/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 2014-2018 Giuseppe Lettieri
 * 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.
 *
 * 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.
 */


#if defined(__FreeBSD__)
#include <sys/cdefs.h> /* prerequisite */

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/param.h>  /* defines used in kernel.h */
#include <sys/kernel.h> /* types used in module initialization */
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#include <sys/selinfo.h>
#include <sys/sysctl.h>
#include <sys/socket.h> /* sockaddrs */
#include <net/if.h>
#include <net/if_var.h>
#include <machine/bus.h>        /* bus_dmamap_* */
#include <sys/refcount.h>


#elif defined(linux)

#include "bsd_glue.h"

#elif defined(__APPLE__)

#warning OSX support is only partial
#include "osx_glue.h"

#elif defined(_WIN32)
#include "win_glue.h"

#else

#error  Unsupported platform

#endif /* unsupported */

/*
 * common headers
 */

#include <net/netmap.h>
#include <dev/netmap/netmap_kern.h>
#include <dev/netmap/netmap_mem2.h>

#ifdef WITH_PIPES

#define NM_PIPE_MAXSLOTS        4096
#define NM_PIPE_MAXRINGS        256

static int netmap_default_pipes = 0; /* ignored, kept for compatibility */
SYSBEGIN(vars_pipes);
SYSCTL_DECL(_dev_netmap);
SYSCTL_INT(_dev_netmap, OID_AUTO, default_pipes, CTLFLAG_RW,
                &netmap_default_pipes, 0, "For compatibility only");
SYSEND;

/* allocate the pipe array in the parent adapter */
static int
nm_pipe_alloc(struct netmap_adapter *na, u_int npipes)
{
        size_t old_len, len;
        struct netmap_pipe_adapter **npa;

        if (npipes <= na->na_max_pipes)
                /* we already have more entries that requested */
                return 0;

        if (npipes < na->na_next_pipe || npipes > NM_MAXPIPES)
                return EINVAL;

        old_len = sizeof(struct netmap_pipe_adapter *)*na->na_max_pipes;
        len = sizeof(struct netmap_pipe_adapter *) * npipes;
        npa = nm_os_realloc(na->na_pipes, len, old_len);
        if (npa == NULL)
                return ENOMEM;

        na->na_pipes = npa;
        na->na_max_pipes = npipes;

        return 0;
}

/* deallocate the parent array in the parent adapter */
void
netmap_pipe_dealloc(struct netmap_adapter *na)
{
        if (na->na_pipes) {
                if (na->na_next_pipe > 0) {
                        nm_prerr("freeing not empty pipe array for %s (%d dangling pipes)!",
                            na->name, na->na_next_pipe);
                }
                nm_os_free(na->na_pipes);
                na->na_pipes = NULL;
                na->na_max_pipes = 0;
                na->na_next_pipe = 0;
        }
}

/* find a pipe endpoint with the given id among the parent's pipes */
static struct netmap_pipe_adapter *
netmap_pipe_find(struct netmap_adapter *parent, const char *pipe_id)
{
        int i;
        struct netmap_pipe_adapter *na;

        for (i = 0; i < parent->na_next_pipe; i++) {
                const char *na_pipe_id;
                na = parent->na_pipes[i];
                na_pipe_id = strrchr(na->up.name,
                        na->role == NM_PIPE_ROLE_MASTER ? '{' : '}');
                KASSERT(na_pipe_id != NULL, ("Invalid pipe name"));
                ++na_pipe_id;
                if (!strcmp(na_pipe_id, pipe_id)) {
                        return na;
                }
        }
        return NULL;
}

/* add a new pipe endpoint to the parent array */
static int
netmap_pipe_add(struct netmap_adapter *parent, struct netmap_pipe_adapter *na)
{
        if (parent->na_next_pipe >= parent->na_max_pipes) {
                u_int npipes = parent->na_max_pipes ?  2*parent->na_max_pipes : 2;
                int error = nm_pipe_alloc(parent, npipes);
                if (error)
                        return error;
        }

        parent->na_pipes[parent->na_next_pipe] = na;
        na->parent_slot = parent->na_next_pipe;
        parent->na_next_pipe++;
        return 0;
}

