text: /*-
   * Copyright (c) 2007-2009 Robert N. M. Watson
   * Copyright (c) 2010-2011 Juniper Networks, Inc.
   * All rights reserved.
   *
   * This software was developed by Robert N. M. Watson under contract
   * to Juniper Networks, Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: releng/9.3/sys/net/netisr.c 248085 2013-03-09 02:36:32Z marius $");
  
  /*
   * netisr is a packet dispatch service, allowing synchronous (directly
   * dispatched) and asynchronous (deferred dispatch) processing of packets by
   * registered protocol handlers.  Callers pass a protocol identifier and
   * packet to netisr, along with a direct dispatch hint, and work will either
   * be immediately processed by the registered handler, or passed to a
   * software interrupt (SWI) thread for deferred dispatch.  Callers will
   * generally select one or the other based on:
   *
   * - Whether directly dispatching a netisr handler lead to code reentrance or
   *   lock recursion, such as entering the socket code from the socket code.
   * - Whether directly dispatching a netisr handler lead to recursive
   *   processing, such as when decapsulating several wrapped layers of tunnel
   *   information (IPSEC within IPSEC within ...).
   *
   * Maintaining ordering for protocol streams is a critical design concern.
   * Enforcing ordering limits the opportunity for concurrency, but maintains
   * the strong ordering requirements found in some protocols, such as TCP.  Of
   * related concern is CPU affinity--it is desirable to process all data
   * associated with a particular stream on the same CPU over time in order to
   * avoid acquiring locks associated with the connection on different CPUs,
   * keep connection data in one cache, and to generally encourage associated
   * user threads to live on the same CPU as the stream.  It's also desirable
   * to avoid lock migration and contention where locks are associated with
   * more than one flow.
   *
   * netisr supports several policy variations, represented by the
   * NETISR_POLICY_* constants, allowing protocols to play various roles in
   * identifying flows, assigning work to CPUs, etc.  These are described in
   * netisr.h.
   */
  
  #include "opt_ddb.h"
  #include "opt_device_polling.h"
  
  #include <sys/param.h>
  #include <sys/bus.h>
  #include <sys/kernel.h>
  #include <sys/kthread.h>
  #include <sys/interrupt.h>
  #include <sys/lock.h>
  #include <sys/mbuf.h>
  #include <sys/mutex.h>
  #include <sys/pcpu.h>
  #include <sys/proc.h>
  #include <sys/rmlock.h>
  #include <sys/sched.h>
  #include <sys/smp.h>
  #include <sys/socket.h>
  #include <sys/sysctl.h>
  #include <sys/systm.h>
  
  #ifdef DDB
  #include <ddb/ddb.h>
  #endif
  
  #define	_WANT_NETISR_INTERNAL	/* Enable definitions from netisr_internal.h */
  #include <net/if.h>
  #include <net/if_var.h>
  #include <net/netisr.h>
  #include <net/netisr_internal.h>
  #include <net/vnet.h>
  
  /*-
   * Synchronize use and modification of the registered netisr data structures;
   * acquire a read lock while modifying the set of registered protocols to
   * prevent partially registered or unregistered protocols from being run.
   *
   * The following data structures and fields are protected by this lock:
   *
   * - The netisr_proto array, including all fields of struct netisr_proto.
   * - The nws array, including all fields of struct netisr_worker.
   * - The nws_array array.
   *
   * Note: the NETISR_LOCKING define controls whether read locks are acquired
   * in packet processing paths requiring netisr registration stability.  This
   * is disabled by default as it can lead to measurable performance
   * degradation even with rmlocks (3%-6% for loopback ping-pong traffic), and
   * because netisr registration and unregistration is extremely rare at
   * runtime.  If it becomes more common, this decision should be revisited.
   *
   * XXXRW: rmlocks don't support assertions.
   */
  static struct rmlock	netisr_rmlock;
  #define	NETISR_LOCK_INIT()	rm_init_flags(&netisr_rmlock, "netisr", \
  				    RM_NOWITNESS)
  #define	NETISR_LOCK_ASSERT()
  #define	NETISR_RLOCK(tracker)	rm_rlock(&netisr_rmlock, (tracker))
  #define	NETISR_RUNLOCK(tracker)	rm_runlock(&netisr_rmlock, (tracker))
  #define	NETISR_WLOCK()		rm_wlock(&netisr_rmlock)
  #define	NETISR_WUNLOCK()	rm_wunlock(&netisr_rmlock)
  /* #define	NETISR_LOCKING */
  
  static SYSCTL_NODE(_net, OID_AUTO, isr, CTLFLAG_RW, 0, "netisr");
  
