io/mac/mac_provider.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2019 Joyent, Inc.
 * Copyright 2017 OmniTI Computer Consulting, Inc. All rights reserved.
 * Copyright 2020 RackTop Systems, Inc.
 * Copyright 2025 Oxide Computer Company
 */

#include <sys/types.h>
#include <sys/conf.h>
#include <sys/id_space.h>
#include <sys/esunddi.h>
#include <sys/stat.h>
#include <sys/mkdev.h>
#include <sys/stream.h>
#include <sys/strsubr.h>
#include <sys/dlpi.h>
#include <sys/modhash.h>
#include <sys/mac.h>
#include <sys/mac_provider.h>
#include <sys/mac_impl.h>
#include <sys/mac_client_impl.h>
#include <sys/mac_client_priv.h>
#include <sys/mac_soft_ring.h>
#include <sys/mac_stat.h>
#include <sys/dld.h>
#include <sys/modctl.h>
#include <sys/fs/dv_node.h>
#include <sys/thread.h>
#include <sys/proc.h>
#include <sys/callb.h>
#include <sys/cpuvar.h>
#include <sys/atomic.h>
#include <sys/sdt.h>
#include <sys/mac_flow.h>
#include <sys/ddi_intr_impl.h>
#include <sys/disp.h>
#include <sys/sdt.h>
#include <sys/stdbool.h>
#include <sys/pattr.h>
#include <sys/strsun.h>
#include <sys/vlan.h>
#include <inet/ip.h>
#include <inet/tcp.h>
#include <netinet/udp.h>
#include <netinet/sctp.h>
#include <netinet/ip_icmp.h>
#include <netinet/icmp6.h>

/*
 * MAC Provider Interface.
 *
 * Interface for GLDv3 compatible NIC drivers.
 */

static void i_mac_notify_thread(void *);

typedef void (*mac_notify_default_cb_fn_t)(mac_impl_t *);

static const mac_notify_default_cb_fn_t mac_notify_cb_list[MAC_NNOTE] = {
	mac_fanout_recompute,	/* MAC_NOTE_LINK */
	NULL,		/* MAC_NOTE_UNICST */
	NULL,		/* MAC_NOTE_TX */
	NULL,		/* MAC_NOTE_DEVPROMISC */
	NULL,		/* MAC_NOTE_FASTPATH_FLUSH */
	NULL,		/* MAC_NOTE_SDU_SIZE */
	NULL,		/* MAC_NOTE_MARGIN */
	NULL,		/* MAC_NOTE_CAPAB_CHG */
	NULL		/* MAC_NOTE_LOWLINK */
};

/*
 * Driver support functions.
 */

/* REGISTRATION */

mac_register_t *
mac_alloc(uint_t mac_version)
{
	mac_register_t *mregp;

	/*
	 * Make sure there isn't a version mismatch between the driver and
	 * the framework.  In the future, if multiple versions are
	 * supported, this check could become more sophisticated.
	 */
	if (mac_version != MAC_VERSION)
		return (NULL);

	mregp = kmem_zalloc(sizeof (mac_register_t), KM_SLEEP);
	mregp->m_version = mac_version;
	return (mregp);
}

void
mac_free(mac_register_t *mregp)
{
	kmem_free(mregp, sizeof (mac_register_t));
}

/*
 * Convert a MAC's offload features into the equivalent DB_CKSUMFLAGS
 * value.
 */
static uint16_t
mac_features_to_flags(mac_handle_t mh)
{
	uint16_t flags = 0;
	uint32_t cap_sum = 0;
	mac_capab_lso_t cap_lso;

	if (mac_capab_get(mh, MAC_CAPAB_HCKSUM, &cap_sum)) {
		if (cap_sum & HCKSUM_IPHDRCKSUM)
			flags |= HCK_IPV4_HDRCKSUM;

		if (cap_sum & HCKSUM_INET_PARTIAL)
			flags |= HCK_PARTIALCKSUM;
		else if (cap_sum & (HCKSUM_INET_FULL_V4 | HCKSUM_INET_FULL_V6))
			flags |= HCK_FULLCKSUM;
	}

	/*
	 * We don't need the information stored in 'cap_lso', but we
	 * need to pass a non-NULL pointer to appease the driver.
	 */
	if (mac_capab_get(mh, MAC_CAPAB_LSO, &cap_lso))
		flags |= HW_LSO;

	return (flags);
}

/*
 * mac_register() is how drivers register new MACs with the GLDv3
 * framework.  The mregp argument is allocated by drivers using the
 * mac_alloc() function, and can be freed using mac_free() immediately upon
 * return from mac_register().  Upon success (0 return value), the mhp
 * opaque pointer becomes the driver's handle to its MAC interface, and is
 * the argument to all other mac module entry points.
 */
/* ARGSUSED */
int
mac_register(mac_register_t *mregp, mac_handle_t *mhp)
{
	mac_impl_t		*mip;
	mactype_t		*mtype;
	int			err = EINVAL;
	struct devnames		*dnp = NULL;
	uint_t			instance;
	boolean_t		style1_created = B_FALSE;
	boolean_t		style2_created = B_FALSE;
	char			*driver;
	minor_t			minor = 0;

	/* A successful call to mac_init_ops() sets the DN_GLDV3_DRIVER flag. */
	if (!GLDV3_DRV(ddi_driver_major(mregp->m_dip)))
		return (EINVAL);

	/* Find the required MAC-Type plugin. */
	if ((mtype = mactype_getplugin(mregp->m_type_ident)) == NULL)
		return (EINVAL);

	/* Create a mac_impl_t to represent this MAC. */
	mip = kmem_cache_alloc(i_mac_impl_cachep, KM_SLEEP);

	/*
	 * The mac is not ready for open yet.
	 */
	mip->mi_state_flags |= MIS_DISABLED;

	/*
	 * When a mac is registered, the m_instance field can be set to:
	 *
	 *  0:	Get the mac's instance number from m_dip.
	 *	This is usually used for physical device dips.
	 *
	 *  [1 .. MAC_MAX_MINOR-1]: Use the value as the mac's instance number.
	 *	For example, when an aggregation is created with the key option,
	 *	"key" will be used as the instance number.
	 *
	 *  -1: Assign an instance number from [MAC_MAX_MINOR .. MAXMIN-1].
	 *	This is often used when a MAC of a virtual link is registered
	 *	(e.g., aggregation when "key" is not specified, or vnic).
	 *
	 * Note that the instance number is used to derive the mi_minor field
	 * of mac_impl_t, which will then be used to derive the name of kstats
	 * and the devfs nodes.  The first 2 cases are needed to preserve
	 * backward compatibility.
	 */
	switch (mregp->m_instance) {
	case 0:
		instance = ddi_get_instance(mregp->m_dip);
		break;
	case ((uint_t)-1):
		minor = mac_minor_hold(B_TRUE);
		if (minor == 0) {
			err = ENOSPC;
			goto fail;
		}
		instance = minor - 1;
		break;
	default:
		instance = mregp->m_instance;
		if (instance >= MAC_MAX_MINOR) {
			err = EINVAL;
			goto fail;
		}
		break;
	}

	mip->mi_minor = (minor_t)(instance + 1);
	mip->mi_dip = mregp->m_dip;
	mip->mi_clients_list = NULL;
	mip->mi_nclients = 0;

	/* Set the default IEEE Port VLAN Identifier */
	mip->mi_pvid = 1;

	/* Default bridge link learning protection values */
	mip->mi_llimit = 1000;
	mip->mi_ldecay = 200;

	driver = (char *)ddi_driver_name(mip->mi_dip);

	/* Construct the MAC name as <drvname><instance> */
	(void) snprintf(mip->mi_name, sizeof (mip->mi_name), "%s%d",
	    driver, instance);

	mip->mi_driver = mregp->m_driver;

	mip->mi_type = mtype;
	mip->mi_margin = mregp->m_margin;
	mip->mi_info.mi_media = mtype->mt_type;
	mip->mi_info.mi_nativemedia = mtype->mt_nativetype;
	if (mregp->m_max_sdu <= mregp->m_min_sdu)
		goto fail;
	if (mregp->m_multicast_sdu == 0)
		mregp->m_multicast_sdu = mregp->m_max_sdu;
	if (mregp->m_multicast_sdu < mregp->m_min_sdu ||
	    mregp->m_multicast_sdu > mregp->m_max_sdu)
		goto fail;
	mip->mi_sdu_min = mregp->m_min_sdu;
	mip->mi_sdu_max = mregp->m_max_sdu;
	mip->mi_sdu_multicast = mregp->m_multicast_sdu;
	mip->mi_info.mi_addr_length = mip->mi_type->mt_addr_length;
	/*
	 * If the media supports a broadcast address, cache a pointer to it
	 * in the mac_info_t so that upper layers can use it.
	 */
	mip->mi_info.mi_brdcst_addr = mip->mi_type->mt_brdcst_addr;

	mip->mi_v12n_level = mregp->m_v12n;

	/*
	 * Copy the unicast source address into the mac_info_t, but only if
	 * the MAC-Type defines a non-zero address length.  We need to
	 * handle MAC-Types that have an address length of 0
	 * (point-to-point protocol MACs for example).
	 */
	if (mip->mi_type->mt_addr_length > 0) {
		if (mregp->m_src_addr == NULL)
			goto fail;
		mip->mi_info.mi_unicst_addr =
		    kmem_alloc(mip->mi_type->mt_addr_length, KM_SLEEP);
		bcopy(mregp->m_src_addr, mip->mi_info.mi_unicst_addr,
		    mip->mi_type->mt_addr_length);

		/*
		 * Copy the fixed 'factory' MAC address from the immutable
		 * info.  This is taken to be the MAC address currently in
		 * use.
		 */
		bcopy(mip->mi_info.mi_unicst_addr, mip->mi_addr,
		    mip->mi_type->mt_addr_length);

