It is 2014 and we have a new version of netmap.

[FreeBSD/FreeBSD.git] / sys / dev / netmap / netmap_kern.h

/*
 * Copyright (C) 2011-2014 Matteo Landi, Luigi Rizzo. All rights reserved.
 * 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.
 */

/*
 * $FreeBSD$
 *
 * The header contains the definitions of constants and function
 * prototypes used only in kernelspace.
 */

#ifndef _NET_NETMAP_KERN_H_
#define _NET_NETMAP_KERN_H_

#define WITH_VALE       // comment out to disable VALE support

#if defined(__FreeBSD__)

#define likely(x)       __builtin_expect((long)!!(x), 1L)
#define unlikely(x)     __builtin_expect((long)!!(x), 0L)

#define NM_LOCK_T       struct mtx
#define NMG_LOCK_T      struct mtx
#define NMG_LOCK_INIT() mtx_init(&netmap_global_lock, \
                                "netmap global lock", NULL, MTX_DEF)
#define NMG_LOCK_DESTROY()      mtx_destroy(&netmap_global_lock)
#define NMG_LOCK()      mtx_lock(&netmap_global_lock)
#define NMG_UNLOCK()    mtx_unlock(&netmap_global_lock)
#define NMG_LOCK_ASSERT()       mtx_assert(&netmap_global_lock, MA_OWNED)

#define NM_SELINFO_T    struct selinfo
#define MBUF_LEN(m)     ((m)->m_pkthdr.len)
#define MBUF_IFP(m)     ((m)->m_pkthdr.rcvif)
#define NM_SEND_UP(ifp, m)      ((NA(ifp))->if_input)(ifp, m)

#define NM_ATOMIC_T     volatile int    // XXX ?
/* atomic operations */
#include <machine/atomic.h>
#define NM_ATOMIC_TEST_AND_SET(p)       (!atomic_cmpset_acq_int((p), 0, 1))
#define NM_ATOMIC_CLEAR(p)              atomic_store_rel_int((p), 0)


MALLOC_DECLARE(M_NETMAP);

// XXX linux struct, not used in FreeBSD
struct net_device_ops {
};
struct hrtimer {
};

#elif defined (linux)

#define NM_LOCK_T       safe_spinlock_t // see bsd_glue.h
#define NM_SELINFO_T    wait_queue_head_t
#define MBUF_LEN(m)     ((m)->len)
#define MBUF_IFP(m)     ((m)->dev)
#define NM_SEND_UP(ifp, m)  \
                        do { \
                            m->priority = NM_MAGIC_PRIORITY; \
                            netif_rx(m); \
                        } while (0)

#define NM_ATOMIC_T     volatile long unsigned int

// XXX a mtx would suffice here too 20130404 gl
#define NMG_LOCK_T              struct semaphore
#define NMG_LOCK_INIT()         sema_init(&netmap_global_lock, 1)
#define NMG_LOCK_DESTROY()
#define NMG_LOCK()              down(&netmap_global_lock)
#define NMG_UNLOCK()            up(&netmap_global_lock)
#define NMG_LOCK_ASSERT()       //      XXX to be completed

#ifndef DEV_NETMAP
#define DEV_NETMAP
#endif /* DEV_NETMAP */

/*
 * IFCAP_NETMAP goes into net_device's priv_flags (if_capenable).
 * This was 16 bits up to linux 2.6.36, so we need a 16 bit value on older
 * platforms and tolerate the clash with IFF_DYNAMIC and IFF_BRIDGE_PORT.
 * For the 32-bit value, 0x100000 has no clashes until at least 3.5.1
 */
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37)
#define IFCAP_NETMAP    0x8000
#else
#define IFCAP_NETMAP    0x200000
#endif

#elif defined (__APPLE__)

#warning apple support is incomplete.
#define likely(x)       __builtin_expect(!!(x), 1)
#define unlikely(x)     __builtin_expect(!!(x), 0)
#define NM_LOCK_T       IOLock *
#define NM_SELINFO_T    struct selinfo
#define MBUF_LEN(m)     ((m)->m_pkthdr.len)
#define NM_SEND_UP(ifp, m)      ((ifp)->if_input)(ifp, m)

#else

#error unsupported platform

#endif /* end - platform-specific code */

#define ND(format, ...)
#define D(format, ...)                                          \
        do {                                                    \
                struct timeval __xxts;                          \
                microtime(&__xxts);                             \
                printf("%03d.%06d [%4d] %-25s " format "\n",    \
                (int)__xxts.tv_sec % 1000, (int)__xxts.tv_usec, \
                __LINE__, __FUNCTION__, ##__VA_ARGS__);         \
        } while (0)

/* rate limited, lps indicates how many per second */
#define RD(lps, format, ...)                                    \
        do {                                                    \
                static int t0, __cnt;                           \
                if (t0 != time_second) {                        \
                        t0 = time_second;                       \
                        __cnt = 0;                              \
                }                                               \
                if (__cnt++ < lps)                              \
                        D(format, ##__VA_ARGS__);               \
        } while (0)

struct netmap_adapter;
struct nm_bdg_fwd;
struct nm_bridge;
struct netmap_priv_d;

const char *nm_dump_buf(char *p, int len, int lim, char *dst);

#include "netmap_mbq.h"

extern NMG_LOCK_T       netmap_global_lock;