  /*-
   * Three global direct dispatch policies are supported:
   *
   * NETISR_DISPATCH_QUEUED: All work is deferred for a netisr, regardless of
   * context (may be overriden by protocols).
   *
   * NETISR_DISPATCH_HYBRID: If the executing context allows direct dispatch,
   * and we're running on the CPU the work would be performed on, then direct
   * dispatch it if it wouldn't violate ordering constraints on the workstream.
   *
   * NETISR_DISPATCH_DIRECT: If the executing context allows direct dispatch,
   * always direct dispatch.  (The default.)
   *
   * Notice that changing the global policy could lead to short periods of
   * misordered processing, but this is considered acceptable as compared to
   * the complexity of enforcing ordering during policy changes.  Protocols can
   * override the global policy (when they're not doing that, they select
   * NETISR_DISPATCH_DEFAULT).
   */
  #define	NETISR_DISPATCH_POLICY_DEFAULT	NETISR_DISPATCH_DIRECT
  #define	NETISR_DISPATCH_POLICY_MAXSTR	20 /* Used for temporary buffers. */
  static u_int	netisr_dispatch_policy = NETISR_DISPATCH_POLICY_DEFAULT;
  static int	sysctl_netisr_dispatch_policy(SYSCTL_HANDLER_ARGS);
  SYSCTL_PROC(_net_isr, OID_AUTO, dispatch, CTLTYPE_STRING | CTLFLAG_RW |
      CTLFLAG_TUN, 0, 0, sysctl_netisr_dispatch_policy, "A",
      "netisr dispatch policy");
  
  /*
   * These sysctls were used in previous versions to control and export
   * dispatch policy state.  Now, we provide read-only export via them so that
   * older netstat binaries work.  At some point they can be garbage collected.
   */
  static int	netisr_direct_force;
  SYSCTL_INT(_net_isr, OID_AUTO, direct_force, CTLFLAG_RD,
      &netisr_direct_force, 0, "compat: force direct dispatch");
  
  static int	netisr_direct;
  SYSCTL_INT(_net_isr, OID_AUTO, direct, CTLFLAG_RD, &netisr_direct, 0,
      "compat: enable direct dispatch");
  
  /*
   * Allow the administrator to limit the number of threads (CPUs) to use for
   * netisr.  We don't check netisr_maxthreads before creating the thread for
   * CPU 0, so in practice we ignore values <= 1.  This must be set at boot.
   * We will create at most one thread per CPU.
   */
  static int	netisr_maxthreads = -1;		/* Max number of threads. */
  TUNABLE_INT("net.isr.maxthreads", &netisr_maxthreads);
  SYSCTL_INT(_net_isr, OID_AUTO, maxthreads, CTLFLAG_RDTUN,
      &netisr_maxthreads, 0,
      "Use at most this many CPUs for netisr processing");
  
  static int	netisr_bindthreads = 0;		/* Bind threads to CPUs. */
  TUNABLE_INT("net.isr.bindthreads", &netisr_bindthreads);
  SYSCTL_INT(_net_isr, OID_AUTO, bindthreads, CTLFLAG_RDTUN,
      &netisr_bindthreads, 0, "Bind netisr threads to CPUs.");
  
  /*
   * Limit per-workstream mbuf queue limits s to at most net.isr.maxqlimit,
   * both for initial configuration and later modification using
   * netisr_setqlimit().
   */
  #define	NETISR_DEFAULT_MAXQLIMIT	10240
  static u_int	netisr_maxqlimit = NETISR_DEFAULT_MAXQLIMIT;
  TUNABLE_INT("net.isr.maxqlimit", &netisr_maxqlimit);
  SYSCTL_UINT(_net_isr, OID_AUTO, maxqlimit, CTLFLAG_RDTUN,
      &netisr_maxqlimit, 0,
      "Maximum netisr per-protocol, per-CPU queue depth.");
  
