text: /*
   * Copyright (c) 2003, 2004 Matthew Dillon. All rights reserved.
   * Copyright (c) 2003, 2004 Jeffrey M. Hsu.  All rights reserved.
   * Copyright (c) 2003 Jonathan Lemon.  All rights reserved.
   * Copyright (c) 2003, 2004 The DragonFly Project.  All rights reserved.
   *
   * This code is derived from software contributed to The DragonFly Project
   * by Jonathan Lemon, Jeffrey M. Hsu, and Matthew Dillon.
   *
   * Jonathan Lemon gave Jeffrey Hsu permission to combine his copyright
   * into this one around July 8 2004.
   *
   * 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.
   * 3. Neither the name of The DragonFly Project nor the names of its
   *    contributors may be used to endorse or promote products derived
   *    from this software without specific, prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
   * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/kernel.h>
  #include <sys/malloc.h>
  #include <sys/msgport.h>
  #include <sys/proc.h>
  #include <sys/interrupt.h>
  #include <sys/socket.h>
  #include <sys/sysctl.h>
  #include <sys/socketvar.h>
  #include <net/if.h>
  #include <net/if_var.h>
  #include <net/netisr2.h>
  #include <machine/cpufunc.h>
  #include <machine/smp.h>
  
  #include <sys/thread2.h>
  #include <sys/msgport2.h>
  #include <net/netmsg2.h>
  
  #include <vm/vm_extern.h>
  
  static void netmsg_service_port_init(lwkt_port_t);
  static void netmsg_service_loop(void *arg);
  static void netisr_hashfn0(struct mbuf **mp, int hoff);
  static void netisr_nohashck(struct mbuf *, const struct pktinfo *);
  
  struct netmsg_port_registration {
  	TAILQ_ENTRY(netmsg_port_registration) npr_entry;
  	lwkt_port_t	npr_port;
  };
  
  struct netisr_rollup {
  	TAILQ_ENTRY(netisr_rollup) ru_entry;
  	netisr_ru_t	ru_func;
  	int		ru_prio;
  	void		*ru_key;
  };
  
  struct netmsg_rollup {
  	struct netmsg_base	base;
  	netisr_ru_t		func;
  	int			prio;
  	void			*key;
  };
  
  struct netmsg_barrier {
  	struct netmsg_base	base;
  	volatile cpumask_t	*br_cpumask;
  	volatile uint32_t	br_done;
  };
  
  #define NETISR_BR_NOTDONE	0x1
  #define NETISR_BR_WAITDONE	0x80000000
  
  struct netisr_barrier {
  	struct netmsg_barrier	*br_msgs[MAXCPU];
  	int			br_isset;
  };
  
  struct netisr_data {
  	struct thread		thread;
  #ifdef INVARIANTS
  	void			*netlastfunc;
  #endif
  	TAILQ_HEAD(, netisr_rollup) netrulist;
  };
  
  static struct netisr_data	*netisr_data[MAXCPU];
  
  static struct netisr netisrs[NETISR_MAX];
  static TAILQ_HEAD(,netmsg_port_registration) netreglist;
  
  /* Per-CPU thread to handle any protocol.  */
  struct thread *netisr_threads[MAXCPU];
  
  lwkt_port netisr_afree_rport;
  lwkt_port netisr_afree_free_so_rport;
  lwkt_port netisr_adone_rport;
  lwkt_port netisr_apanic_rport;
  lwkt_port netisr_sync_port;
  
  static int (*netmsg_fwd_port_fn)(lwkt_port_t, lwkt_msg_t);
  
  SYSCTL_NODE(_net, OID_AUTO, netisr, CTLFLAG_RW, 0, "netisr");
  
  __read_frequently static int netisr_rollup_limit = 32;
  SYSCTL_INT(_net_netisr, OID_AUTO, rollup_limit, CTLFLAG_RW,
  	&netisr_rollup_limit, 0, "Message to process before rollup");
  
  __read_frequently int netisr_ncpus;
  TUNABLE_INT("net.netisr.ncpus", &netisr_ncpus);
  SYSCTL_INT(_net_netisr, OID_AUTO, ncpus, CTLFLAG_RD,
  	&netisr_ncpus, 0, "# of CPUs to handle network messages");
  