/* remove the given pipe endpoint from the parent array */
static void
netmap_pipe_remove(struct netmap_adapter *parent, struct netmap_pipe_adapter *na)
{
        u_int n;
        n = --parent->na_next_pipe;
        if (n != na->parent_slot) {
                struct netmap_pipe_adapter **p =
                        &parent->na_pipes[na->parent_slot];
                *p = parent->na_pipes[n];
                (*p)->parent_slot = na->parent_slot;
        }
        parent->na_pipes[n] = NULL;
}

int
netmap_pipe_txsync(struct netmap_kring *txkring, int flags)
{
        struct netmap_kring *rxkring = txkring->pipe;
        u_int k, lim = txkring->nkr_num_slots - 1, nk;
        int m; /* slots to transfer */
        int complete; /* did we see a complete packet ? */
        struct netmap_ring *txring = txkring->ring, *rxring = rxkring->ring;

        nm_prdis("%p: %s %x -> %s", txkring, txkring->name, flags, rxkring->name);
        nm_prdis(20, "TX before: hwcur %d hwtail %d cur %d head %d tail %d",
                txkring->nr_hwcur, txkring->nr_hwtail,
                txkring->rcur, txkring->rhead, txkring->rtail);

        /* update the hwtail */
        txkring->nr_hwtail = txkring->pipe_tail;

        m = txkring->rhead - txkring->nr_hwcur; /* new slots */
        if (m < 0)
                m += txkring->nkr_num_slots;

        if (m == 0) {
                /* nothing to send */
                return 0;
        }

        for (k = txkring->nr_hwcur, nk = lim + 1, complete = 0; m;
                        m--, k = nm_next(k, lim), nk = (complete ? k : nk)) {
                struct netmap_slot *rs = &rxring->slot[k];
                struct netmap_slot *ts = &txring->slot[k];
                uint64_t off = nm_get_offset(rxkring, rs);

                *rs = *ts;
                if (nm_get_offset(rxkring, rs) < off) {
                        nm_write_offset(rxkring, rs, off);
                }
                if (ts->flags & NS_BUF_CHANGED) {
                        ts->flags &= ~NS_BUF_CHANGED;
                }
                complete = !(ts->flags & NS_MOREFRAG);
        }

        txkring->nr_hwcur = k;

        nm_prdis(20, "TX after : hwcur %d hwtail %d cur %d head %d tail %d k %d",
                txkring->nr_hwcur, txkring->nr_hwtail,
                txkring->rcur, txkring->rhead, txkring->rtail, k);

        if (likely(nk <= lim)) {
                mb(); /* make sure the slots are updated before publishing them */
                rxkring->pipe_tail = nk; /* only publish complete packets */
                rxkring->nm_notify(rxkring, 0);
        }

        return 0;
}

int
netmap_pipe_rxsync(struct netmap_kring *rxkring, int flags)
{
        struct netmap_kring *txkring = rxkring->pipe;
        u_int k, lim = rxkring->nkr_num_slots - 1;
        int m; /* slots to release */
        struct netmap_ring *txring = txkring->ring, *rxring = rxkring->ring;

        nm_prdis("%p: %s %x -> %s", txkring, txkring->name, flags, rxkring->name);
        nm_prdis(20, "RX before: hwcur %d hwtail %d cur %d head %d tail %d",
                rxkring->nr_hwcur, rxkring->nr_hwtail,
                rxkring->rcur, rxkring->rhead, rxkring->rtail);

        /* update the hwtail */
        rxkring->nr_hwtail = rxkring->pipe_tail;

        m = rxkring->rhead - rxkring->nr_hwcur; /* released slots */
        if (m < 0)
                m += rxkring->nkr_num_slots;

        if (m == 0) {
                /* nothing to release */
                return 0;
        }

        for (k = rxkring->nr_hwcur; m; m--, k = nm_next(k, lim)) {
                struct netmap_slot *rs = &rxring->slot[k];
                struct netmap_slot *ts = &txring->slot[k];