		/*
		 * At this point, we should set up the classification
		 * rules etc but we delay it till mac_open() so that
		 * the resource discovery has taken place and we
		 * know someone wants to use the device. Otherwise
		 * memory gets allocated for Rx ring structures even
		 * during probe.
		 */

		/* Copy the destination address if one is provided. */
		if (mregp->m_dst_addr != NULL) {
			bcopy(mregp->m_dst_addr, mip->mi_dstaddr,
			    mip->mi_type->mt_addr_length);
			mip->mi_dstaddr_set = B_TRUE;
		}
	} else if (mregp->m_src_addr != NULL) {
		goto fail;
	}

	/*
	 * The format of the m_pdata is specific to the plugin.  It is
	 * passed in as an argument to all of the plugin callbacks.  The
	 * driver can update this information by calling
	 * mac_pdata_update().
	 */
	if (mip->mi_type->mt_ops.mtops_ops & MTOPS_PDATA_VERIFY) {
		/*
		 * Verify if the supplied plugin data is valid.  Note that
		 * even if the caller passed in a NULL pointer as plugin data,
		 * we still need to verify if that's valid as the plugin may
		 * require plugin data to function.
		 */
		if (!mip->mi_type->mt_ops.mtops_pdata_verify(mregp->m_pdata,
		    mregp->m_pdata_size)) {
			goto fail;
		}
		if (mregp->m_pdata != NULL) {
			mip->mi_pdata =
			    kmem_alloc(mregp->m_pdata_size, KM_SLEEP);
			bcopy(mregp->m_pdata, mip->mi_pdata,
			    mregp->m_pdata_size);
			mip->mi_pdata_size = mregp->m_pdata_size;
		}
	} else if (mregp->m_pdata != NULL) {
		/*
		 * The caller supplied non-NULL plugin data, but the plugin
		 * does not recognize plugin data.
		 */
		err = EINVAL;
		goto fail;
	}

	/*
	 * Register the private properties.
	 */
	mac_register_priv_prop(mip, mregp->m_priv_props);

	/*
	 * Stash the driver callbacks into the mac_impl_t, but first sanity
	 * check to make sure all mandatory callbacks are set.
	 */
	if (mregp->m_callbacks->mc_getstat == NULL ||
	    mregp->m_callbacks->mc_start == NULL ||
	    mregp->m_callbacks->mc_stop == NULL ||
	    mregp->m_callbacks->mc_setpromisc == NULL ||
	    mregp->m_callbacks->mc_multicst == NULL) {
		goto fail;
	}
	mip->mi_callbacks = mregp->m_callbacks;

	if (mac_capab_get((mac_handle_t)mip, MAC_CAPAB_LEGACY,
	    &mip->mi_capab_legacy)) {
		mip->mi_state_flags |= MIS_LEGACY;
		mip->mi_phy_dev = mip->mi_capab_legacy.ml_dev;
	} else {
		mip->mi_phy_dev = makedevice(ddi_driver_major(mip->mi_dip),
		    mip->mi_minor);
	}

	/*
	 * Allocate a notification thread. thread_create blocks for memory
	 * if needed, it never fails.
	 */
	mip->mi_notify_thread = thread_create(NULL, 0, i_mac_notify_thread,
	    mip, 0, &p0, TS_RUN, minclsyspri);

	/*
	 * Cache the DB_CKSUMFLAGS that this MAC supports.
	 */
	mip->mi_tx_cksum_flags = mac_features_to_flags((mac_handle_t)mip);

	/*
	 * Initialize the capabilities
	 */
	bzero(&mip->mi_rx_rings_cap, sizeof (mac_capab_rings_t));
	bzero(&mip->mi_tx_rings_cap, sizeof (mac_capab_rings_t));

	if (i_mac_capab_get((mac_handle_t)mip, MAC_CAPAB_VNIC, NULL))
		mip->mi_state_flags |= MIS_IS_VNIC;

	if (i_mac_capab_get((mac_handle_t)mip, MAC_CAPAB_AGGR, NULL))
		mip->mi_state_flags |= MIS_IS_AGGR;

	if (i_mac_capab_get((mac_handle_t)mip, MAC_CAPAB_OVERLAY, NULL))
		mip->mi_state_flags |= MIS_IS_OVERLAY;

	mac_addr_factory_init(mip);

	mac_transceiver_init(mip);

	mac_led_init(mip);

	/*
	 * Enforce the virtrualization level registered.
	 */
	if (mip->mi_v12n_level & MAC_VIRT_LEVEL1) {
		if (mac_init_rings(mip, MAC_RING_TYPE_RX) != 0 ||
		    mac_init_rings(mip, MAC_RING_TYPE_TX) != 0)
			goto fail;

		/*
		 * The driver needs to register at least rx rings for this
		 * virtualization level.
		 */
		if (mip->mi_rx_groups == NULL)
			goto fail;
	}

	/*
	 * The driver must set mc_unicst entry point to NULL when it advertises
	 * CAP_RINGS for rx groups.
	 */
	if (mip->mi_rx_groups != NULL) {
		if (mregp->m_callbacks->mc_unicst != NULL)
			goto fail;
	} else {
		if (mregp->m_callbacks->mc_unicst == NULL)
			goto fail;
	}

	/*
	 * Initialize MAC addresses. Must be called after mac_init_rings().
	 */
	mac_init_macaddr(mip);

	mip->mi_share_capab.ms_snum = 0;
	if (mip->mi_v12n_level & MAC_VIRT_HIO) {
		(void) mac_capab_get((mac_handle_t)mip, MAC_CAPAB_SHARES,
		    &mip->mi_share_capab);
	}

	/*
	 * Initialize the kstats for this device.
	 */
	mac_driver_stat_create(mip);

	/* Zero out any properties. */
	bzero(&mip->mi_resource_props, sizeof (mac_resource_props_t));

	if (mip->mi_minor <= MAC_MAX_MINOR) {
		/* Create a style-2 DLPI device */
		if (ddi_create_minor_node(mip->mi_dip, driver, S_IFCHR, 0,
		    DDI_NT_NET, CLONE_DEV) != DDI_SUCCESS)
			goto fail;
		style2_created = B_TRUE;

		/* Create a style-1 DLPI device */
		if (ddi_create_minor_node(mip->mi_dip, mip->mi_name, S_IFCHR,
		    mip->mi_minor, DDI_NT_NET, 0) != DDI_SUCCESS)
			goto fail;
		style1_created = B_TRUE;
	}

	mac_flow_l2tab_create(mip, &mip->mi_flow_tab);

	rw_enter(&i_mac_impl_lock, RW_WRITER);
	if (mod_hash_insert(i_mac_impl_hash,
	    (mod_hash_key_t)mip->mi_name, (mod_hash_val_t)mip) != 0) {
		rw_exit(&i_mac_impl_lock);
		err = EEXIST;
		goto fail;
	}

	DTRACE_PROBE2(mac__register, struct devnames *, dnp,
	    (mac_impl_t *), mip);

	/*
	 * Mark the MAC to be ready for open.
	 */
	mip->mi_state_flags &= ~MIS_DISABLED;
	rw_exit(&i_mac_impl_lock);

	atomic_inc_32(&i_mac_impl_count);

	cmn_err(CE_NOTE, "!%s registered", mip->mi_name);
	*mhp = (mac_handle_t)mip;
	return (0);

fail:
	if (style1_created)
		ddi_remove_minor_node(mip->mi_dip, mip->mi_name);

	if (style2_created)
		ddi_remove_minor_node(mip->mi_dip, driver);

	mac_addr_factory_fini(mip);

	/* Clean up registered MAC addresses */
	mac_fini_macaddr(mip);

	/* Clean up registered rings */
	mac_free_rings(mip, MAC_RING_TYPE_RX);
	mac_free_rings(mip, MAC_RING_TYPE_TX);

	/* Clean up notification thread */
	if (mip->mi_notify_thread != NULL)
		i_mac_notify_exit(mip);

	if (mip->mi_info.mi_unicst_addr != NULL) {
		kmem_free(mip->mi_info.mi_unicst_addr,
		    mip->mi_type->mt_addr_length);
		mip->mi_info.mi_unicst_addr = NULL;
	}

	mac_driver_stat_delete(mip);

	if (mip->mi_type != NULL) {
		atomic_dec_32(&mip->mi_type->mt_ref);
		mip->mi_type = NULL;
	}

	if (mip->mi_pdata != NULL) {
		kmem_free(mip->mi_pdata, mip->mi_pdata_size);
		mip->mi_pdata = NULL;
		mip->mi_pdata_size = 0;
	}

	if (minor != 0) {
		ASSERT(minor > MAC_MAX_MINOR);
		mac_minor_rele(minor);
	}

	mip->mi_state_flags = 0;
	mac_unregister_priv_prop(mip);

	/*
	 * Clear the state before destroying the mac_impl_t
	 */
	mip->mi_state_flags = 0;

	kmem_cache_free(i_mac_impl_cachep, mip);
	return (err);
}

/*
 * Unregister from the GLDv3 framework
 */
int
mac_unregister(mac_handle_t mh)
{
	int			err;
	mac_impl_t		*mip = (mac_impl_t *)mh;
	mod_hash_val_t		val;
	mac_margin_req_t	*mmr, *nextmmr;

	/* Fail the unregister if there are any open references to this mac. */
	if ((err = mac_disable_nowait(mh)) != 0)
		return (err);

	/*
	 * Clean up notification thread and wait for it to exit.
	 */
	i_mac_notify_exit(mip);

	/*
	 * Prior to acquiring the MAC perimeter, remove the MAC instance from
	 * the internal hash table. Such removal means table-walkers that
	 * acquire the perimeter will not do so on behalf of what we are
	 * unregistering, which prevents a deadlock.
	 */
	rw_enter(&i_mac_impl_lock, RW_WRITER);
	(void) mod_hash_remove(i_mac_impl_hash,
	    (mod_hash_key_t)mip->mi_name, &val);
	rw_exit(&i_mac_impl_lock);
	ASSERT(mip == (mac_impl_t *)val);

	i_mac_perim_enter(mip);

