/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 2013-2014 Universita` di Pisa. 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.
 */

#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/module.h>
#include <sys/errno.h>
#include <sys/eventhandler.h>
#include <sys/jail.h>
#include <sys/poll.h>  /* POLLIN, POLLOUT */
#include <sys/kernel.h> /* types used in module initialization */
#include <sys/conf.h>   /* DEV_MODULE_ORDERED */
#include <sys/endian.h>
#include <sys/syscallsubr.h> /* kern_ioctl() */

#include <sys/rwlock.h>

#include <vm/vm.h>      /* vtophys */
#include <vm/pmap.h>    /* vtophys */
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/uma.h>


#include <sys/malloc.h>
#include <sys/socket.h> /* sockaddrs */
#include <sys/selinfo.h>
#include <sys/kthread.h> /* kthread_add() */
#include <sys/proc.h> /* PROC_LOCK() */
#include <sys/unistd.h> /* RFNOWAIT */
#include <sys/sched.h> /* sched_bind() */
#include <sys/smp.h> /* mp_maxid */
#include <sys/taskqueue.h> /* taskqueue_enqueue(), taskqueue_create(), ... */
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_types.h> /* IFT_ETHER */
#include <net/ethernet.h> /* ether_ifdetach */
#include <net/if_dl.h> /* LLADDR */
#include <machine/bus.h>        /* bus_dmamap_* */
#include <netinet/in.h>         /* in6_cksum_pseudo() */
#include <machine/in_cksum.h>  /* in_pseudo(), in_cksum_hdr() */

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


/* ======================== FREEBSD-SPECIFIC ROUTINES ================== */

static void
nm_kqueue_notify(void *opaque, int pending)
{
        struct nm_selinfo *si = opaque;

        /* We use a non-zero hint to distinguish this notification call
         * from the call done in kqueue_scan(), which uses hint=0.
         */
        KNOTE_UNLOCKED(&si->si.si_note, /*hint=*/0x100);
}

int nm_os_selinfo_init(NM_SELINFO_T *si, const char *name) {
        int err;

        TASK_INIT(&si->ntfytask, 0, nm_kqueue_notify, si);
        si->ntfytq = taskqueue_create(name, M_NOWAIT,
            taskqueue_thread_enqueue, &si->ntfytq);
        if (si->ntfytq == NULL)
                return -ENOMEM;
        err = taskqueue_start_threads(&si->ntfytq, 1, PI_NET, "tq %s", name);
        if (err) {
                taskqueue_free(si->ntfytq);
                si->ntfytq = NULL;
                return err;
        }

        snprintf(si->mtxname, sizeof(si->mtxname), "nmkl%s", name);
        mtx_init(&si->m, si->mtxname, NULL, MTX_DEF);
        knlist_init_mtx(&si->si.si_note, &si->m);
        si->kqueue_users = 0;

        return (0);
}

void
nm_os_selinfo_uninit(NM_SELINFO_T *si)
{
        if (si->ntfytq == NULL) {
                return; /* si was not initialized */
        }
        taskqueue_drain(si->ntfytq, &si->ntfytask);
        taskqueue_free(si->ntfytq);
        si->ntfytq = NULL;
        seldrain(&si->si);
        knlist_delete(&si->si.si_note, curthread, /*islocked=*/0);
        knlist_destroy(&si->si.si_note);
        /* now we don't need the mutex anymore */
        mtx_destroy(&si->m);
}

void *
nm_os_malloc(size_t size)
{
        return malloc(size, M_DEVBUF, M_NOWAIT | M_ZERO);
}

void *
nm_os_realloc(void *addr, size_t new_size, size_t old_size __unused)
{
        return realloc(addr, new_size, M_DEVBUF, M_NOWAIT | M_ZERO);
}

void
nm_os_free(void *addr)
{
        free(addr, M_DEVBUF);
}

void
nm_os_ifnet_lock(void)
{
        IFNET_RLOCK();
}

void
nm_os_ifnet_unlock(void)
{
        IFNET_RUNLOCK();
}

static int netmap_use_count = 0;

void
nm_os_get_module(void)
{
        netmap_use_count++;
}

void
nm_os_put_module(void)
{
        netmap_use_count--;
}

static void
netmap_ifnet_arrival_handler(void *arg __unused, if_t ifp)
{
        netmap_undo_zombie(ifp);
}

static void
netmap_ifnet_departure_handler(void *arg __unused, if_t ifp)
{
        netmap_make_zombie(ifp);
}

static eventhandler_tag nm_ifnet_ah_tag;
static eventhandler_tag nm_ifnet_dh_tag;

int
nm_os_ifnet_init(void)
{
        nm_ifnet_ah_tag =
                EVENTHANDLER_REGISTER(ifnet_arrival_event,
                                netmap_ifnet_arrival_handler,
                                NULL, EVENTHANDLER_PRI_ANY);
        nm_ifnet_dh_tag =
                EVENTHANDLER_REGISTER(ifnet_departure_event,
                                netmap_ifnet_departure_handler,
                                NULL, EVENTHANDLER_PRI_ANY);
        return 0;
}

void
nm_os_ifnet_fini(void)
{
        EVENTHANDLER_DEREGISTER(ifnet_arrival_event,
                        nm_ifnet_ah_tag);
        EVENTHANDLER_DEREGISTER(ifnet_departure_event,
                        nm_ifnet_dh_tag);
}

unsigned
nm_os_ifnet_mtu(if_t ifp)
{
        return if_getmtu(ifp);
}

rawsum_t
nm_os_csum_raw(uint8_t *data, size_t len, rawsum_t cur_sum)
{
        /* TODO XXX please use the FreeBSD implementation for this. */
        uint16_t *words = (uint16_t *)data;
        int nw = len / 2;
        int i;

        for (i = 0; i < nw; i++)
                cur_sum += be16toh(words[i]);

        if (len & 1)
                cur_sum += (data[len-1] << 8);

        return cur_sum;
}

/* Fold a raw checksum: 'cur_sum' is in host byte order, while the
 * return value is in network byte order.
 */
uint16_t
nm_os_csum_fold(rawsum_t cur_sum)
{
        /* TODO XXX please use the FreeBSD implementation for this. */
        while (cur_sum >> 16)
                cur_sum = (cur_sum & 0xFFFF) + (cur_sum >> 16);

        return htobe16((~cur_sum) & 0xFFFF);
}

uint16_t nm_os_csum_ipv4(struct nm_iphdr *iph)
{
#if 0
        return in_cksum_hdr((void *)iph);
#else
        return nm_os_csum_fold(nm_os_csum_raw((uint8_t*)iph, sizeof(struct nm_iphdr), 0));
#endif
}

void
nm_os_csum_tcpudp_ipv4(struct nm_iphdr *iph, void *data,
                                        size_t datalen, uint16_t *check)
{
#ifdef INET
        uint16_t pseudolen = datalen + iph->protocol;