/*
 * private, kernel view of a ring. Keeps track of the status of
 * a ring across system calls.
 *
 *      nr_hwcur        index of the next buffer to refill.
 *                      It corresponds to ring->head
 *                      at the time the system call returns.
 *
 *      nr_hwtail       index of the first buffer owned by the kernel.
 *                      On RX, hwcur->hwtail are receive buffers
 *                      not yet released. hwcur is advanced following
 *                      ring->head, hwtail is advanced on incoming packets,
 *                      and a wakeup is generated when hwtail passes ring->cur
 *                          On TX, hwcur->rcur have been filled by the sender
 *                      but not sent yet to the NIC; rcur->hwtail are available
 *                      for new transmissions, and hwtail->hwcur-1 are pending
 *                      transmissions not yet acknowledged.
 *
 * The indexes in the NIC and netmap rings are offset by nkr_hwofs slots.
 * This is so that, on a reset, buffers owned by userspace are not
 * modified by the kernel. In particular:
 * RX rings: the next empty buffer (hwtail + hwofs) coincides with
 *      the next empty buffer as known by the hardware (next_to_check or so).
 * TX rings: hwcur + hwofs coincides with next_to_send
 *
 * Clients cannot issue concurrent syscall on a ring. The system
 * detects this and reports an error using two flags,
 * NKR_WBUSY and NKR_RBUSY
 * For received packets, slot->flags is set to nkr_slot_flags
 * so we can provide a proper initial value (e.g. set NS_FORWARD
 * when operating in 'transparent' mode).
 *
 * The following fields are used to implement lock-free copy of packets
 * from input to output ports in VALE switch:
 *      nkr_hwlease     buffer after the last one being copied.
 *                      A writer in nm_bdg_flush reserves N buffers
 *                      from nr_hwlease, advances it, then does the
 *                      copy outside the lock.
 *                      In RX rings (used for VALE ports),
 *                      nkr_hwtail <= nkr_hwlease < nkr_hwcur+N-1
 *                      In TX rings (used for NIC or host stack ports)
 *                      nkr_hwcur <= nkr_hwlease < nkr_hwtail
 *      nkr_leases      array of nkr_num_slots where writers can report
 *                      completion of their block. NR_NOSLOT (~0) indicates
 *                      that the writer has not finished yet
 *      nkr_lease_idx   index of next free slot in nr_leases, to be assigned
 *
 * The kring is manipulated by txsync/rxsync and generic netmap function.
 *
 * Concurrent rxsync or txsync on the same ring are prevented through
 * by nm_kr_lock() which in turn uses nr_busy. This is all we need
 * for NIC rings, and for TX rings attached to the host stack.
 *
 * RX rings attached to the host stack use an mbq (rx_queue) on both
 * rxsync_from_host() and netmap_transmit(). The mbq is protected
 * by its internal lock.
 *
 * RX rings attached to the VALE switch are accessed by both sender
 * and receiver. They are protected through the q_lock on the RX ring.
 */
struct netmap_kring {
        struct netmap_ring      *ring;

        uint32_t        nr_hwcur;
        uint32_t        nr_hwtail;

        /*
         * Copies of values in user rings, so we do not need to look
         * at the ring (which could be modified). These are set in the
         * *sync_prologue()/finalize() routines.
         */
        uint32_t        rhead;
        uint32_t        rcur;
        uint32_t        rtail;

        uint32_t        nr_kflags;      /* private driver flags */
#define NKR_PENDINTR    0x1             // Pending interrupt.
        uint32_t        nkr_num_slots;

        /*
         * On a NIC reset, the NIC ring indexes may be reset but the
         * indexes in the netmap rings remain the same. nkr_hwofs
         * keeps track of the offset between the two.
         */
        int32_t         nkr_hwofs;

        uint16_t        nkr_slot_flags; /* initial value for flags */

        /* last_reclaim is opaque marker to help reduce the frequency
         * of operations such as reclaiming tx buffers. A possible use
         * is set it to ticks and do the reclaim only once per tick.
         */
        uint64_t        last_reclaim;


        NM_SELINFO_T    si;             /* poll/select wait queue */
        NM_LOCK_T       q_lock;         /* protects kring and ring. */
        NM_ATOMIC_T     nr_busy;        /* prevent concurrent syscalls */

        struct netmap_adapter *na;

        /* The folloiwing fields are for VALE switch support */
        struct nm_bdg_fwd *nkr_ft;
        uint32_t        *nkr_leases;
#define NR_NOSLOT       ((uint32_t)~0)  /* used in nkr_*lease* */
        uint32_t        nkr_hwlease;
        uint32_t        nkr_lease_idx;

        volatile int nkr_stopped;       // XXX what for ?

        /* support for adapters without native netmap support.
         * On tx rings we preallocate an array of tx buffers
         * (same size as the netmap ring), on rx rings we
         * store incoming packets in a queue.
         * XXX who writes to the rx queue ?
         */
        struct mbuf **tx_pool;
        // u_int nr_ntc;                /* Emulation of a next-to-clean RX ring pointer. */
        struct mbq rx_queue;            /* intercepted rx mbufs. */

        uint32_t        ring_id;        /* debugging */
        char name[64];                  /* diagnostic */

} __attribute__((__aligned__(64)));


/* return the next index, with wraparound */
static inline uint32_t
nm_next(uint32_t i, uint32_t lim)
{
        return unlikely (i == lim) ? 0 : i + 1;
}


/* return the previous index, with wraparound */
static inline uint32_t
nm_prev(uint32_t i, uint32_t lim)
{
        return unlikely (i == 0) ? lim : i - 1;
}


/*
 *
 * Here is the layout for the Rx and Tx rings.