	/*
	 * There is still resource properties configured over this mac.
	 */
	if (mip->mi_resource_props.mrp_mask != 0)
		mac_fastpath_enable((mac_handle_t)mip);

	if (mip->mi_minor < MAC_MAX_MINOR + 1) {
		ddi_remove_minor_node(mip->mi_dip, mip->mi_name);
		ddi_remove_minor_node(mip->mi_dip,
		    (char *)ddi_driver_name(mip->mi_dip));
	}

	ASSERT(mip->mi_nactiveclients == 0 && !(mip->mi_state_flags &
	    MIS_EXCLUSIVE));

	mac_driver_stat_delete(mip);

	ASSERT(i_mac_impl_count > 0);
	atomic_dec_32(&i_mac_impl_count);

	if (mip->mi_pdata != NULL)
		kmem_free(mip->mi_pdata, mip->mi_pdata_size);
	mip->mi_pdata = NULL;
	mip->mi_pdata_size = 0;

	/*
	 * Free the list of margin request.
	 */
	for (mmr = mip->mi_mmrp; mmr != NULL; mmr = nextmmr) {
		nextmmr = mmr->mmr_nextp;
		kmem_free(mmr, sizeof (mac_margin_req_t));
	}
	mip->mi_mmrp = NULL;

	mip->mi_linkstate = mip->mi_lowlinkstate = LINK_STATE_UNKNOWN;
	kmem_free(mip->mi_info.mi_unicst_addr, mip->mi_type->mt_addr_length);
	mip->mi_info.mi_unicst_addr = NULL;

	atomic_dec_32(&mip->mi_type->mt_ref);
	mip->mi_type = NULL;

	/*
	 * Free the primary MAC address.
	 */
	mac_fini_macaddr(mip);

	/*
	 * free all rings
	 */
	mac_free_rings(mip, MAC_RING_TYPE_RX);
	mac_free_rings(mip, MAC_RING_TYPE_TX);

	mac_addr_factory_fini(mip);

	bzero(mip->mi_addr, MAXMACADDRLEN);
	bzero(mip->mi_dstaddr, MAXMACADDRLEN);
	mip->mi_dstaddr_set = B_FALSE;

	/* and the flows */
	mac_flow_tab_destroy(mip->mi_flow_tab);
	mip->mi_flow_tab = NULL;

	if (mip->mi_minor > MAC_MAX_MINOR)
		mac_minor_rele(mip->mi_minor);

	cmn_err(CE_NOTE, "!%s unregistered", mip->mi_name);

	/*
	 * Reset the perim related fields to default values before
	 * kmem_cache_free
	 */
	i_mac_perim_exit(mip);
	mip->mi_state_flags = 0;

	mac_unregister_priv_prop(mip);

	ASSERT(mip->mi_bridge_link == NULL);
	kmem_cache_free(i_mac_impl_cachep, mip);

	return (0);
}

/* DATA RECEPTION */

/*
 * This function is invoked for packets received by the MAC driver in
 * interrupt context. The ring generation number provided by the driver
 * is matched with the ring generation number held in MAC. If they do not
 * match, received packets are considered stale packets coming from an older
 * assignment of the ring. Drop them.
 */
void
mac_rx_ring(mac_handle_t mh, mac_ring_handle_t mrh, mblk_t *mp_chain,
    uint64_t mr_gen_num)
{
	mac_ring_t		*mr = (mac_ring_t *)mrh;

	if ((mr != NULL) && (mr->mr_gen_num != mr_gen_num)) {
		DTRACE_PROBE2(mac__rx__rings__stale__packet, uint64_t,
		    mr->mr_gen_num, uint64_t, mr_gen_num);
		freemsgchain(mp_chain);
		return;
	}
	mac_rx(mh, (mac_resource_handle_t)mrh, mp_chain);
}

/*
 * This function is invoked for each packet received by the underlying driver.
 */
void
mac_rx(mac_handle_t mh, mac_resource_handle_t mrh, mblk_t *mp_chain)
{
	mac_impl_t *mip = (mac_impl_t *)mh;

	/*
	 * Check if the link is part of a bridge.  If not, then we don't need
	 * to take the lock to remain consistent.  Make this common case
	 * lock-free and tail-call optimized.
	 */
	if (mip->mi_bridge_link == NULL) {
		mac_rx_common(mh, mrh, mp_chain);
	} else {
		/*
		 * Once we take a reference on the bridge link, the bridge
		 * module itself can't unload, so the callback pointers are
		 * stable.
		 */
		mutex_enter(&mip->mi_bridge_lock);
		if ((mh = mip->mi_bridge_link) != NULL)
			mac_bridge_ref_cb(mh, B_TRUE);
		mutex_exit(&mip->mi_bridge_lock);
		if (mh == NULL) {
			mac_rx_common((mac_handle_t)mip, mrh, mp_chain);
		} else {
			mac_bridge_rx_cb(mh, mrh, mp_chain);
			mac_bridge_ref_cb(mh, B_FALSE);
		}
	}
}

/*
 * Special case function: this allows snooping of packets transmitted and
 * received by TRILL. By design, they go directly into the TRILL module.
 */
void
mac_trill_snoop(mac_handle_t mh, mblk_t *mp)
{
	mac_impl_t *mip = (mac_impl_t *)mh;

	if (mip->mi_promisc_list != NULL)
		mac_promisc_dispatch(mip, mp, NULL, B_FALSE);
}

/*
 * This is the upward reentry point for packets arriving from the bridging
 * module and from mac_rx for links not part of a bridge.
 */
void
mac_rx_common(mac_handle_t mh, mac_resource_handle_t mrh, mblk_t *mp_chain)
{
	mac_impl_t		*mip = (mac_impl_t *)mh;
	mac_ring_t		*mr = (mac_ring_t *)mrh;
	mac_soft_ring_set_t	*mac_srs;
	mblk_t			*bp = mp_chain;

	/*
	 * If there are any promiscuous mode callbacks defined for
	 * this MAC, pass them a copy if appropriate.
	 */
	if (mip->mi_promisc_list != NULL)
		mac_promisc_dispatch(mip, mp_chain, NULL, B_FALSE);

	if (mr != NULL) {
		/*
		 * If the SRS teardown has started, just return. The 'mr'
		 * continues to be valid until the driver unregisters the MAC.
		 * Hardware classified packets will not make their way up
		 * beyond this point once the teardown has started. The driver
		 * is never passed a pointer to a flow entry or SRS or any
		 * structure that can be freed much before mac_unregister.
		 */
		mutex_enter(&mr->mr_lock);
		if ((mr->mr_state != MR_INUSE) || (mr->mr_flag &
		    (MR_INCIPIENT | MR_CONDEMNED | MR_QUIESCE))) {
			mutex_exit(&mr->mr_lock);
			freemsgchain(mp_chain);
			return;
		}

		/*
		 * The ring is in passthru mode; pass the chain up to
		 * the pseudo ring.
		 */
		if (mr->mr_classify_type == MAC_PASSTHRU_CLASSIFIER) {
			MR_REFHOLD_LOCKED(mr);
			mutex_exit(&mr->mr_lock);
			mr->mr_pt_fn(mr->mr_pt_arg1, mr->mr_pt_arg2, mp_chain,
			    B_FALSE);
			MR_REFRELE(mr);
			return;
		}

		/*
		 * The passthru callback should only be set when in
		 * MAC_PASSTHRU_CLASSIFIER mode.
		 */
		ASSERT3P(mr->mr_pt_fn, ==, NULL);

		/*
		 * We check if an SRS is controlling this ring.
		 * If so, we can directly call the srs_lower_proc
		 * routine otherwise we need to go through mac_rx_classify
		 * to reach the right place.
		 */
		if (mr->mr_classify_type == MAC_HW_CLASSIFIER) {
			MR_REFHOLD_LOCKED(mr);
			mutex_exit(&mr->mr_lock);
			ASSERT3P(mr->mr_srs, !=, NULL);
			mac_srs = mr->mr_srs;

			/*
			 * This is the fast path. All packets received
			 * on this ring are hardware classified and
			 * share the same MAC header info.
			 */
			mac_srs->srs_rx.sr_lower_proc(mh,
			    (mac_resource_handle_t)mac_srs, mp_chain, B_FALSE);
			MR_REFRELE(mr);
			return;
		}

		mutex_exit(&mr->mr_lock);
		/* We'll fall through to software classification */
	} else {
		flow_entry_t *flent;
		int err;

		rw_enter(&mip->mi_rw_lock, RW_READER);
		if (mip->mi_single_active_client != NULL) {
			flent = mip->mi_single_active_client->mci_flent_list;
			FLOW_TRY_REFHOLD(flent, err);
			rw_exit(&mip->mi_rw_lock);
			if (err == 0) {
				(flent->fe_cb_fn)(flent->fe_cb_arg1,
				    flent->fe_cb_arg2, mp_chain, B_FALSE);
				FLOW_REFRELE(flent);
				return;
			}
		} else {
			rw_exit(&mip->mi_rw_lock);
		}
	}

	if (!FLOW_TAB_EMPTY(mip->mi_flow_tab)) {
		if ((bp = mac_rx_flow(mh, mrh, bp)) == NULL)
			return;
	}

	freemsgchain(bp);
}

/* DATA TRANSMISSION */

/*
 * A driver's notification to resume transmission, in case of a provider
 * without TX rings.
 */
void
mac_tx_update(mac_handle_t mh)
{
	mac_tx_ring_update(mh, NULL);
}

/*
 * A driver's notification to resume transmission on the specified TX ring.
 */
void
mac_tx_ring_update(mac_handle_t mh, mac_ring_handle_t rh)
{
	i_mac_tx_srs_notify((mac_impl_t *)mh, rh);
}

/* LINK STATE */
/*
 * Notify the MAC layer about a link state change
 */
void
mac_link_update(mac_handle_t mh, link_state_t link)
{
	mac_impl_t	*mip = (mac_impl_t *)mh;

	/*
	 * Save the link state.
	 */
	mip->mi_lowlinkstate = link;