                /* copy the slot. This also propagates any offset */
                *ts = *rs;
                if (rs->flags & NS_BUF_CHANGED) {
                        rs->flags &= ~NS_BUF_CHANGED;
                }
        }

        mb(); /* make sure the slots are updated before publishing them */
        txkring->pipe_tail = nm_prev(k, lim);
        rxkring->nr_hwcur = k;

        nm_prdis(20, "RX after : hwcur %d hwtail %d cur %d head %d tail %d k %d",
                rxkring->nr_hwcur, rxkring->nr_hwtail,
                rxkring->rcur, rxkring->rhead, rxkring->rtail, k);

        txkring->nm_notify(txkring, 0);

        return 0;
}

/* Pipe endpoints are created and destroyed together, so that endopoints do not
 * have to check for the existence of their peer at each ?xsync.
 *
 * To play well with the existing netmap infrastructure (refcounts etc.), we
 * adopt the following strategy:
 *
 * 1) The first endpoint that is created also creates the other endpoint and
 * grabs a reference to it.
 *
 *    state A)  user1 --> endpoint1 --> endpoint2
 *
 * 2) If, starting from state A, endpoint2 is then registered, endpoint1 gives
 * its reference to the user:
 *
 *    state B)  user1 --> endpoint1     endpoint2 <--- user2
 *
 * 3) Assume that, starting from state B endpoint2 is closed. In the unregister
 * callback endpoint2 notes that endpoint1 is still active and adds a reference
 * from endpoint1 to itself. When user2 then releases her own reference,
 * endpoint2 is not destroyed and we are back to state A. A symmetrical state
 * would be reached if endpoint1 were released instead.
 *
 * 4) If, starting from state A, endpoint1 is closed, the destructor notes that
 * it owns a reference to endpoint2 and releases it.
 *
 * Something similar goes on for the creation and destruction of the krings.
 */


int netmap_pipe_krings_create_both(struct netmap_adapter *na,
                                  struct netmap_adapter *ona)
{
        enum txrx t;
        int error;
        int i;

        /* case 1) below */
        nm_prdis("%p: case 1, create both ends", na);
        error = netmap_krings_create(na, 0);
        if (error)
                return error;

        /* create the krings of the other end */
        error = netmap_krings_create(ona, 0);
        if (error)
                goto del_krings1;

        /* cross link the krings and initialize the pipe_tails */
        for_rx_tx(t) {
                enum txrx r = nm_txrx_swap(t); /* swap NR_TX <-> NR_RX */
                for (i = 0; i < nma_get_nrings(na, t); i++) {
                        struct netmap_kring *k1 = NMR(na, t)[i],
                                            *k2 = NMR(ona, r)[i];
                        k1->pipe = k2;
                        k2->pipe = k1;
                        /* mark all peer-adapter rings as fake */
                        k2->nr_kflags |= NKR_FAKERING;
                        /* init tails */
                        k1->pipe_tail = k1->nr_hwtail;
                        k2->pipe_tail = k2->nr_hwtail;
                }
        }

        return 0;

del_krings1:
        netmap_krings_delete(na);
        return error;
}

/* netmap_pipe_krings_create.
 *
 * There are two cases:
 *
 * 1) state is
 *
 *        usr1 --> e1 --> e2
 *
 *    and we are e1. We have to create both sets
 *    of krings.
 *
 * 2) state is
 *
 *        usr1 --> e1 --> e2
 *
 *    and we are e2. e1 is certainly registered and our
 *    krings already exist. Nothing to do.
 */
static int
netmap_pipe_krings_create(struct netmap_adapter *na)
{
        struct netmap_pipe_adapter *pna =
                (struct netmap_pipe_adapter *)na;
        struct netmap_adapter *ona = &pna->peer->up;

        if (pna->peer_ref)
                return netmap_pipe_krings_create_both(na, ona);

        return 0;
}

int
netmap_pipe_reg_both(struct netmap_adapter *na, struct netmap_adapter *ona)
{
        int i, error = 0;
        enum txrx t;

        for_rx_tx(t) {
                for (i = 0; i < nma_get_nrings(na, t); i++) {
                        struct netmap_kring *kring = NMR(na, t)[i];