  /*
   * The default per-workstream mbuf queue limit for protocols that don't
   * initialize the nh_qlimit field of their struct netisr_handler.  If this is
   * set above netisr_maxqlimit, we truncate it to the maximum during boot.
   */
  #define	NETISR_DEFAULT_DEFAULTQLIMIT	256
  static u_int	netisr_defaultqlimit = NETISR_DEFAULT_DEFAULTQLIMIT;
  TUNABLE_INT("net.isr.defaultqlimit", &netisr_defaultqlimit);
  SYSCTL_UINT(_net_isr, OID_AUTO, defaultqlimit, CTLFLAG_RDTUN,
      &netisr_defaultqlimit, 0,
      "Default netisr per-protocol, per-CPU queue limit if not set by protocol");
  
  /*
   * Store and export the compile-time constant NETISR_MAXPROT limit on the
   * number of protocols that can register with netisr at a time.  This is
   * required for crashdump analysis, as it sizes netisr_proto[].
   */
  static u_int	netisr_maxprot = NETISR_MAXPROT;
  SYSCTL_UINT(_net_isr, OID_AUTO, maxprot, CTLFLAG_RD,
      &netisr_maxprot, 0,
      "Compile-time limit on the number of protocols supported by netisr.");
  
  /*
   * The netisr_proto array describes all registered protocols, indexed by
   * protocol number.  See netisr_internal.h for more details.
   */
  static struct netisr_proto	netisr_proto[NETISR_MAXPROT];
  
  /*
   * Per-CPU workstream data.  See netisr_internal.h for more details.
   */
  DPCPU_DEFINE(struct netisr_workstream, nws);
  
  /*
   * Map contiguous values between 0 and nws_count into CPU IDs appropriate for
   * accessing workstreams.  This allows constructions of the form
   * DPCPU_ID_GET(nws_array[arbitraryvalue % nws_count], nws).
   */
  static u_int				 nws_array[MAXCPU];
  
  /*
   * Number of registered workstreams.  Will be at most the number of running
   * CPUs once fully started.
   */
  static u_int				 nws_count;
  SYSCTL_UINT(_net_isr, OID_AUTO, numthreads, CTLFLAG_RD,
      &nws_count, 0, "Number of extant netisr threads.");
  
  /*
   * Synchronization for each workstream: a mutex protects all mutable fields
   * in each stream, including per-protocol state (mbuf queues).  The SWI is
   * woken up if asynchronous dispatch is required.
   */
  #define	NWS_LOCK(s)		mtx_lock(&(s)->nws_mtx)
  #define	NWS_LOCK_ASSERT(s)	mtx_assert(&(s)->nws_mtx, MA_OWNED)
  #define	NWS_UNLOCK(s)		mtx_unlock(&(s)->nws_mtx)
  #define	NWS_SIGNAL(s)		swi_sched((s)->nws_swi_cookie, 0)
  
  /*
   * Utility routines for protocols that implement their own mapping of flows
   * to CPUs.
   */
  u_int
  netisr_get_cpucount(void)
  {
  
  	return (nws_count);
  }
  
  u_int
  netisr_get_cpuid(u_int cpunumber)
  {
  
  	KASSERT(cpunumber < nws_count, ("%s: %u > %u", __func__, cpunumber,
  	    nws_count));
  
  	return (nws_array[cpunumber]);
  }
  
  /*
   * The default implementation of flow -> CPU ID mapping.
   *
   * Non-static so that protocols can use it to map their own work to specific
   * CPUs in a manner consistent to netisr for affinity purposes.
   */
  u_int
  netisr_default_flow2cpu(u_int flowid)
  {
  
  	return (nws_array[flowid % nws_count]);
  }
  
  /*
   * Dispatch tunable and sysctl configuration.
   */
  struct netisr_dispatch_table_entry {
  	u_int		 ndte_policy;
  	const char	*ndte_policy_str;
  };
  static const struct netisr_dispatch_table_entry netisr_dispatch_table[] = {
  	{ NETISR_DISPATCH_DEFAULT, "default" },
  	{ NETISR_DISPATCH_DEFERRED, "deferred" },
  	{ NETISR_DISPATCH_HYBRID, "hybrid" },
  	{ NETISR_DISPATCH_DIRECT, "direct" },
  };
  static const u_int netisr_dispatch_table_len =
      (sizeof(netisr_dispatch_table) / sizeof(netisr_dispatch_table[0]));
  