        /* Compute and insert the pseudo-header checksum. */
        *check = in_pseudo(iph->saddr, iph->daddr,
                                 htobe16(pseudolen));
        /* Compute the checksum on TCP/UDP header + payload
         * (includes the pseudo-header).
         */
        *check = nm_os_csum_fold(nm_os_csum_raw(data, datalen, 0));
#else
        static int notsupported = 0;
        if (!notsupported) {
                notsupported = 1;
                nm_prerr("inet4 segmentation not supported");
        }
#endif
}

void
nm_os_csum_tcpudp_ipv6(struct nm_ipv6hdr *ip6h, void *data,
                                        size_t datalen, uint16_t *check)
{
#ifdef INET6
        *check = in6_cksum_pseudo((void*)ip6h, datalen, ip6h->nexthdr, 0);
        *check = nm_os_csum_fold(nm_os_csum_raw(data, datalen, 0));
#else
        static int notsupported = 0;
        if (!notsupported) {
                notsupported = 1;
                nm_prerr("inet6 segmentation not supported");
        }
#endif
}

/* on FreeBSD we send up one packet at a time */
void *
nm_os_send_up(if_t ifp, struct mbuf *m, struct mbuf *prev)
{
        NA(ifp)->if_input(ifp, m);
        return NULL;
}

int
nm_os_mbuf_has_csum_offld(struct mbuf *m)
{
        return m->m_pkthdr.csum_flags & (CSUM_TCP | CSUM_UDP | CSUM_SCTP |
                                         CSUM_TCP_IPV6 | CSUM_UDP_IPV6 |
                                         CSUM_SCTP_IPV6);
}

int
nm_os_mbuf_has_seg_offld(struct mbuf *m)
{
        return m->m_pkthdr.csum_flags & CSUM_TSO;
}

static void
freebsd_generic_rx_handler(if_t ifp, struct mbuf *m)
{
        int stolen;

        if (unlikely(!NM_NA_VALID(ifp))) {
                nm_prlim(1, "Warning: RX packet intercepted, but no"
                                " emulated adapter");
                return;
        }

        do {
                struct mbuf *n;

                n = m->m_nextpkt;
                m->m_nextpkt = NULL;
                stolen = generic_rx_handler(ifp, m);
                if (!stolen) {
                        NA(ifp)->if_input(ifp, m);
                }
                m = n;
        } while (m != NULL);
}

/*
 * Intercept the rx routine in the standard device driver.
 * Second argument is non-zero to intercept, 0 to restore
 */
int
nm_os_catch_rx(struct netmap_generic_adapter *gna, int intercept)
{
        struct netmap_adapter *na = &gna->up.up;
        if_t ifp = na->ifp;
        int ret = 0;

        nm_os_ifnet_lock();
        if (intercept) {
                if_setcapenablebit(ifp, IFCAP_NETMAP, 0);
                if_setinputfn(ifp, freebsd_generic_rx_handler);
        } else {
                if_setcapenablebit(ifp, 0, IFCAP_NETMAP);
                if_setinputfn(ifp, na->if_input);
        }
        nm_os_ifnet_unlock();

        return ret;
}


/*
 * Intercept the packet steering routine in the tx path,
 * so that we can decide which queue is used for an mbuf.
 * Second argument is non-zero to intercept, 0 to restore.
 * On freebsd we just intercept if_transmit.
 */
int
nm_os_catch_tx(struct netmap_generic_adapter *gna, int intercept)
{
        struct netmap_adapter *na = &gna->up.up;
        if_t ifp = netmap_generic_getifp(gna);

        nm_os_ifnet_lock();
        if (intercept) {
                na->if_transmit = if_gettransmitfn(ifp);
                if_settransmitfn(ifp, netmap_transmit);
        } else {
                if_settransmitfn(ifp, na->if_transmit);
        }
        nm_os_ifnet_unlock();

        return 0;
}


/*
 * Transmit routine used by generic_netmap_txsync(). Returns 0 on success
 * and non-zero on error (which may be packet drops or other errors).
 * addr and len identify the netmap buffer, m is the (preallocated)
 * mbuf to use for transmissions.
 *
 * Zero-copy transmission is possible if netmap is attached directly to a
 * hardware interface: when cleaning we simply wait for the mbuf cluster
 * refcount to decrement to 1, indicating that the driver has completed
 * transmission and is done with the buffer.  However, this approach can
 * lead to queue deadlocks when attaching to software interfaces (e.g.,
 * if_bridge) since we cannot rely on member ports to promptly reclaim
 * transmitted mbufs.  Since there is no easy way to distinguish these
 * cases, we currently always copy the buffer.
 *
 * On multiqueue cards, we can force the queue using
 *      if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE)
 *              i = m->m_pkthdr.flowid % adapter->num_queues;
 *      else
 *              i = curcpu % adapter->num_queues;
 */
int
nm_os_generic_xmit_frame(struct nm_os_gen_arg *a)
{
        int ret;
        u_int len = a->len;
        if_t ifp = a->ifp;
        struct mbuf *m = a->m;