                        if (nm_kring_pending_on(kring)) {
                                /* mark the peer ring as needed */
                                kring->pipe->nr_kflags |= NKR_NEEDRING;
                        }
                }
        }

        /* create all missing needed rings on the other end.
         * Either our end, or the other, has been marked as
         * fake, so the allocation will not be done twice.
         */
        error = netmap_mem_rings_create(ona);
        if (error)
                return error;

        /* In case of no error we put our rings in netmap mode */
        for_rx_tx(t) {
                for (i = 0; i < nma_get_nrings(na, t); i++) {
                        struct netmap_kring *kring = NMR(na, t)[i];
                        if (nm_kring_pending_on(kring)) {

                                kring->nr_mode = NKR_NETMAP_ON;
                                if ((kring->nr_kflags & NKR_FAKERING) &&
                                    (kring->pipe->nr_kflags & NKR_FAKERING)) {
                                        /* this is a re-open of a pipe
                                         * end-point kept alive by the other end.
                                         * We need to leave everything as it is
                                         */
                                        continue;
                                }

                                /* copy the buffers from the non-fake ring
                                 * (this also propagates any initial offset)
                                 */
                                memcpy(kring->pipe->ring->slot,
                                       kring->ring->slot,
                                       sizeof(struct netmap_slot) *
                                                kring->nkr_num_slots);
                                /* copy the offset-related fields */
                                *(uint64_t *)(uintptr_t)&kring->pipe->ring->offset_mask =
                                        kring->ring->offset_mask;
                                *(uint64_t *)(uintptr_t)&kring->pipe->ring->buf_align =
                                        kring->ring->buf_align;
                                /* mark both rings as fake and needed,
                                 * so that buffers will not be
                                 * deleted by the standard machinery
                                 * (we will delete them by ourselves in
                                 * netmap_pipe_krings_delete)
                                 */
                                kring->nr_kflags |=
                                        (NKR_FAKERING | NKR_NEEDRING);
                                kring->nr_mode = NKR_NETMAP_ON;
                        }
                }
        }

        return 0;
}

/* netmap_pipe_reg.
 *
 * There are two cases on registration (onoff==1)
 *
 * 1.a) state is
 *
 *        usr1 --> e1 --> e2
 *
 *      and we are e1. Create the needed rings of the
 *      other end.
 *
 * 1.b) state is
 *
 *        usr1 --> e1 --> e2 <-- usr2
 *
 *      and we are e2. Drop the ref e1 is holding.
 *
 *  There are two additional cases on unregister (onoff==0)
 *
 *  2.a) state is
 *
 *         usr1 --> e1 --> e2
 *
 *       and we are e1. Nothing special to do, e2 will
 *       be cleaned up by the destructor of e1.
 *
 *  2.b) state is
 *
 *         usr1 --> e1     e2 <-- usr2
 *
 *       and we are either e1 or e2. Add a ref from the
 *       other end.
 */
static int
netmap_pipe_reg(struct netmap_adapter *na, int onoff)
{
        struct netmap_pipe_adapter *pna =
                (struct netmap_pipe_adapter *)na;
        struct netmap_adapter *ona = &pna->peer->up;
        int error = 0;

        nm_prdis("%p: onoff %d", na, onoff);
        if (onoff) {
                error = netmap_pipe_reg_both(na, ona);
                if (error) {
                        return error;
                }
                if (na->active_fds == 0)
                        na->na_flags |= NAF_NETMAP_ON;
        } else {
                if (na->active_fds == 0)
                        na->na_flags &= ~NAF_NETMAP_ON;
                netmap_krings_mode_commit(na, onoff);
        }

        if (na->active_fds) {
                nm_prdis("active_fds %d", na->active_fds);
                return 0;
        }

