FreeBSD/Linux Kernel Cross Reference
sys/dev/netmap/netmap_kern.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (C) 2011-2014 Matteo Landi, Luigi Rizzo
      * Copyright (C) 2013-2016 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_
    
    #if defined(linux)
    
    #if defined(CONFIG_NETMAP_EXTMEM)
    #define WITH_EXTMEM
    #endif
    #if  defined(CONFIG_NETMAP_VALE)
    #define WITH_VALE
    #endif
    #if defined(CONFIG_NETMAP_PIPE)
    #define WITH_PIPES
    #endif
    #if defined(CONFIG_NETMAP_MONITOR)
    #define WITH_MONITOR
    #endif
    #if defined(CONFIG_NETMAP_GENERIC)
    #define WITH_GENERIC
    #endif
    #if defined(CONFIG_NETMAP_PTNETMAP)
    #define WITH_PTNETMAP
    #endif
    #if defined(CONFIG_NETMAP_SINK)
    #define WITH_SINK
    #endif
    #if defined(CONFIG_NETMAP_NULL)
    #define WITH_NMNULL
    #endif
    
    #elif defined (_WIN32)
    #define WITH_VALE       // comment out to disable VALE support
    #define WITH_PIPES
    #define WITH_MONITOR
    #define WITH_GENERIC
    #define WITH_NMNULL
    
    #else   /* neither linux nor windows */
    #define WITH_VALE       // comment out to disable VALE support
    #define WITH_PIPES
    #define WITH_MONITOR
    #define WITH_GENERIC
    #define WITH_EXTMEM
    #define WITH_NMNULL
    #endif
    
    #if defined(__FreeBSD__)
    #include <sys/selinfo.h>
    
    #define likely(x)       __builtin_expect((long)!!(x), 1L)
    #define unlikely(x)     __builtin_expect((long)!!(x), 0L)
    #define __user
    
    #define NM_LOCK_T       struct mtx      /* low level spinlock, used to protect queues */
    
    #define NM_MTX_T        struct sx       /* OS-specific mutex (sleepable) */
    #define NM_MTX_INIT(m)          sx_init(&(m), #m)
    #define NM_MTX_DESTROY(m)       sx_destroy(&(m))
    #define NM_MTX_LOCK(m)          sx_xlock(&(m))
    #define NM_MTX_SPINLOCK(m)      while (!sx_try_xlock(&(m))) ;
    #define NM_MTX_UNLOCK(m)        sx_xunlock(&(m))
    #define NM_MTX_ASSERT(m)        sx_assert(&(m), SA_XLOCKED)
    
   #define NM_SELINFO_T    struct nm_selinfo
   #define NM_SELRECORD_T  struct thread
   #define MBUF_LEN(m)     ((m)->m_pkthdr.len)
   #define MBUF_TXQ(m)     ((m)->m_pkthdr.flowid)
   #define MBUF_TRANSMIT(na, ifp, m)       ((na)->if_transmit(ifp, m))
   #define GEN_TX_MBUF_IFP(m)      ((m)->m_pkthdr.rcvif)
   
   #define NM_ATOMIC_T     volatile int /* required by atomic/bitops.h */
   /* 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)
   
   #define WNA(_ifp)       (_ifp)->if_netmap
   
   struct netmap_adapter *netmap_getna(if_t ifp);
   
   #define MBUF_REFCNT(m)          ((m)->m_ext.ext_count)
   #define SET_MBUF_REFCNT(m, x)   (m)->m_ext.ext_count = x
   
   #define MBUF_QUEUED(m)          1
   
   struct nm_selinfo {
           /* Support for select(2) and poll(2). */
           struct selinfo si;
           /* Support for kqueue(9). See comments in netmap_freebsd.c */
           struct taskqueue *ntfytq;
           struct task ntfytask;
           struct mtx m;
           char mtxname[32];
           int kqueue_users;
   };
   
   
   struct hrtimer {
       /* Not used in FreeBSD. */
   };
   
   #define NM_BNS_GET(b)
   #define NM_BNS_PUT(b)
   
   #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_TRANSMIT(na, ifp, m)                                                       \
           ({                                                                              \
                   /* Avoid infinite recursion with generic. */                            \
                   m->priority = NM_MAGIC_PRIORITY_TX;                                     \
                   (((struct net_device_ops *)(na)->if_transmit)->ndo_start_xmit(m, ifp)); \
                   0;                                                                      \
           })
   
   /* See explanation in nm_os_generic_xmit_frame. */
   #define GEN_TX_MBUF_IFP(m)      ((struct ifnet *)skb_shinfo(m)->destructor_arg)
   
   #define NM_ATOMIC_T     volatile long unsigned int
   
   #define NM_MTX_T        struct mutex    /* OS-specific sleepable lock */
   #define NM_MTX_INIT(m)  mutex_init(&(m))
   #define NM_MTX_DESTROY(m)       do { (void)(m); } while (0)
   #define NM_MTX_LOCK(m)          mutex_lock(&(m))
   #define NM_MTX_UNLOCK(m)        mutex_unlock(&(m))
   #define NM_MTX_ASSERT(m)        mutex_is_locked(&(m))
   
   #ifndef DEV_NETMAP
   #define DEV_NETMAP
   #endif /* DEV_NETMAP */
   
   #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)
   
   #elif defined (_WIN32)
   #include "../../../WINDOWS/win_glue.h"
   
   #define NM_SELRECORD_T          IO_STACK_LOCATION
   #define NM_SELINFO_T            win_SELINFO             // see win_glue.h
   #define NM_LOCK_T               win_spinlock_t  // see win_glue.h
   #define NM_MTX_T                KGUARDED_MUTEX  /* OS-specific mutex (sleepable) */
   
   #define NM_MTX_INIT(m)          KeInitializeGuardedMutex(&m);
   #define NM_MTX_DESTROY(m)       do { (void)(m); } while (0)
   #define NM_MTX_LOCK(m)          KeAcquireGuardedMutex(&(m))
   #define NM_MTX_UNLOCK(m)        KeReleaseGuardedMutex(&(m))
   #define NM_MTX_ASSERT(m)        assert(&m.Count>0)
   
   //These linknames are for the NDIS driver
   #define NETMAP_NDIS_LINKNAME_STRING             L"\\DosDevices\\NMAPNDIS"
   #define NETMAP_NDIS_NTDEVICE_STRING             L"\\Device\\NMAPNDIS"
   
   //Definition of internal driver-to-driver ioctl codes
   #define NETMAP_KERNEL_XCHANGE_POINTERS          _IO('i', 180)
   #define NETMAP_KERNEL_SEND_SHUTDOWN_SIGNAL      _IO_direct('i', 195)
   
   typedef struct hrtimer{
           KTIMER timer;
           BOOLEAN active;
           KDPC deferred_proc;
   };
   
   /* MSVC does not have likely/unlikely support */
   #ifdef _MSC_VER
   #define likely(x)       (x)
   #define unlikely(x)     (x)
   #else
   #define likely(x)       __builtin_expect((long)!!(x), 1L)
   #define unlikely(x)     __builtin_expect((long)!!(x), 0L)
   #endif //_MSC_VER
   
   #else
   
   #error unsupported platform
   
   #endif /* end - platform-specific code */
   
   #ifndef _WIN32 /* support for emulated sysctl */
   #define SYSBEGIN(x)
   #define SYSEND
   #endif /* _WIN32 */
   
   #define NM_ACCESS_ONCE(x)       (*(volatile __typeof__(x) *)&(x))
   
   #define NMG_LOCK_T              NM_MTX_T
   #define NMG_LOCK_INIT()         NM_MTX_INIT(netmap_global_lock)
   #define NMG_LOCK_DESTROY()      NM_MTX_DESTROY(netmap_global_lock)
   #define NMG_LOCK()              NM_MTX_LOCK(netmap_global_lock)
   #define NMG_UNLOCK()            NM_MTX_UNLOCK(netmap_global_lock)
   #define NMG_LOCK_ASSERT()       NM_MTX_ASSERT(netmap_global_lock)
   
   #if defined(__FreeBSD__)
   #define nm_prerr_int    printf
   #define nm_prinf_int    printf
   #elif defined (_WIN32)
   #define nm_prerr_int    DbgPrint
   #define nm_prinf_int    DbgPrint
   #elif defined(linux)
   #define nm_prerr_int(fmt, arg...)    printk(KERN_ERR fmt, ##arg)
   #define nm_prinf_int(fmt, arg...)    printk(KERN_INFO fmt, ##arg)
   #endif
   
   #define nm_prinf(format, ...)                                   \
           do {                                                    \
                   struct timeval __xxts;                          \
                   microtime(&__xxts);                             \
                   nm_prinf_int("%03d.%06d [%4d] %-25s " format "\n",\
                   (int)__xxts.tv_sec % 1000, (int)__xxts.tv_usec, \
                   __LINE__, __FUNCTION__, ##__VA_ARGS__);         \
           } while (0)
   
   #define nm_prerr(format, ...)                                   \
           do {                                                    \
                   struct timeval __xxts;                          \
                   microtime(&__xxts);                             \
                   nm_prerr_int("%03d.%06d [%4d] %-25s " format "\n",\
                   (int)__xxts.tv_sec % 1000, (int)__xxts.tv_usec, \
                   __LINE__, __FUNCTION__, ##__VA_ARGS__);         \
           } while (0)
   
   /* Disabled printf (used to be nm_prdis). */
   #define nm_prdis(format, ...)
   