        M_ASSERTPKTHDR(m);
        KASSERT((m->m_flags & M_EXT) != 0,
            ("%s: mbuf %p has no cluster", __func__, m));

        if (MBUF_REFCNT(m) != 1) {
                nm_prerr("invalid refcnt %d for %p", MBUF_REFCNT(m), m);
                panic("in generic_xmit_frame");
        }
        if (unlikely(m->m_ext.ext_size < len)) {
                nm_prlim(2, "size %d < len %d", m->m_ext.ext_size, len);
                len = m->m_ext.ext_size;
        }

        m_copyback(m, 0, len, a->addr);
        m->m_len = m->m_pkthdr.len = len;
        SET_MBUF_REFCNT(m, 2);
        M_HASHTYPE_SET(m, M_HASHTYPE_OPAQUE);
        m->m_pkthdr.flowid = a->ring_nr;
        m->m_pkthdr.rcvif = ifp; /* used for tx notification */
        CURVNET_SET(if_getvnet(ifp));
        ret = NA(ifp)->if_transmit(ifp, m);
        CURVNET_RESTORE();
        return ret ? -1 : 0;
}

struct netmap_adapter *
netmap_getna(if_t ifp)
{
        return (NA(ifp));
}

/*
 * The following two functions are empty until we have a generic
 * way to extract the info from the ifp
 */
int
nm_os_generic_find_num_desc(if_t ifp, unsigned int *tx, unsigned int *rx)
{
        return 0;
}


void
nm_os_generic_find_num_queues(if_t ifp, u_int *txq, u_int *rxq)
{
        unsigned num_rings = netmap_generic_rings ? netmap_generic_rings : 1;

        *txq = num_rings;
        *rxq = num_rings;
}

void
nm_os_generic_set_features(struct netmap_generic_adapter *gna)
{

        gna->rxsg = 1; /* Supported through m_copydata. */
        gna->txqdisc = 0; /* Not supported. */
}

void
nm_os_mitigation_init(struct nm_generic_mit *mit, int idx, struct netmap_adapter *na)
{
        mit->mit_pending = 0;
        mit->mit_ring_idx = idx;
        mit->mit_na = na;
}


void
nm_os_mitigation_start(struct nm_generic_mit *mit)
{
}


void
nm_os_mitigation_restart(struct nm_generic_mit *mit)
{
}


int
nm_os_mitigation_active(struct nm_generic_mit *mit)
{

        return 0;
}


void
nm_os_mitigation_cleanup(struct nm_generic_mit *mit)
{
}

static int
nm_vi_dummy(if_t ifp, u_long cmd, caddr_t addr)
{

        return EINVAL;
}

static void
nm_vi_start(if_t ifp)
{
        panic("nm_vi_start() must not be called");
}

/*
 * Index manager of persistent virtual interfaces.
 * It is used to decide the lowest byte of the MAC address.
 * We use the same algorithm with management of bridge port index.
 */
#define NM_VI_MAX       255
static struct {
        uint8_t index[NM_VI_MAX]; /* XXX just for a reasonable number */
        uint8_t active;
        struct mtx lock;
} nm_vi_indices;

void
nm_os_vi_init_index(void)
{
        int i;
        for (i = 0; i < NM_VI_MAX; i++)
                nm_vi_indices.index[i] = i;
        nm_vi_indices.active = 0;
        mtx_init(&nm_vi_indices.lock, "nm_vi_indices_lock", NULL, MTX_DEF);
}

/* return -1 if no index available */
static int
nm_vi_get_index(void)
{
        int ret;

        mtx_lock(&nm_vi_indices.lock);
        ret = nm_vi_indices.active == NM_VI_MAX ? -1 :
                nm_vi_indices.index[nm_vi_indices.active++];
        mtx_unlock(&nm_vi_indices.lock);
        return ret;
}

static void
nm_vi_free_index(uint8_t val)
{
        int i, lim;

        mtx_lock(&nm_vi_indices.lock);
        lim = nm_vi_indices.active;
        for (i = 0; i < lim; i++) {
                if (nm_vi_indices.index[i] == val) {
                        /* swap index[lim-1] and j */
                        int tmp = nm_vi_indices.index[lim-1];
                        nm_vi_indices.index[lim-1] = val;
                        nm_vi_indices.index[i] = tmp;
                        nm_vi_indices.active--;
                        break;
                }
        }
        if (lim == nm_vi_indices.active)
                nm_prerr("Index %u not found", val);
        mtx_unlock(&nm_vi_indices.lock);
}
#undef NM_VI_MAX

/*
 * Implementation of a netmap-capable virtual interface that
 * registered to the system.
 * It is based on if_tap.c and ip_fw_log.c in FreeBSD 9.
 *
 * Note: Linux sets refcount to 0 on allocation of net_device,
 * then increments it on registration to the system.
 * FreeBSD sets refcount to 1 on if_alloc(), and does not
 * increment this refcount on if_attach().
 */
int
nm_os_vi_persist(const char *name, if_t *ret)
{
        if_t ifp;
        u_short macaddr_hi;
        uint32_t macaddr_mid;
        u_char eaddr[6];
        int unit = nm_vi_get_index(); /* just to decide MAC address */

        if (unit < 0)
                return EBUSY;
        /*
         * We use the same MAC address generation method with tap
         * except for the highest octet is 00:be instead of 00:bd
         */
        macaddr_hi = htons(0x00be); /* XXX tap + 1 */
        macaddr_mid = (uint32_t) ticks;
        bcopy(&macaddr_hi, eaddr, sizeof(short));
        bcopy(&macaddr_mid, &eaddr[2], sizeof(uint32_t));
        eaddr[5] = (uint8_t)unit;

        ifp = if_alloc(IFT_ETHER);
        if_initname(ifp, name, IF_DUNIT_NONE);
        if_setflags(ifp, IFF_UP | IFF_SIMPLEX | IFF_MULTICAST);
        if_setinitfn(ifp, (void *)nm_vi_dummy);
        if_setioctlfn(ifp, nm_vi_dummy);
        if_setstartfn(ifp, nm_vi_start);
        if_setmtu(ifp, ETHERMTU);
        if_setsendqlen(ifp, ifqmaxlen);
        if_setcapabilitiesbit(ifp, IFCAP_LINKSTATE, 0);
        if_setcapenablebit(ifp, IFCAP_LINKSTATE, 0);

        ether_ifattach(ifp, eaddr);
        *ret = ifp;
        return 0;
}

/* unregister from the system and drop the final refcount */
void
nm_os_vi_detach(if_t ifp)
{
        nm_vi_free_index(((char *)if_getlladdr(ifp))[5]);
        ether_ifdetach(ifp);
        if_free(ifp);
}