  static void
  netisr_dispatch_policy_to_str(u_int dispatch_policy, char *buffer,
      u_int buflen)
  {
  	const struct netisr_dispatch_table_entry *ndtep;
  	const char *str;
  	u_int i;
  
  	str = "unknown";
  	for (i = 0; i < netisr_dispatch_table_len; i++) {
  		ndtep = &netisr_dispatch_table[i];
  		if (ndtep->ndte_policy == dispatch_policy) {
  			str = ndtep->ndte_policy_str;
  			break;
  		}
  	}
  	snprintf(buffer, buflen, "%s", str);
  }
  
  static int
  netisr_dispatch_policy_from_str(const char *str, u_int *dispatch_policyp)
  {
  	const struct netisr_dispatch_table_entry *ndtep;
  	u_int i;
  
  	for (i = 0; i < netisr_dispatch_table_len; i++) {
  		ndtep = &netisr_dispatch_table[i];
  		if (strcmp(ndtep->ndte_policy_str, str) == 0) {
  			*dispatch_policyp = ndtep->ndte_policy;
  			return (0);
  		}
  	}
  	return (EINVAL);
  }
  
  static void
  netisr_dispatch_policy_compat(void)
  {
  
  	switch (netisr_dispatch_policy) {
  	case NETISR_DISPATCH_DEFERRED:
  		netisr_direct_force = 0;
  		netisr_direct = 0;
  		break;
  
  	case NETISR_DISPATCH_HYBRID:
  		netisr_direct_force = 0;
  		netisr_direct = 1;
  		break;
  
  	case NETISR_DISPATCH_DIRECT:
  		netisr_direct_force = 1;
  		netisr_direct = 1;
  		break;
  
  	default:
  		panic("%s: unknown policy %u", __func__,
  		    netisr_dispatch_policy);
  	}
  }
  
  static int
  sysctl_netisr_dispatch_policy(SYSCTL_HANDLER_ARGS)
  {
  	char tmp[NETISR_DISPATCH_POLICY_MAXSTR];
  	u_int dispatch_policy;
  	int error;
  
  	netisr_dispatch_policy_to_str(netisr_dispatch_policy, tmp,
  	    sizeof(tmp));
  	error = sysctl_handle_string(oidp, tmp, sizeof(tmp), req);
  	if (error == 0 && req->newptr != NULL) {
  		error = netisr_dispatch_policy_from_str(tmp,
  		    &dispatch_policy);
  		if (error == 0 && dispatch_policy == NETISR_DISPATCH_DEFAULT)
  			error = EINVAL;
  		if (error == 0) {
  			netisr_dispatch_policy = dispatch_policy;
  			netisr_dispatch_policy_compat();
  		}
  	}
  	return (error);
  }
  
  /*
   * Register a new netisr handler, which requires initializing per-protocol
   * fields for each workstream.  All netisr work is briefly suspended while
   * the protocol is installed.
   */
  void
  netisr_register(const struct netisr_handler *nhp)
  {
  	struct netisr_work *npwp;
  	const char *name;
  	u_int i, proto;
  
  	proto = nhp->nh_proto;
  	name = nhp->nh_name;
  
  	/*
  	 * Test that the requested registration is valid.
  	 */
  	KASSERT(nhp->nh_name != NULL,
  	    ("%s: nh_name NULL for %u", __func__, proto));
  	KASSERT(nhp->nh_handler != NULL,
  	    ("%s: nh_handler NULL for %s", __func__, name));
  	KASSERT(nhp->nh_policy == NETISR_POLICY_SOURCE ||
  	    nhp->nh_policy == NETISR_POLICY_FLOW ||
  	    nhp->nh_policy == NETISR_POLICY_CPU,
  	    ("%s: unsupported nh_policy %u for %s", __func__,
  	    nhp->nh_policy, name));
  	KASSERT(nhp->nh_policy == NETISR_POLICY_FLOW ||
  	    nhp->nh_m2flow == NULL,
  	    ("%s: nh_policy != FLOW but m2flow defined for %s", __func__,
  	    name));
  	KASSERT(nhp->nh_policy == NETISR_POLICY_CPU || nhp->nh_m2cpuid == NULL,
  	    ("%s: nh_policy != CPU but m2cpuid defined for %s", __func__,
  	    name));
  	KASSERT(nhp->nh_policy != NETISR_POLICY_CPU || nhp->nh_m2cpuid != NULL,
  	    ("%s: nh_policy == CPU but m2cpuid not defined for %s", __func__,
  	    name));
  	KASSERT(nhp->nh_dispatch == NETISR_DISPATCH_DEFAULT ||
  	    nhp->nh_dispatch == NETISR_DISPATCH_DEFERRED ||
  	    nhp->nh_dispatch == NETISR_DISPATCH_HYBRID ||
  	    nhp->nh_dispatch == NETISR_DISPATCH_DIRECT,
  	    ("%s: invalid nh_dispatch (%u)", __func__, nhp->nh_dispatch));
  