       RxRING                            TxRING

      +-----------------+            +-----------------+
      |                 |            |                 |
      |XXX free slot XXX|            |XXX free slot XXX|
      +-----------------+            +-----------------+
head->| owned by user   |<-hwcur     | not sent to nic |<-hwcur
      |                 |            | yet             |
      +-----------------+            |                 |
 cur->| available to    |            |                 |
      | user, not read  |            +-----------------+
      | yet             |       cur->| (being          |
      |                 |            |  prepared)      |
      |                 |            |                 |
      +-----------------+            +     ------      +
tail->|                 |<-hwtail    |                 |<-hwlease
      | (being          | ...        |                 | ...
      |  prepared)      | ...        |                 | ...
      +-----------------+ ...        |                 | ...
      |                 |<-hwlease   +-----------------+
      |                 |      tail->|                 |<-hwtail
      |                 |            |                 |
      |                 |            |                 |
      |                 |            |                 |
      +-----------------+            +-----------------+

 * The cur/tail (user view) and hwcur/hwtail (kernel view)
 * are used in the normal operation of the card.
 *
 * When a ring is the output of a switch port (Rx ring for
 * a VALE port, Tx ring for the host stack or NIC), slots
 * are reserved in blocks through 'hwlease' which points
 * to the next unused slot.
 * On an Rx ring, hwlease is always after hwtail,
 * and completions cause hwtail to advance.
 * On a Tx ring, hwlease is always between cur and hwtail,
 * and completions cause cur to advance.
 *
 * nm_kr_space() returns the maximum number of slots that
 * can be assigned.
 * nm_kr_lease() reserves the required number of buffers,
 *    advances nkr_hwlease and also returns an entry in
 *    a circular array where completions should be reported.
 */



enum txrx { NR_RX = 0, NR_TX = 1 };

/*
 * The "struct netmap_adapter" extends the "struct adapter"
 * (or equivalent) device descriptor.
 * It contains all base fields needed to support netmap operation.
 * There are in fact different types of netmap adapters
 * (native, generic, VALE switch...) so a netmap_adapter is
 * just the first field in the derived type.
 */
struct netmap_adapter {
        /*
         * On linux we do not have a good way to tell if an interface
         * is netmap-capable. So we always use the following trick:
         * NA(ifp) points here, and the first entry (which hopefully
         * always exists and is at least 32 bits) contains a magic
         * value which we can use to detect that the interface is good.
         */
        uint32_t magic;
        uint32_t na_flags;      /* enabled, and other flags */
#define NAF_SKIP_INTR   1       /* use the regular interrupt handler.
                                 * useful during initialization
                                 */
#define NAF_SW_ONLY     2       /* forward packets only to sw adapter */
#define NAF_BDG_MAYSLEEP 4      /* the bridge is allowed to sleep when
                                 * forwarding packets coming from this
                                 * interface
                                 */
#define NAF_MEM_OWNER   8       /* the adapter is responsible for the
                                 * deallocation of the memory allocator
                                 */
#define NAF_NATIVE_ON   16      /* the adapter is native and the attached
                                 * interface is in netmap mode
                                 */
#define NAF_NETMAP_ON   32      /* netmap is active (either native or
                                 * emulated. Where possible (e.g. FreeBSD)
                                 * IFCAP_NETMAP also mirrors this flag.
                                 */
        int active_fds; /* number of user-space descriptors using this
                         interface, which is equal to the number of
                         struct netmap_if objs in the mapped region. */

        u_int num_rx_rings; /* number of adapter receive rings */
        u_int num_tx_rings; /* number of adapter transmit rings */

        u_int num_tx_desc; /* number of descriptor in each queue */
        u_int num_rx_desc;

        /* tx_rings and rx_rings are private but allocated
         * as a contiguous chunk of memory. Each array has
         * N+1 entries, for the adapter queues and for the host queue.
         */
        struct netmap_kring *tx_rings; /* array of TX rings. */
        struct netmap_kring *rx_rings; /* array of RX rings. */

        void *tailroom;                /* space below the rings array */
                                       /* (used for leases) */


        NM_SELINFO_T tx_si, rx_si;      /* global wait queues */

        /* copy of if_qflush and if_transmit pointers, to intercept
         * packets from the network stack when netmap is active.
         */
        int     (*if_transmit)(struct ifnet *, struct mbuf *);

        /* copy of if_input for netmap_send_up() */
        void     (*if_input)(struct ifnet *, struct mbuf *);

        /* references to the ifnet and device routines, used by
         * the generic netmap functions.
         */
        struct ifnet *ifp; /* adapter is ifp->if_softc */

        /*---- callbacks for this netmap adapter -----*/
        /*
         * nm_dtor() is the cleanup routine called when destroying
         *      the adapter.
         *
         * nm_register() is called on NIOCREGIF and close() to enter
         *      or exit netmap mode on the NIC
         *
         * nm_txsync() pushes packets to the underlying hw/switch
         *
         * nm_rxsync() collects packets from the underlying hw/switch
         *
         * nm_config() returns configuration information from the OS
         *
         * nm_krings_create() XXX
         *
         * nm_krings_delete() XXX
         *
         * nm_notify() is used to act after data have become available.
         *      For hw devices this is typically a selwakeup(),
         *      but for NIC/host ports attached to a switch (or vice-versa)
         *      we also need to invoke the 'txsync' code downstream.
         */