  /*
   * netisr_afree_rport replymsg function, only used to handle async
   * messages which the sender has abandoned to their fate.
   */
  static void
  netisr_autofree_reply(lwkt_port_t port, lwkt_msg_t msg)
  {
  	kfree(msg, M_LWKTMSG);
  }
  
  static void
  netisr_autofree_free_so_reply(lwkt_port_t port, lwkt_msg_t msg)
  {
  	sofree(((netmsg_t)msg)->base.nm_so);
  	kfree(msg, M_LWKTMSG);
  }
  
  /*
   * We need a custom putport function to handle the case where the
   * message target is the current thread's message port.  This case
   * can occur when the TCP or UDP stack does a direct callback to NFS and NFS
   * then turns around and executes a network operation synchronously.
   *
   * To prevent deadlocking, we must execute these self-referential messages
   * synchronously, effectively turning the message into a glorified direct
   * procedure call back into the protocol stack.  The operation must be
   * complete on return or we will deadlock, so panic if it isn't.
   *
   * However, the target function is under no obligation to immediately
   * reply the message.  It may forward it elsewhere.
   */
  static int
  netmsg_put_port(lwkt_port_t port, lwkt_msg_t lmsg)
  {
  	netmsg_base_t nmsg = (void *)lmsg;
  
  	if ((lmsg->ms_flags & MSGF_SYNC) && port == &curthread->td_msgport) {
  		nmsg->nm_dispatch((netmsg_t)nmsg);
  		return(EASYNC);
  	} else {
  		return(netmsg_fwd_port_fn(port, lmsg));
  	}
  }
  
  /*
   * UNIX DOMAIN sockets still have to run their uipc functions synchronously,
   * because they depend on the user proc context for a number of things 
   * (like creds) which we have not yet incorporated into the message structure.
   *
   * However, we maintain or message/port abstraction.  Having a special 
   * synchronous port which runs the commands synchronously gives us the
   * ability to serialize operations in one place later on when we start
   * removing the BGL.
   */
  static int
  netmsg_sync_putport(lwkt_port_t port, lwkt_msg_t lmsg)
  {
  	netmsg_base_t nmsg = (void *)lmsg;
  
  	KKASSERT((lmsg->ms_flags & MSGF_DONE) == 0);
  
  	lmsg->ms_target_port = port;	/* required for abort */
  	nmsg->nm_dispatch((netmsg_t)nmsg);
  	return(EASYNC);
  }
  
  static void
  netisr_init(void)
  {
  	int i;
  
  	if (netisr_ncpus <= 0 || netisr_ncpus > ncpus) {
  		/* Default. */
  		netisr_ncpus = ncpus;
  	}
  	if (netisr_ncpus > NETISR_CPUMAX)
  		netisr_ncpus = NETISR_CPUMAX;
  
  	TAILQ_INIT(&netreglist);
  
  	/*
  	 * Create default per-cpu threads for generic protocol handling.
  	 */
  	for (i = 0; i < ncpus; ++i) {
  		struct netisr_data *nd;
  
  		nd = (void *)kmem_alloc3(&kernel_map, sizeof(*nd),
  		    VM_SUBSYS_GD, KM_CPU(i));
  		memset(nd, 0, sizeof(*nd));
  		TAILQ_INIT(&nd->netrulist);
  		netisr_data[i] = nd;
  
  		lwkt_create(netmsg_service_loop, NULL, &netisr_threads[i],
  		    &nd->thread, TDF_NOSTART|TDF_FORCE_SPINPORT|TDF_FIXEDCPU,
  		    i, "netisr %d", i);
  		netmsg_service_port_init(&netisr_threads[i]->td_msgport);
  		lwkt_schedule(netisr_threads[i]);
  	}
  
  	/*
  	 * The netisr_afree_rport is a special reply port which automatically
  	 * frees the replied message.  The netisr_adone_rport simply marks
  	 * the message as being done.  The netisr_apanic_rport panics if
  	 * the message is replied to.
  	 */
  	lwkt_initport_replyonly(&netisr_afree_rport, netisr_autofree_reply);
  	lwkt_initport_replyonly(&netisr_afree_free_so_rport,
  				netisr_autofree_free_so_reply);
  	lwkt_initport_replyonly_null(&netisr_adone_rport);
  	lwkt_initport_panic(&netisr_apanic_rport);
  