   /* Rate limited, lps indicates how many per second. */
   #define nm_prlim(lps, format, ...)                              \
           do {                                                    \
                   static int t0, __cnt;                           \
                   if (t0 != time_second) {                        \
                           t0 = time_second;                       \
                           __cnt = 0;                              \
                   }                                               \
                   if (__cnt++ < lps)                              \
                           nm_prinf(format, ##__VA_ARGS__);        \
           } while (0)
   
   struct netmap_adapter;
   struct nm_bdg_fwd;
   struct nm_bridge;
   struct netmap_priv_d;
   struct nm_bdg_args;
   
   /* os-specific NM_SELINFO_T initialization/destruction functions */
   int nm_os_selinfo_init(NM_SELINFO_T *, const char *name);
   void nm_os_selinfo_uninit(NM_SELINFO_T *);
   
   const char *nm_dump_buf(char *p, int len, int lim, char *dst);
   
   void nm_os_selwakeup(NM_SELINFO_T *si);
   void nm_os_selrecord(NM_SELRECORD_T *sr, NM_SELINFO_T *si);
   
   int nm_os_ifnet_init(void);
   void nm_os_ifnet_fini(void);
   void nm_os_ifnet_lock(void);
   void nm_os_ifnet_unlock(void);
   
   unsigned nm_os_ifnet_mtu(struct ifnet *ifp);
   
   void nm_os_get_module(void);
   void nm_os_put_module(void);
   
   void netmap_make_zombie(struct ifnet *);
   void netmap_undo_zombie(struct ifnet *);
   
   /* os independent alloc/realloc/free */
   void *nm_os_malloc(size_t);
   void *nm_os_vmalloc(size_t);
   void *nm_os_realloc(void *, size_t new_size, size_t old_size);
   void nm_os_free(void *);
   void nm_os_vfree(void *);
   
   /* os specific attach/detach enter/exit-netmap-mode routines */
   void nm_os_onattach(struct ifnet *);
   void nm_os_ondetach(struct ifnet *);
   void nm_os_onenter(struct ifnet *);
   void nm_os_onexit(struct ifnet *);
   
   /* passes a packet up to the host stack.
    * If the packet is sent (or dropped) immediately it returns NULL,
    * otherwise it links the packet to prev and returns m.
    * In this case, a final call with m=NULL and prev != NULL will send up
    * the entire chain to the host stack.
    */
   void *nm_os_send_up(struct ifnet *, struct mbuf *m, struct mbuf *prev);
   
   int nm_os_mbuf_has_seg_offld(struct mbuf *m);
   int nm_os_mbuf_has_csum_offld(struct mbuf *m);
   
   #include "netmap_mbq.h"
   
   extern NMG_LOCK_T       netmap_global_lock;
   
   enum txrx { NR_RX = 0, NR_TX = 1, NR_TXRX };
   
   static __inline const char*
   nm_txrx2str(enum txrx t)
   {
           return (t== NR_RX ? "RX" : "TX");
   }
   
   static __inline enum txrx
   nm_txrx_swap(enum txrx t)
   {
           return (t== NR_RX ? NR_TX : NR_RX);
   }
   
   #define for_rx_tx(t)    for ((t) = 0; (t) < NR_TXRX; (t)++)
   
   #ifdef WITH_MONITOR
   struct netmap_zmon_list {
           struct netmap_kring *next;
           struct netmap_kring *prev;
   };
   #endif /* WITH_MONITOR */
   
   /*
    * 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
    *
    * 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_(try)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 senders
    * and receiver. They are protected through the q_lock on the RX ring.
    */
   struct netmap_kring {
           struct netmap_ring      *ring;
   
           uint32_t        nr_hwcur;  /* should be nr_hwhead */
           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.
   #define NKR_EXCLUSIVE   0x2             /* exclusive binding */
   #define NKR_FORWARD     0x4             /* (host ring only) there are
                                              packets to forward
                                            */
   #define NKR_NEEDRING    0x8             /* ring needed even if users==0
                                            * (used internally by pipes and
                                            *  by ptnetmap host ports)
                                            */
   #define NKR_NOINTR      0x10            /* don't use interrupts on this ring */
   #define NKR_FAKERING    0x20            /* don't allocate/free buffers */
   
           uint32_t        nr_mode;
           uint32_t        nr_pending_mode;
   #define NKR_NETMAP_OFF  0x0
   #define NKR_NETMAP_ON   0x1
   
           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.
            *
            * Moreover, during reset, we can restore only the subset of
            * the NIC ring that corresponds to the kernel-owned part of
            * the netmap ring. The rest of the slots must be restored
            * by the *sync routines when the user releases more slots.
            * The nkr_to_refill field keeps track of the number of slots
            * that still need to be restored.
            */
           int32_t         nkr_hwofs;
           int32_t         nkr_to_refill;
   
           /* 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 */
   
           /* the adapter the owns this kring */
           struct netmap_adapter *na;
   
           /* the adapter that wants to be notified when this kring has
            * new slots available. This is usually the same as the above,
            * but wrappers may let it point to themselves
            */
           struct netmap_adapter *notify_na;
   
           /* The following 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;
   
           /* while nkr_stopped is set, no new [tr]xsync operations can
            * be started on this kring.
            * This is used by netmap_disable_all_rings()
            * to find a synchronization point where critical data
            * structures pointed to by the kring can be added or removed
            */
           volatile int nkr_stopped;
   
           /* 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 mbufs in a queue that is drained by
            * a rxsync.
            */
           struct mbuf     **tx_pool;
           struct mbuf     *tx_event;      /* TX event used as a notification */
           NM_LOCK_T       tx_event_lock;  /* protects the tx_event mbuf */
           struct mbq      rx_queue;       /* intercepted rx mbufs. */
   
           uint32_t        users;          /* existing bindings for this ring */
   
           uint32_t        ring_id;        /* kring identifier */
           enum txrx       tx;             /* kind of ring (tx or rx) */
           char name[64];                  /* diagnostic */
   
           /* [tx]sync callback for this kring.
            * The default nm_kring_create callback (netmap_krings_create)
            * sets the nm_sync callback of each hardware tx(rx) kring to
            * the corresponding nm_txsync(nm_rxsync) taken from the
            * netmap_adapter; moreover, it sets the sync callback
            * of the host tx(rx) ring to netmap_txsync_to_host
            * (netmap_rxsync_from_host).
            *
            * Overrides: the above configuration is not changed by
            * any of the nm_krings_create callbacks.
            */
           int (*nm_sync)(struct netmap_kring *kring, int flags);
           int (*nm_notify)(struct netmap_kring *kring, int flags);
   
   #ifdef WITH_PIPES
           struct netmap_kring *pipe;      /* if this is a pipe ring,
                                            * pointer to the other end
                                            */
           uint32_t pipe_tail;             /* hwtail updated by the other end */
   #endif /* WITH_PIPES */
   
           /* mask for the offset-related part of the ptr field in the slots */
           uint64_t offset_mask;
           /* maximum user-specified offset, as stipulated at bind time.
            * Larger offset requests will be silently capped to offset_max.
            */
           uint64_t offset_max;
           /* minimum gap between two consecutive offsets into the same
            * buffer, as stipulated at bind time. This is used to choose
            * the hwbuf_len, but is not otherwise checked for compliance
            * at runtime.
            */
           uint64_t offset_gap;
   
           /* size of hardware buffer. This may be less than the size of
            * the netmap buffers because of non-zero offsets, or because
            * the netmap buffer size exceeds the capability of the hardware.
            */
           uint64_t hwbuf_len;
   
           /* required alignment (in bytes) for the buffers used by this ring.
            * Netmap buffers are aligned to cachelines, which should suffice
            * for most NICs. If the user is passing offsets, though, we need
            * to check that the resulting buf address complies with any
            * alignment restriction.
            */
           uint64_t buf_align;
   
           /* hardware specific logic for the selection of the hwbuf_len */
           int (*nm_bufcfg)(struct netmap_kring *kring, uint64_t target);
   
           int (*save_notify)(struct netmap_kring *kring, int flags);
   
   #ifdef WITH_MONITOR
           /* array of krings that are monitoring this kring */
           struct netmap_kring **monitors;
           uint32_t max_monitors; /* current size of the monitors array */
           uint32_t n_monitors;    /* next unused entry in the monitor array */
           uint32_t mon_pos[NR_TXRX]; /* index of this ring in the monitored ring array */
           uint32_t mon_tail;  /* last seen slot on rx */
   
           /* circular list of zero-copy monitors */
           struct netmap_zmon_list zmon_list[NR_TXRX];
   
           /*
            * Monitors work by intercepting the sync and notify callbacks of the
            * monitored krings. This is implemented by replacing the pointers
            * above and saving the previous ones in mon_* pointers below
            */
           int (*mon_sync)(struct netmap_kring *kring, int flags);
           int (*mon_notify)(struct netmap_kring *kring, int flags);
   
   #endif
   }
   #ifdef _WIN32
   __declspec(align(64));
   #else
   __attribute__((__aligned__(64)));
   #endif
   
   /* return 1 iff the kring needs to be turned on */
   static inline int
   nm_kring_pending_on(struct netmap_kring *kring)
   {
           return kring->nr_pending_mode == NKR_NETMAP_ON &&
                  kring->nr_mode == NKR_NETMAP_OFF;
   }
   
   /* return 1 iff the kring needs to be turned off */
   static inline int
   nm_kring_pending_off(struct netmap_kring *kring)
   {
           return kring->nr_pending_mode == NKR_NETMAP_OFF &&
                  kring->nr_mode == NKR_NETMAP_ON;
   }
   
   /* 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
   
         +-----------------+            +-----------------+
         |                 |            |                 |
         |      free       |            |      free       |
         +-----------------+            +-----------------+
   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.
    */
   
   struct lut_entry;
   #ifdef __FreeBSD__
   #define plut_entry lut_entry
   #endif
   
   struct netmap_lut {
           struct lut_entry *lut;
           struct plut_entry *plut;
           uint32_t objtotal;      /* max buffer index */
           uint32_t objsize;       /* buffer size */
   };
   
   struct netmap_vp_adapter; // forward
   struct nm_bridge;
   