        /* private cleanup */
        void (*nm_dtor)(struct netmap_adapter *);

        int (*nm_register)(struct netmap_adapter *, int onoff);

        int (*nm_txsync)(struct netmap_adapter *, u_int ring, int flags);
        int (*nm_rxsync)(struct netmap_adapter *, u_int ring, int flags);
#define NAF_FORCE_READ    1
#define NAF_FORCE_RECLAIM 2
        /* return configuration information */
        int (*nm_config)(struct netmap_adapter *,
                u_int *txr, u_int *txd, u_int *rxr, u_int *rxd);
        int (*nm_krings_create)(struct netmap_adapter *);
        void (*nm_krings_delete)(struct netmap_adapter *);
        int (*nm_notify)(struct netmap_adapter *,
                u_int ring, enum txrx, int flags);
#define NAF_GLOBAL_NOTIFY 4
#define NAF_DISABLE_NOTIFY 8

        /* standard refcount to control the lifetime of the adapter
         * (it should be equal to the lifetime of the corresponding ifp)
         */
        int na_refcount;

        /* memory allocator (opaque)
         * We also cache a pointer to the lut_entry for translating
         * buffer addresses, and the total number of buffers.
         */
        struct netmap_mem_d *nm_mem;
        struct lut_entry *na_lut;
        uint32_t na_lut_objtotal;       /* max buffer index */

        /* used internally. If non-null, the interface cannot be bound
         * from userspace
         */
        void *na_private;
};


/*
 * If the NIC is owned by the kernel
 * (i.e., bridge), neither another bridge nor user can use it;
 * if the NIC is owned by a user, only users can share it.
 * Evaluation must be done under NMG_LOCK().
 */
#define NETMAP_OWNED_BY_KERN(na)        (na->na_private)
#define NETMAP_OWNED_BY_ANY(na) \
        (NETMAP_OWNED_BY_KERN(na) || (na->active_fds > 0))


/*
 * derived netmap adapters for various types of ports
 */
struct netmap_vp_adapter {      /* VALE software port */
        struct netmap_adapter up;

        /*
         * Bridge support:
         *
         * bdg_port is the port number used in the bridge;
         * na_bdg points to the bridge this NA is attached to.
         */
        int bdg_port;
        struct nm_bridge *na_bdg;
        int retry;

        u_int offset;   /* Offset of ethernet header for each packet. */
};


struct netmap_hw_adapter {      /* physical device */
        struct netmap_adapter up;

        struct net_device_ops nm_ndo;   // XXX linux only
};


struct netmap_generic_adapter { /* emulated device */
        struct netmap_hw_adapter up;

        /* Pointer to a previously used netmap adapter. */
        struct netmap_adapter *prev;

        /* generic netmap adapters support:
         * a net_device_ops struct overrides ndo_select_queue(),
         * save_if_input saves the if_input hook (FreeBSD),
         * mit_timer and mit_pending implement rx interrupt mitigation,
         */
        struct net_device_ops generic_ndo;
        void (*save_if_input)(struct ifnet *, struct mbuf *);

        struct hrtimer mit_timer;
        int mit_pending;
#ifdef linux
        netdev_tx_t (*save_start_xmit)(struct mbuf *, struct ifnet *);
#endif
};

#ifdef WITH_VALE

/*
 * Bridge wrapper for non VALE ports attached to a VALE switch.
 *
 * The real device must already have its own netmap adapter (hwna).
 * The bridge wrapper and the hwna adapter share the same set of
 * netmap rings and buffers, but they have two separate sets of
 * krings descriptors, with tx/rx meanings swapped:
 *
 *                                  netmap
 *           bwrap     krings       rings      krings      hwna
 *         +------+   +------+     +-----+    +------+   +------+
 *         |tx_rings->|      |\   /|     |----|      |<-tx_rings|
 *         |      |   +------+ \ / +-----+    +------+   |      |
 *         |      |             X                        |      |
 *         |      |            / \                       |      |
 *         |      |   +------+/   \+-----+    +------+   |      |
 *         |rx_rings->|      |     |     |----|      |<-rx_rings|
 *         |      |   +------+     +-----+    +------+   |      |
 *         +------+                                      +------+
 *
 * - packets coming from the bridge go to the brwap rx rings,
 *   which are also the hwna tx rings.  The bwrap notify callback
 *   will then complete the hwna tx (see netmap_bwrap_notify).
 *
 * - packets coming from the outside go to the hwna rx rings,
 *   which are also the bwrap tx rings.  The (overwritten) hwna
 *   notify method will then complete the bridge tx
 *   (see netmap_bwrap_intr_notify).
 *
 *   The bridge wrapper may optionally connect the hwna 'host' rings
 *   to the bridge. This is done by using a second port in the
 *   bridge and connecting it to the 'host' netmap_vp_adapter
 *   contained in the netmap_bwrap_adapter. The brwap host adapter
 *   cross-links the hwna host rings in the same way as shown above.
 *
 * - packets coming from the bridge and directed to the host stack
 *   are handled by the bwrap host notify callback
 *   (see netmap_bwrap_host_notify)
 *
 * - packets coming from the host stack are still handled by the
 *   overwritten hwna notify callback (netmap_bwrap_intr_notify),
 *   but are diverted to the host adapter depending on the ring number.
 *
 */
struct netmap_bwrap_adapter {
        struct netmap_vp_adapter up;
        struct netmap_vp_adapter host;  /* for host rings */
        struct netmap_adapter *hwna;    /* the underlying device */