        if (pna->peer_ref) {
                nm_prdis("%p: case 1.a or 2.a, nothing to do", na);
                return 0;
        }
        if (onoff) {
                nm_prdis("%p: case 1.b, drop peer", na);
                pna->peer->peer_ref = 0;
                netmap_adapter_put(na);
        } else {
                nm_prdis("%p: case 2.b, grab peer", na);
                netmap_adapter_get(na);
                pna->peer->peer_ref = 1;
        }
        return error;
}

void
netmap_pipe_krings_delete_both(struct netmap_adapter *na,
                               struct netmap_adapter *ona)
{
        struct netmap_adapter *sna;
        enum txrx t;
        int i;

        /* case 1) below */
        nm_prdis("%p: case 1, deleting everything", na);
        /* To avoid double-frees we zero-out all the buffers in the kernel part
         * of each ring. The reason is this: If the user is behaving correctly,
         * all buffers are found in exactly one slot in the userspace part of
         * some ring.  If the user is not behaving correctly, we cannot release
         * buffers cleanly anyway. In the latter case, the allocator will
         * return to a clean state only when all its users will close.
         */
        sna = na;
cleanup:
        for_rx_tx(t) {
                for (i = 0; i < nma_get_nrings(sna, t); i++) {
                        struct netmap_kring *kring = NMR(sna, t)[i];
                        struct netmap_ring *ring = kring->ring;
                        uint32_t j, lim = kring->nkr_num_slots - 1;

                        nm_prdis("%s ring %p hwtail %u hwcur %u",
                                kring->name, ring, kring->nr_hwtail, kring->nr_hwcur);

                        if (ring == NULL)
                                continue;

                        if (kring->tx == NR_RX)
                                ring->slot[kring->pipe_tail].buf_idx = 0;

                        for (j = nm_next(kring->pipe_tail, lim);
                             j != kring->nr_hwcur;
                             j = nm_next(j, lim))
                        {
                                nm_prdis("%s[%d] %u", kring->name, j, ring->slot[j].buf_idx);
                                ring->slot[j].buf_idx = 0;
                        }
                        kring->nr_kflags &= ~(NKR_FAKERING | NKR_NEEDRING);
                }

        }
        if (sna != ona && ona->tx_rings) {
                sna = ona;
                goto cleanup;
        }

        netmap_mem_rings_delete(na);
        netmap_krings_delete(na); /* also zeroes tx_rings etc. */

        if (ona->tx_rings == NULL) {
                /* already deleted, we must be on an
                 * cleanup-after-error path */
                return;
        }
        netmap_mem_rings_delete(ona);
        netmap_krings_delete(ona);
}

/* netmap_pipe_krings_delete.
 *
 * There are two cases:
 *
 * 1) state is
 *
 *                usr1 --> e1 --> e2
 *
 *    and we are e1 (e2 is not registered, so krings_delete cannot be
 *    called on it);
 *
 * 2) state is
 *
 *                usr1 --> e1     e2 <-- usr2
 *
 *    and we are either e1 or e2.
 *
 * In the former case we have to also delete the krings of e2;
 * in the latter case we do nothing.
 */
static void
netmap_pipe_krings_delete(struct netmap_adapter *na)
{
        struct netmap_pipe_adapter *pna =
                (struct netmap_pipe_adapter *)na;
        struct netmap_adapter *ona; /* na of the other end */

        if (!pna->peer_ref) {
                nm_prdis("%p: case 2, kept alive by peer",  na);
                return;
        }
        ona = &pna->peer->up;
        netmap_pipe_krings_delete_both(na, ona);
}


static void
netmap_pipe_dtor(struct netmap_adapter *na)
{
        struct netmap_pipe_adapter *pna =
                (struct netmap_pipe_adapter *)na;
        nm_prdis("%p %p", na, pna->parent_ifp);
        if (pna->peer_ref) {
                nm_prdis("%p: clean up peer", na);
                pna->peer_ref = 0;
                netmap_adapter_put(&pna->peer->up);
        }
        if (pna->role == NM_PIPE_ROLE_MASTER)
                netmap_pipe_remove(pna->parent, pna);
        if (pna->parent_ifp)
                if_rele(pna->parent_ifp);
        netmap_adapter_put(pna->parent);
        pna->parent = NULL;
}