   /* Struct to be filled by nm_config callbacks. */
   struct nm_config_info {
           unsigned num_tx_rings;
           unsigned num_rx_rings;
           unsigned num_tx_descs;
           unsigned num_rx_descs;
           unsigned rx_buf_maxsize;
   };
   
   /*
    * default type for the magic field.
    * May be overridden in glue code.
    */
   #ifndef NM_OS_MAGIC
   #define NM_OS_MAGIC uint32_t
   #endif /* !NM_OS_MAGIC */
   
   /*
    * 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.
            */
           NM_OS_MAGIC 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 uses its own memory area
                                    * that cannot be changed
                                    */
   #define NAF_NATIVE      16      /* the adapter is native.
                                    * Virtual ports (non persistent vale ports,
                                    * pipes, monitors...) should never use
                                    * this flag.
                                    */
   #define NAF_NETMAP_ON   32      /* netmap is active (either native or
                                    * emulated). Where possible (e.g. FreeBSD)
                                    * IFCAP_NETMAP also mirrors this flag.
                                    */
   #define NAF_HOST_RINGS  64      /* the adapter supports the host rings */
   #define NAF_FORCE_NATIVE 128    /* the adapter is always NATIVE */
   /* free */
   #define NAF_MOREFRAG    512     /* the adapter supports NS_MOREFRAG */
   #define NAF_OFFSETS     1024    /* the adapter supports the slot offsets */
   #define NAF_HOST_ALL    2048    /* the adapter wants as many host rings as hw */
   #define NAF_ZOMBIE      (1U<<30) /* the nic driver has been unloaded */
   #define NAF_BUSY        (1U<<31) /* the adapter is used internally and
                                     * cannot be registered from userspace
                                     */
           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_host_rx_rings; /* number of host receive rings */
           u_int num_host_tx_rings; /* number of host 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+K entries,
            * N for the hardware rings and K for the host rings.
            */
           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 si[NR_TXRX];       /* global wait queues */
   
           /* count users of the global wait queues */
           int si_users[NR_TXRX];
   
           void *pdev; /* used to store pci device */
   
           /* 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 *);
   
           /* Back reference to the parent ifnet struct. Used for
            * hardware ports (emulated netmap included). */
           struct ifnet *ifp; /* adapter is ifp->if_softc */
   
           /*---- callbacks for this netmap adapter -----*/
           /*
            * nm_dtor() is the cleanup routine called when destroying
            *      the adapter.
            *      Called with NMG_LOCK held.
            *
            * nm_register() is called on NIOCREGIF and close() to enter
            *      or exit netmap mode on the NIC
            *      Called with NNG_LOCK held.
            *
            * 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
            *      Called with NMG_LOCK held.
            *
            * nm_bufcfg()
            *      the purpose of this callback is to fill the kring->hwbuf_len
            *      (l) and kring->buf_align fields. The l value is most important
            *      for RX rings, where we want to disallow writes outside of the
            *      netmap buffer. The l value must be computed taking into account
            *      the stipulated max_offset (o), possibly increased if there are
            *      alignment constraints, the maxframe (m), if known, and the
            *      current NETMAP_BUF_SIZE (b) of the memory region used by the
            *      adapter. We want the largest supported l such that o + l <= b.
            *      If m is known to be <= b - o, the callback may also choose the
            *      largest l <= m, ignoring the offset.  The buf_align field is
            *      most important for TX rings when there are offsets.  The user
            *      will see this value in the ring->buf_align field.  Misaligned
            *      offsets will cause the corresponding packets to be silently
            *      dropped.
            *
            * nm_krings_create() create and init the tx_rings and
            *      rx_rings arrays of kring structures. In particular,
            *      set the nm_sync callbacks for each ring.
            *      There is no need to also allocate the corresponding
            *      netmap_rings, since netmap_mem_rings_create() will always
            *      be called to provide the missing ones.
            *      Called with NNG_LOCK held.
            *
            * nm_krings_delete() cleanup and delete the tx_rings and rx_rings
            *      arrays
            *      Called with NMG_LOCK held.
            *
            * nm_notify() is used to act after data have become available
            *      (or the stopped state of the ring has changed)
            *      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.
            *      This callback pointer is actually used only to initialize
            *      kring->nm_notify.
            *      Return values are the same as for netmap_rx_irq().
            */
           void (*nm_dtor)(struct netmap_adapter *);
   
           int (*nm_register)(struct netmap_adapter *, int onoff);
           void (*nm_intr)(struct netmap_adapter *, int onoff);
   
           int (*nm_txsync)(struct netmap_kring *kring, int flags);
           int (*nm_rxsync)(struct netmap_kring *kring, int flags);
           int (*nm_notify)(struct netmap_kring *kring, int flags);
           int (*nm_bufcfg)(struct netmap_kring *kring, uint64_t target);
   #define NAF_FORCE_READ      1
   #define NAF_FORCE_RECLAIM   2
   #define NAF_CAN_FORWARD_DOWN 4
           /* return configuration information */
           int (*nm_config)(struct netmap_adapter *, struct nm_config_info *info);
           int (*nm_krings_create)(struct netmap_adapter *);
           void (*nm_krings_delete)(struct netmap_adapter *);
           /*
            * nm_bdg_attach() initializes the na_vp field to point
            *      to an adapter that can be attached to a VALE switch. If the
            *      current adapter is already a VALE port, na_vp is simply a cast;
            *      otherwise, na_vp points to a netmap_bwrap_adapter.
            *      If applicable, this callback also initializes na_hostvp,
            *      that can be used to connect the adapter host rings to the
            *      switch.
            *      Called with NMG_LOCK held.
            *
            * nm_bdg_ctl() is called on the actual attach/detach to/from
            *      to/from the switch, to perform adapter-specific
            *      initializations
            *      Called with NMG_LOCK held.
            */
           int (*nm_bdg_attach)(const char *bdg_name, struct netmap_adapter *,
                           struct nm_bridge *);
           int (*nm_bdg_ctl)(struct nmreq_header *, struct netmap_adapter *);
   
           /* adapter used to attach this adapter to a VALE switch (if any) */
           struct netmap_vp_adapter *na_vp;
           /* adapter used to attach the host rings of this adapter
            * to a VALE switch (if any) */
           struct netmap_vp_adapter *na_hostvp;
   
           /* 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, the total number of buffers and the buffer size.
            */
           struct netmap_mem_d *nm_mem;
           struct netmap_mem_d *nm_mem_prev;
           struct netmap_lut na_lut;
   
           /* additional information attached to this adapter
            * by other netmap subsystems. Currently used by
            * bwrap, LINUX/v1000 and ptnetmap
            */
           void *na_private;
   
           /* array of pipes that have this adapter as a parent */
           struct netmap_pipe_adapter **na_pipes;
           int na_next_pipe;       /* next free slot in the array */
           int na_max_pipes;       /* size of the array */
   
           /* Offset of ethernet header for each packet. */
           u_int virt_hdr_len;
   
           /* Max number of bytes that the NIC can store in the buffer
            * referenced by each RX descriptor. This translates to the maximum
            * bytes that a single netmap slot can reference. Larger packets
            * require NS_MOREFRAG support. */
           unsigned rx_buf_maxsize;
   
           char name[NETMAP_REQ_IFNAMSIZ]; /* used at least by pipes */
   
   #ifdef WITH_MONITOR
           unsigned long   monitor_id;     /* debugging */
   #endif
   };
   
   static __inline u_int
   nma_get_ndesc(struct netmap_adapter *na, enum txrx t)
   {
           return (t == NR_TX ? na->num_tx_desc : na->num_rx_desc);
   }
   
   static __inline void
   nma_set_ndesc(struct netmap_adapter *na, enum txrx t, u_int v)
   {
           if (t == NR_TX)
                   na->num_tx_desc = v;
           else
                   na->num_rx_desc = v;
   }
   
   static __inline u_int
   nma_get_nrings(struct netmap_adapter *na, enum txrx t)
   {
           return (t == NR_TX ? na->num_tx_rings : na->num_rx_rings);
   }
   
   static __inline u_int
   nma_get_host_nrings(struct netmap_adapter *na, enum txrx t)
   {
           return (t == NR_TX ? na->num_host_tx_rings : na->num_host_rx_rings);
   }
   
   static __inline void
   nma_set_nrings(struct netmap_adapter *na, enum txrx t, u_int v)
   {
           if (t == NR_TX)
                   na->num_tx_rings = v;
           else
                   na->num_rx_rings = v;
   }
   
   static __inline void
   nma_set_host_nrings(struct netmap_adapter *na, enum txrx t, u_int v)
   {
           if (t == NR_TX)
                   na->num_host_tx_rings = v;
           else
                   na->num_host_rx_rings = v;
   }
   
   static __inline struct netmap_kring**
   NMR(struct netmap_adapter *na, enum txrx t)
   {
           return (t == NR_TX ? na->tx_rings : na->rx_rings);
   }
   
   int nma_intr_enable(struct netmap_adapter *na, int onoff);
   
   /*
    * 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_flags & NAF_BUSY)
   #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;
          int autodelete; /* remove the ifp on last reference */
  
          /* Maximum Frame Size, used in bdg_mismatch_datapath() */
          u_int mfs;
          /* Last source MAC on this port */
          uint64_t last_smac;
  };
  
  
  struct netmap_hw_adapter {      /* physical device */
          struct netmap_adapter up;
  
  #ifdef linux
          struct net_device_ops nm_ndo;
          struct ethtool_ops    nm_eto;
  #endif
          const struct ethtool_ops*   save_ethtool;
  
          int (*nm_hw_register)(struct netmap_adapter *, int onoff);
  };
  