  	/*
  	 * The netisr_syncport is a special port which executes the message
  	 * synchronously and waits for it if EASYNC is returned.
  	 */
  	lwkt_initport_putonly(&netisr_sync_port, netmsg_sync_putport);
  }
  SYSINIT(netisr, SI_SUB_PRE_DRIVERS, SI_ORDER_FIRST, netisr_init, NULL);
  
  /*
   * Finish initializing the message port for a netmsg service.  This also
   * registers the port for synchronous cleanup operations such as when an
   * ifnet is being destroyed.  There is no deregistration API yet.
   */
  static void
  netmsg_service_port_init(lwkt_port_t port)
  {
  	struct netmsg_port_registration *reg;
  
  	/*
  	 * Override the putport function.  Our custom function checks for
  	 * self-references and executes such commands synchronously.
  	 */
  	if (netmsg_fwd_port_fn == NULL)
  		netmsg_fwd_port_fn = port->mp_putport;
  	KKASSERT(netmsg_fwd_port_fn == port->mp_putport);
  	port->mp_putport = netmsg_put_port;
  
  	/*
  	 * Keep track of ports using the netmsg API so we can synchronize
  	 * certain operations (such as freeing an ifnet structure) across all
  	 * consumers.
  	 */
  	reg = kmalloc(sizeof(*reg), M_TEMP, M_WAITOK|M_ZERO);
  	reg->npr_port = port;
  	TAILQ_INSERT_TAIL(&netreglist, reg, npr_entry);
  }
  
  /*
   * This function synchronizes the caller with all netmsg services.  For
   * example, if an interface is being removed we must make sure that all
   * packets related to that interface complete processing before the structure
   * can actually be freed.  This sort of synchronization is an alternative to
   * ref-counting the netif, removing the ref counting overhead in favor of
   * placing additional overhead in the netif freeing sequence (where it is
   * inconsequential).
   */
  void
  netmsg_service_sync(void)
  {
  	struct netmsg_port_registration *reg;
  	struct netmsg_base smsg;
  
  	netmsg_init(&smsg, NULL, &curthread->td_msgport, 0, netmsg_sync_handler);
  
  	TAILQ_FOREACH(reg, &netreglist, npr_entry) {
  		lwkt_domsg(reg->npr_port, &smsg.lmsg, 0);
  	}
  }
  
  /*
   * The netmsg function simply replies the message.  API semantics require
   * EASYNC to be returned if the netmsg function disposes of the message.
   */
  void
  netmsg_sync_handler(netmsg_t msg)
  {
  	lwkt_replymsg(&msg->lmsg, 0);
  }
  
  /*
   * Generic netmsg service loop.  Some protocols may roll their own but all
   * must do the basic command dispatch function call done here.
   */
  static void
  netmsg_service_loop(void *arg)
  {
  	netmsg_base_t msg;
  	thread_t td = curthread;
  	int limit;
  	struct netisr_data *nd = netisr_data[mycpuid];
  
  	td->td_type = TD_TYPE_NETISR;
  
  	while ((msg = lwkt_waitport(&td->td_msgport, 0))) {
  		struct netisr_rollup *ru;
  
  		/*
  		 * Run up to 512 pending netmsgs.
  		 */
  		limit = netisr_rollup_limit;
  		do {
  			KASSERT(msg->nm_dispatch != NULL,
  				("netmsg_service isr %d badmsg",
  				msg->lmsg.u.ms_result));
  			/*
  			 * Don't match so_port, if the msg explicitly
  			 * asks us to ignore its so_port.
  			 */
  			if ((msg->lmsg.ms_flags & MSGF_IGNSOPORT) == 0 &&
  			    msg->nm_so &&
  			    msg->nm_so->so_port != &td->td_msgport) {
  				/*
  				 * Sockets undergoing connect or disconnect
  				 * ops can change ports on us.  Chase the
  				 * port.
  				 */
  #ifdef foo
  				/*
  				 * This could be quite common for protocols
  				 * which support asynchronous pru_connect,
  				 * e.g. TCP, so kprintf socket port chasing
  				 * could be too verbose for the console.
  				 */
  				kprintf("%s: Warning, port changed so=%p\n",
  					__func__, msg->nm_so);
  #endif
  				lwkt_forwardmsg(msg->nm_so->so_port,
  						&msg->lmsg);
  			} else {
  				/*
  				 * We are on the correct port, dispatch it.
  				 */
  #ifdef INVARIANTS
  				nd->netlastfunc = msg->nm_dispatch;
  #endif
  				msg->nm_dispatch((netmsg_t)msg);
  			}
  			if (--limit == 0)
  				break;
  		} while ((msg = lwkt_getport(&td->td_msgport)) != NULL);
  