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s(%u, %s): protocol too big", __func__, proto, name));
  
  	/*
  	 * Test that no existing registration exists for this protocol.
  	 */
  	NETISR_WLOCK();
  	KASSERT(netisr_proto[proto].np_name == NULL,
  	    ("%s(%u, %s): name present", __func__, proto, name));
  	KASSERT(netisr_proto[proto].np_handler == NULL,
  	    ("%s(%u, %s): handler present", __func__, proto, name));
  
  	netisr_proto[proto].np_name = name;
  	netisr_proto[proto].np_handler = nhp->nh_handler;
  	netisr_proto[proto].np_m2flow = nhp->nh_m2flow;
  	netisr_proto[proto].np_m2cpuid = nhp->nh_m2cpuid;
  	netisr_proto[proto].np_drainedcpu = nhp->nh_drainedcpu;
  	if (nhp->nh_qlimit == 0)
  		netisr_proto[proto].np_qlimit = netisr_defaultqlimit;
  	else if (nhp->nh_qlimit > netisr_maxqlimit) {
  		printf("%s: %s requested queue limit %u capped to "
  		    "net.isr.maxqlimit %u\n", __func__, name, nhp->nh_qlimit,
  		    netisr_maxqlimit);
  		netisr_proto[proto].np_qlimit = netisr_maxqlimit;
  	} else
  		netisr_proto[proto].np_qlimit = nhp->nh_qlimit;
  	netisr_proto[proto].np_policy = nhp->nh_policy;
  	netisr_proto[proto].np_dispatch = nhp->nh_dispatch;
  	CPU_FOREACH(i) {
  		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  		bzero(npwp, sizeof(*npwp));
  		npwp->nw_qlimit = netisr_proto[proto].np_qlimit;
  	}
  	NETISR_WUNLOCK();
  }
  
  /*
   * Clear drop counters across all workstreams for a protocol.
   */
  void
  netisr_clearqdrops(const struct netisr_handler *nhp)
  {
  	struct netisr_work *npwp;
  #ifdef INVARIANTS
  	const char *name;
  #endif
  	u_int i, proto;
  
  	proto = nhp->nh_proto;
  #ifdef INVARIANTS
  	name = nhp->nh_name;
  #endif
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s(%u): protocol too big for %s", __func__, proto, name));
  
  	NETISR_WLOCK();
  	KASSERT(netisr_proto[proto].np_handler != NULL,
  	    ("%s(%u): protocol not registered for %s", __func__, proto,
  	    name));
  
  	CPU_FOREACH(i) {
  		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  		npwp->nw_qdrops = 0;
  	}
  	NETISR_WUNLOCK();
  }
  
  /*
   * Query current drop counters across all workstreams for a protocol.
   */
  void
  netisr_getqdrops(const struct netisr_handler *nhp, u_int64_t *qdropp)
  {
  	struct netisr_work *npwp;
  	struct rm_priotracker tracker;
  #ifdef INVARIANTS
  	const char *name;
  #endif
  	u_int i, proto;
  
  	*qdropp = 0;
  	proto = nhp->nh_proto;
  #ifdef INVARIANTS
  	name = nhp->nh_name;
  #endif
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s(%u): protocol too big for %s", __func__, proto, name));
  
  	NETISR_RLOCK(&tracker);
  	KASSERT(netisr_proto[proto].np_handler != NULL,
  	    ("%s(%u): protocol not registered for %s", __func__, proto,
  	    name));
  
  	CPU_FOREACH(i) {
  		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  		*qdropp += npwp->nw_qdrops;
  	}
  	NETISR_RUNLOCK(&tracker);
  }
  