  #ifdef WITH_GENERIC
  /* Mitigation support. */
  struct nm_generic_mit {
          struct hrtimer mit_timer;
          int mit_pending;
          int mit_ring_idx;  /* index of the ring being mitigated */
          struct netmap_adapter *mit_na;  /* backpointer */
  };
  
  struct netmap_generic_adapter { /* emulated device */
          struct netmap_hw_adapter up;
  
          /* Pointer to a previously used netmap adapter. */
          struct netmap_adapter *prev;
  
          /* Emulated netmap adapters support:
           *  - save_if_input saves the if_input hook (FreeBSD);
           *  - mit implements rx interrupt mitigation;
           */
          void (*save_if_input)(struct ifnet *, struct mbuf *);
  
          struct nm_generic_mit *mit;
  #ifdef linux
          netdev_tx_t (*save_start_xmit)(struct mbuf *, struct ifnet *);
  #endif
          /* Is the adapter able to use multiple RX slots to scatter
           * each packet pushed up by the driver? */
          int rxsg;
  
          /* Is the transmission path controlled by a netmap-aware
           * device queue (i.e. qdisc on linux)? */
          int txqdisc;
  };
  #endif  /* WITH_GENERIC */
  
  static __inline u_int
  netmap_real_rings(struct netmap_adapter *na, enum txrx t)
  {
          return nma_get_nrings(na, t) +
                  !!(na->na_flags & NAF_HOST_RINGS) * nma_get_host_nrings(na, t);
  }
  
  /* account for fake rings */
  static __inline u_int
  netmap_all_rings(struct netmap_adapter *na, enum txrx t)
  {
          return max(nma_get_nrings(na, t) + 1, netmap_real_rings(na, t));
  }
  
  int netmap_default_bdg_attach(const char *name, struct netmap_adapter *na,
                  struct nm_bridge *);
  struct nm_bdg_polling_state;
  /*
   * 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 */
  
          /*
           * When we attach a physical interface to the bridge, we
           * allow the controlling process to terminate, so we need
           * a place to store the n_detmap_priv_d data structure.
           * This is only done when physical interfaces
           * are attached to a bridge.
           */
          struct netmap_priv_d *na_kpriv;
          struct nm_bdg_polling_state *na_polling_state;
          /* we overwrite the hwna->na_vp pointer, so we save
           * here its original value, to be restored at detach
           */
          struct netmap_vp_adapter *saved_na_vp;
          int (*nm_intr_notify)(struct netmap_kring *kring, int flags);
  };
  int nm_is_bwrap(struct netmap_adapter *na);
  int nm_bdg_polling(struct nmreq_header *hdr);
  
  int netmap_bdg_attach(struct nmreq_header *hdr, void *auth_token);
  int netmap_bdg_detach(struct nmreq_header *hdr, void *auth_token);
  #ifdef WITH_VALE
  int netmap_vale_list(struct nmreq_header *hdr);
  int netmap_vi_create(struct nmreq_header *hdr, int);
  int nm_vi_create(struct nmreq_header *);
  int nm_vi_destroy(const char *name);
  #else /* !WITH_VALE */
  #define netmap_vi_create(hdr, a) (EOPNOTSUPP)
  #endif /* WITH_VALE */
  
  #ifdef WITH_PIPES
  
  #define NM_MAXPIPES     64      /* max number of pipes per adapter */
  
  struct netmap_pipe_adapter {
          /* pipe identifier is up.name */
          struct netmap_adapter up;
  
  #define NM_PIPE_ROLE_MASTER     0x1
  #define NM_PIPE_ROLE_SLAVE      0x2
          int role;       /* either NM_PIPE_ROLE_MASTER or NM_PIPE_ROLE_SLAVE */
  
          struct netmap_adapter *parent; /* adapter that owns the memory */
          struct netmap_pipe_adapter *peer; /* the other end of the pipe */
          int peer_ref;           /* 1 iff we are holding a ref to the peer */
          struct ifnet *parent_ifp;       /* maybe null */
  
          u_int parent_slot; /* index in the parent pipe array */
  };
  
  #endif /* WITH_PIPES */
  
  #ifdef WITH_NMNULL
  struct netmap_null_adapter {
          struct netmap_adapter up;
  };
  #endif /* WITH_NMNULL */
  
  
  /* 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;
          nm_prdis("preserving %d rx slots %d -> %d", space, k->nr_hwcur, k->nr_hwtail);
  
          return space;
  }
  
  /* return slots reserved to tx clients */
  #define nm_kr_txspace(_k) nm_kr_rxspace(_k)
  
  
  /* 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->rhead == kring->nr_hwtail;
  }
  
  /* True if no more completed slots in the rx ring, only valid after
   * rxsync_prologue */
  #define nm_kr_rxempty(_k)       nm_kr_txempty(_k)
  
  /* True if the application needs to wait for more space on the ring
   * (more received packets or more free tx slots).
   * Only valid after *xsync_prologue. */
  static inline int
  nm_kr_wouldblock(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 or locked
   */
  #define NM_KR_BUSY      1       /* some other thread is syncing the ring */
  #define NM_KR_STOPPED   2       /* unbounded stop (ifconfig down or driver unload) */
  #define NM_KR_LOCKED    3       /* bounded, brief stop for mutual exclusion */
  
  
  /* release the previously acquired right to use the *sync() methods of the ring */
  static __inline void nm_kr_put(struct netmap_kring *kr)
  {
          NM_ATOMIC_CLEAR(&kr->nr_busy);
  }
  
  
  /* true if the ifp that backed the adapter has disappeared (e.g., the
   * driver has been unloaded)
   */
  static inline int nm_iszombie(struct netmap_adapter *na);
  
  /* try to obtain exclusive right to issue the *sync() operations on the ring.
   * The right is obtained and must be later relinquished via nm_kr_put() if and
   * only if nm_kr_tryget() returns 0.
   * If can_sleep is 1 there are only two other possible outcomes:
   * - the function returns NM_KR_BUSY
   * - the function returns NM_KR_STOPPED and sets the POLLERR bit in *perr
   *   (if non-null)
   * In both cases the caller will typically skip the ring, possibly collecting
   * errors along the way.
   * If the calling context does not allow sleeping, the caller must pass 0 in can_sleep.
   * In the latter case, the function may also return NM_KR_LOCKED and leave *perr
   * untouched: ideally, the caller should try again at a later time.
   */
  static __inline int nm_kr_tryget(struct netmap_kring *kr, int can_sleep, int *perr)
  {
          int busy = 1, stopped;
          /* check a first time without taking the lock
           * to avoid starvation for nm_kr_get()
           */
  retry:
          stopped = kr->nkr_stopped;
          if (unlikely(stopped)) {
                  goto stop;
          }
          busy = NM_ATOMIC_TEST_AND_SET(&kr->nr_busy);
          /* we should not return NM_KR_BUSY if the ring was
           * actually stopped, so check another time after
           * the barrier provided by the atomic operation
           */
          stopped = kr->nkr_stopped;
          if (unlikely(stopped)) {
                  goto stop;
          }
  
          if (unlikely(nm_iszombie(kr->na))) {
                  stopped = NM_KR_STOPPED;
                  goto stop;
          }
  
          return unlikely(busy) ? NM_KR_BUSY : 0;
  
  stop:
          if (!busy)
                  nm_kr_put(kr);
          if (stopped == NM_KR_STOPPED) {
  /* if POLLERR is defined we want to use it to simplify netmap_poll().
   * Otherwise, any non-zero value will do.
   */
  #ifdef POLLERR
  #define NM_POLLERR POLLERR
  #else
  #define NM_POLLERR 1
  #endif /* POLLERR */
                  if (perr)
                          *perr |= NM_POLLERR;
  #undef NM_POLLERR
          } else if (can_sleep) {
                  tsleep(kr, 0, "NM_KR_TRYGET", 4);
                  goto retry;
          }
          return stopped;
  }
  
  /* put the ring in the 'stopped' state and wait for the current user (if any) to
   * notice. stopped must be either NM_KR_STOPPED or NM_KR_LOCKED
   */
  static __inline void nm_kr_stop(struct netmap_kring *kr, int stopped)
  {
          kr->nkr_stopped = stopped;
          while (NM_ATOMIC_TEST_AND_SET(&kr->nr_busy))
                  tsleep(kr, 0, "NM_KR_GET", 4);
  }
  
  /* restart a ring after a stop */
  static __inline void nm_kr_start(struct netmap_kring *kr)
  {
          kr->nkr_stopped = 0;
          nm_kr_put(kr);
  }
  
  
  /*
   * 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 hw driver
   *      when reinitializing a ring. It should not be called by
   *      virtual ports (vale, pipes, monitor)
   */
  int netmap_attach(struct netmap_adapter *);
  int netmap_attach_ext(struct netmap_adapter *, size_t size, int override_reg);
  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 *);
  int netmap_rings_config_get(struct netmap_adapter *, struct nm_config_info *);
  
  /* Return codes for netmap_*x_irq. */
  enum {
          /* Driver should do normal interrupt processing, e.g. because
           * the interface is not in netmap mode. */
          NM_IRQ_PASS = 0,
          /* Port is in netmap mode, and the interrupt work has been
           * completed. The driver does not have to notify netmap
           * again before the next interrupt. */
          NM_IRQ_COMPLETED = -1,
          /* Port is in netmap mode, but the interrupt work has not been
           * completed. The driver has to make sure netmap will be
           * notified again soon, even if no more interrupts come (e.g.
           * on Linux the driver should not call napi_complete()). */
          NM_IRQ_RESCHED = -2,
  };
  
  /* 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)
  int netmap_common_irq(struct netmap_adapter *, u_int, u_int *work_done);
  