  		/*
  		 * Run all registered rollup functions for this cpu
  		 * (e.g. tcp_willblock()).
  		 */
  		TAILQ_FOREACH(ru, &nd->netrulist, ru_entry)
  			ru->ru_func();
  	}
  }
  
  /*
   * Forward a packet to a netisr service function.
   *
   * If the packet has not been assigned to a protocol thread we call
   * the port characterization function to assign it.  The caller must
   * clear M_HASH (or not have set it in the first place) if the caller
   * wishes the packet to be recharacterized.
   */
  int
  netisr_queue(int num, struct mbuf *m)
  {
  	struct netisr *ni;
  	struct netmsg_packet *pmsg;
  	lwkt_port_t port;
  
  	KASSERT((num > 0 && num <= NELEM(netisrs)),
  		("Bad isr %d", num));
  
  	ni = &netisrs[num];
  	if (ni->ni_handler == NULL) {
  		kprintf("%s: Unregistered isr %d\n", __func__, num);
  		m_freem(m);
  		return (EIO);
  	}
  
  	/*
  	 * Figure out which protocol thread to send to.  This does not
  	 * have to be perfect but performance will be really good if it
  	 * is correct.  Major protocol inputs such as ip_input() will
  	 * re-characterize the packet as necessary.
  	 */
  	if ((m->m_flags & M_HASH) == 0) {
  		ni->ni_hashfn(&m, 0);
  		if (m == NULL)
  			return (EIO);
  		if ((m->m_flags & M_HASH) == 0) {
  			kprintf("%s(%d): packet hash failed\n",
  				__func__, num);
  			m_freem(m);
  			return (EIO);
  		}
  	}
  
  	/*
  	 * Get the protocol port based on the packet hash, initialize
  	 * the netmsg, and send it off.
  	 */
  	port = netisr_hashport(m->m_pkthdr.hash);
  	pmsg = &m->m_hdr.mh_netmsg;
  	netmsg_init(&pmsg->base, NULL, &netisr_apanic_rport,
  		    0, ni->ni_handler);
  	pmsg->nm_packet = m;
  	pmsg->base.lmsg.u.ms_result = num;
  	lwkt_sendmsg(port, &pmsg->base.lmsg);
  
  	return (0);
  }
  
  /*
   * Run a netisr service function on the packet.
   *
   * The packet must have been correctly characterized!
   */
  int
  netisr_handle(int num, struct mbuf *m)
  {
  	struct netisr *ni;
  	struct netmsg_packet *pmsg;
  	lwkt_port_t port;
  
  	/*
  	 * Get the protocol port based on the packet hash
  	 */
  	KASSERT((m->m_flags & M_HASH), ("packet not characterized"));
  	port = netisr_hashport(m->m_pkthdr.hash);
  	KASSERT(&curthread->td_msgport == port, ("wrong msgport"));
  
  	KASSERT((num > 0 && num <= NELEM(netisrs)), ("bad isr %d", num));
  	ni = &netisrs[num];
  	if (ni->ni_handler == NULL) {
  		kprintf("%s: unregistered isr %d\n", __func__, num);
  		m_freem(m);
  		return EIO;
  	}
  