        /* backup of the hwna notify callback */
        int (*save_notify)(struct netmap_adapter *,
                        u_int ring, enum txrx, int flags);

        /*
         * When we attach a physical interface to the bridge, we
         * allow the controlling process to terminate, so we need
         * a place to store the netmap_priv_d data structure.
         * This is only done when physical interfaces
         * are attached to a bridge.
         */
        struct netmap_priv_d *na_kpriv;
};


#endif /* WITH_VALE */


/* return slots reserved to rx clients; used in drivers */
static inline uint32_t
nm_kr_rxspace(struct netmap_kring *k)
{
        int space = k->nr_hwtail - k->nr_hwcur;
        if (space < 0) 
                space += k->nkr_num_slots;
        ND("preserving %d rx slots %d -> %d", space, k->nr_hwcur, k->nr_hwtail);

        return space;
}


/* True if no space in the tx ring. only valid after txsync_prologue */
static inline int
nm_kr_txempty(struct netmap_kring *kring)
{
        return kring->rcur == kring->nr_hwtail;
}


/*
 * protect against multiple threads using the same ring.
 * also check that the ring has not been stopped.
 * We only care for 0 or !=0 as a return code.
 */
#define NM_KR_BUSY      1
#define NM_KR_STOPPED   2


static __inline void nm_kr_put(struct netmap_kring *kr)
{
        NM_ATOMIC_CLEAR(&kr->nr_busy);
}


static __inline int nm_kr_tryget(struct netmap_kring *kr)
{
        /* check a first time without taking the lock
         * to avoid starvation for nm_kr_get()
         */
        if (unlikely(kr->nkr_stopped)) {
                ND("ring %p stopped (%d)", kr, kr->nkr_stopped);
                return NM_KR_STOPPED;
        }
        if (unlikely(NM_ATOMIC_TEST_AND_SET(&kr->nr_busy)))
                return NM_KR_BUSY;
        /* check a second time with lock held */
        if (unlikely(kr->nkr_stopped)) {
                ND("ring %p stopped (%d)", kr, kr->nkr_stopped);
                nm_kr_put(kr);
                return NM_KR_STOPPED;
        }
        return 0;
}


/*
 * The following functions are used by individual drivers to
 * support netmap operation.
 *
 * netmap_attach() initializes a struct netmap_adapter, allocating the
 *      struct netmap_ring's and the struct selinfo.
 *
 * netmap_detach() frees the memory allocated by netmap_attach().
 *
 * netmap_transmit() replaces the if_transmit routine of the interface,
 *      and is used to intercept packets coming from the stack.
 *
 * netmap_load_map/netmap_reload_map are helper routines to set/reset
 *      the dmamap for a packet buffer
 *
 * netmap_reset() is a helper routine to be called in the driver
 *      when reinitializing a ring.
 */
int netmap_attach(struct netmap_adapter *);
int netmap_attach_common(struct netmap_adapter *);
void netmap_detach_common(struct netmap_adapter *na);
void netmap_detach(struct ifnet *);
int netmap_transmit(struct ifnet *, struct mbuf *);
struct netmap_slot *netmap_reset(struct netmap_adapter *na,
        enum txrx tx, u_int n, u_int new_cur);
int netmap_ring_reinit(struct netmap_kring *);

/* default functions to handle rx/tx interrupts */
int netmap_rx_irq(struct ifnet *, u_int, u_int *);
#define netmap_tx_irq(_n, _q) netmap_rx_irq(_n, _q, NULL)
void netmap_common_irq(struct ifnet *, u_int, u_int *work_done);

void netmap_disable_all_rings(struct ifnet *);
void netmap_enable_all_rings(struct ifnet *);
void netmap_disable_ring(struct netmap_kring *kr);


/* set/clear native flags and if_transmit/netdev_ops */
static inline void
nm_set_native_flags(struct netmap_adapter *na)
{
        struct ifnet *ifp = na->ifp;

        na->na_flags |= (NAF_NATIVE_ON | NAF_NETMAP_ON);
#ifdef IFCAP_NETMAP /* or FreeBSD ? */
        ifp->if_capenable |= IFCAP_NETMAP;
#endif
#ifdef __FreeBSD__
        na->if_transmit = ifp->if_transmit;
        ifp->if_transmit = netmap_transmit;
#else
        na->if_transmit = (void *)ifp->netdev_ops;
        ifp->netdev_ops = &((struct netmap_hw_adapter *)na)->nm_ndo;
#endif
}


static inline void
nm_clear_native_flags(struct netmap_adapter *na)
{
        struct ifnet *ifp = na->ifp;

#ifdef __FreeBSD__
        ifp->if_transmit = na->if_transmit;
#else
        ifp->netdev_ops = (void *)na->if_transmit;
#endif
        na->na_flags &= ~(NAF_NATIVE_ON | NAF_NETMAP_ON);
#ifdef IFCAP_NETMAP /* or FreeBSD ? */
        ifp->if_capenable &= ~IFCAP_NETMAP;
#endif
}


/*
 * validates parameters in the ring/kring, returns a value for head
 * If any error, returns ring_size to force a reinit.
 */
uint32_t nm_txsync_prologue(struct netmap_kring *);


/*
 * validates parameters in the ring/kring, returns a value for head,
 * and the 'reserved' value in the argument.
 * If any error, returns ring_size lim to force a reinit.
 */
uint32_t nm_rxsync_prologue(struct netmap_kring *);