	/*
	 * Send a MAC_NOTE_LOWLINK notification.  This tells the notification
	 * thread to deliver both lower and upper notifications.
	 */
	i_mac_notify(mip, MAC_NOTE_LOWLINK);
}

/*
 * Notify the MAC layer about a link state change due to bridging.
 */
void
mac_link_redo(mac_handle_t mh, link_state_t link)
{
	mac_impl_t	*mip = (mac_impl_t *)mh;

	/*
	 * Save the link state.
	 */
	mip->mi_linkstate = link;

	/*
	 * Send a MAC_NOTE_LINK notification.  Only upper notifications are
	 * made.
	 */
	i_mac_notify(mip, MAC_NOTE_LINK);
}

/* MINOR NODE HANDLING */

/*
 * Given a dev_t, return the instance number (PPA) associated with it.
 * Drivers can use this in their getinfo(9e) implementation to lookup
 * the instance number (i.e. PPA) of the device, to use as an index to
 * their own array of soft state structures.
 *
 * Returns -1 on error.
 */
int
mac_devt_to_instance(dev_t devt)
{
	return (dld_devt_to_instance(devt));
}

/*
 * Drivers that make use of the private minor number space are expected to
 * provide their own getinfo(9e) entry point. This function simply forwards
 * to the default MAC framework getinfo(9e) implementation as a convenience
 * if they don't need any special mapping (mac instance != ddi_get_instance())
 */
int
mac_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg, void **resp)
{
	return (dld_getinfo(dip, cmd, arg, resp));
}

/*
 * This function returns the first minor number that is available for
 * driver private use.  All minor numbers smaller than this are
 * reserved for GLDv3 use.
 */
minor_t
mac_private_minor(void)
{
	return (MAC_PRIVATE_MINOR);
}

/* OTHER CONTROL INFORMATION */

/*
 * A driver notified us that its primary MAC address has changed.
 */
void
mac_unicst_update(mac_handle_t mh, const uint8_t *addr)
{
	mac_impl_t	*mip = (mac_impl_t *)mh;

	if (mip->mi_type->mt_addr_length == 0)
		return;

	i_mac_perim_enter(mip);

	/*
	 * If address changes, freshen the MAC address value and update
	 * all MAC clients that share this MAC address.
	 */
	if (bcmp(addr, mip->mi_addr, mip->mi_type->mt_addr_length) != 0) {
		mac_freshen_macaddr(mac_find_macaddr(mip, mip->mi_addr),
		    (uint8_t *)addr);
	}

	i_mac_perim_exit(mip);

	/*
	 * Send a MAC_NOTE_UNICST notification.
	 */
	i_mac_notify(mip, MAC_NOTE_UNICST);
}

void
mac_dst_update(mac_handle_t mh, const uint8_t *addr)
{
	mac_impl_t	*mip = (mac_impl_t *)mh;

	if (mip->mi_type->mt_addr_length == 0)
		return;

	i_mac_perim_enter(mip);
	bcopy(addr, mip->mi_dstaddr, mip->mi_type->mt_addr_length);
	i_mac_perim_exit(mip);
	i_mac_notify(mip, MAC_NOTE_DEST);
}

/*
 * MAC plugin information changed.
 */
int
mac_pdata_update(mac_handle_t mh, void *mac_pdata, size_t dsize)
{
	mac_impl_t	*mip = (mac_impl_t *)mh;

	/*
	 * Verify that the plugin supports MAC plugin data and that the
	 * supplied data is valid.
	 */
	if (!(mip->mi_type->mt_ops.mtops_ops & MTOPS_PDATA_VERIFY))
		return (EINVAL);
	if (!mip->mi_type->mt_ops.mtops_pdata_verify(mac_pdata, dsize))
		return (EINVAL);

	if (mip->mi_pdata != NULL)
		kmem_free(mip->mi_pdata, mip->mi_pdata_size);

	mip->mi_pdata = kmem_alloc(dsize, KM_SLEEP);
	bcopy(mac_pdata, mip->mi_pdata, dsize);
	mip->mi_pdata_size = dsize;

	/*
	 * Since the MAC plugin data is used to construct MAC headers that
	 * were cached in fast-path headers, we need to flush fast-path
	 * information for links associated with this mac.
	 */
	i_mac_notify(mip, MAC_NOTE_FASTPATH_FLUSH);
	return (0);
}

/*
 * The mac provider or mac frameowrk calls this function when it wants
 * to notify upstream consumers that the capabilities have changed and
 * that they should modify their own internal state accordingly.
 *
 * We currently have no regard for the fact that a provider could
 * decide to drop capabilities which would invalidate pending traffic.
 * For example, if one was to disable the Tx checksum offload while
 * TCP/IP traffic was being sent by mac clients relying on that
 * feature, then those packets would hit the write with missing or
 * partial checksums. A proper solution involves not only providing
 * notfication, but also performing client quiescing. That is, a capab
 * change should be treated as an atomic transaction that forms a
 * barrier between traffic relying on the current capabs and traffic
 * relying on the new capabs. In practice, simnet is currently the
 * only provider that could hit this, and it's an easily avoidable
 * situation (and at worst it should only lead to some dropped
 * packets). But if we ever want better on-the-fly capab change to
 * actual hardware providers, then we should give this update
 * mechanism a proper implementation.
 */
void
mac_capab_update(mac_handle_t mh)
{
	/*
	 * Send a MAC_NOTE_CAPAB_CHG notification to alert upstream
	 * clients to renegotiate capabilities.
	 */
	i_mac_notify((mac_impl_t *)mh, MAC_NOTE_CAPAB_CHG);
}

/*
 * Used by normal drivers to update the max sdu size.
 * We need to handle the case of a smaller mi_sdu_multicast
 * since this is called by mac_set_mtu() even for drivers that
 * have differing unicast and multicast mtu and we don't want to
 * increase the multicast mtu by accident in that case.
 */
int
mac_maxsdu_update(mac_handle_t mh, uint_t sdu_max)
{
	mac_impl_t	*mip = (mac_impl_t *)mh;

	if (sdu_max == 0 || sdu_max < mip->mi_sdu_min)
		return (EINVAL);
	mip->mi_sdu_max = sdu_max;
	if (mip->mi_sdu_multicast > mip->mi_sdu_max)
		mip->mi_sdu_multicast = mip->mi_sdu_max;

	/* Send a MAC_NOTE_SDU_SIZE notification. */
	i_mac_notify(mip, MAC_NOTE_SDU_SIZE);
	return (0);
}

/*
 * Version of the above function that is used by drivers that have a different
 * max sdu size for multicast/broadcast vs. unicast.
 */
int
mac_maxsdu_update2(mac_handle_t mh, uint_t sdu_max, uint_t sdu_multicast)
{
	mac_impl_t	*mip = (mac_impl_t *)mh;

	if (sdu_max == 0 || sdu_max < mip->mi_sdu_min)
		return (EINVAL);
	if (sdu_multicast == 0)
		sdu_multicast = sdu_max;
	if (sdu_multicast > sdu_max || sdu_multicast < mip->mi_sdu_min)
		return (EINVAL);
	mip->mi_sdu_max = sdu_max;
	mip->mi_sdu_multicast = sdu_multicast;

	/* Send a MAC_NOTE_SDU_SIZE notification. */
	i_mac_notify(mip, MAC_NOTE_SDU_SIZE);
	return (0);
}

static void
mac_ring_intr_retarget(mac_group_t *group, mac_ring_t *ring)
{
	mac_client_impl_t *mcip;
	flow_entry_t *flent;
	mac_soft_ring_set_t *mac_rx_srs;
	mac_cpus_t *srs_cpu;
	int i;

	if (((mcip = MAC_GROUP_ONLY_CLIENT(group)) != NULL) &&
	    (!ring->mr_info.mri_intr.mi_ddi_shared)) {
		/* interrupt can be re-targeted */
		ASSERT(group->mrg_state == MAC_GROUP_STATE_RESERVED);
		flent = mcip->mci_flent;
		if (ring->mr_type == MAC_RING_TYPE_RX) {
			for (i = 0; i < flent->fe_rx_srs_cnt; i++) {
				mac_rx_srs = flent->fe_rx_srs[i];
				if (mac_rx_srs->srs_ring != ring)
					continue;
				srs_cpu = &mac_rx_srs->srs_cpu;
				mutex_enter(&cpu_lock);
				mac_rx_srs_retarget_intr(mac_rx_srs,
				    srs_cpu->mc_rx_intr_cpu);
				mutex_exit(&cpu_lock);
				break;
			}
		} else {
			if (flent->fe_tx_srs != NULL) {
				mutex_enter(&cpu_lock);
				mac_tx_srs_retarget_intr(
				    flent->fe_tx_srs);
				mutex_exit(&cpu_lock);
			}
		}
	}
}

/*
 * Clients like aggr create pseudo rings (mac_ring_t) and expose them to
 * their clients. There is a 1-1 mapping pseudo ring and the hardware
 * ring. ddi interrupt handles are exported from the hardware ring to
 * the pseudo ring. Thus when the interrupt handle changes, clients of
 * aggr that are using the handle need to use the new handle and
 * re-target their interrupts.
 */
static void
mac_pseudo_ring_intr_retarget(mac_impl_t *mip, mac_ring_t *ring,
    ddi_intr_handle_t ddh)
{
	mac_ring_t *pring;
	mac_group_t *pgroup;
	mac_impl_t *pmip;
	char macname[MAXNAMELEN];
	mac_perim_handle_t p_mph;
	uint64_t saved_gen_num;

again:
	pring = (mac_ring_t *)ring->mr_prh;
	pgroup = (mac_group_t *)pring->mr_gh;
	pmip = (mac_impl_t *)pgroup->mrg_mh;
	saved_gen_num = ring->mr_gen_num;
	(void) strlcpy(macname, pmip->mi_name, MAXNAMELEN);
	/*
	 * We need to enter aggr's perimeter. The locking hierarchy
	 * dictates that aggr's perimeter should be entered first
	 * and then the port's perimeter. So drop the port's
	 * perimeter, enter aggr's and then re-enter port's
	 * perimeter.
	 */
	i_mac_perim_exit(mip);
	/*
	 * While we know pmip is the aggr's mip, there is a
	 * possibility that aggr could have unregistered by
	 * the time we exit port's perimeter (mip) and
	 * enter aggr's perimeter (pmip). To avoid that
	 * scenario, enter aggr's perimeter using its name.
	 */
	if (mac_perim_enter_by_macname(macname, &p_mph) != 0)
		return;
	i_mac_perim_enter(mip);
	/*
	 * Check if the ring got assigned to another aggregation before
	 * be could enter aggr's and the port's perimeter. When a ring
	 * gets deleted from an aggregation, it calls mac_stop_ring()
	 * which increments the generation number. So checking
	 * generation number will be enough.
	 */
	if (ring->mr_gen_num != saved_gen_num && ring->mr_prh != NULL) {
		i_mac_perim_exit(mip);
		mac_perim_exit(p_mph);
		i_mac_perim_enter(mip);
		goto again;
	}