#ifdef WITH_EXTMEM
#include <vm/vm_map.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
struct nm_os_extmem {
        vm_object_t obj;
        vm_offset_t kva;
        vm_offset_t size;
        uintptr_t scan;
};

void
nm_os_extmem_delete(struct nm_os_extmem *e)
{
        nm_prinf("freeing %zx bytes", (size_t)e->size);
        vm_map_remove(kernel_map, e->kva, e->kva + e->size);
        nm_os_free(e);
}

char *
nm_os_extmem_nextpage(struct nm_os_extmem *e)
{
        char *rv = NULL;
        if (e->scan < e->kva + e->size) {
                rv = (char *)e->scan;
                e->scan += PAGE_SIZE;
        }
        return rv;
}

int
nm_os_extmem_isequal(struct nm_os_extmem *e1, struct nm_os_extmem *e2)
{
        return (e1->obj == e2->obj);
}

int
nm_os_extmem_nr_pages(struct nm_os_extmem *e)
{
        return e->size >> PAGE_SHIFT;
}

struct nm_os_extmem *
nm_os_extmem_create(unsigned long p, struct nmreq_pools_info *pi, int *perror)
{
        vm_map_t map;
        vm_map_entry_t entry;
        vm_object_t obj;
        vm_prot_t prot;
        vm_pindex_t index;
        boolean_t wired;
        struct nm_os_extmem *e = NULL;
        int rv, error = 0;

        e = nm_os_malloc(sizeof(*e));
        if (e == NULL) {
                error = ENOMEM;
                goto out;
        }

        map = &curthread->td_proc->p_vmspace->vm_map;
        rv = vm_map_lookup(&map, p, VM_PROT_RW, &entry,
                        &obj, &index, &prot, &wired);
        if (rv != KERN_SUCCESS) {
                nm_prerr("address %lx not found", p);
                error = vm_mmap_to_errno(rv);
                goto out_free;
        }
        vm_object_reference(obj);

        /* check that we are given the whole vm_object ? */
        vm_map_lookup_done(map, entry);

        e->obj = obj;
        /* Wire the memory and add the vm_object to the kernel map,
         * to make sure that it is not freed even if all the processes
         * that are mmap()ing should munmap() it.
         */
        e->kva = vm_map_min(kernel_map);
        e->size = obj->size << PAGE_SHIFT;
        rv = vm_map_find(kernel_map, obj, 0, &e->kva, e->size, 0,
                        VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
                        VM_PROT_READ | VM_PROT_WRITE, 0);
        if (rv != KERN_SUCCESS) {
                nm_prerr("vm_map_find(%zx) failed", (size_t)e->size);
                error = vm_mmap_to_errno(rv);
                goto out_rel;
        }
        rv = vm_map_wire(kernel_map, e->kva, e->kva + e->size,
                        VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
        if (rv != KERN_SUCCESS) {
                nm_prerr("vm_map_wire failed");
                error = vm_mmap_to_errno(rv);
                goto out_rem;
        }

        e->scan = e->kva;

        return e;

out_rem:
        vm_map_remove(kernel_map, e->kva, e->kva + e->size);
        e->obj = NULL; /* reference consumed by vm_map_remove() */
out_rel:
        vm_object_deallocate(e->obj);
        e->obj = NULL;
out_free:
        nm_os_free(e);
out:
        if (perror)
                *perror = error;
        return NULL;
}
#endif /* WITH_EXTMEM */

/* ================== PTNETMAP GUEST SUPPORT ==================== */

#ifdef WITH_PTNETMAP
#include <sys/bus.h>
#include <sys/rman.h>
#include <machine/bus.h>        /* bus_dmamap_* */
#include <machine/resource.h>
#include <dev/pci/pcivar.h>
#include <dev/pci/pcireg.h>
/*
 * ptnetmap memory device (memdev) for freebsd guest,
 * ssed to expose host netmap memory to the guest through a PCI BAR.
 */

/*
 * ptnetmap memdev private data structure
 */
struct ptnetmap_memdev {
        device_t dev;
        struct resource *pci_io;
        struct resource *pci_mem;
        struct netmap_mem_d *nm_mem;
};

static int      ptn_memdev_probe(device_t);
static int      ptn_memdev_attach(device_t);
static int      ptn_memdev_detach(device_t);
static int      ptn_memdev_shutdown(device_t);

static device_method_t ptn_memdev_methods[] = {
        DEVMETHOD(device_probe, ptn_memdev_probe),
        DEVMETHOD(device_attach, ptn_memdev_attach),
        DEVMETHOD(device_detach, ptn_memdev_detach),
        DEVMETHOD(device_shutdown, ptn_memdev_shutdown),
        DEVMETHOD_END
};

static driver_t ptn_memdev_driver = {
        PTNETMAP_MEMDEV_NAME,
        ptn_memdev_methods,
        sizeof(struct ptnetmap_memdev),
};

/* We use (SI_ORDER_MIDDLE+1) here, see DEV_MODULE_ORDERED() invocation
 * below. */
DRIVER_MODULE_ORDERED(ptn_memdev, pci, ptn_memdev_driver, NULL, NULL,
                      SI_ORDER_MIDDLE + 1);

/*
 * Map host netmap memory through PCI-BAR in the guest OS,
 * returning physical (nm_paddr) and virtual (nm_addr) addresses
 * of the netmap memory mapped in the guest.
 */
int
nm_os_pt_memdev_iomap(struct ptnetmap_memdev *ptn_dev, vm_paddr_t *nm_paddr,
                      void **nm_addr, uint64_t *mem_size)
{
        int rid;

        nm_prinf("ptn_memdev_driver iomap");

        rid = PCIR_BAR(PTNETMAP_MEM_PCI_BAR);
        *mem_size = bus_read_4(ptn_dev->pci_io, PTNET_MDEV_IO_MEMSIZE_HI);
        *mem_size = bus_read_4(ptn_dev->pci_io, PTNET_MDEV_IO_MEMSIZE_LO) |
                        (*mem_size << 32);