  
  #ifdef WITH_VALE
  /* functions used by external modules to interface with VALE */
  #define netmap_vp_to_ifp(_vp)   ((_vp)->up.ifp)
  #define netmap_ifp_to_vp(_ifp)  (NA(_ifp)->na_vp)
  #define netmap_ifp_to_host_vp(_ifp) (NA(_ifp)->na_hostvp)
  #define netmap_bdg_idx(_vp)     ((_vp)->bdg_port)
  const char *netmap_bdg_name(struct netmap_vp_adapter *);
  #else /* !WITH_VALE */
  #define netmap_vp_to_ifp(_vp)   NULL
  #define netmap_ifp_to_vp(_ifp)  NULL
  #define netmap_ifp_to_host_vp(_ifp) NULL
  #define netmap_bdg_idx(_vp)     -1
  #endif /* WITH_VALE */
  
  static inline int
  nm_netmap_on(struct netmap_adapter *na)
  {
          return na && na->na_flags & NAF_NETMAP_ON;
  }
  
  static inline int
  nm_native_on(struct netmap_adapter *na)
  {
          return nm_netmap_on(na) && (na->na_flags & NAF_NATIVE);
  }
  
  static inline struct netmap_kring *
  netmap_kring_on(struct netmap_adapter *na, u_int q, enum txrx t)
  {
          struct netmap_kring *kring = NULL;
  
          if (!nm_native_on(na))
                  return NULL;
  
          if (t == NR_RX && q < na->num_rx_rings)
                  kring = na->rx_rings[q];
          else if (t == NR_TX && q < na->num_tx_rings)
                  kring = na->tx_rings[q];
          else
                  return NULL;
  
          return (kring->nr_mode == NKR_NETMAP_ON) ? kring : NULL;
  }
  
  static inline int
  nm_iszombie(struct netmap_adapter *na)
  {
          return na == NULL || (na->na_flags & NAF_ZOMBIE);
  }
  
  void nm_set_native_flags(struct netmap_adapter *);
  void nm_clear_native_flags(struct netmap_adapter *);
  
  void netmap_krings_mode_commit(struct netmap_adapter *na, int onoff);
  
  /*
   * nm_*sync_prologue() functions are used in ioctl/poll and ptnetmap
   * kthreads.
   * We need netmap_ring* parameter, because in ptnetmap it is decoupled
   * from host kring.
   * The user-space ring pointers (head/cur/tail) are shared through
   * CSB between host and guest.
   */
  
  /*
   * 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 *, struct netmap_ring *);
  
  
  /*
   * validates parameters in the ring/kring, returns a value for head
   * If any error, returns ring_size lim to force a reinit.
   */
  uint32_t nm_rxsync_prologue(struct netmap_kring *, struct netmap_ring *);
  
  
  /* check/fix address and len in tx rings */
  #if 1 /* debug version */
  #define NM_CHECK_ADDR_LEN(_na, _a, _l)  do {                            \
          if (_a == NETMAP_BUF_BASE(_na) || _l > NETMAP_BUF_SIZE(_na)) {  \
                  nm_prlim(5, "bad addr/len ring %d slot %d idx %d len %d",       \
                          kring->ring_id, nm_i, slot->buf_idx, len);      \
                  if (_l > NETMAP_BUF_SIZE(_na))                          \
                          _l = NETMAP_BUF_SIZE(_na);                      \
          } } while (0)
  #else /* no debug version */
  #define NM_CHECK_ADDR_LEN(_na, _a, _l)  do {                            \
                  if (_l > NETMAP_BUF_SIZE(_na))                          \
                          _l = NETMAP_BUF_SIZE(_na);                      \
          } while (0)
  #endif
  
  #define NM_CHECK_ADDR_LEN_OFF(na_, l_, o_) do {                         \
          if ((l_) + (o_) < (l_) ||                                       \
              (l_) + (o_) > NETMAP_BUF_SIZE(na_)) {                       \
                  (l_) = NETMAP_BUF_SIZE(na_) - (o_);                     \
          } } while (0)
  
  
  /*---------------------------------------------------------------*/
  /*
   * Support routines used by netmap subsystems
   * (native drivers, VALE, generic, pipes, monitors, ...)
   */
  
  
  /* common routine for all functions that create a netmap adapter. It performs
   * two main tasks:
   * - if the na points to an ifp, mark the ifp as netmap capable
   *   using na as its native adapter;
   * - provide defaults for the setup callbacks and the memory allocator
   */
  int netmap_attach_common(struct netmap_adapter *);
  /* fill priv->np_[tr]xq{first,last} using the ringid and flags information
   * coming from a struct nmreq_register
   */
  int netmap_interp_ringid(struct netmap_priv_d *priv, struct nmreq_header *hdr);
  /* update the ring parameters (number and size of tx and rx rings).
   * It calls the nm_config callback, if available.
   */
  int netmap_update_config(struct netmap_adapter *na);
  /* create and initialize the common fields of the krings array.
   * using the information that must be already available in the na.
   * tailroom can be used to request the allocation of additional
   * tailroom bytes after the krings array. This is used by
   * netmap_vp_adapter's (i.e., VALE ports) to make room for
   * leasing-related data structures
   */
  int netmap_krings_create(struct netmap_adapter *na, u_int tailroom);
  /* deletes the kring array of the adapter. The array must have
   * been created using netmap_krings_create
   */
  void netmap_krings_delete(struct netmap_adapter *na);
  
  int netmap_hw_krings_create(struct netmap_adapter *na);
  void netmap_hw_krings_delete(struct netmap_adapter *na);
  
  /* set the stopped/enabled status of ring
   * When stopping, they also wait for all current activity on the ring to
   * terminate. The status change is then notified using the na nm_notify
   * callback.
   */
  void netmap_set_ring(struct netmap_adapter *, u_int ring_id, enum txrx, int stopped);
  /* set the stopped/enabled status of all rings of the adapter. */
  void netmap_set_all_rings(struct netmap_adapter *, int stopped);
  /* convenience wrappers for netmap_set_all_rings */
  void netmap_disable_all_rings(struct ifnet *);
  void netmap_enable_all_rings(struct ifnet *);
  
  int netmap_buf_size_validate(const struct netmap_adapter *na, unsigned mtu);
  int netmap_do_regif(struct netmap_priv_d *priv, struct netmap_adapter *na,
                  struct nmreq_header *);
  void netmap_do_unregif(struct netmap_priv_d *priv);
  
  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_header *hdr, struct netmap_adapter **na,
                  struct ifnet **ifp, struct netmap_mem_d *nmd, int create);
  void netmap_unget_na(struct netmap_adapter *na, struct ifnet *ifp);
  int netmap_get_hw_na(struct ifnet *ifp,
                  struct netmap_mem_d *nmd, struct netmap_adapter **na);
  void netmap_mem_restore(struct netmap_adapter *na);
  
  #ifdef WITH_VALE
  uint32_t netmap_vale_learning(struct nm_bdg_fwd *ft, uint8_t *dst_ring,
                  struct netmap_vp_adapter *, void *private_data);
  
  /* these are redefined in case of no VALE support */
  int netmap_get_vale_na(struct nmreq_header *hdr, struct netmap_adapter **na,
                  struct netmap_mem_d *nmd, int create);
  void *netmap_vale_create(const char *bdg_name, int *return_status);
  int netmap_vale_destroy(const char *bdg_name, void *auth_token);
  
  extern unsigned int vale_max_bridges;
  
  #else /* !WITH_VALE */
  #define netmap_bdg_learning(_1, _2, _3, _4)     0
  #define netmap_get_vale_na(_1, _2, _3, _4)      0
  #define netmap_bdg_create(_1, _2)       NULL
  #define netmap_bdg_destroy(_1, _2)      0
  #define vale_max_bridges                1
  #endif /* !WITH_VALE */
  
  #ifdef WITH_PIPES
  /* max number of pipes per device */
  #define NM_MAXPIPES     64      /* XXX this should probably be a sysctl */
  void netmap_pipe_dealloc(struct netmap_adapter *);
  int netmap_get_pipe_na(struct nmreq_header *hdr, struct netmap_adapter **na,
                          struct netmap_mem_d *nmd, int create);
  #else /* !WITH_PIPES */
  #define NM_MAXPIPES     0
  #define netmap_pipe_alloc(_1, _2)       0
  #define netmap_pipe_dealloc(_1)
  #define netmap_get_pipe_na(hdr, _2, _3, _4)     \
          ((strchr(hdr->nr_name, '{') != NULL || strchr(hdr->nr_name, '}') != NULL) ? EOPNOTSUPP : 0)
  #endif
  
  #ifdef WITH_MONITOR
  int netmap_get_monitor_na(struct nmreq_header *hdr, struct netmap_adapter **na,
                  struct netmap_mem_d *nmd, int create);
  void netmap_monitor_stop(struct netmap_adapter *na);
  #else
  #define netmap_get_monitor_na(hdr, _2, _3, _4) \
          (((struct nmreq_register *)(uintptr_t)hdr->nr_body)->nr_flags & (NR_MONITOR_TX | NR_MONITOR_RX) ? EOPNOTSUPP : 0)
  #endif
  
  #ifdef WITH_NMNULL
  int netmap_get_null_na(struct nmreq_header *hdr, struct netmap_adapter **na,
                  struct netmap_mem_d *nmd, int create);
  #else /* !WITH_NMNULL */
  #define netmap_get_null_na(hdr, _2, _3, _4) \
          (((struct nmreq_register *)(uintptr_t)hdr->nr_body)->nr_flags & (NR_MONITOR_TX | NR_MONITOR_RX) ? EOPNOTSUPP : 0)
  #endif /* WITH_NMNULL */
  
  #ifdef CONFIG_NET_NS
  struct net *netmap_bns_get(void);
  void netmap_bns_put(struct net *);
  void netmap_bns_getbridges(struct nm_bridge **, u_int *);
  #else
  extern struct nm_bridge *nm_bridges;
  #define netmap_bns_get()
  #define netmap_bns_put(_1)
  #define netmap_bns_getbridges(b, n) \
          do { *b = nm_bridges; *n = vale_max_bridges; } while (0)
  #endif
  