	/* Check if pseudo ring is still present */
	if (ring->mr_prh != NULL) {
		pring->mr_info.mri_intr.mi_ddi_handle = ddh;
		pring->mr_info.mri_intr.mi_ddi_shared =
		    ring->mr_info.mri_intr.mi_ddi_shared;
		if (ddh != NULL)
			mac_ring_intr_retarget(pgroup, pring);
	}
	i_mac_perim_exit(mip);
	mac_perim_exit(p_mph);
}
/*
 * API called by driver to provide new interrupt handle for TX/RX rings.
 * This usually happens when IRM (Interrupt Resource Manangement)
 * framework either gives the driver more MSI-x interrupts or takes
 * away MSI-x interrupts from the driver.
 */
void
mac_ring_intr_set(mac_ring_handle_t mrh, ddi_intr_handle_t ddh)
{
	mac_ring_t	*ring = (mac_ring_t *)mrh;
	mac_group_t	*group = (mac_group_t *)ring->mr_gh;
	mac_impl_t	*mip = (mac_impl_t *)group->mrg_mh;

	i_mac_perim_enter(mip);
	ring->mr_info.mri_intr.mi_ddi_handle = ddh;
	if (ddh == NULL) {
		/* Interrupts being reset */
		ring->mr_info.mri_intr.mi_ddi_shared = B_FALSE;
		if (ring->mr_prh != NULL) {
			mac_pseudo_ring_intr_retarget(mip, ring, ddh);
			return;
		}
	} else {
		/* New interrupt handle */
		mac_compare_ddi_handle(mip->mi_rx_groups,
		    mip->mi_rx_group_count, ring);
		if (!ring->mr_info.mri_intr.mi_ddi_shared) {
			mac_compare_ddi_handle(mip->mi_tx_groups,
			    mip->mi_tx_group_count, ring);
		}
		if (ring->mr_prh != NULL) {
			mac_pseudo_ring_intr_retarget(mip, ring, ddh);
			return;
		} else {
			mac_ring_intr_retarget(group, ring);
		}
	}
	i_mac_perim_exit(mip);
}

/* PRIVATE FUNCTIONS, FOR INTERNAL USE ONLY */

/*
 * Updates the mac_impl structure with the current state of the link
 */
static void
i_mac_log_link_state(mac_impl_t *mip)
{
	/*
	 * If no change, then it is not interesting.
	 */
	if (mip->mi_lastlowlinkstate == mip->mi_lowlinkstate)
		return;

	switch (mip->mi_lowlinkstate) {
	case LINK_STATE_UP:
		if (mip->mi_type->mt_ops.mtops_ops & MTOPS_LINK_DETAILS) {
			char det[200];

			mip->mi_type->mt_ops.mtops_link_details(det,
			    sizeof (det), (mac_handle_t)mip, mip->mi_pdata);

			cmn_err(CE_NOTE, "!%s link up, %s", mip->mi_name, det);
		} else {
			cmn_err(CE_NOTE, "!%s link up", mip->mi_name);
		}
		break;

	case LINK_STATE_DOWN:
		/*
		 * Only transitions from UP to DOWN are interesting
		 */
		if (mip->mi_lastlowlinkstate != LINK_STATE_UNKNOWN)
			cmn_err(CE_NOTE, "!%s link down", mip->mi_name);
		break;

	case LINK_STATE_UNKNOWN:
		/*
		 * This case is normally not interesting.
		 */
		break;
	}
	mip->mi_lastlowlinkstate = mip->mi_lowlinkstate;
}

/*
 * Main routine for the callbacks notifications thread
 */
static void
i_mac_notify_thread(void *arg)
{
	mac_impl_t	*mip = arg;
	callb_cpr_t	cprinfo;
	mac_cb_t	*mcb;
	mac_cb_info_t	*mcbi;
	mac_notify_cb_t	*mncb;

	mcbi = &mip->mi_notify_cb_info;
	CALLB_CPR_INIT(&cprinfo, mcbi->mcbi_lockp, callb_generic_cpr,
	    "i_mac_notify_thread");

	mutex_enter(mcbi->mcbi_lockp);

	for (;;) {
		uint32_t	bits;
		uint32_t	type;

		bits = mip->mi_notify_bits;
		if (bits == 0) {
			CALLB_CPR_SAFE_BEGIN(&cprinfo);
			cv_wait(&mcbi->mcbi_cv, mcbi->mcbi_lockp);
			CALLB_CPR_SAFE_END(&cprinfo, mcbi->mcbi_lockp);
			continue;
		}
		mip->mi_notify_bits = 0;
		if ((bits & (1 << MAC_NNOTE)) != 0) {
			/* request to quit */
			ASSERT(mip->mi_state_flags & MIS_DISABLED);
			break;
		}

		mutex_exit(mcbi->mcbi_lockp);

		/*
		 * Log link changes on the actual link, but then do reports on
		 * synthetic state (if part of a bridge).
		 */
		if ((bits & (1 << MAC_NOTE_LOWLINK)) != 0) {
			link_state_t newstate;
			mac_handle_t mh;

			i_mac_log_link_state(mip);
			newstate = mip->mi_lowlinkstate;
			if (mip->mi_bridge_link != NULL) {
				mutex_enter(&mip->mi_bridge_lock);
				if ((mh = mip->mi_bridge_link) != NULL) {
					newstate = mac_bridge_ls_cb(mh,
					    newstate);
				}
				mutex_exit(&mip->mi_bridge_lock);
			}
			if (newstate != mip->mi_linkstate) {
				mip->mi_linkstate = newstate;
				bits |= 1 << MAC_NOTE_LINK;
			}
		}

		/*
		 * Depending on which capabs have changed, the Tx
		 * checksum flags may also need to be updated.
		 */
		if ((bits & (1 << MAC_NOTE_CAPAB_CHG)) != 0) {
			mac_perim_handle_t mph;
			mac_handle_t mh = (mac_handle_t)mip;

			mac_perim_enter_by_mh(mh, &mph);
			mip->mi_tx_cksum_flags = mac_features_to_flags(mh);
			mac_perim_exit(mph);
		}

		/*
		 * Do notification callbacks for each notification type.
		 */
		for (type = 0; type < MAC_NNOTE; type++) {
			if ((bits & (1 << type)) == 0) {
				continue;
			}

			if (mac_notify_cb_list[type] != NULL)
				(*mac_notify_cb_list[type])(mip);

			/*
			 * Walk the list of notifications.
			 */
			MAC_CALLBACK_WALKER_INC(&mip->mi_notify_cb_info);
			for (mcb = mip->mi_notify_cb_list; mcb != NULL;
			    mcb = mcb->mcb_nextp) {
				mncb = (mac_notify_cb_t *)mcb->mcb_objp;
				mncb->mncb_fn(mncb->mncb_arg, type);
			}
			MAC_CALLBACK_WALKER_DCR(&mip->mi_notify_cb_info,
			    &mip->mi_notify_cb_list);
		}

		mutex_enter(mcbi->mcbi_lockp);
	}

	mip->mi_state_flags |= MIS_NOTIFY_DONE;
	cv_broadcast(&mcbi->mcbi_cv);

	/* CALLB_CPR_EXIT drops the lock */
	CALLB_CPR_EXIT(&cprinfo);
	thread_exit();
}

/*
 * Signal the i_mac_notify_thread asking it to quit.
 * Then wait till it is done.
 */
void
i_mac_notify_exit(mac_impl_t *mip)
{
	mac_cb_info_t	*mcbi;

	mcbi = &mip->mi_notify_cb_info;

	mutex_enter(mcbi->mcbi_lockp);
	mip->mi_notify_bits = (1 << MAC_NNOTE);
	cv_broadcast(&mcbi->mcbi_cv);


	while ((mip->mi_notify_thread != NULL) &&
	    !(mip->mi_state_flags & MIS_NOTIFY_DONE)) {
		cv_wait(&mcbi->mcbi_cv, mcbi->mcbi_lockp);
	}

	/* Necessary clean up before doing kmem_cache_free */
	mip->mi_state_flags &= ~MIS_NOTIFY_DONE;
	mip->mi_notify_bits = 0;
	mip->mi_notify_thread = NULL;
	mutex_exit(mcbi->mcbi_lockp);
}

/*
 * Entry point invoked by drivers to dynamically add a ring to an
 * existing group.
 */
int
mac_group_add_ring(mac_group_handle_t gh, int index)
{
	mac_group_t *group = (mac_group_t *)gh;
	mac_impl_t *mip = (mac_impl_t *)group->mrg_mh;
	int ret;

	i_mac_perim_enter(mip);
	ret = i_mac_group_add_ring(group, NULL, index);
	i_mac_perim_exit(mip);
	return (ret);
}