        /* map memory allocator */
        ptn_dev->pci_mem = bus_alloc_resource(ptn_dev->dev, SYS_RES_MEMORY,
                        &rid, 0, ~0, *mem_size, RF_ACTIVE);
        if (ptn_dev->pci_mem == NULL) {
                *nm_paddr = 0;
                *nm_addr = NULL;
                return ENOMEM;
        }

        *nm_paddr = rman_get_start(ptn_dev->pci_mem);
        *nm_addr = rman_get_virtual(ptn_dev->pci_mem);

        nm_prinf("=== BAR %d start %lx len %lx mem_size %lx ===",
                        PTNETMAP_MEM_PCI_BAR,
                        (unsigned long)(*nm_paddr),
                        (unsigned long)rman_get_size(ptn_dev->pci_mem),
                        (unsigned long)*mem_size);
        return (0);
}

uint32_t
nm_os_pt_memdev_ioread(struct ptnetmap_memdev *ptn_dev, unsigned int reg)
{
        return bus_read_4(ptn_dev->pci_io, reg);
}

/* Unmap host netmap memory. */
void
nm_os_pt_memdev_iounmap(struct ptnetmap_memdev *ptn_dev)
{
        nm_prinf("ptn_memdev_driver iounmap");

        if (ptn_dev->pci_mem) {
                bus_release_resource(ptn_dev->dev, SYS_RES_MEMORY,
                        PCIR_BAR(PTNETMAP_MEM_PCI_BAR), ptn_dev->pci_mem);
                ptn_dev->pci_mem = NULL;
        }
}

/* Device identification routine, return BUS_PROBE_DEFAULT on success,
 * positive on failure */
static int
ptn_memdev_probe(device_t dev)
{
        if (pci_get_vendor(dev) != PTNETMAP_PCI_VENDOR_ID)
                return (ENXIO);
        if (pci_get_device(dev) != PTNETMAP_PCI_DEVICE_ID)
                return (ENXIO);

        device_set_descf(dev, "%s PCI adapter", PTNETMAP_MEMDEV_NAME);

        return (BUS_PROBE_DEFAULT);
}

/* Device initialization routine. */
static int
ptn_memdev_attach(device_t dev)
{
        struct ptnetmap_memdev *ptn_dev;
        int rid;
        uint16_t mem_id;

        ptn_dev = device_get_softc(dev);
        ptn_dev->dev = dev;

        pci_enable_busmaster(dev);

        rid = PCIR_BAR(PTNETMAP_IO_PCI_BAR);
        ptn_dev->pci_io = bus_alloc_resource_any(dev, SYS_RES_IOPORT, &rid,
                                                 RF_ACTIVE);
        if (ptn_dev->pci_io == NULL) {
                device_printf(dev, "cannot map I/O space\n");
                return (ENXIO);
        }

        mem_id = bus_read_4(ptn_dev->pci_io, PTNET_MDEV_IO_MEMID);

        /* create guest allocator */
        ptn_dev->nm_mem = netmap_mem_pt_guest_attach(ptn_dev, mem_id);
        if (ptn_dev->nm_mem == NULL) {
                ptn_memdev_detach(dev);
                return (ENOMEM);
        }
        netmap_mem_get(ptn_dev->nm_mem);

        nm_prinf("ptnetmap memdev attached, host memid: %u", mem_id);

        return (0);
}

/* Device removal routine. */
static int
ptn_memdev_detach(device_t dev)
{
        struct ptnetmap_memdev *ptn_dev;

        ptn_dev = device_get_softc(dev);

        if (ptn_dev->nm_mem) {
                nm_prinf("ptnetmap memdev detached, host memid %u",
                        netmap_mem_get_id(ptn_dev->nm_mem));
                netmap_mem_put(ptn_dev->nm_mem);
                ptn_dev->nm_mem = NULL;
        }
        if (ptn_dev->pci_mem) {
                bus_release_resource(dev, SYS_RES_MEMORY,
                        PCIR_BAR(PTNETMAP_MEM_PCI_BAR), ptn_dev->pci_mem);
                ptn_dev->pci_mem = NULL;
        }
        if (ptn_dev->pci_io) {
                bus_release_resource(dev, SYS_RES_IOPORT,
                        PCIR_BAR(PTNETMAP_IO_PCI_BAR), ptn_dev->pci_io);
                ptn_dev->pci_io = NULL;
        }

        return (0);
}

static int
ptn_memdev_shutdown(device_t dev)
{
        return bus_generic_shutdown(dev);
}

#endif /* WITH_PTNETMAP */

/*
 * In order to track whether pages are still mapped, we hook into
 * the standard cdev_pager and intercept the constructor and
 * destructor.
 */

struct netmap_vm_handle_t {
        struct cdev             *dev;
        struct netmap_priv_d    *priv;
};


static int
netmap_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
                vm_ooffset_t foff, struct ucred *cred, u_short *color)
{
        struct netmap_vm_handle_t *vmh = handle;

        if (netmap_verbose)
                nm_prinf("handle %p size %jd prot %d foff %jd",
                        handle, (intmax_t)size, prot, (intmax_t)foff);
        if (color)
                *color = 0;
        dev_ref(vmh->dev);
        return 0;
}


static void
netmap_dev_pager_dtor(void *handle)
{
        struct netmap_vm_handle_t *vmh = handle;
        struct cdev *dev = vmh->dev;
        struct netmap_priv_d *priv = vmh->priv;

        if (netmap_verbose)
                nm_prinf("handle %p", handle);
        netmap_dtor(priv);
        free(vmh, M_DEVBUF);
        dev_rel(dev);
}