  /* Various prototypes */
  int netmap_poll(struct netmap_priv_d *, int events, NM_SELRECORD_T *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_ioctl(struct netmap_priv_d *priv, u_long cmd, caddr_t data,
                  struct thread *, int nr_body_is_user);
  int netmap_ioctl_legacy(struct netmap_priv_d *priv, u_long cmd, caddr_t data,
                          struct thread *td);
  size_t nmreq_size_by_type(uint16_t nr_reqtype);
  
  /* netmap_adapter creation/destruction */
  
  // #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;       \
                  __netmap_adapter_get(__na);             \
                  nm_prinf("getting %p:%s -> %d", __na, (__na)->name, (__na)->na_refcount);       \
          } while (0)
  
  int __netmap_adapter_put(struct netmap_adapter *na);
  
  #define netmap_adapter_put(na)                          \
          ({                                              \
                  struct netmap_adapter *__na = na;       \
                  if (__na == NULL)                       \
                          nm_prinf("putting NULL");       \
                  else                                    \
                          nm_prinf("putting %p:%s -> %d", __na, (__na)->name, (__na)->na_refcount - 1);   \
                  __netmap_adapter_put(__na);     \
          })
  
  #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
   */
  #define NETMAP_BUF_BASE(_na)    ((_na)->na_lut.lut[0].vaddr)
  #define NETMAP_BUF_SIZE(_na)    ((_na)->na_lut.objsize)
  extern int netmap_no_pendintr;
  extern int netmap_verbose;
  #ifdef CONFIG_NETMAP_DEBUG
  extern int netmap_debug;                /* for debugging */
  #else /* !CONFIG_NETMAP_DEBUG */
  #define netmap_debug (0)
  #endif /* !CONFIG_NETMAP_DEBUG */
  enum {                                  /* debug flags */
          NM_DEBUG_ON = 1,                /* generic debug messages */
          NM_DEBUG_HOST = 0x2,            /* debug host stack */
          NM_DEBUG_RXSYNC = 0x10,         /* debug on rxsync/txsync */
          NM_DEBUG_TXSYNC = 0x20,
          NM_DEBUG_RXINTR = 0x100,        /* debug on rx/tx intr (driver) */
          NM_DEBUG_TXINTR = 0x200,
          NM_DEBUG_NIC_RXSYNC = 0x1000,   /* debug on rx/tx intr (driver) */
          NM_DEBUG_NIC_TXSYNC = 0x2000,
          NM_DEBUG_MEM = 0x4000,          /* verbose memory allocations/deallocations */
          NM_DEBUG_VALE = 0x8000,         /* debug messages from memory allocators */
          NM_DEBUG_BDG = NM_DEBUG_VALE,
  };
  
  extern int netmap_txsync_retry;
  extern int netmap_generic_hwcsum;
  extern int netmap_generic_mit;
  extern int netmap_generic_ringsize;
  extern int netmap_generic_rings;
  #ifdef linux
  extern int netmap_generic_txqdisc;
  #endif
  
  /*
   * NA returns a pointer to the struct netmap adapter from the ifp.
   * WNA is os-specific and must be defined in glue code.
   */
  #define NA(_ifp)        ((struct netmap_adapter *)WNA(_ifp))
  
  /*
   * we provide a default implementation of NM_ATTACH_NA/NM_DETACH_NA
   * based on the WNA field.
   * Glue code may override this by defining its own NM_ATTACH_NA
   */
  #ifndef NM_ATTACH_NA
  /*
   * On old versions of FreeBSD, NA(ifp) is a pspare. On linux we
   * overload another pointer in the netdev.
   *
   * 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 NM_NA_VALID(ifp)        (NA(ifp) &&             \
          ((uint32_t)(uintptr_t)NA(ifp) ^ NA(ifp)->magic) == NETMAP_MAGIC )
  
  #define NM_ATTACH_NA(ifp, na) do {                                      \
          WNA(ifp) = na;                                                  \
          if (NA(ifp))                                                    \
                  NA(ifp)->magic =                                        \
                          ((uint32_t)(uintptr_t)NA(ifp)) ^ NETMAP_MAGIC;  \
  } while(0)
  #define NM_RESTORE_NA(ifp, na)  WNA(ifp) = na;
  
  #define NM_DETACH_NA(ifp)       do { WNA(ifp) = NULL; } while (0)
  #define NM_NA_CLASH(ifp)        (NA(ifp) && !NM_NA_VALID(ifp))
  #endif /* !NM_ATTACH_NA */
  
  
  #define NM_IS_NATIVE(ifp)       (NM_NA_VALID(ifp) && NA(ifp)->nm_dtor == netmap_hw_dtor)
  
  #if defined(__FreeBSD__)
  
  /* Assigns the device IOMMU domain to an allocator.
   * Returns -ENOMEM in case the domain is different */
  #define nm_iommu_group_id(dev) (-1)
  
  /* 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 int
  netmap_load_map(struct netmap_adapter *na,
          bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
  {
          if (map)
                  bus_dmamap_load(tag, map, buf, NETMAP_BUF_SIZE(na),
                      netmap_dmamap_cb, NULL, BUS_DMA_NOWAIT);
          return 0;
  }
  
  static inline void
  netmap_unload_map(struct netmap_adapter *na,
          bus_dma_tag_t tag, bus_dmamap_t map)
  {
          if (map)
                  bus_dmamap_unload(tag, map);
  }
  
  #define netmap_sync_map(na, tag, map, sz, t)
  
  /* update the map when a buffer changes. */
  static inline void
  netmap_reload_map(struct netmap_adapter *na,
          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(na),
                      netmap_dmamap_cb, NULL, BUS_DMA_NOWAIT);
          }
  }
  
  #elif defined(_WIN32)
  
  #else /* linux */
  
  int nm_iommu_group_id(bus_dma_tag_t dev);
  #include <linux/dma-mapping.h>
  
  /*
   * on linux we need
   *      dma_map_single(&pdev->dev, virt_addr, len, direction)
   *      dma_unmap_single(&adapter->pdev->dev, phys_addr, len, direction)
   */
  #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)) {
                  nm_prerr("dma mapping error");
                  /* goto dma_error; See e1000_put_txbuf() */
                  /* XXX reset */
          }
          tx_desc->buffer_addr = htole64(buffer_info->dma); //XXX
  
  #endif
  
  static inline int
  netmap_load_map(struct netmap_adapter *na,
          bus_dma_tag_t tag, bus_dmamap_t map, void *buf, u_int size)
  {
          if (map) {
                  *map = dma_map_single(na->pdev, buf, size,
                                        DMA_BIDIRECTIONAL);
                  if (dma_mapping_error(na->pdev, *map)) {
                          *map = 0;
                          return ENOMEM;
                  }
          }
          return 0;
  }
  
  static inline void
  netmap_unload_map(struct netmap_adapter *na,
          bus_dma_tag_t tag, bus_dmamap_t map, u_int sz)
  {
          if (*map) {
                  dma_unmap_single(na->pdev, *map, sz,
                                   DMA_BIDIRECTIONAL);
          }
  }
  
  #ifdef NETMAP_LINUX_HAVE_DMASYNC
  static inline void
  netmap_sync_map_cpu(struct netmap_adapter *na,
          bus_dma_tag_t tag, bus_dmamap_t map, u_int sz, enum txrx t)
  {
          if (*map) {
                  dma_sync_single_for_cpu(na->pdev, *map, sz,
                          (t == NR_TX ? DMA_TO_DEVICE : DMA_FROM_DEVICE));
          }
  }
  
  static inline void
  netmap_sync_map_dev(struct netmap_adapter *na,
          bus_dma_tag_t tag, bus_dmamap_t map, u_int sz, enum txrx t)
  {
          if (*map) {
                  dma_sync_single_for_device(na->pdev, *map, sz,
                          (t == NR_TX ? DMA_TO_DEVICE : DMA_FROM_DEVICE));
          }
  }
  
  static inline void
  netmap_reload_map(struct netmap_adapter *na,
          bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
  {
          u_int sz = NETMAP_BUF_SIZE(na);
  
          if (*map) {
                  dma_unmap_single(na->pdev, *map, sz,
                                  DMA_BIDIRECTIONAL);
          }
  
          *map = dma_map_single(na->pdev, buf, sz,
                                  DMA_BIDIRECTIONAL);
  }
  #else /* !NETMAP_LINUX_HAVE_DMASYNC */
  #define netmap_sync_map_cpu(na, tag, map, sz, t)
  #define netmap_sync_map_dev(na, tag, map, sz, t)
  #endif /* NETMAP_LINUX_HAVE_DMASYNC */
  
  #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;
  
          if (likely(kr->nkr_hwofs == 0)) {
                  return idx;
          }
  
          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;
  
          if (likely(kr->nkr_hwofs == 0)) {
                  return idx;
          }
  
          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. */
  #ifdef __FreeBSD__
  struct lut_entry {
          void *vaddr;            /* virtual address. */
          vm_paddr_t paddr;       /* physical address. */
  };
  #else /* linux & _WIN32 */
  /* dma-mapping in linux can assign a buffer a different address
   * depending on the device, so we need to have a separate
   * physical-address look-up table for each na.
   * We can still share the vaddrs, though, therefore we split
   * the lut_entry structure.
   */
  struct lut_entry {
          void *vaddr;            /* virtual address. */
  };
  
  struct plut_entry {
          vm_paddr_t paddr;       /* physical address. */
  };
  #endif /* linux & _WIN32 */
  
  struct netmap_obj_pool;
  