/*
 * Entry point invoked by drivers to dynamically remove a ring
 * from an existing group. The specified ring handle must no longer
 * be used by the driver after a call to this function.
 */
void
mac_group_rem_ring(mac_group_handle_t gh, mac_ring_handle_t rh)
{
	mac_group_t *group = (mac_group_t *)gh;
	mac_impl_t *mip = (mac_impl_t *)group->mrg_mh;

	i_mac_perim_enter(mip);
	i_mac_group_rem_ring(group, (mac_ring_t *)rh, B_TRUE);
	i_mac_perim_exit(mip);
}

/*
 * mac_prop_info_*() callbacks called from the driver's prefix_propinfo()
 * entry points.
 */

void
mac_prop_info_set_default_uint8(mac_prop_info_handle_t ph, uint8_t val)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;

	/* nothing to do if the caller doesn't want the default value */
	if (pr->pr_default == NULL)
		return;

	ASSERT(pr->pr_default_size >= sizeof (uint8_t));

	*(uint8_t *)(pr->pr_default) = val;
	pr->pr_flags |= MAC_PROP_INFO_DEFAULT;
}

void
mac_prop_info_set_default_uint64(mac_prop_info_handle_t ph, uint64_t val)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;

	/* nothing to do if the caller doesn't want the default value */
	if (pr->pr_default == NULL)
		return;

	ASSERT(pr->pr_default_size >= sizeof (uint64_t));

	bcopy(&val, pr->pr_default, sizeof (val));

	pr->pr_flags |= MAC_PROP_INFO_DEFAULT;
}

void
mac_prop_info_set_default_uint32(mac_prop_info_handle_t ph, uint32_t val)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;

	/* nothing to do if the caller doesn't want the default value */
	if (pr->pr_default == NULL)
		return;

	ASSERT(pr->pr_default_size >= sizeof (uint32_t));

	bcopy(&val, pr->pr_default, sizeof (val));

	pr->pr_flags |= MAC_PROP_INFO_DEFAULT;
}

void
mac_prop_info_set_default_str(mac_prop_info_handle_t ph, const char *str)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;

	/* nothing to do if the caller doesn't want the default value */
	if (pr->pr_default == NULL)
		return;

	if (strlen(str) >= pr->pr_default_size)
		pr->pr_errno = ENOBUFS;
	else
		(void) strlcpy(pr->pr_default, str, pr->pr_default_size);
	pr->pr_flags |= MAC_PROP_INFO_DEFAULT;
}

void
mac_prop_info_set_default_link_flowctrl(mac_prop_info_handle_t ph,
    link_flowctrl_t val)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;

	/* nothing to do if the caller doesn't want the default value */
	if (pr->pr_default == NULL)
		return;

	ASSERT(pr->pr_default_size >= sizeof (link_flowctrl_t));

	bcopy(&val, pr->pr_default, sizeof (val));

	pr->pr_flags |= MAC_PROP_INFO_DEFAULT;
}

void
mac_prop_info_set_default_fec(mac_prop_info_handle_t ph, link_fec_t val)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;

	/* nothing to do if the caller doesn't want the default value */
	if (pr->pr_default == NULL)
		return;

	ASSERT(pr->pr_default_size >= sizeof (link_fec_t));

	bcopy(&val, pr->pr_default, sizeof (val));

	pr->pr_flags |= MAC_PROP_INFO_DEFAULT;
}

void
mac_prop_info_set_range_uint32(mac_prop_info_handle_t ph, uint32_t min,
    uint32_t max)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;
	mac_propval_range_t *range = pr->pr_range;
	mac_propval_uint32_range_t *range32;

	/* nothing to do if the caller doesn't want the range info */
	if (range == NULL)
		return;

	if (pr->pr_range_cur_count++ == 0) {
		/* first range */
		pr->pr_flags |= MAC_PROP_INFO_RANGE;
		range->mpr_type = MAC_PROPVAL_UINT32;
	} else {
		/* all ranges of a property should be of the same type */
		ASSERT(range->mpr_type == MAC_PROPVAL_UINT32);
		if (pr->pr_range_cur_count > range->mpr_count) {
			pr->pr_errno = ENOSPC;
			return;
		}
	}

	range32 = range->mpr_range_uint32;
	range32[pr->pr_range_cur_count - 1].mpur_min = min;
	range32[pr->pr_range_cur_count - 1].mpur_max = max;
}

void
mac_prop_info_set_perm(mac_prop_info_handle_t ph, uint8_t perm)
{
	mac_prop_info_state_t *pr = (mac_prop_info_state_t *)ph;

	pr->pr_perm = perm;
	pr->pr_flags |= MAC_PROP_INFO_PERM;
}

void
mac_hcksum_get(const mblk_t *mp, uint32_t *start, uint32_t *stuff,
    uint32_t *end, uint32_t *value, uint32_t *flags_ptr)
{
	uint32_t flags;

	ASSERT(DB_TYPE(mp) == M_DATA);

	flags = DB_CKSUMFLAGS(mp) & HCK_FLAGS;
	if ((flags & (HCK_PARTIALCKSUM | HCK_FULLCKSUM)) != 0) {
		if (value != NULL)
			*value = (uint32_t)DB_CKSUM16(mp);
		if ((flags & HCK_PARTIALCKSUM) != 0) {
			if (start != NULL)
				*start = (uint32_t)DB_CKSUMSTART(mp);
			if (stuff != NULL)
				*stuff = (uint32_t)DB_CKSUMSTUFF(mp);
			if (end != NULL)
				*end = (uint32_t)DB_CKSUMEND(mp);
		}
	}

	if (flags_ptr != NULL)
		*flags_ptr = flags;
}

void
mac_hcksum_set(mblk_t *mp, uint32_t start, uint32_t stuff, uint32_t end,
    uint32_t value, uint32_t flags)
{
	ASSERT(DB_TYPE(mp) == M_DATA);

	DB_CKSUMSTART(mp) = (intptr_t)start;
	DB_CKSUMSTUFF(mp) = (intptr_t)stuff;
	DB_CKSUMEND(mp) = (intptr_t)end;
	DB_CKSUMFLAGS(mp) = (uint16_t)flags;
	DB_CKSUM16(mp) = (uint16_t)value;
}

void
mac_hcksum_clone(const mblk_t *src, mblk_t *dst)
{
	ASSERT3U(DB_TYPE(src), ==, M_DATA);
	ASSERT3U(DB_TYPE(dst), ==, M_DATA);

	/*
	 * Do these assignments unconditionally, rather than only when
	 * flags is non-zero. This protects a situation where zeroed
	 * hcksum data does not make the jump onto an mblk_t with
	 * stale data in those fields. It's important to copy all
	 * possible flags (HCK_* as well as HW_*) and not just the
	 * checksum specific flags. Dropping flags during a clone
	 * could result in dropped packets. If the caller has good
	 * reason to drop those flags then it should do it manually,
	 * after the clone.
	 */
	DB_CKSUMFLAGS(dst) = DB_CKSUMFLAGS(src);
	DB_CKSUMSTART(dst) = DB_CKSUMSTART(src);
	DB_CKSUMSTUFF(dst) = DB_CKSUMSTUFF(src);
	DB_CKSUMEND(dst) = DB_CKSUMEND(src);
	DB_CKSUM16(dst) = DB_CKSUM16(src);
	DB_LSOMSS(dst) = DB_LSOMSS(src);
}

void
mac_lso_get(mblk_t *mp, uint32_t *mss, uint32_t *flags)
{
	ASSERT(DB_TYPE(mp) == M_DATA);

	if (flags != NULL) {
		*flags = DB_CKSUMFLAGS(mp) & HW_LSO;
		if ((*flags != 0) && (mss != NULL))
			*mss = (uint32_t)DB_LSOMSS(mp);
	}
}

void
mac_transceiver_info_set_present(mac_transceiver_info_t *infop,
    boolean_t present)
{
	infop->mti_present = present;
}

void
mac_transceiver_info_set_usable(mac_transceiver_info_t *infop,
    boolean_t usable)
{
	infop->mti_usable = usable;
}

static bool
mac_parse_is_ipv6eh(uint8_t id)
{
	switch (id) {
	case IPPROTO_HOPOPTS:
	case IPPROTO_ROUTING:
	case IPPROTO_FRAGMENT:
	case IPPROTO_AH:
	case IPPROTO_DSTOPTS:
	case IPPROTO_MH:
	case IPPROTO_HIP:
	case IPPROTO_SHIM6:
		/* Currently known extension headers */
		return (true);
	case IPPROTO_ESP:
		/*
		 * While the IANA protocol numbers listing notes ESP as an IPv6
		 * extension header, we cannot effectively parse it like one.
		 *
		 * For now, mac_ether_offload_info() will report it as the L4
		 * protocol for a parsed packet containing this EH.
		 */
	default:
		return (false);
	}
}

typedef struct mac_mblk_cursor {
	mblk_t	*mmc_head;
	mblk_t	*mmc_cur;
	size_t	mmc_off_total;
	size_t	mmc_off_mp;
} mac_mblk_cursor_t;

static void mac_mmc_advance(mac_mblk_cursor_t *, size_t);
static void mac_mmc_reset(mac_mblk_cursor_t *);

static void
mac_mmc_init(mac_mblk_cursor_t *cursor, mblk_t *mp)
{
	cursor->mmc_head = mp;
	mac_mmc_reset(cursor);
}

static void
mac_mmc_reset(mac_mblk_cursor_t *cursor)
{
	ASSERT(cursor->mmc_head != NULL);

	cursor->mmc_cur = cursor->mmc_head;
	cursor->mmc_off_total = cursor->mmc_off_mp = 0;

	/* Advance past any zero-length mblks at head */
	mac_mmc_advance(cursor, 0);
}

static inline size_t
mac_mmc_mp_left(const mac_mblk_cursor_t *cursor)
{
	if (cursor->mmc_cur != NULL) {
		const size_t mp_len = MBLKL(cursor->mmc_cur);