static int
netmap_dev_pager_fault(vm_object_t object, vm_ooffset_t offset,
        int prot, vm_page_t *mres)
{
        struct netmap_vm_handle_t *vmh = object->handle;
        struct netmap_priv_d *priv = vmh->priv;
        struct netmap_adapter *na = priv->np_na;
        vm_paddr_t paddr;
        vm_page_t page;
        vm_memattr_t memattr;

        nm_prdis("object %p offset %jd prot %d mres %p",
                        object, (intmax_t)offset, prot, mres);
        memattr = object->memattr;
        paddr = netmap_mem_ofstophys(na->nm_mem, offset);
        if (paddr == 0)
                return VM_PAGER_FAIL;

        if (((*mres)->flags & PG_FICTITIOUS) != 0) {
                /*
                 * If the passed in result page is a fake page, update it with
                 * the new physical address.
                 */
                page = *mres;
                vm_page_updatefake(page, paddr, memattr);
        } else {
                /*
                 * Replace the passed in reqpage page with our own fake page and
                 * free up the all of the original pages.
                 */
                VM_OBJECT_WUNLOCK(object);
                page = vm_page_getfake(paddr, memattr);
                VM_OBJECT_WLOCK(object);
                vm_page_replace(page, object, (*mres)->pindex, *mres);
                *mres = page;
        }
        page->valid = VM_PAGE_BITS_ALL;
        return (VM_PAGER_OK);
}

static void
netmap_dev_pager_path(void *handle, char *path, size_t len)
{
        struct netmap_vm_handle_t *vmh = handle;
        struct cdev *dev = vmh->dev;

        dev_copyname(dev, path, len);
}

static struct cdev_pager_ops netmap_cdev_pager_ops = {
        .cdev_pg_ctor = netmap_dev_pager_ctor,
        .cdev_pg_dtor = netmap_dev_pager_dtor,
        .cdev_pg_fault = netmap_dev_pager_fault,
        .cdev_pg_path = netmap_dev_pager_path,
};


static int
netmap_mmap_single(struct cdev *cdev, vm_ooffset_t *foff,
        vm_size_t objsize,  vm_object_t *objp, int prot)
{
        int error;
        struct netmap_vm_handle_t *vmh;
        struct netmap_priv_d *priv;
        vm_object_t obj;

        if (netmap_verbose)
                nm_prinf("cdev %p foff %jd size %jd objp %p prot %d", cdev,
                    (intmax_t )*foff, (intmax_t )objsize, objp, prot);

        vmh = malloc(sizeof(struct netmap_vm_handle_t), M_DEVBUF,
                              M_NOWAIT | M_ZERO);
        if (vmh == NULL)
                return ENOMEM;
        vmh->dev = cdev;

        NMG_LOCK();
        error = devfs_get_cdevpriv((void**)&priv);
        if (error)
                goto err_unlock;
        if (priv->np_nifp == NULL) {
                error = EINVAL;
                goto err_unlock;
        }
        vmh->priv = priv;
        priv->np_refs++;
        NMG_UNLOCK();

        obj = cdev_pager_allocate(vmh, OBJT_DEVICE,
                &netmap_cdev_pager_ops, objsize, prot,
                *foff, NULL);
        if (obj == NULL) {
                nm_prerr("cdev_pager_allocate failed");
                error = EINVAL;
                goto err_deref;
        }

        *objp = obj;
        return 0;

err_deref:
        NMG_LOCK();
        priv->np_refs--;
err_unlock:
        NMG_UNLOCK();
// err:
        free(vmh, M_DEVBUF);
        return error;
}

/*
 * On FreeBSD the close routine is only called on the last close on
 * the device (/dev/netmap) so we cannot do anything useful.
 * To track close() on individual file descriptors we pass netmap_dtor() to
 * devfs_set_cdevpriv() on open(). The FreeBSD kernel will call the destructor
 * when the last fd pointing to the device is closed.
 *
 * Note that FreeBSD does not even munmap() on close() so we also have
 * to track mmap() ourselves, and postpone the call to
 * netmap_dtor() is called when the process has no open fds and no active
 * memory maps on /dev/netmap, as in linux.
 */
static int
netmap_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
{
        if (netmap_verbose)
                nm_prinf("dev %p fflag 0x%x devtype %d td %p",
                        dev, fflag, devtype, td);
        return 0;
}


static int
netmap_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
{
        struct netmap_priv_d *priv;
        int error;

        (void)dev;
        (void)oflags;
        (void)devtype;
        (void)td;

        NMG_LOCK();
        priv = netmap_priv_new();
        if (priv == NULL) {
                error = ENOMEM;
                goto out;
        }
        error = devfs_set_cdevpriv(priv, netmap_dtor);
        if (error) {
                netmap_priv_delete(priv);
        }
out:
        NMG_UNLOCK();
        return error;
}

/******************** kthread wrapper ****************/
#include <sys/sysproto.h>
u_int
nm_os_ncpus(void)
{
        return mp_maxid + 1;
}

struct nm_kctx_ctx {
        /* Userspace thread (kthread creator). */
        struct thread *user_td;

        /* worker function and parameter */
        nm_kctx_worker_fn_t worker_fn;
        void *worker_private;

        struct nm_kctx *nmk;

        /* integer to manage multiple worker contexts (e.g., RX or TX on ptnetmap) */
        long type;
};

struct nm_kctx {
        struct thread *worker;
        struct mtx worker_lock;
        struct nm_kctx_ctx worker_ctx;
        int run;                        /* used to stop kthread */
        int attach_user;                /* kthread attached to user_process */
        int affinity;
};

static void
nm_kctx_worker(void *data)
{
        struct nm_kctx *nmk = data;
        struct nm_kctx_ctx *ctx = &nmk->worker_ctx;

        if (nmk->affinity >= 0) {
                thread_lock(curthread);
                sched_bind(curthread, nmk->affinity);
                thread_unlock(curthread);
        }

        while (nmk->run) {
                /*
                 * check if the parent process dies
                 * (when kthread is attached to user process)
                 */
                if (ctx->user_td) {
                        PROC_LOCK(curproc);
                        thread_suspend_check(0);
                        PROC_UNLOCK(curproc);
                } else {
                        kthread_suspend_check();
                }