int
netmap_get_pipe_na(struct nmreq_header *hdr, struct netmap_adapter **na,
                struct netmap_mem_d *nmd, int create)
{
        struct nmreq_register *req = (struct nmreq_register *)(uintptr_t)hdr->nr_body;
        struct netmap_adapter *pna; /* parent adapter */
        struct netmap_pipe_adapter *mna, *sna, *reqna;
        if_t ifp = NULL;
        const char *pipe_id = NULL;
        int role = 0;
        int error, retries = 0;
        char *cbra, pipe_char;

        /* Try to parse the pipe syntax 'xx{yy' or 'xx}yy'. */
        cbra = strrchr(hdr->nr_name, '{');
        if (cbra != NULL) {
                role = NM_PIPE_ROLE_MASTER;
        } else {
                cbra = strrchr(hdr->nr_name, '}');
                if (cbra != NULL) {
                        role = NM_PIPE_ROLE_SLAVE;
                } else {
                        nm_prdis("not a pipe");
                        return 0;
                }
        }
        pipe_char = *cbra;
        pipe_id = cbra + 1;
        if (*pipe_id == '\0' || cbra == hdr->nr_name) {
                /* Bracket is the last character, so pipe name is missing;
                 * or bracket is the first character, so base port name
                 * is missing. */
                return EINVAL;
        }

        if (req->nr_mode != NR_REG_ALL_NIC && req->nr_mode != NR_REG_ONE_NIC) {
                /* We only accept modes involving hardware rings. */
                return EINVAL;
        }

        /* first, try to find the parent adapter */
        for (;;) {
                int create_error;

                /* Temporarily remove the pipe suffix. */
                *cbra = '\0';
                error = netmap_get_na(hdr, &pna, &ifp, nmd, create);
                /* Restore the pipe suffix. */
                *cbra = pipe_char;
                if (!error)
                        break;
                if (error != ENXIO || retries++) {
                        nm_prdis("parent lookup failed: %d", error);
                        return error;
                }
                nm_prdis("try to create a persistent vale port");
                /* create a persistent vale port and try again */
                *cbra = '\0';
                NMG_UNLOCK();
                create_error = netmap_vi_create(hdr, 1 /* autodelete */);
                NMG_LOCK();
                *cbra = pipe_char;
                if (create_error && create_error != EEXIST) {
                        if (create_error != EOPNOTSUPP) {
                                nm_prerr("failed to create a persistent vale port: %d",
                                    create_error);
                        }
                        return error;
                }
        }

        if (NETMAP_OWNED_BY_KERN(pna)) {
                nm_prdis("parent busy");
                error = EBUSY;
                goto put_out;
        }

        /* next, lookup the pipe id in the parent list */
        reqna = NULL;
        mna = netmap_pipe_find(pna, pipe_id);
        if (mna) {
                if (mna->role == role) {
                        nm_prdis("found %s directly at %d", pipe_id, mna->parent_slot);
                        reqna = mna;
                } else {
                        nm_prdis("found %s indirectly at %d", pipe_id, mna->parent_slot);
                        reqna = mna->peer;
                }
                /* the pipe we have found already holds a ref to the parent,
                 * so we need to drop the one we got from netmap_get_na()
                 */
                netmap_unget_na(pna, ifp);
                goto found;
        }
        nm_prdis("pipe %s not found, create %d", pipe_id, create);
        if (!create) {
                error = ENODEV;
                goto put_out;
        }
        /* we create both master and slave.
         * The endpoint we were asked for holds a reference to
         * the other one.
         */
        mna = nm_os_malloc(sizeof(*mna));
        if (mna == NULL) {
                error = ENOMEM;
                goto put_out;
        }
        snprintf(mna->up.name, sizeof(mna->up.name), "%s{%s", pna->name, pipe_id);