		ASSERT3U(mp_len, >=, cursor->mmc_off_mp);

		return (mp_len - cursor->mmc_off_mp);
	} else {
		return (0);
	}
}

static inline uint8_t *
mac_mmc_mp_ptr(const mac_mblk_cursor_t *cursor)
{
	return (cursor->mmc_cur->b_rptr + cursor->mmc_off_mp);
}

static inline size_t
mac_mmc_offset(const mac_mblk_cursor_t *cursor)
{
	return (cursor->mmc_off_total);
}

/*
 * Advance cursor forward `len` bytes.
 *
 * The length to advance must be no greater than the number of bytes remaining
 * in the current mblk.  If the position reaches (exactly) the end of the
 * current mblk, the cursor will be pushed forward to the next non-zero-length
 * mblk in the chain.
 */
static inline void
mac_mmc_advance(mac_mblk_cursor_t *cursor, size_t len)
{
	ASSERT(cursor->mmc_cur != NULL);

	const size_t mp_len = MBLKL(cursor->mmc_cur);

	ASSERT3U(cursor->mmc_off_mp + len, <=, mp_len);

	cursor->mmc_off_total += len;
	cursor->mmc_off_mp += len;

	if (cursor->mmc_off_mp == mp_len) {
		cursor->mmc_off_mp = 0;
		cursor->mmc_cur = cursor->mmc_cur->b_cont;
	}

	/* Skip over any 0-length mblks */
	while (cursor->mmc_cur != NULL && MBLKL(cursor->mmc_cur) == 0) {
		cursor->mmc_cur = cursor->mmc_cur->b_cont;
	}
}

/*
 * Attempt to seek to byte offset `off` in mblk chain.
 *
 * Returns true if the offset is <= the total chain length.
 */
static bool
mac_mmc_seek(mac_mblk_cursor_t *cursor, const size_t off)
{
	ASSERT(cursor->mmc_head != NULL);

	if (off == cursor->mmc_off_total) {
		/*
		 * Any prior init, reset, or seek operation will have advanced
		 * past any zero-length mblks, making this short-circuit safe.
		 */
		return (true);
	} else if (off < cursor->mmc_off_total) {
		/* Rewind to beginning if offset precedes current position */
		mac_mmc_reset(cursor);
	}

	size_t seek_left = off - cursor->mmc_off_total;
	while (cursor->mmc_cur != NULL) {
		const size_t mp_left = mac_mmc_mp_left(cursor);

		if (mp_left > seek_left) {
			/* Target position is within current mblk */
			cursor->mmc_off_mp += seek_left;
			cursor->mmc_off_total += seek_left;
			return (true);
		}

		/* Move on to the next mblk... */
		mac_mmc_advance(cursor, mp_left);
		seek_left -= mp_left;
	}

	/*
	 * We have reached the end of the mblk chain, but there is a chance that
	 * it corresponds to the target seek position.
	 */
	return (cursor->mmc_off_total == off);
}

/*
 * Attempt to read uint8_t at offset `pos` in mblk chain.
 *
 * Returns true (and sets value in `out`) if the offset is within the chain.
 */
static bool
mac_mmc_get_uint8(mac_mblk_cursor_t *cursor, size_t pos, uint8_t *out)
{
	if (!mac_mmc_seek(cursor, pos)) {
		return (false);
	}

	if (mac_mmc_mp_left(cursor) != 0) {
		*out = *(mac_mmc_mp_ptr(cursor));
		mac_mmc_advance(cursor, 1);
		return (true);
	}

	return (false);
}

/*
 * Attempt to read uint16_t at offset `pos` in mblk chain.  The two
 * network-order bytes are converted into a host-order value.
 *
 * Returns true (and sets value in `out`) if the 16-bit region specified by the
 * offset is within the chain.
 */
static bool
mac_mmc_get_uint16(mac_mblk_cursor_t *cursor, size_t pos, uint16_t *out)
{
	if (!mac_mmc_seek(cursor, pos)) {
		return (false);
	}

	const size_t mp_left = mac_mmc_mp_left(cursor);
	uint16_t result = 0;

	if (mp_left >= 2) {
		uint8_t *bp = mac_mmc_mp_ptr(cursor);

		result = (uint16_t)bp[0] << 8;
		result |= bp[1];
		mac_mmc_advance(cursor, 2);
		*out = result;
		return (true);
	} else if (mp_left == 1) {
		result = (uint16_t)*(mac_mmc_mp_ptr(cursor));
		mac_mmc_advance(cursor, 1);

		if (mac_mmc_mp_left(cursor) == 0) {
			return (false);
		}

		result = result << 8;
		result |= (uint16_t)*(mac_mmc_mp_ptr(cursor));
		mac_mmc_advance(cursor, 1);
		*out = result;
		return (true);
	}

	return (false);
}

/*
 * Attempt to read `count` bytes at offset `pos` in mblk chain.
 *
 * Returns true (and copies data to `out`) if `count` length region is available
 * at offset within the chain.
 */
static bool
mac_mmc_get_bytes(mac_mblk_cursor_t *cursor, size_t pos, uint8_t *out,
    size_t count)
{
	if (!mac_mmc_seek(cursor, pos)) {
		return (false);
	}

	while (count > 0) {
		const size_t mp_left = mac_mmc_mp_left(cursor);

		if (mp_left == 0) {
			return (false);
		}
		const size_t to_copy = MIN(mp_left, count);

		bcopy(mac_mmc_mp_ptr(cursor), out, to_copy);
		out += to_copy;
		mac_mmc_advance(cursor, to_copy);
		count -= to_copy;
	}
	return (true);
}

/*
 * Attempt to parse ethernet header (VLAN or not) from mblk chain.
 *
 * Returns true if header was successfully parsed.  Parsing will begin at
 * current offset of `cursor`.  Any non-NULL arguments for VLAN, SAP, and header
 * size will be populated on success.  A value of MEOI_VLAN_TCI_INVALID will be
 * reported for the TCI if the header does not bear VLAN infomation.
 */
static bool
mac_mmc_parse_ether(mac_mblk_cursor_t *cursor, uint8_t *dst_addrp,
    uint32_t *vlan_tcip, uint16_t *ethertypep, uint16_t *hdr_sizep)
{
	const size_t l2_off = mac_mmc_offset(cursor);

	if (dst_addrp != NULL) {
		if (!mac_mmc_get_bytes(cursor, l2_off, dst_addrp, ETHERADDRL)) {
			return (false);
		}
	}

	uint16_t ethertype = 0;
	if (!mac_mmc_get_uint16(cursor,
	    l2_off + offsetof(struct ether_header, ether_type), &ethertype)) {
		return (false);
	}

	uint32_t tci = MEOI_VLAN_TCI_INVALID;
	uint16_t hdrsize = sizeof (struct ether_header);

	if (ethertype == ETHERTYPE_VLAN) {
		uint16_t tci_val;

		if (!mac_mmc_get_uint16(cursor,
		    l2_off + offsetof(struct ether_vlan_header, ether_tci),
		    &tci_val)) {
			return (false);
		}
		if (!mac_mmc_get_uint16(cursor,
		    l2_off + offsetof(struct ether_vlan_header, ether_type),
		    &ethertype)) {
			return (false);
		}
		hdrsize = sizeof (struct ether_vlan_header);
		tci = (uint32_t)tci_val;
	}

	if (vlan_tcip != NULL) {
		*vlan_tcip = tci;
	}
	if (ethertypep != NULL) {
		*ethertypep = ethertype;
	}
	if (hdr_sizep != NULL) {
		*hdr_sizep = hdrsize;
	}
	return (true);
}

/*
 * Attempt to parse L3 protocol header from mblk chain.
 *
 * The SAP/ethertype of the containing header must be specified by the caller.
 *
 * Returns true if header was successfully parsed.  Parsing will begin at
 * current offset of `cursor`.  Any non-NULL arguments for IP protocol and
 * header size will be populated on success.
 */
static bool
mac_mmc_parse_l3(mac_mblk_cursor_t *cursor, uint16_t l3_sap, uint8_t *ipprotop,
    mac_ether_offload_flags_t *fragp, uint16_t *hdr_sizep)
{
	const size_t l3_off = mac_mmc_offset(cursor);

	if (l3_sap == ETHERTYPE_IP) {
		uint8_t verlen, ipproto;
		uint16_t frag_off;

		if (!mac_mmc_get_uint8(cursor, l3_off, &verlen)) {
			return (false);
		}
		verlen &= 0x0f;
		if (verlen < 5 || verlen > 0x0f) {
			return (false);
		}

		if (!mac_mmc_get_uint16(cursor,
		    l3_off + offsetof(ipha_t, ipha_fragment_offset_and_flags),
		    &frag_off)) {
			return (false);
		}

		if (!mac_mmc_get_uint8(cursor,
		    l3_off + offsetof(ipha_t, ipha_protocol), &ipproto)) {
			return (false);
		}

		if (ipprotop != NULL) {
			*ipprotop = ipproto;
		}
		if (fragp != NULL) {
			mac_ether_offload_flags_t frag_flags = 0;
			if ((frag_off & IPH_MF) != 0) {
				frag_flags |= MEOI_L3_FRAG_MORE;
			}
			if ((frag_off & IPH_OFFSET) != 0) {
				frag_flags |= MEOI_L3_FRAG_OFFSET;
			}
			*fragp = frag_flags;
		}
		if (hdr_sizep != NULL) {
			*hdr_sizep = verlen * 4;
		}
		return (true);
	}
	if (l3_sap == ETHERTYPE_IPV6) {
		uint16_t ip_len = sizeof (ip6_t);
		uint8_t ipproto;
		mac_ether_offload_flags_t frag_flags = 0;

		if (!mac_mmc_get_uint8(cursor,
		    l3_off + offsetof(ip6_t, ip6_nxt), &ipproto)) {
			return (false);
		}