/*
 * update kring and ring at the end of txsync.
 */
static inline void
nm_txsync_finalize(struct netmap_kring *kring)
{
        /* update ring head/tail to what the kernel knows */
        kring->ring->tail = kring->rtail = kring->nr_hwtail;
        kring->ring->head = kring->rhead = kring->nr_hwcur;
        
        /* note, head/rhead/hwcur might be behind cur/rcur
         * if no carrier
         */
        ND(5, "%s now hwcur %d hwtail %d head %d cur %d tail %d",
                kring->name, kring->nr_hwcur, kring->nr_hwtail,
                kring->rhead, kring->rcur, kring->rtail);
}


/*
 * update kring and ring at the end of rxsync
 */
static inline void
nm_rxsync_finalize(struct netmap_kring *kring)
{
        /* tell userspace that there might be new packets */
        //struct netmap_ring *ring = kring->ring;
        ND("head %d cur %d tail %d -> %d", ring->head, ring->cur, ring->tail,
                kring->nr_hwtail);
        kring->ring->tail = kring->rtail = kring->nr_hwtail;
        /* make a copy of the state for next round */
        kring->rhead = kring->ring->head;
        kring->rcur = kring->ring->cur;
}


/* check/fix address and len in tx rings */
#if 1 /* debug version */
#define NM_CHECK_ADDR_LEN(_a, _l)       do {                            \
        if (_a == netmap_buffer_base || _l > NETMAP_BUF_SIZE) {         \
                RD(5, "bad addr/len ring %d slot %d idx %d len %d",     \
                        ring_nr, nm_i, slot->buf_idx, len);             \
                if (_l > NETMAP_BUF_SIZE)                               \
                        _l = NETMAP_BUF_SIZE;                           \
        } } while (0)
#else /* no debug version */
#define NM_CHECK_ADDR_LEN(_a, _l)       do {                            \
                if (_l > NETMAP_BUF_SIZE)                               \
                        _l = NETMAP_BUF_SIZE;                           \
        } while (0)
#endif


/*---------------------------------------------------------------*/
/*
 * Support routines to be used with the VALE switch
 */
int netmap_update_config(struct netmap_adapter *na);
int netmap_krings_create(struct netmap_adapter *na, u_int ntx, u_int nrx, u_int tailroom);
void netmap_krings_delete(struct netmap_adapter *na);
int netmap_rxsync_from_host(struct netmap_adapter *na, struct thread *td, void *pwait);


struct netmap_if *
netmap_do_regif(struct netmap_priv_d *priv, struct netmap_adapter *na,
        uint16_t ringid, int *err);



u_int nm_bound_var(u_int *v, u_int dflt, u_int lo, u_int hi, const char *msg);
int netmap_get_na(struct nmreq *nmr, struct netmap_adapter **na, int create);
int netmap_get_hw_na(struct ifnet *ifp, struct netmap_adapter **na);


#ifdef WITH_VALE
/*
 * The following bridge-related functions are used by other
 * kernel modules.
 *
 * VALE only supports unicast or broadcast. The lookup
 * function can return 0 .. NM_BDG_MAXPORTS-1 for regular ports,
 * NM_BDG_MAXPORTS for broadcast, NM_BDG_MAXPORTS+1 for unknown.
 * XXX in practice "unknown" might be handled same as broadcast.
 */
typedef u_int (*bdg_lookup_fn_t)(char *buf, u_int len,
                uint8_t *ring_nr, struct netmap_vp_adapter *);
u_int netmap_bdg_learning(char *, u_int, uint8_t *,
                struct netmap_vp_adapter *);

#define NM_BDG_MAXPORTS         254     /* up to 254 */
#define NM_BDG_BROADCAST        NM_BDG_MAXPORTS
#define NM_BDG_NOPORT           (NM_BDG_MAXPORTS+1)

#define NM_NAME                 "vale"  /* prefix for bridge port name */


/* these are redefined in case of no VALE support */
int netmap_get_bdg_na(struct nmreq *nmr, struct netmap_adapter **na, int create);
void netmap_init_bridges(void);
int netmap_bdg_ctl(struct nmreq *nmr, bdg_lookup_fn_t func);

#else /* !WITH_VALE */
#define netmap_get_bdg_na(_1, _2, _3)   0
#define netmap_init_bridges(_1)
#define netmap_bdg_ctl(_1, _2)  EINVAL
#endif /* !WITH_VALE */

/* Various prototypes */
int netmap_poll(struct cdev *dev, int events, struct thread *td);
int netmap_init(void);
void netmap_fini(void);
int netmap_get_memory(struct netmap_priv_d* p);
void netmap_dtor(void *data);
int netmap_dtor_locked(struct netmap_priv_d *priv);

int netmap_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct thread *td);

/* netmap_adapter creation/destruction */
#define NM_IFPNAME(ifp) ((ifp) ? (ifp)->if_xname : "zombie")

// #define NM_DEBUG_PUTGET 1

#ifdef NM_DEBUG_PUTGET

#define NM_DBG(f) __##f

void __netmap_adapter_get(struct netmap_adapter *na);

#define netmap_adapter_get(na)                          \
        do {                                            \
                struct netmap_adapter *__na = na;       \
                D("getting %p:%s (%d)", __na, NM_IFPNAME(__na->ifp), __na->na_refcount);        \
                __netmap_adapter_get(__na);             \
        } while (0)

int __netmap_adapter_put(struct netmap_adapter *na);

