  Once all drivers have
been converted, the old ABI will be removed, and per-cpu stats will be
enabled universally.


(thorpej)

/*	$NetBSD: if_stats.c,v 1.1 2020/01/29 03:16:28 thorpej Exp $	*/

/*-
 * Copyright (c) 2020 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__KERNEL_RCSID(0, "$NetBSD: if_stats.c,v 1.1 2020/01/29 03:16:28 thorpej Exp $");

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/systm.h>

#include <net/if.h>

#define	IF_STATS_SIZE	(sizeof(uint64_t) * IF_NSTATS)

/*
 * if_stats_init --
 *	Initialize statistics storage for a network interface.
 */
int
if_stats_init(ifnet_t * const ifp)
{
#ifdef __IF_STATS_PERCPU
	ifp->if_stats = percpu_alloc(IF_STATS_SIZE);
	if (ifp->if_stats == NULL)
		return ENOMEM;
#endif /* __IF_STATS_PERCPU */
	return 0;
}

/*
 * if_stats_fini --
 *	Tear down statistics storage for a network interface.
 */
void
if_stats_fini(ifnet_t * const ifp)
{
#ifdef __IF_STATS_PERCPU
	percpu_t *pc = ifp->if_stats;
	ifp->if_stats = NULL;
	if (pc) {
		percpu_free(pc, IF_STATS_SIZE);
	}
#endif /* __IF_STATS_PERCPU */
}

#ifdef __IF_STATS_PERCPU

struct if_stats_to_if_data_ctx {
	struct if_data * const ifi;
	const bool zero_stats;
};

static void
if_stats_to_if_data_cb(void *v1, void *v2, struct cpu_info *ci)
{
	const uint64_t * const local_counters = v1;
	struct if_stats_to_if_data_ctx *ctx = v2;

	int s = splnet();

	if (ctx->ifi) {
		ctx->ifi->ifi_ipackets   += local_counters[if_ipackets];
		ctx->ifi->ifi_ierrors    += local_counters[if_ierrors];
		ctx->ifi->ifi_opackets   += local_counters[if_opackets];
		ctx->ifi->ifi_oerrors    += local_counters[if_oerrors];
		ctx->ifi->ifi_collisions += local_counters[if_collisions];
		ctx->ifi->ifi_ibytes     += local_counters[if_ibytes];
		ctx->ifi->ifi_obytes     += local_counters[if_obytes];
		ctx->ifi->ifi_imcasts    += local_counters[if_imcasts];
		ctx->ifi->ifi_omcasts    += local_counters[if_omcasts];
		ctx->ifi->ifi_iqdrops    += local_counters[if_iqdrops];
		ctx->ifi->ifi_noproto    += local_counters[if_noproto];
	}

	if (ctx->zero_stats) {
		memset(v1, 0, IF_STATS_SIZE);
	}

	splx(s);
}

/*
 * if_stats_to_if_data --
 *	Collect the interface statistics and place them into the
 *	legacy if_data structure for reportig to user space.
 *	Optionally zeros the stats after collection.
 */
void
if_stats_to_if_data(ifnet_t * const ifp, struct if_data * const ifi,
		    const bool zero_stats)
{
	struct if_stats_to_if_data_ctx ctx = {
		.ifi = ifi,
		.zero_stats = zero_stats,
	};

	memset(ifi, 0, sizeof(*ifi));
	percpu_foreach(ifp->if_stats, if_stats_to_if_data_cb, &ctx);
}

#else /* ! __IF_STATS_PERCPU */

/*
 * if_stats_to_if_data --
 *	Collect the interface statistics and place them into the
 *	legacy if_data structure for reportig to user space.
 *	Optionally zeros the stats after collection.
 */
void
if_stats_to_if_data(ifnet_t * const ifp, struct if_data * const ifi,
		    const bool zero_stats)
{

	memset(ifi, 0, sizeof(*ifi));

	int s = splnet();

	if (ifi) {
		memcpy(&ifi->ifi_ipackets, &ifp->if_data.ifi_ipackets,
		    offsetof(struct if_data, ifi_lastchange) -
		    offsetof(struct if_data, ifi_ipackets));
	}

	if (zero_stats) {
		memset(&ifp->if_data.ifi_ipackets, 0,
		    offsetof(struct if_data, ifi_lastchange) -
		    offsetof(struct if_data, ifi_ipackets));
	}

	splx(s);
}

#endif /* __IF_STATS_PERCPU */

/*	$NetBSD: if_stats.h,v 1.1 2020/01/29 03:16:28 thorpej Exp $	*/

/*-
 * Copyright (c) 2020 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#ifndef _NET_IF_STATS_H_
#define _NET_IF_STATS_H_