                /* Continuously execute worker process. */
                ctx->worker_fn(ctx->worker_private); /* worker body */
        }

        kthread_exit();
}

void
nm_os_kctx_worker_setaff(struct nm_kctx *nmk, int affinity)
{
        nmk->affinity = affinity;
}

struct nm_kctx *
nm_os_kctx_create(struct nm_kctx_cfg *cfg, void *opaque)
{
        struct nm_kctx *nmk = NULL;

        nmk = malloc(sizeof(*nmk),  M_DEVBUF, M_NOWAIT | M_ZERO);
        if (!nmk)
                return NULL;

        mtx_init(&nmk->worker_lock, "nm_kthread lock", NULL, MTX_DEF);
        nmk->worker_ctx.worker_fn = cfg->worker_fn;
        nmk->worker_ctx.worker_private = cfg->worker_private;
        nmk->worker_ctx.type = cfg->type;
        nmk->affinity = -1;

        /* attach kthread to user process (ptnetmap) */
        nmk->attach_user = cfg->attach_user;

        return nmk;
}

int
nm_os_kctx_worker_start(struct nm_kctx *nmk)
{
        struct proc *p = NULL;
        int error = 0;

        /* Temporarily disable this function as it is currently broken
         * and causes kernel crashes. The failure can be triggered by
         * the "vale_polling_enable_disable" test in ctrl-api-test.c. */
        return EOPNOTSUPP;

        if (nmk->worker)
                return EBUSY;

        /* check if we want to attach kthread to user process */
        if (nmk->attach_user) {
                nmk->worker_ctx.user_td = curthread;
                p = curthread->td_proc;
        }

        /* enable kthread main loop */
        nmk->run = 1;
        /* create kthread */
        if((error = kthread_add(nm_kctx_worker, nmk, p,
                        &nmk->worker, RFNOWAIT /* to be checked */, 0, "nm-kthread-%ld",
                        nmk->worker_ctx.type))) {
                goto err;
        }

        nm_prinf("nm_kthread started td %p", nmk->worker);

        return 0;
err:
        nm_prerr("nm_kthread start failed err %d", error);
        nmk->worker = NULL;
        return error;
}

void
nm_os_kctx_worker_stop(struct nm_kctx *nmk)
{
        if (!nmk->worker)
                return;

        /* tell to kthread to exit from main loop */
        nmk->run = 0;

        /* wake up kthread if it sleeps */
        kthread_resume(nmk->worker);

        nmk->worker = NULL;
}

void
nm_os_kctx_destroy(struct nm_kctx *nmk)
{
        if (!nmk)
                return;

        if (nmk->worker)
                nm_os_kctx_worker_stop(nmk);

        free(nmk, M_DEVBUF);
}

/******************** kqueue support ****************/

/*
 * In addition to calling selwakeuppri(), nm_os_selwakeup() also
 * needs to call knote() to wake up kqueue listeners.
 * This operation is deferred to a taskqueue in order to avoid possible
 * lock order reversals; these may happen because knote() grabs a
 * private lock associated to the 'si' (see struct selinfo,
 * struct nm_selinfo, and nm_os_selinfo_init), and nm_os_selwakeup()
 * can be called while holding the lock associated to a different
 * 'si'.
 * When calling knote() we use a non-zero 'hint' argument to inform
 * the netmap_knrw() function that it is being called from
 * 'nm_os_selwakeup'; this is necessary because when netmap_knrw() is
 * called by the kevent subsystem (i.e. kevent_scan()) we also need to
 * call netmap_poll().
 *
 * The netmap_kqfilter() function registers one or another f_event
 * depending on read or write mode. A pointer to the struct
 * 'netmap_priv_d' is stored into kn->kn_hook, so that it can later
 * be passed to netmap_poll(). We pass NULL as a third argument to
 * netmap_poll(), so that the latter only runs the txsync/rxsync
 * (if necessary), and skips the nm_os_selrecord() calls.
 */


void
nm_os_selwakeup(struct nm_selinfo *si)
{
        selwakeuppri(&si->si, PI_NET);
        if (si->kqueue_users > 0) {
                taskqueue_enqueue(si->ntfytq, &si->ntfytask);
        }
}

void
nm_os_selrecord(struct thread *td, struct nm_selinfo *si)
{
        selrecord(td, &si->si);
}

static void
netmap_knrdetach(struct knote *kn)
{
        struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
        struct nm_selinfo *si = priv->np_si[NR_RX];

        knlist_remove(&si->si.si_note, kn, /*islocked=*/0);
        NMG_LOCK();
        KASSERT(si->kqueue_users > 0, ("kqueue_user underflow on %s",
            si->mtxname));
        si->kqueue_users--;
        nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
        NMG_UNLOCK();
}

static void
netmap_knwdetach(struct knote *kn)
{
        struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
        struct nm_selinfo *si = priv->np_si[NR_TX];

        knlist_remove(&si->si.si_note, kn, /*islocked=*/0);
        NMG_LOCK();
        si->kqueue_users--;
        nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
        NMG_UNLOCK();
}

/*
 * Callback triggered by netmap notifications (see netmap_notify()),
 * and by the application calling kevent(). In the former case we
 * just return 1 (events ready), since we are not able to do better.
 * In the latter case we use netmap_poll() to see which events are
 * ready.
 */
static int
netmap_knrw(struct knote *kn, long hint, int events)
{
        struct netmap_priv_d *priv;
        int revents;

        if (hint != 0) {
                /* Called from netmap_notify(), typically from a
                 * thread different from the one issuing kevent().
                 * Assume we are ready. */
                return 1;
        }