        mna->role = NM_PIPE_ROLE_MASTER;
        mna->parent = pna;
        mna->parent_ifp = ifp;

        mna->up.nm_txsync = netmap_pipe_txsync;
        mna->up.nm_rxsync = netmap_pipe_rxsync;
        mna->up.nm_register = netmap_pipe_reg;
        mna->up.nm_dtor = netmap_pipe_dtor;
        mna->up.nm_krings_create = netmap_pipe_krings_create;
        mna->up.nm_krings_delete = netmap_pipe_krings_delete;
        mna->up.nm_mem = netmap_mem_get(pna->nm_mem);
        mna->up.na_flags |= NAF_MEM_OWNER | NAF_OFFSETS;
        mna->up.na_lut = pna->na_lut;

        mna->up.num_tx_rings = req->nr_tx_rings;
        nm_bound_var(&mna->up.num_tx_rings, 1,
                        1, NM_PIPE_MAXRINGS, NULL);
        mna->up.num_rx_rings = req->nr_rx_rings;
        nm_bound_var(&mna->up.num_rx_rings, 1,
                        1, NM_PIPE_MAXRINGS, NULL);
        mna->up.num_tx_desc = req->nr_tx_slots;
        nm_bound_var(&mna->up.num_tx_desc, pna->num_tx_desc,
                        1, NM_PIPE_MAXSLOTS, NULL);
        mna->up.num_rx_desc = req->nr_rx_slots;
        nm_bound_var(&mna->up.num_rx_desc, pna->num_rx_desc,
                        1, NM_PIPE_MAXSLOTS, NULL);
        error = netmap_attach_common(&mna->up);
        if (error)
                goto free_mna;
        /* register the master with the parent */
        error = netmap_pipe_add(pna, mna);
        if (error)
                goto free_mna;

        /* create the slave */
        sna = nm_os_malloc(sizeof(*mna));
        if (sna == NULL) {
                error = ENOMEM;
                goto unregister_mna;
        }
        /* most fields are the same, copy from master and then fix */
        *sna = *mna;
        sna->up.nm_mem = netmap_mem_get(mna->up.nm_mem);
        /* swap the number of tx/rx rings and slots */
        sna->up.num_tx_rings = mna->up.num_rx_rings;
        sna->up.num_tx_desc  = mna->up.num_rx_desc;
        sna->up.num_rx_rings = mna->up.num_tx_rings;
        sna->up.num_rx_desc  = mna->up.num_tx_desc;
        snprintf(sna->up.name, sizeof(sna->up.name), "%s}%s", pna->name, pipe_id);
        sna->role = NM_PIPE_ROLE_SLAVE;
        error = netmap_attach_common(&sna->up);
        if (error)
                goto free_sna;

        /* join the two endpoints */
        mna->peer = sna;
        sna->peer = mna;

        /* we already have a reference to the parent, but we
         * need another one for the other endpoint we created
         */
        netmap_adapter_get(pna);
        /* likewise for the ifp, if any */
        if (ifp)
                if_ref(ifp);

        if (role == NM_PIPE_ROLE_MASTER) {
                reqna = mna;
                mna->peer_ref = 1;
                netmap_adapter_get(&sna->up);
        } else {
                reqna = sna;
                sna->peer_ref = 1;
                netmap_adapter_get(&mna->up);
        }
        nm_prdis("created master %p and slave %p", mna, sna);
found:

        nm_prdis("pipe %s %s at %p", pipe_id,
                (reqna->role == NM_PIPE_ROLE_MASTER ? "master" : "slave"), reqna);
        *na = &reqna->up;
        netmap_adapter_get(*na);

        /* keep the reference to the parent.
         * It will be released by the req destructor
         */

        return 0;

free_sna:
        nm_os_free(sna);
unregister_mna:
        netmap_pipe_remove(pna, mna);
free_mna:
        nm_os_free(mna);
put_out:
        netmap_unget_na(pna, ifp);
        return error;
}


#endif /* WITH_PIPES */