  /*
   * Query current per-workstream queue limit for a protocol.
   */
  void
  netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp)
  {
  	struct rm_priotracker tracker;
  #ifdef INVARIANTS
  	const char *name;
  #endif
  	u_int proto;
  
  	proto = nhp->nh_proto;
  #ifdef INVARIANTS
  	name = nhp->nh_name;
  #endif
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s(%u): protocol too big for %s", __func__, proto, name));
  
  	NETISR_RLOCK(&tracker);
  	KASSERT(netisr_proto[proto].np_handler != NULL,
  	    ("%s(%u): protocol not registered for %s", __func__, proto,
  	    name));
  	*qlimitp = netisr_proto[proto].np_qlimit;
  	NETISR_RUNLOCK(&tracker);
  }
  
  /*
   * Update the queue limit across per-workstream queues for a protocol.  We
   * simply change the limits, and don't drain overflowed packets as they will
   * (hopefully) take care of themselves shortly.
   */
  int
  netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit)
  {
  	struct netisr_work *npwp;
  #ifdef INVARIANTS
  	const char *name;
  #endif
  	u_int i, proto;
  
  	if (qlimit > netisr_maxqlimit)
  		return (EINVAL);
  
  	proto = nhp->nh_proto;
  #ifdef INVARIANTS
  	name = nhp->nh_name;
  #endif
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s(%u): protocol too big for %s", __func__, proto, name));
  
  	NETISR_WLOCK();
  	KASSERT(netisr_proto[proto].np_handler != NULL,
  	    ("%s(%u): protocol not registered for %s", __func__, proto,
  	    name));
  
  	netisr_proto[proto].np_qlimit = qlimit;
  	CPU_FOREACH(i) {
  		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  		npwp->nw_qlimit = qlimit;
  	}
  	NETISR_WUNLOCK();
  	return (0);
  }
  
  /*
   * Drain all packets currently held in a particular protocol work queue.
   */
  static void
  netisr_drain_proto(struct netisr_work *npwp)
  {
  	struct mbuf *m;
  
  	/*
  	 * We would assert the lock on the workstream but it's not passed in.
  	 */
  	while ((m = npwp->nw_head) != NULL) {
  		npwp->nw_head = m->m_nextpkt;
  		m->m_nextpkt = NULL;
  		if (npwp->nw_head == NULL)
  			npwp->nw_tail = NULL;
  		npwp->nw_len--;
  		m_freem(m);
  	}
  	KASSERT(npwp->nw_tail == NULL, ("%s: tail", __func__));
  	KASSERT(npwp->nw_len == 0, ("%s: len", __func__));
  }
  
  /*
   * Remove the registration of a network protocol, which requires clearing
   * per-protocol fields across all workstreams, including freeing all mbufs in
   * the queues at time of unregister.  All work in netisr is briefly suspended
   * while this takes place.
   */
  void
  netisr_unregister(const struct netisr_handler *nhp)
  {
  	struct netisr_work *npwp;
  #ifdef INVARIANTS
  	const char *name;
  #endif
  	u_int i, proto;
  
  	proto = nhp->nh_proto;
  #ifdef INVARIANTS
  	name = nhp->nh_name;
  #endif
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s(%u): protocol too big for %s", __func__, proto, name));
  
  	NETISR_WLOCK();
  	KASSERT(netisr_proto[proto].np_handler != NULL,
  	    ("%s(%u): protocol not registered for %s", __func__, proto,
  	    name));
  
  	netisr_proto[proto].np_name = NULL;
  	netisr_proto[proto].np_handler = NULL;
  	netisr_proto[proto].np_m2flow = NULL;
  	netisr_proto[proto].np_m2cpuid = NULL;
  	netisr_proto[proto].np_qlimit = 0;
  	netisr_proto[proto].np_policy = 0;
  	CPU_FOREACH(i) {
  		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  		netisr_drain_proto(npwp);
  		bzero(npwp, sizeof(*npwp));
  	}
  	NETISR_WUNLOCK();
  }
  
  /*
   * Compose the global and per-protocol policies on dispatch, and return the
   * dispatch policy to use.
   */
  static u_int
  netisr_get_dispatch(struct netisr_proto *npp)
  {
  
  	/*
  	 * Protocol-specific configuration overrides the global default.
  	 */
  	if (npp->np_dispatch != NETISR_DISPATCH_DEFAULT)
  		return (npp->np_dispatch);
  	return (netisr_dispatch_policy);
  }
  