#include <net/net_stats.h>

#ifdef __IF_STATS_PERCPU
/*
 * Interface statistics.  All values are unsigned 64-bit.
 */
typedef enum {
	if_ipackets		= 0,	/* packets received on interface */
	if_ierrors		= 1,	/* input errors on interface */
	if_opackets		= 2,	/* packets sent on interface */
	if_oerrors		= 3,	/* output errors on interface */
	if_collisions		= 4,	/* collisions on csma interfaces */
	if_ibytes		= 5,	/* total number of octets received */
	if_obytes		= 6,	/* total number of octets sent */
	if_imcasts		= 7,	/* packets received via multicast */
	if_omcasts		= 8,	/* packets sent via multicast */
	if_iqdrops		= 9,	/* dropped on input, this interface */
	if_noproto		= 10,	/* destined for unsupported protocol */

	IF_NSTATS		= 11
} if_stat_t;

#ifdef _KERNEL

#define	IF_STAT_GETREF(ifp)	_NET_STAT_GETREF((ifp)->if_stats)
#define	IF_STAT_PUTREF(ifp)	_NET_STAT_PUTREF((ifp)->if_stats)

static inline void
if_statinc(ifnet_t *ifp, if_stat_t x)
{
	_NET_STATINC((ifp)->if_stats, x);
}

static inline void
if_statinc_ref(net_stat_ref_t nsr, if_stat_t x)
{
	_NET_STATINC_REF(nsr, x);
}

static inline void
if_statdec(ifnet_t *ifp, if_stat_t x)
{
	_NET_STATDEC((ifp)->if_stats, x);
}

static inline void
if_statdec_ref(net_stat_ref_t nsr, if_stat_t x)
{
	_NET_STATDEC_REF(nsr, x);
}

static inline void
if_statadd(ifnet_t *ifp, if_stat_t x, uint64_t v)
{
	_NET_STATADD((ifp)->if_stats, x, v);
}

static inline void
if_statadd_ref(net_stat_ref_t nsr, if_stat_t x, uint64_t v)
{
	_NET_STATADD_REF(nsr, x, v);
}

static inline void
if_statadd2(ifnet_t *ifp, if_stat_t x1, uint64_t v1, if_stat_t x2, uint64_t v2)
{
	net_stat_ref_t _nsr_ = IF_STAT_GETREF(ifp);
	_NET_STATADD_REF(_nsr_, x1, v1);
	_NET_STATADD_REF(_nsr_, x2, v2);
	IF_STAT_PUTREF(ifp);
}

static inline void
if_statsub(ifnet_t *ifp, if_stat_t x, uint64_t v)
{
	_NET_STATSUB((ifp)->if_stats, x, v);
}

static inline void
if_statsub_ref(net_stat_ref_t nsr, if_stat_t x, uint64_t v)
{
	_NET_STATSUB_REF(nsr, x, v);
}

#endif /* _KERNEL */

#else /* ! __IF_STATS_PERCPU */

#ifdef _KERNEL

/*
 * Transitional aid to allow drivers to migrate to the new API.  Once
 * all drivers are transitioned, the implementation will be replaced
 * with per-cpu counters.
 */

static inline net_stat_ref_t
IF_STAT_GETREF(ifnet_t *ifp)
{
	return (net_stat_ref_t)ifp;
}

#define	IF_STAT_PUTREF(ifp)	__nothing

#define	if_statinc(ifp, x)	do { ++(ifp)->x; } while (/*CONSTCOND*/0)
#define	if_statdec(ifp, x)	do { --(ifp)->x; } while (/*CONSTCOND*/0)
#define	if_statadd(ifp, x, v)	do { (ifp)->x += (v); } while (/*CONSTCOND*/0)
#define	if_statsub(ifp, x, v)	do { (ifp)->x -= (v); } while (/*CONSTCOND*/0)

#define	if_statadd2(ifp, x1, v1, x2, v2)				\
do {									\
	(ifp)->x1 += (v1);						\
	(ifp)->x2 += (v2);						\
} while (/*CONSTCOND*/0)

#define	if_statinc_ref(r, x)	if_statinc((ifnet_t *)(r), x)
#define	if_statdec_ref(r, x)	if_statdec((ifnet_t *)(r), x)
#define	if_statadd_ref(r, x, v)	if_statadd((ifnet_t *)(r), x, v)
#define	if_statsub_ref(r, x, v)	if_statsub((ifnet_t *)(r), x, v)

#endif /* _KERNEL */

#endif /* __IF_STATS_PERCPU */

#ifdef _KERNEL
int	if_stats_init(ifnet_t *);
void	if_stats_fini(ifnet_t *);
void	if_stats_to_if_data(ifnet_t *, struct if_data *, bool);
#endif /* _KERNEL */

#endif /* !_NET_IF_STATS_H_ */