		/* Chase any extension headers present in packet */
		while (mac_parse_is_ipv6eh(ipproto)) {
			uint8_t len_val, next_hdr;
			uint16_t eh_len;

			const size_t hdr_off = l3_off + ip_len;
			if (!mac_mmc_get_uint8(cursor, hdr_off, &next_hdr)) {
				return (false);
			}

			if (ipproto == IPPROTO_FRAGMENT) {
				/*
				 * The Fragment extension header bears a
				 * predefined fixed length, rather than
				 * communicating it through the EH itself.
				 */
				eh_len = 8;

				uint16_t frag_off;
				if (!mac_mmc_get_uint16(cursor, hdr_off + 2,
				    &frag_off)) {
					return (false);
				}
				/* IP6F_* defines already in network order */
				frag_off = htons(frag_off);
				if ((frag_off & IP6F_MORE_FRAG) != 0) {
					frag_flags |= MEOI_L3_FRAG_MORE;
				}
				if ((frag_off & IP6F_OFF_MASK) != 0) {
					frag_flags |= MEOI_L3_FRAG_OFFSET;
				}
			} else if (ipproto == IPPROTO_AH) {
				/*
				 * The length of the IP Authentication EH is
				 * stored as (n + 2) * 32-bits, where 'n' is the
				 * recorded EH length field
				 */
				if (!mac_mmc_get_uint8(cursor, hdr_off + 1,
				    &len_val)) {
					return (false);
				}
				eh_len = ((uint16_t)len_val + 2) * 4;
			} else {
				/*
				 * All other EHs should follow the sizing
				 * formula of (n + 1) * 64-bits, where 'n' is
				 * the recorded EH length field.
				 */
				if (!mac_mmc_get_uint8(cursor, hdr_off + 1,
				    &len_val)) {
					return (false);
				}
				eh_len = ((uint16_t)len_val + 1) * 8;
			}
			/*
			 * Protect against overflow in the case of a very
			 * contrived packet.
			 */
			if ((ip_len + eh_len) < ip_len) {
				return (-1);
			}

			ipproto = next_hdr;
			ip_len += eh_len;
		}

		if (ipprotop != NULL) {
			*ipprotop = ipproto;
		}
		if (fragp != NULL) {
			*fragp = frag_flags;
		}
		if (hdr_sizep != NULL) {
			*hdr_sizep = ip_len;
		}
		return (true);
	}

	return (false);
}

/*
 * Attempt to parse L4 protocol header from mblk chain.
 *
 * The IP protocol of the containing header must be specified by the caller.
 *
 * Returns true if header was successfully parsed.  Parsing will begin at
 * current offset of `cursor`.  A non-NULL argument for header size will be
 * populated on success.
 */
static bool
mac_mmc_parse_l4(mac_mblk_cursor_t *cursor, uint8_t ipproto, uint8_t *hdr_sizep)
{
	ASSERT(hdr_sizep != NULL);

	const size_t l4_off = mac_mmc_offset(cursor);
	uint8_t tcp_doff;

	switch (ipproto) {
	case IPPROTO_TCP:
		if (!mac_mmc_get_uint8(cursor,
		    l4_off + offsetof(tcph_t, th_offset_and_rsrvd),
		    &tcp_doff)) {
			return (false);
		}
		tcp_doff = (tcp_doff & 0xf0) >> 4;
		if (tcp_doff < 5 || tcp_doff > 0xf) {
			return (false);
		}
		*hdr_sizep = tcp_doff * 4;
		return (true);
	case IPPROTO_UDP:
		*hdr_sizep = sizeof (struct udphdr);
		return (true);
	case IPPROTO_ICMP:
		/*
		 * Only count the parts of the header which are common to
		 * message types.
		 */
		*hdr_sizep = offsetof(struct icmp, icmp_hun);
		return (true);
	case IPPROTO_ICMPV6:
		*hdr_sizep = sizeof (icmp6_t);
		return (true);
	case IPPROTO_SCTP:
		*hdr_sizep = sizeof (sctp_hdr_t);
		return (true);
	default:
		return (false);
	}
}

/*
 * Parse destination MAC address and VLAN TCI (if any) from mblk chain.
 *
 * If packet ethertype does not indicate that a VLAN is present,
 * MEOI_VLAN_TCI_INVALID will be returned for the TCI.
 *
 * Returns B_TRUE if header could be parsed for destination MAC address and VLAN
 * TCI, otherwise B_FALSE.
 */
boolean_t
mac_ether_l2_info(mblk_t *mp, uint8_t *dst_addrp, uint32_t *vlan_tcip)
{
	mac_mblk_cursor_t cursor;

	mac_mmc_init(&cursor, mp);
	if (!mac_mmc_parse_ether(&cursor, dst_addrp, vlan_tcip, NULL, NULL)) {
		return (B_FALSE);
	}

	return (B_TRUE);
}

/*
 * Perform a partial parsing of offload info from a frame and/or packet.
 *
 * Beginning at the provided byte offset (`off`) in the mblk, attempt to parse
 * any offload info which has not yet been populated in `meoi`.  The contents of
 * `meoi_flags` upon entry will be considered as "already parsed", their
 * corresponding data fields will be considered valid.
 *
 * A motivating example: A non-Ethernet packet could be parsed for L3/L4 offload
 * information by setting MEOI_L2INFO_SET in `meoi_flags`, and the L3 SAP in
 * `meoi_l3_proto`. With a value in `meoi_l2hlen` that, when combined with the
 * provided `off`, will direct the parser to the start of the L3 header in the
 * mblk, the rest of the logic will be free to run.
 *
 * Alternatively, this could be used to parse the headers in an encapsulated
 * Ethernet packet by simply specifying the start of its header in `off`.
 *
 * The degree to which parsing was able to proceed is stored in `meoi_flags`.
 */
void
mac_partial_offload_info(mblk_t *mp, size_t off, mac_ether_offload_info_t *meoi)
{
	mac_mblk_cursor_t cursor;

	mac_mmc_init(&cursor, mp);

	if (!mac_mmc_seek(&cursor, off)) {
		return;
	}

	if ((meoi->meoi_flags & MEOI_L2INFO_SET) == 0) {
		uint32_t vlan_tci;
		uint16_t l2_sz, ethertype;
		if (!mac_mmc_parse_ether(&cursor, NULL, &vlan_tci, &ethertype,
		    &l2_sz)) {
			return;
		}

		meoi->meoi_flags |= MEOI_L2INFO_SET;
		meoi->meoi_l2hlen = l2_sz;
		meoi->meoi_l3proto = ethertype;
		if (vlan_tci != MEOI_VLAN_TCI_INVALID) {
			ASSERT3U(meoi->meoi_l2hlen, ==,
			    sizeof (struct ether_vlan_header));
			meoi->meoi_flags |= MEOI_VLAN_TAGGED;
		}
	}
	const size_t l2_end = off + (size_t)meoi->meoi_l2hlen;
	if (!mac_mmc_seek(&cursor, l2_end)) {
		meoi->meoi_flags &= ~MEOI_L2INFO_SET;
		return;
	}

	if ((meoi->meoi_flags & MEOI_L3INFO_SET) == 0) {
		uint8_t ipproto;
		uint16_t l3_sz;
		mac_ether_offload_flags_t frag_flags;

		if (!mac_mmc_parse_l3(&cursor, meoi->meoi_l3proto, &ipproto,
		    &frag_flags, &l3_sz)) {
			return;
		}

		/* Only the fragment-related flags should be emitted */
		ASSERT3U(frag_flags &
		    ~(MEOI_L3_FRAG_MORE | MEOI_L3_FRAG_OFFSET), ==, 0);

		meoi->meoi_l3hlen = l3_sz;
		meoi->meoi_l4proto = ipproto;
		meoi->meoi_flags |= MEOI_L3INFO_SET | frag_flags;
	}
	const size_t l3_end = l2_end + (size_t)meoi->meoi_l3hlen;
	if (!mac_mmc_seek(&cursor, l3_end)) {
		meoi->meoi_flags &= ~MEOI_L3INFO_SET;
		return;
	}

	if ((meoi->meoi_flags & MEOI_L4INFO_SET) == 0) {
		if ((meoi->meoi_flags & MEOI_L3_FRAG_OFFSET) != 0) {
			/*
			 * If this packet is a fragment, and is offset into the
			 * data (not at the "head"), then we are past where the
			 * L4 header would be, and should parse no further.
			 */
			return;
		}

		uint8_t l4_sz;
		if (!mac_mmc_parse_l4(&cursor, meoi->meoi_l4proto, &l4_sz)) {
			return;
		}

		meoi->meoi_l4hlen = l4_sz;
		meoi->meoi_flags |= MEOI_L4INFO_SET;
	}
	const size_t l4_end = l3_end + (size_t)meoi->meoi_l4hlen;
	if (!mac_mmc_seek(&cursor, l4_end)) {
		meoi->meoi_flags &= ~MEOI_L4INFO_SET;
	}
}

/*
 * Attempt to parse packet headers to extract information useful for various
 * offloads.  This includes header protocols and lengths.
 *
 * The meoi_flags field will indicate the extent to which parsing was able to
 * complete.  Each in turn promises that subsequent fields are populated, and
 * that the mblk chain is large enough to contain the parsed header(s):
 *
 * - MEOI_L2INFO_SET: meoi_l3_proto and meoi_l2hlen
 * - MEOI_L3INFO_SET: meoi_l4_proto and meoi_l3hlen
 * - MEOI_L4INFO_SET: meoi_l4hlen
 *
 * When any of those flags are absent, their corresponding data fields will be
 * zeroed.
 *
 * These additional flags are set when certain conditions are met during
 * parsing:
 *
 * - MEOI_VLAN_TAGGED: Ethernet header is tagged with a VLAN
 * - MEOI_L3_FRAG_MORE: L3 indicated that this packet is fragmented into one or
 *   more packets to follow
 * - MEOI_L3_FRAG_OFFSET: L3 header that this packet is a fragment which is
 *   offset (following) from the head of the data
 */
void
mac_ether_offload_info(mblk_t *mp, mac_ether_offload_info_t *meoi)
{
	bzero(meoi, sizeof (mac_ether_offload_info_t));
	meoi->meoi_len = msgdsize(mp);

	mac_partial_offload_info(mp, 0, meoi);
}