  /* alignment for netmap buffers */
  #define NM_BUF_ALIGN    64
  
  /*
   * 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_adapter *na, struct netmap_slot *slot)
  {
          struct lut_entry *lut = na->na_lut.lut;
          uint32_t i = slot->buf_idx;
          return (unlikely(i >= na->na_lut.objtotal)) ?
                  lut[0].vaddr : lut[i].vaddr;
  }
  
  static inline void *
  PNMB(struct netmap_adapter *na, struct netmap_slot *slot, uint64_t *pp)
  {
          uint32_t i = slot->buf_idx;
          struct lut_entry *lut = na->na_lut.lut;
          struct plut_entry *plut = na->na_lut.plut;
          void *ret = (i >= na->na_lut.objtotal) ? lut[0].vaddr : lut[i].vaddr;
  
  #ifdef _WIN32
          *pp = (i >= na->na_lut.objtotal) ? (uint64_t)plut[0].paddr.QuadPart : (uint64_t)plut[i].paddr.QuadPart;
  #else
          *pp = (i >= na->na_lut.objtotal) ? plut[0].paddr : plut[i].paddr;
  #endif
          return ret;
  }
  
  static inline void
  nm_write_offset(struct netmap_kring *kring,
                  struct netmap_slot *slot, uint64_t offset)
  {
          slot->ptr = (slot->ptr & ~kring->offset_mask) |
                  (offset & kring->offset_mask);
  }
  
  static inline uint64_t
  nm_get_offset(struct netmap_kring *kring, struct netmap_slot *slot)
  {
          uint64_t offset = (slot->ptr & kring->offset_mask);
          if (unlikely(offset > kring->offset_max))
                  offset = kring->offset_max;
          return offset;
  }
  
  static inline void *
  NMB_O(struct netmap_kring *kring, struct netmap_slot *slot)
  {
          void *addr = NMB(kring->na, slot);
          return (char *)addr + nm_get_offset(kring, slot);
  }
  
  static inline void *
  PNMB_O(struct netmap_kring *kring, struct netmap_slot *slot, uint64_t *pp)
  {
          void *addr = PNMB(kring->na, slot, pp);
          uint64_t offset = nm_get_offset(kring, slot);
          addr = (char *)addr + offset;
          *pp += offset;
          return addr;
  }
  
  
  /*
   * Structure associated to each netmap file descriptor.
   * It is created on open and left unbound (np_nifp == NULL).
   * A successful NIOCREGIF will set np_nifp and the first few fields;
   * this is protected by a global lock (NMG_LOCK) due to low contention.
   *
   * np_refs counts the number of references to the structure: one for the fd,
   * plus (on FreeBSD) one for each active mmap which we track ourselves
   * (linux automatically tracks them, but FreeBSD does not).
   * np_refs is protected by NMG_LOCK.
   *
   * Read access to the structure is lock free, because ni_nifp once set
   * can only go to 0 when nobody is using the entry anymore. Readers
   * must check that np_nifp != NULL before using the other fields.
   */
  struct netmap_priv_d {
          struct netmap_if * volatile np_nifp;    /* netmap if descriptor. */
  
          struct netmap_adapter   *np_na;
          struct ifnet    *np_ifp;
          uint32_t        np_flags;       /* from the ioctl */
          u_int           np_qfirst[NR_TXRX],
                          np_qlast[NR_TXRX]; /* range of tx/rx rings to scan */
          uint16_t        np_txpoll;
          uint16_t        np_kloop_state; /* use with NMG_LOCK held */
  #define NM_SYNC_KLOOP_RUNNING   (1 << 0)
  #define NM_SYNC_KLOOP_STOPPING  (1 << 1)
          int             np_sync_flags; /* to be passed to nm_sync */
  
          int             np_refs;        /* use with NMG_LOCK held */
  
          /* pointers to the selinfo to be used for selrecord.
           * Either the local or the global one depending on the
           * number of rings.
           */
          NM_SELINFO_T *np_si[NR_TXRX];
  
          /* In the optional CSB mode, the user must specify the start address
           * of two arrays of Communication Status Block (CSB) entries, for the
           * two directions (kernel read application write, and kernel write
           * application read).
           * The number of entries must agree with the number of rings bound to
           * the netmap file descriptor. The entries corresponding to the TX
           * rings are laid out before the ones corresponding to the RX rings.
           *
           * Array of CSB entries for application --> kernel communication
           * (N entries). */
          struct nm_csb_atok      *np_csb_atok_base;
          /* Array of CSB entries for kernel --> application communication
           * (N entries). */
          struct nm_csb_ktoa      *np_csb_ktoa_base;
  
  #ifdef linux
          struct file     *np_filp;  /* used by sync kloop */
  #endif /* linux */
  };
  
  struct netmap_priv_d *netmap_priv_new(void);
  void netmap_priv_delete(struct netmap_priv_d *);
  
  static inline int nm_kring_pending(struct netmap_priv_d *np)
  {
          struct netmap_adapter *na = np->np_na;
          enum txrx t;
          int i;
  
          for_rx_tx(t) {
                  for (i = np->np_qfirst[t]; i < np->np_qlast[t]; i++) {
                          struct netmap_kring *kring = NMR(na, t)[i];
                          if (kring->nr_mode != kring->nr_pending_mode) {
                                  return 1;
                          }
                  }
          }
          return 0;
  }
  
  /* call with NMG_LOCK held */
  static __inline int
  nm_si_user(struct netmap_priv_d *priv, enum txrx t)
  {
          return (priv->np_na != NULL &&
                  (priv->np_qlast[t] - priv->np_qfirst[t] > 1));
  }
  
  #ifdef WITH_PIPES
  int netmap_pipe_txsync(struct netmap_kring *txkring, int flags);
  int netmap_pipe_rxsync(struct netmap_kring *rxkring, int flags);
  int netmap_pipe_krings_create_both(struct netmap_adapter *na,
                                    struct netmap_adapter *ona);
  void netmap_pipe_krings_delete_both(struct netmap_adapter *na,
                                      struct netmap_adapter *ona);
  int netmap_pipe_reg_both(struct netmap_adapter *na,
                           struct netmap_adapter *ona);
  #endif /* WITH_PIPES */
  
  #ifdef WITH_MONITOR
  
  struct netmap_monitor_adapter {
          struct netmap_adapter up;
  
          struct netmap_priv_d priv;
          uint32_t flags;
  };
  
  #endif /* WITH_MONITOR */
  
  
  #ifdef WITH_GENERIC
  /*
   * generic netmap emulation for devices that do not have
   * native netmap support.
   */
  int generic_netmap_attach(struct ifnet *ifp);
  int generic_rx_handler(struct ifnet *ifp, struct mbuf *m);
  
  int nm_os_catch_rx(struct netmap_generic_adapter *gna, int intercept);
  int nm_os_catch_tx(struct netmap_generic_adapter *gna, int intercept);
  
  int na_is_generic(struct netmap_adapter *na);
  
  /*
   * the generic transmit routine is passed a structure to optionally
   * build a queue of descriptors, in an OS-specific way.
   * The payload is at addr, if non-null, and the routine should send or queue
   * the packet, returning 0 if successful, 1 on failure.
   *
   * At the end, if head is non-null, there will be an additional call
   * to the function with addr = NULL; this should tell the OS-specific
   * routine to send the queue and free any resources. Failure is ignored.
   */
  struct nm_os_gen_arg {
          struct ifnet *ifp;
          void *m;        /* os-specific mbuf-like object */
          void *head, *tail; /* tailq, if the OS-specific routine needs to build one */
          void *addr;     /* payload of current packet */
          u_int len;      /* packet length */
          u_int ring_nr;  /* transmit ring index */
          u_int qevent;   /* in txqdisc mode, place an event on this mbuf */
  };
  
  int nm_os_generic_xmit_frame(struct nm_os_gen_arg *);
  int nm_os_generic_find_num_desc(struct ifnet *ifp, u_int *tx, u_int *rx);
  void nm_os_generic_find_num_queues(struct ifnet *ifp, u_int *txq, u_int *rxq);
  void nm_os_generic_set_features(struct netmap_generic_adapter *gna);
  
  static inline struct ifnet*
  netmap_generic_getifp(struct netmap_generic_adapter *gna)
  {
          if (gna->prev)
              return gna->prev->ifp;
  
          return gna->up.up.ifp;
  }
  
  void netmap_generic_irq(struct netmap_adapter *na, u_int q, u_int *work_done);
  
  //#define RATE_GENERIC  /* Enables communication statistics for generic. */
  #ifdef RATE_GENERIC
  void generic_rate(int txp, int txs, int txi, int rxp, int rxs, int rxi);
  #else
  #define generic_rate(txp, txs, txi, rxp, rxs, rxi)
  #endif
  
  /*
   * netmap_mitigation API. This is used by the generic adapter
   * to reduce the number of interrupt requests/selwakeup
   * to clients on incoming packets.
   */
  void nm_os_mitigation_init(struct nm_generic_mit *mit, int idx,
                                  struct netmap_adapter *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);
  void nm_os_mitigation_cleanup(struct nm_generic_mit *mit);
  #else /* !WITH_GENERIC */
  #define generic_netmap_attach(ifp)      (EOPNOTSUPP)
  #define na_is_generic(na)               (0)
  #endif /* WITH_GENERIC */
  
  /* Shared declarations for the VALE switch. */
  
  /*
   * Each transmit queue accumulates a batch of packets into
   * a structure before forwarding. Packets to the same
   * destination are put in a list using ft_next as a link field.
   * ft_frags and ft_next are valid only on the first fragment.
   */
  struct nm_bdg_fwd {     /* forwarding entry for a bridge */
          void *ft_buf;           /* netmap or indirect buffer */
          uint8_t ft_frags;       /* how many fragments (only on 1st frag) */
          uint16_t ft_offset;     /* dst port (unused) */
          uint16_t ft_flags;      /* flags, e.g. indirect */
          uint16_t ft_len;        /* src fragment len */
          uint16_t ft_next;       /* next packet to same destination */
  };
  