  	/*
  	 * Initialize the netmsg, and run the handler directly.
  	 */
  	pmsg = &m->m_hdr.mh_netmsg;
  	netmsg_init(&pmsg->base, NULL, &netisr_apanic_rport,
  		    0, ni->ni_handler);
  	pmsg->nm_packet = m;
  	pmsg->base.lmsg.u.ms_result = num;
  	ni->ni_handler((netmsg_t)&pmsg->base);
  
  	return 0;
  }
  
  /*
   * Pre-characterization of a deeper portion of the packet for the
   * requested isr.
   *
   * The base of the ISR type (e.g. IP) that we want to characterize is
   * at (hoff) relative to the beginning of the mbuf.  This allows
   * e.g. ether_characterize() to not have to adjust the m_data/m_len.
   */
  void
  netisr_characterize(int num, struct mbuf **mp, int hoff)
  {
  	struct netisr *ni;
  	struct mbuf *m;
  
  	/*
  	 * Validation
  	 */
  	m = *mp;
  	KKASSERT(m != NULL);
  
  	if (num < 0 || num >= NETISR_MAX) {
  		if (num == NETISR_MAX) {
  			m_sethash(m, 0);
  			return;
  		}
  		panic("Bad isr %d", num);
  	}
  
  	/*
  	 * Valid netisr?
  	 */
  	ni = &netisrs[num];
  	if (ni->ni_handler == NULL) {
  		kprintf("%s: Unregistered isr %d\n", __func__, num);
  		m_freem(m);
  		*mp = NULL;
  	}
  
  	/*
  	 * Characterize the packet
  	 */
  	if ((m->m_flags & M_HASH) == 0) {
  		ni->ni_hashfn(mp, hoff);
  		m = *mp;
  		if (m && (m->m_flags & M_HASH) == 0) {
  			kprintf("%s(%d): packet hash failed\n",
  				__func__, num);
  		}
  	}
  }
  
  void
  netisr_register(int num, netisr_fn_t handler, netisr_hashfn_t hashfn)
  {
  	struct netisr *ni;
  
  	KASSERT((num > 0 && num <= NELEM(netisrs)),
  		("netisr_register: bad isr %d", num));
  	KKASSERT(handler != NULL);
  
  	if (hashfn == NULL)
  		hashfn = netisr_hashfn0;
  
  	ni = &netisrs[num];
  
  	ni->ni_handler = handler;
  	ni->ni_hashck = netisr_nohashck;
  	ni->ni_hashfn = hashfn;
  	netmsg_init(&ni->ni_netmsg, NULL, &netisr_adone_rport, 0, NULL);
  }
  
  void
  netisr_register_hashcheck(int num, netisr_hashck_t hashck)
  {
  	struct netisr *ni;
  
  	KASSERT((num > 0 && num <= NELEM(netisrs)),
  		("netisr_register: bad isr %d", num));
  
  	ni = &netisrs[num];
  	ni->ni_hashck = hashck;
  }
  
  static void
  netisr_register_rollup_dispatch(netmsg_t nmsg)
  {
  	struct netmsg_rollup *nm = (struct netmsg_rollup *)nmsg;
  	int cpuid = mycpuid;
  	struct netisr_data *nd = netisr_data[cpuid];
  	struct netisr_rollup *new_ru, *ru;
  
  	new_ru = kmalloc(sizeof(*new_ru), M_TEMP, M_WAITOK|M_ZERO);
  	new_ru->ru_func = nm->func;
  	new_ru->ru_prio = nm->prio;
  
  	/*
  	 * Higher priority "rollup" appears first
  	 */
  	TAILQ_FOREACH(ru, &nd->netrulist, ru_entry) {
  		if (ru->ru_prio < new_ru->ru_prio) {
  			TAILQ_INSERT_BEFORE(ru, new_ru, ru_entry);
  			goto done;
  		}
  	}
  	TAILQ_INSERT_TAIL(&nd->netrulist, new_ru, ru_entry);
  done:
  	if (cpuid == 0)
  		nm->key = new_ru;
  	KKASSERT(nm->key != NULL);
  	new_ru->ru_key = nm->key;
  
  	netisr_forwardmsg_all(&nm->base, cpuid + 1);
  }
  
  struct netisr_rollup *
  netisr_register_rollup(netisr_ru_t func, int prio)
  {
  	struct netmsg_rollup nm;
  
  	netmsg_init(&nm.base, NULL, &curthread->td_msgport, MSGF_PRIORITY,
  	    netisr_register_rollup_dispatch);
  	nm.func = func;
  	nm.prio = prio;
  	nm.key = NULL;
  	netisr_domsg_global(&nm.base);
  