#define netmap_adapter_put(na)                          \
        do {                                            \
                struct netmap_adapter *__na = na;       \
                D("putting %p:%s (%d)", __na, NM_IFPNAME(__na->ifp), __na->na_refcount);        \
                __netmap_adapter_put(__na);             \
        } while (0)

#else /* !NM_DEBUG_PUTGET */

#define NM_DBG(f) f
void netmap_adapter_get(struct netmap_adapter *na);
int netmap_adapter_put(struct netmap_adapter *na);

#endif /* !NM_DEBUG_PUTGET */


/*
 * module variables
 */
extern u_int netmap_buf_size;
#define NETMAP_BUF_SIZE netmap_buf_size // XXX remove
extern int netmap_mitigate;     // XXX not really used
extern int netmap_no_pendintr;
extern u_int netmap_total_buffers;      // global allocator
extern char *netmap_buffer_base;        // global allocator
extern int netmap_verbose;      // XXX debugging
enum {                                  /* verbose flags */
        NM_VERB_ON = 1,                 /* generic verbose */
        NM_VERB_HOST = 0x2,             /* verbose host stack */
        NM_VERB_RXSYNC = 0x10,          /* verbose on rxsync/txsync */
        NM_VERB_TXSYNC = 0x20,
        NM_VERB_RXINTR = 0x100,         /* verbose on rx/tx intr (driver) */
        NM_VERB_TXINTR = 0x200,
        NM_VERB_NIC_RXSYNC = 0x1000,    /* verbose on rx/tx intr (driver) */
        NM_VERB_NIC_TXSYNC = 0x2000,
};

extern int netmap_txsync_retry;
extern int netmap_generic_mit;
extern int netmap_generic_ringsize;

/*
 * NA returns a pointer to the struct netmap adapter from the ifp,
 * WNA is used to write it.
 */
#ifndef WNA
#define WNA(_ifp)       (_ifp)->if_pspare[0]
#endif
#define NA(_ifp)        ((struct netmap_adapter *)WNA(_ifp))

/*
 * Macros to determine if an interface is netmap capable or netmap enabled.
 * See the magic field in struct netmap_adapter.
 */
#ifdef __FreeBSD__
/*
 * on FreeBSD just use if_capabilities and if_capenable.
 */
#define NETMAP_CAPABLE(ifp)     (NA(ifp) &&             \
        (ifp)->if_capabilities & IFCAP_NETMAP )

#define NETMAP_SET_CAPABLE(ifp)                         \
        (ifp)->if_capabilities |= IFCAP_NETMAP

#else   /* linux */

/*
 * on linux:
 * we check if NA(ifp) is set and its first element has a related
 * magic value. The capenable is within the struct netmap_adapter.
 */
#define NETMAP_MAGIC    0x52697a7a

#define NETMAP_CAPABLE(ifp)     (NA(ifp) &&             \
        ((uint32_t)(uintptr_t)NA(ifp) ^ NA(ifp)->magic) == NETMAP_MAGIC )

#define NETMAP_SET_CAPABLE(ifp)                         \
        NA(ifp)->magic = ((uint32_t)(uintptr_t)NA(ifp)) ^ NETMAP_MAGIC

#endif  /* linux */

#ifdef __FreeBSD__

/* Callback invoked by the dma machinery after a successful dmamap_load */
static void netmap_dmamap_cb(__unused void *arg,
    __unused bus_dma_segment_t * segs, __unused int nseg, __unused int error)
{
}

/* bus_dmamap_load wrapper: call aforementioned function if map != NULL.
 * XXX can we do it without a callback ?
 */
static inline void
netmap_load_map(bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
{
        if (map)
                bus_dmamap_load(tag, map, buf, NETMAP_BUF_SIZE,
                    netmap_dmamap_cb, NULL, BUS_DMA_NOWAIT);
}

/* update the map when a buffer changes. */
static inline void
netmap_reload_map(bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
{
        if (map) {
                bus_dmamap_unload(tag, map);
                bus_dmamap_load(tag, map, buf, NETMAP_BUF_SIZE,
                    netmap_dmamap_cb, NULL, BUS_DMA_NOWAIT);
        }
}

#else /* linux */

/*
 * XXX How do we redefine these functions:
 *
 * on linux we need
 *      dma_map_single(&pdev->dev, virt_addr, len, direction)
 *      dma_unmap_single(&adapter->pdev->dev, phys_addr, len, direction
 * The len can be implicit (on netmap it is NETMAP_BUF_SIZE)
 * unfortunately the direction is not, so we need to change
 * something to have a cross API
 */
#define netmap_load_map(_t, _m, _b)
#define netmap_reload_map(_t, _m, _b)
#if 0
        struct e1000_buffer *buffer_info =  &tx_ring->buffer_info[l];
        /* set time_stamp *before* dma to help avoid a possible race */
        buffer_info->time_stamp = jiffies;
        buffer_info->mapped_as_page = false;
        buffer_info->length = len;
        //buffer_info->next_to_watch = l;
        /* reload dma map */
        dma_unmap_single(&adapter->pdev->dev, buffer_info->dma,
                        NETMAP_BUF_SIZE, DMA_TO_DEVICE);
        buffer_info->dma = dma_map_single(&adapter->pdev->dev,
                        addr, NETMAP_BUF_SIZE, DMA_TO_DEVICE);

        if (dma_mapping_error(&adapter->pdev->dev, buffer_info->dma)) {
                D("dma mapping error");
                /* goto dma_error; See e1000_put_txbuf() */
                /* XXX reset */
        }
        tx_desc->buffer_addr = htole64(buffer_info->dma); //XXX