        /* Called from kevent(). */
        priv = kn->kn_hook;
        revents = netmap_poll(priv, events, /*thread=*/NULL);

        return (events & revents) ? 1 : 0;
}

static int
netmap_knread(struct knote *kn, long hint)
{
        return netmap_knrw(kn, hint, POLLIN);
}

static int
netmap_knwrite(struct knote *kn, long hint)
{
        return netmap_knrw(kn, hint, POLLOUT);
}

static int
netmap_kncopy(struct knote *kn, struct proc *p1)
{
        struct netmap_priv_d *priv;
        struct nm_selinfo *si;

        priv = kn->kn_hook;
        si = priv->np_si[kn->kn_filter == EVFILT_WRITE ? NR_TX : NR_RX];
        NMG_LOCK();
        si->kqueue_users++;
        NMG_UNLOCK();
        return (0);
}

static const struct filterops netmap_rfiltops = {
        .f_isfd = 1,
        .f_detach = netmap_knrdetach,
        .f_event = netmap_knread,
        .f_copy = netmap_kncopy,
};

static const struct filterops netmap_wfiltops = {
        .f_isfd = 1,
        .f_detach = netmap_knwdetach,
        .f_event = netmap_knwrite,
        .f_copy = netmap_kncopy,
};

/*
 * This is called when a thread invokes kevent() to record
 * a change in the configuration of the kqueue().
 * The 'priv' is the one associated to the open netmap device.
 */
static int
netmap_kqfilter(struct cdev *dev, struct knote *kn)
{
        struct netmap_priv_d *priv;
        int error;
        struct netmap_adapter *na;
        struct nm_selinfo *si;
        int ev = kn->kn_filter;

        if (ev != EVFILT_READ && ev != EVFILT_WRITE) {
                nm_prerr("bad filter request %d", ev);
                return 1;
        }
        error = devfs_get_cdevpriv((void**)&priv);
        if (error) {
                nm_prerr("device not yet setup");
                return 1;
        }
        na = priv->np_na;
        if (na == NULL) {
                nm_prerr("no netmap adapter for this file descriptor");
                return 1;
        }
        /* the si is indicated in the priv */
        si = priv->np_si[(ev == EVFILT_WRITE) ? NR_TX : NR_RX];
        kn->kn_fop = (ev == EVFILT_WRITE) ?
                &netmap_wfiltops : &netmap_rfiltops;
        kn->kn_hook = priv;
        NMG_LOCK();
        si->kqueue_users++;
        nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
        NMG_UNLOCK();
        knlist_add(&si->si.si_note, kn, /*islocked=*/0);

        return 0;
}

static int
freebsd_netmap_poll(struct cdev *cdevi __unused, int events, struct thread *td)
{
        struct netmap_priv_d *priv;
        if (devfs_get_cdevpriv((void **)&priv)) {
                return POLLERR;
        }
        return netmap_poll(priv, events, td);
}

static int
freebsd_netmap_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data,
                int ffla __unused, struct thread *td)
{
        int error;
        struct netmap_priv_d *priv;

        CURVNET_SET(TD_TO_VNET(td));
        error = devfs_get_cdevpriv((void **)&priv);
        if (error) {
                /* XXX ENOENT should be impossible, since the priv
                 * is now created in the open */
                if (error == ENOENT)
                        error = ENXIO;
                goto out;
        }
        error = netmap_ioctl(priv, cmd, data, td, /*nr_body_is_user=*/1);
out:
        CURVNET_RESTORE();

        return error;
}

void
nm_os_onattach(if_t ifp)
{
        if_setcapabilitiesbit(ifp, IFCAP_NETMAP, 0);
}

void
nm_os_onenter(if_t ifp)
{
        struct netmap_adapter *na = NA(ifp);

        na->if_transmit = if_gettransmitfn(ifp);
        if_settransmitfn(ifp, netmap_transmit);
        if_setcapenablebit(ifp, IFCAP_NETMAP, 0);
}

void
nm_os_onexit(if_t ifp)
{
        struct netmap_adapter *na = NA(ifp);

        if_settransmitfn(ifp, na->if_transmit);
        if_setcapenablebit(ifp, 0, IFCAP_NETMAP);
}

extern struct cdevsw netmap_cdevsw; /* XXX used in netmap.c, should go elsewhere */
struct cdevsw netmap_cdevsw = {
        .d_version = D_VERSION,
        .d_name = "netmap",
        .d_open = netmap_open,
        .d_mmap_single = netmap_mmap_single,
        .d_ioctl = freebsd_netmap_ioctl,
        .d_poll = freebsd_netmap_poll,
        .d_kqfilter = netmap_kqfilter,
        .d_close = netmap_close,
};
/*--- end of kqueue support ----*/

/*
 * Kernel entry point.
 *
 * Initialize/finalize the module and return.
 *
 * Return 0 on success, errno on failure.
 */
static int
netmap_loader(__unused struct module *module, int event, __unused void *arg)
{
        int error = 0;

        switch (event) {
        case MOD_LOAD:
                error = netmap_init();
                break;

        case MOD_UNLOAD:
                /*
                 * if some one is still using netmap,
                 * then the module can not be unloaded.
                 */
                if (netmap_use_count) {
                        nm_prerr("netmap module can not be unloaded - netmap_use_count: %d",
                                        netmap_use_count);
                        error = EBUSY;
                        break;
                }
                netmap_fini();
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}

#ifdef DEV_MODULE_ORDERED
/*
 * The netmap module contains three drivers: (i) the netmap character device
 * driver; (ii) the ptnetmap memdev PCI device driver, (iii) the ptnet PCI
 * device driver. The attach() routines of both (ii) and (iii) need the
 * lock of the global allocator, and such lock is initialized in netmap_init(),
 * which is part of (i).
 * Therefore, we make sure that (i) is loaded before (ii) and (iii), using
 * the 'order' parameter of driver declaration macros. For (i), we specify
 * SI_ORDER_MIDDLE, while higher orders are used with the DRIVER_MODULE_ORDERED
 * macros for (ii) and (iii).
 */
DEV_MODULE_ORDERED(netmap, netmap_loader, NULL, SI_ORDER_MIDDLE);
#else /* !DEV_MODULE_ORDERED */
DEV_MODULE(netmap, netmap_loader, NULL);
#endif /* DEV_MODULE_ORDERED  */
MODULE_DEPEND(netmap, pci, 1, 1, 1);
MODULE_VERSION(netmap, 1);
/* reduce conditional code */
// linux API, use for the knlist in FreeBSD
/* use a private mutex for the knlist */