  	KKASSERT(nm.key != NULL);
  	return (nm.key);
  }
  
  static void
  netisr_unregister_rollup_dispatch(netmsg_t nmsg)
  {
  	struct netmsg_rollup *nm = (struct netmsg_rollup *)nmsg;
  	int cpuid = mycpuid;
  	struct netisr_data *nd = netisr_data[cpuid];
  	struct netisr_rollup *ru;
  
  	TAILQ_FOREACH(ru, &nd->netrulist, ru_entry) {
  		if (ru->ru_key == nm->key)
  			break;
  	}
  	if (ru == NULL)
  		panic("netisr: no rullup for %p", nm->key);
  
  	TAILQ_REMOVE(&nd->netrulist, ru, ru_entry);
  	kfree(ru, M_TEMP);
  
  	netisr_forwardmsg_all(&nm->base, cpuid + 1);
  }
  
  void
  netisr_unregister_rollup(struct netisr_rollup *key)
  {
  	struct netmsg_rollup nm;
  
  	netmsg_init(&nm.base, NULL, &curthread->td_msgport, MSGF_PRIORITY,
  	    netisr_unregister_rollup_dispatch);
  	nm.key = key;
  	netisr_domsg_global(&nm.base);
  }
  
  /*
   * Return a default protocol control message processing thread port
   */
  lwkt_port_t
  cpu0_ctlport(int cmd __unused, struct sockaddr *sa __unused,
      void *extra __unused, int *cpuid)
  {
  	*cpuid = 0;
  	return netisr_cpuport(*cpuid);
  }
  
  /*
   * This is a default netisr packet characterization function which
   * sets M_HASH.  If a netisr is registered with a NULL hashfn function
   * this one is assigned.
   *
   * This function makes no attempt to validate the packet.
   */
  static void
  netisr_hashfn0(struct mbuf **mp, int hoff __unused)
  {
  
  	m_sethash(*mp, 0);
  }
  
  /*
   * schednetisr() is used to call the netisr handler from the appropriate
   * netisr thread for polling and other purposes.
   *
   * This function may be called from a hard interrupt or IPI and must be
   * MP SAFE and non-blocking.  We use a fixed per-cpu message instead of
   * trying to allocate one.  We must get ourselves onto the target cpu
   * to safely check the MSGF_DONE bit on the message but since the message
   * will be sent to that cpu anyway this does not add any extra work beyond
   * what lwkt_sendmsg() would have already had to do to schedule the target
   * thread.
   */
  static void
  schednetisr_remote(void *data)
  {
  	int num = (int)(intptr_t)data;
  	struct netisr *ni = &netisrs[num];
  	lwkt_port_t port = &netisr_threads[0]->td_msgport;
  	netmsg_base_t pmsg;
  
  	pmsg = &netisrs[num].ni_netmsg;
  	if (pmsg->lmsg.ms_flags & MSGF_DONE) {
  		netmsg_init(pmsg, NULL, &netisr_adone_rport, 0, ni->ni_handler);
  		pmsg->lmsg.u.ms_result = num;
  		lwkt_sendmsg(port, &pmsg->lmsg);
  	}
  }
  
  void
  schednetisr(int num)
  {
  	KASSERT((num > 0 && num <= NELEM(netisrs)),
  		("schednetisr: bad isr %d", num));
  	KKASSERT(netisrs[num].ni_handler != NULL);
  	if (mycpu->gd_cpuid != 0) {
  		lwkt_send_ipiq(globaldata_find(0),
  			       schednetisr_remote, (void *)(intptr_t)num);
  	} else {
  		crit_enter();
  		schednetisr_remote((void *)(intptr_t)num);
  		crit_exit();
  	}
  }
  
  static void
  netisr_barrier_dispatch(netmsg_t nmsg)
  {
  	struct netmsg_barrier *msg = (struct netmsg_barrier *)nmsg;
  