#endif

/*
 * The bus_dmamap_sync() can be one of wmb() or rmb() depending on direction.
 */
#define bus_dmamap_sync(_a, _b, _c)

#endif /* linux */


/*
 * functions to map NIC to KRING indexes (n2k) and vice versa (k2n)
 */
static inline int
netmap_idx_n2k(struct netmap_kring *kr, int idx)
{
        int n = kr->nkr_num_slots;
        idx += kr->nkr_hwofs;
        if (idx < 0)
                return idx + n;
        else if (idx < n)
                return idx;
        else
                return idx - n;
}


static inline int
netmap_idx_k2n(struct netmap_kring *kr, int idx)
{
        int n = kr->nkr_num_slots;
        idx -= kr->nkr_hwofs;
        if (idx < 0)
                return idx + n;
        else if (idx < n)
                return idx;
        else
                return idx - n;
}


/* Entries of the look-up table. */
struct lut_entry {
        void *vaddr;            /* virtual address. */
        vm_paddr_t paddr;       /* physical address. */
};

struct netmap_obj_pool;
extern struct lut_entry *netmap_buffer_lut;
#define NMB_VA(i)       (netmap_buffer_lut[i].vaddr)
#define NMB_PA(i)       (netmap_buffer_lut[i].paddr)

/*
 * NMB return the virtual address of a buffer (buffer 0 on bad index)
 * PNMB also fills the physical address
 */
static inline void *
NMB(struct netmap_slot *slot)
{
        uint32_t i = slot->buf_idx;
        return (unlikely(i >= netmap_total_buffers)) ?  NMB_VA(0) : NMB_VA(i);
}

static inline void *
PNMB(struct netmap_slot *slot, uint64_t *pp)
{
        uint32_t i = slot->buf_idx;
        void *ret = (i >= netmap_total_buffers) ? NMB_VA(0) : NMB_VA(i);

        *pp = (i >= netmap_total_buffers) ? NMB_PA(0) : NMB_PA(i);
        return ret;
}

/* Generic version of NMB, which uses device-specific memory. */
static inline void *
BDG_NMB(struct netmap_adapter *na, struct netmap_slot *slot)
{
        struct lut_entry *lut = na->na_lut;
        uint32_t i = slot->buf_idx;
        return (unlikely(i >= na->na_lut_objtotal)) ?
                lut[0].vaddr : lut[i].vaddr;
}



void netmap_txsync_to_host(struct netmap_adapter *na);


/*
 * Structure associated to each thread which registered an interface.
 *
 * The first 4 fields of this structure are written by NIOCREGIF and
 * read by poll() and NIOC?XSYNC.
 *
 * There is low contention among writers (a correct user program
 * should have none) and among writers and readers, so we use a
 * single global lock to protect the structure initialization;
 * since initialization involves the allocation of memory,
 * we reuse the memory allocator lock.
 *
 * Read access to the structure is lock free. Readers must check that
 * np_nifp is not NULL before using the other fields.
 * If np_nifp is NULL initialization has not been performed,
 * so they should return an error to userspace.
 *
 * The ref_done field is used to regulate access to the refcount in the
 * memory allocator. The refcount must be incremented at most once for
 * each open("/dev/netmap"). The increment is performed by the first
 * function that calls netmap_get_memory() (currently called by
 * mmap(), NIOCGINFO and NIOCREGIF).
 * If the refcount is incremented, it is then decremented when the
 * private structure is destroyed.
 */
struct netmap_priv_d {
        struct netmap_if * volatile np_nifp;    /* netmap if descriptor. */

        struct netmap_adapter   *np_na;
        int             np_ringid;      /* from the ioctl */
        u_int           np_qfirst, np_qlast;    /* range of rings to scan */
        uint16_t        np_txpoll;

        struct netmap_mem_d     *np_mref;       /* use with NMG_LOCK held */
        /* np_refcount is only used on FreeBSD */
        int             np_refcount;    /* use with NMG_LOCK held */
};


/*
 * generic netmap emulation for devices that do not have
 * native netmap support.
 */
int generic_netmap_attach(struct ifnet *ifp);

int netmap_catch_rx(struct netmap_adapter *na, int intercept);
void generic_rx_handler(struct ifnet *ifp, struct mbuf *m);;
void netmap_catch_tx(struct netmap_generic_adapter *na, int enable);
int generic_xmit_frame(struct ifnet *ifp, struct mbuf *m, void *addr, u_int len, u_int ring_nr);
int generic_find_num_desc(struct ifnet *ifp, u_int *tx, u_int *rx);
void generic_find_num_queues(struct ifnet *ifp, u_int *txq, u_int *rxq);

/*
 * netmap_mitigation API. This is used by the generic adapter
 * to reduce the number of interrupt requests/selwakeup
 * to clients on incoming packets.
 */
void netmap_mitigation_init(struct netmap_generic_adapter *na);
void netmap_mitigation_start(struct netmap_generic_adapter *na);
void netmap_mitigation_restart(struct netmap_generic_adapter *na);
int netmap_mitigation_active(struct netmap_generic_adapter *na);
void netmap_mitigation_cleanup(struct netmap_generic_adapter *na);

#endif /* _NET_NETMAP_KERN_H_ */