  /* struct 'virtio_net_hdr' from linux. */
  struct nm_vnet_hdr {
  #define VIRTIO_NET_HDR_F_NEEDS_CSUM     1       /* Use csum_start, csum_offset */
  #define VIRTIO_NET_HDR_F_DATA_VALID    2        /* Csum is valid */
      uint8_t flags;
  #define VIRTIO_NET_HDR_GSO_NONE         0       /* Not a GSO frame */
  #define VIRTIO_NET_HDR_GSO_TCPV4        1       /* GSO frame, IPv4 TCP (TSO) */
  #define VIRTIO_NET_HDR_GSO_UDP          3       /* GSO frame, IPv4 UDP (UFO) */
  #define VIRTIO_NET_HDR_GSO_TCPV6        4       /* GSO frame, IPv6 TCP */
  #define VIRTIO_NET_HDR_GSO_ECN          0x80    /* TCP has ECN set */
      uint8_t gso_type;
      uint16_t hdr_len;
      uint16_t gso_size;
      uint16_t csum_start;
      uint16_t csum_offset;
  };
  
  #define WORST_CASE_GSO_HEADER   (14+40+60)  /* IPv6 + TCP */
  
  /* Private definitions for IPv4, IPv6, UDP and TCP headers. */
  
  struct nm_iphdr {
          uint8_t         version_ihl;
          uint8_t         tos;
          uint16_t        tot_len;
          uint16_t        id;
          uint16_t        frag_off;
          uint8_t         ttl;
          uint8_t         protocol;
          uint16_t        check;
          uint32_t        saddr;
          uint32_t        daddr;
          /*The options start here. */
  };
  
  struct nm_tcphdr {
          uint16_t        source;
          uint16_t        dest;
          uint32_t        seq;
          uint32_t        ack_seq;
          uint8_t         doff;  /* Data offset + Reserved */
          uint8_t         flags;
          uint16_t        window;
          uint16_t        check;
          uint16_t        urg_ptr;
  };
  
  struct nm_udphdr {
          uint16_t        source;
          uint16_t        dest;
          uint16_t        len;
          uint16_t        check;
  };
  
  struct nm_ipv6hdr {
          uint8_t         priority_version;
          uint8_t         flow_lbl[3];
  
          uint16_t        payload_len;
          uint8_t         nexthdr;
          uint8_t         hop_limit;
  
          uint8_t         saddr[16];
          uint8_t         daddr[16];
  };
  
  /* Type used to store a checksum (in host byte order) that hasn't been
   * folded yet.
   */
  #define rawsum_t uint32_t
  
  rawsum_t nm_os_csum_raw(uint8_t *data, size_t len, rawsum_t cur_sum);
  uint16_t nm_os_csum_ipv4(struct nm_iphdr *iph);
  void nm_os_csum_tcpudp_ipv4(struct nm_iphdr *iph, void *data,
                        size_t datalen, uint16_t *check);
  void nm_os_csum_tcpudp_ipv6(struct nm_ipv6hdr *ip6h, void *data,
                        size_t datalen, uint16_t *check);
  uint16_t nm_os_csum_fold(rawsum_t cur_sum);
  
  void bdg_mismatch_datapath(struct netmap_vp_adapter *na,
                             struct netmap_vp_adapter *dst_na,
                             const struct nm_bdg_fwd *ft_p,
                             struct netmap_ring *dst_ring,
                             u_int *j, u_int lim, u_int *howmany);
  
  /* persistent virtual port routines */
  int nm_os_vi_persist(const char *, struct ifnet **);
  void nm_os_vi_detach(struct ifnet *);
  void nm_os_vi_init_index(void);
  
  /*
   * kernel thread routines
   */
  struct nm_kctx; /* OS-specific kernel context - opaque */
  typedef void (*nm_kctx_worker_fn_t)(void *data);
  
  /* kthread configuration */
  struct nm_kctx_cfg {
          long                    type;           /* kthread type/identifier */
          nm_kctx_worker_fn_t     worker_fn;      /* worker function */
          void                    *worker_private;/* worker parameter */
          int                     attach_user;    /* attach kthread to user process */
  };
  /* kthread configuration */
  struct nm_kctx *nm_os_kctx_create(struct nm_kctx_cfg *cfg,
                                          void *opaque);
  int nm_os_kctx_worker_start(struct nm_kctx *);
  void nm_os_kctx_worker_stop(struct nm_kctx *);
  void nm_os_kctx_destroy(struct nm_kctx *);
  void nm_os_kctx_worker_setaff(struct nm_kctx *, int);
  u_int nm_os_ncpus(void);
  
  int netmap_sync_kloop(struct netmap_priv_d *priv,
                        struct nmreq_header *hdr);
  int netmap_sync_kloop_stop(struct netmap_priv_d *priv);
  
  #ifdef WITH_PTNETMAP
  /* ptnetmap guest routines */
  
  /*
   * ptnetmap_memdev routines used to talk with ptnetmap_memdev device driver
   */
  struct ptnetmap_memdev;
  int nm_os_pt_memdev_iomap(struct ptnetmap_memdev *, vm_paddr_t *, void **,
                            uint64_t *);
  void nm_os_pt_memdev_iounmap(struct ptnetmap_memdev *);
  uint32_t nm_os_pt_memdev_ioread(struct ptnetmap_memdev *, unsigned int);
  
  /*
   * netmap adapter for guest ptnetmap ports
   */
  struct netmap_pt_guest_adapter {
          /* The netmap adapter to be used by netmap applications.
           * This field must be the first, to allow upcast. */
          struct netmap_hw_adapter hwup;
  
          /* The netmap adapter to be used by the driver. */
          struct netmap_hw_adapter dr;
  
          /* Reference counter to track users of backend netmap port: the
           * network stack and netmap clients.
           * Used to decide when we need (de)allocate krings/rings and
           * start (stop) ptnetmap kthreads. */
          int backend_users;
  
  };
  
  int netmap_pt_guest_attach(struct netmap_adapter *na,
                          unsigned int nifp_offset,
                          unsigned int memid);
  bool netmap_pt_guest_txsync(struct nm_csb_atok *atok,
                          struct nm_csb_ktoa *ktoa,
                          struct netmap_kring *kring, int flags);
  bool netmap_pt_guest_rxsync(struct nm_csb_atok *atok,
                          struct nm_csb_ktoa *ktoa,
                          struct netmap_kring *kring, int flags);
  int ptnet_nm_krings_create(struct netmap_adapter *na);
  void ptnet_nm_krings_delete(struct netmap_adapter *na);
  void ptnet_nm_dtor(struct netmap_adapter *na);
  
  /* Helper function wrapping nm_sync_kloop_appl_read(). */
  static inline void
  ptnet_sync_tail(struct nm_csb_ktoa *ktoa, struct netmap_kring *kring)
  {
          struct netmap_ring *ring = kring->ring;
  
          /* Update hwcur and hwtail as known by the host. */
          nm_sync_kloop_appl_read(ktoa, &kring->nr_hwtail, &kring->nr_hwcur);
  
          /* nm_sync_finalize */
          ring->tail = kring->rtail = kring->nr_hwtail;
  }
  #endif /* WITH_PTNETMAP */
  
  #ifdef __FreeBSD__
  /*
   * FreeBSD mbuf allocator/deallocator in emulation mode:
   *
   * We allocate mbufs with m_gethdr(), since the mbuf header is needed
   * by the driver. We also attach a customly-provided external storage,
   * which in this case is a netmap buffer. When calling m_extadd(), however
   * we pass a NULL address, since the real address (and length) will be
   * filled in by nm_os_generic_xmit_frame() right before calling
   * if_transmit().
   *
   * The dtor function does nothing, however we need it since mb_free_ext()
   * has a KASSERT(), checking that the mbuf dtor function is not NULL.
   */
  
  static void void_mbuf_dtor(struct mbuf *m) { }
  
  #define SET_MBUF_DESTRUCTOR(m, fn)      do {            \
          (m)->m_ext.ext_free = (fn != NULL) ?            \
              (void *)fn : (void *)void_mbuf_dtor;        \
  } while (0)
  
  static inline struct mbuf *
  nm_os_get_mbuf(struct ifnet *ifp, int len)
  {
          struct mbuf *m;
  
          (void)ifp;
          (void)len;
  
          m = m_gethdr(M_NOWAIT, MT_DATA);
          if (m == NULL) {
                  return m;
          }
  
          m_extadd(m, NULL /* buf */, 0 /* size */, void_mbuf_dtor,
                   NULL, NULL, 0, EXT_NET_DRV);
  
          return m;
  }
  
  #endif /* __FreeBSD__ */
  
  struct nmreq_option * nmreq_getoption(struct nmreq_header *, uint16_t);
  
  int netmap_init_bridges(void);
  void netmap_uninit_bridges(void);
  
  /* Functions to read and write CSB fields from the kernel. */
  #if defined (linux)
  #define CSB_READ(csb, field, r) (get_user(r, &csb->field))
  #define CSB_WRITE(csb, field, v) (put_user(v, &csb->field))
  #else  /* ! linux */
  #define CSB_READ(csb, field, r) (r = fuword32(&csb->field))
  #define CSB_WRITE(csb, field, v) (suword32(&csb->field, v))
  #endif /* ! linux */
  
  /* some macros that may not be defined */
  #ifndef ETH_HLEN
  #define ETH_HLEN 6
  #endif
  #ifndef ETH_FCS_LEN
  #define ETH_FCS_LEN 4
  #endif
  #ifndef VLAN_HLEN
  #define VLAN_HLEN 4
  #endif
  
  #endif /* _NET_NETMAP_KERN_H_ */

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