  	ATOMIC_CPUMASK_NANDBIT(*msg->br_cpumask, mycpu->gd_cpuid);
  	if (CPUMASK_TESTZERO(*msg->br_cpumask))
  		wakeup(msg->br_cpumask);
  
  	for (;;) {
  		uint32_t done = msg->br_done;
  
  		cpu_ccfence();
  		if ((done & NETISR_BR_NOTDONE) == 0)
  			break;
  
  		tsleep_interlock(&msg->br_done, 0);
  		if (atomic_cmpset_int(&msg->br_done,
  		    done, done | NETISR_BR_WAITDONE))
  			tsleep(&msg->br_done, PINTERLOCKED, "nbrdsp", 0);
  	}
  
  	lwkt_replymsg(&nmsg->lmsg, 0);
  }
  
  struct netisr_barrier *
  netisr_barrier_create(void)
  {
  	struct netisr_barrier *br;
  
  	br = kmalloc(sizeof(*br), M_LWKTMSG, M_WAITOK | M_ZERO);
  	return br;
  }
  
  void
  netisr_barrier_set(struct netisr_barrier *br)
  {
  	volatile cpumask_t other_cpumask;
  	int i, cur_cpuid;
  
  	ASSERT_NETISR0;
  	KKASSERT(!br->br_isset);
  
  	other_cpumask = mycpu->gd_other_cpus;
  	CPUMASK_ANDMASK(other_cpumask, smp_active_mask);
  	cur_cpuid = mycpuid;
  
  	for (i = 0; i < ncpus; ++i) {
  		struct netmsg_barrier *msg;
  
  		if (i == cur_cpuid)
  			continue;
  
  		msg = kmalloc(sizeof(struct netmsg_barrier),
  			      M_LWKTMSG, M_WAITOK);
  
  		/*
  		 * Don't use priority message here; mainly to keep
  		 * it ordered w/ the previous data packets sent by
  		 * the caller.
  		 */
  		netmsg_init(&msg->base, NULL, &netisr_afree_rport, 0,
  			    netisr_barrier_dispatch);
  		msg->br_cpumask = &other_cpumask;
  		msg->br_done = NETISR_BR_NOTDONE;
  
  		KKASSERT(br->br_msgs[i] == NULL);
  		br->br_msgs[i] = msg;
  	}
  
  	for (i = 0; i < ncpus; ++i) {
  		if (i == cur_cpuid)
  			continue;
  		lwkt_sendmsg(netisr_cpuport(i), &br->br_msgs[i]->base.lmsg);
  	}
  
  	while (CPUMASK_TESTNZERO(other_cpumask)) {
  		tsleep_interlock(&other_cpumask, 0);
  		if (CPUMASK_TESTNZERO(other_cpumask))
  			tsleep(&other_cpumask, PINTERLOCKED, "nbrset", 0);
  	}
  	br->br_isset = 1;
  }
  
  void
  netisr_barrier_rem(struct netisr_barrier *br)
  {
  	int i, cur_cpuid;
  
  	ASSERT_NETISR0;
  	KKASSERT(br->br_isset);
  
  	cur_cpuid = mycpuid;
  	for (i = 0; i < ncpus; ++i) {
  		struct netmsg_barrier *msg = br->br_msgs[i];
  		uint32_t done;
  
  		msg = br->br_msgs[i];
  		br->br_msgs[i] = NULL;
  
  		if (i == cur_cpuid)
  			continue;
  
  		done = atomic_swap_int(&msg->br_done, 0);
  		if (done & NETISR_BR_WAITDONE)
  			wakeup(&msg->br_done);
  	}
  	br->br_isset = 0;
  }
  
  static void
  netisr_nohashck(struct mbuf *m, const struct pktinfo *pi __unused)
  {
  	m->m_flags &= ~M_HASH;
  }
  
  void
  netisr_hashcheck(int num, struct mbuf *m, const struct pktinfo *pi)
  {
  	struct netisr *ni;
  
  	if (num < 0 || num >= NETISR_MAX)
  		panic("Bad isr %d", num);
  
  	/*
  	 * Valid netisr?
  	 */
  	ni = &netisrs[num];
  	if (ni->ni_handler == NULL)
  		panic("Unregistered isr %d", num);
  
  	ni->ni_hashck(m, pi);
  }
  