  /*
   * Look up the workstream given a packet and source identifier.  Do this by
   * checking the protocol's policy, and optionally call out to the protocol
   * for assistance if required.
   */
  static struct mbuf *
  netisr_select_cpuid(struct netisr_proto *npp, u_int dispatch_policy,
      uintptr_t source, struct mbuf *m, u_int *cpuidp)
  {
  	struct ifnet *ifp;
  	u_int policy;
  
  	NETISR_LOCK_ASSERT();
  
  	/*
  	 * In the event we have only one worker, shortcut and deliver to it
  	 * without further ado.
  	 */
  	if (nws_count == 1) {
  		*cpuidp = nws_array[0];
  		return (m);
  	}
  
  	/*
  	 * What happens next depends on the policy selected by the protocol.
  	 * If we want to support per-interface policies, we should do that
  	 * here first.
  	 */
  	policy = npp->np_policy;
  	if (policy == NETISR_POLICY_CPU) {
  		m = npp->np_m2cpuid(m, source, cpuidp);
  		if (m == NULL)
  			return (NULL);
  
  		/*
  		 * It's possible for a protocol not to have a good idea about
  		 * where to process a packet, in which case we fall back on
  		 * the netisr code to decide.  In the hybrid case, return the
  		 * current CPU ID, which will force an immediate direct
  		 * dispatch.  In the queued case, fall back on the SOURCE
  		 * policy.
  		 */
  		if (*cpuidp != NETISR_CPUID_NONE)
  			return (m);
  		if (dispatch_policy == NETISR_DISPATCH_HYBRID) {
  			*cpuidp = curcpu;
  			return (m);
  		}
  		policy = NETISR_POLICY_SOURCE;
  	}
  
  	if (policy == NETISR_POLICY_FLOW) {
  		if (!(m->m_flags & M_FLOWID) && npp->np_m2flow != NULL) {
  			m = npp->np_m2flow(m, source);
  			if (m == NULL)
  				return (NULL);
  		}
  		if (m->m_flags & M_FLOWID) {
  			*cpuidp =
  			    netisr_default_flow2cpu(m->m_pkthdr.flowid);
  			return (m);
  		}
  		policy = NETISR_POLICY_SOURCE;
  	}
  
  	KASSERT(policy == NETISR_POLICY_SOURCE,
  	    ("%s: invalid policy %u for %s", __func__, npp->np_policy,
  	    npp->np_name));
  
  	ifp = m->m_pkthdr.rcvif;
  	if (ifp != NULL)
  		*cpuidp = nws_array[(ifp->if_index + source) % nws_count];
  	else
  		*cpuidp = nws_array[source % nws_count];
  	return (m);
  }
  
  /*
   * Process packets associated with a workstream and protocol.  For reasons of
   * fairness, we process up to one complete netisr queue at a time, moving the
   * queue to a stack-local queue for processing, but do not loop refreshing
   * from the global queue.  The caller is responsible for deciding whether to
   * loop, and for setting the NWS_RUNNING flag.  The passed workstream will be
   * locked on entry and relocked before return, but will be released while
   * processing.  The number of packets processed is returned.
   */
  static u_int
  netisr_process_workstream_proto(struct netisr_workstream *nwsp, u_int proto)
  {
  	struct netisr_work local_npw, *npwp;
  	u_int handled;
  	struct mbuf *m;
  
  	NETISR_LOCK_ASSERT();
  	NWS_LOCK_ASSERT(nwsp);
  
  	KASSERT(nwsp->nws_flags & NWS_RUNNING,
  	    ("%s(%u): not running", __func__, proto));
  	KASSERT(proto >= 0 && proto < NETISR_MAXPROT,
  	    ("%s(%u): invalid proto\n", __func__, proto));
  
  	npwp = &nwsp->nws_work[proto];
  	if (npwp->nw_len == 0)
  		return (0);
  
  	/*
  	 * Move the global work queue to a thread-local work queue.
  	 *
  	 * Notice that this means the effective maximum length of the queue
  	 * is actually twice that of the maximum queue length specified in
  	 * the protocol registration call.
  	 */
  	handled = npwp->nw_len;
  	local_npw = *npwp;
  	npwp->nw_head = NULL;
  	npwp->nw_tail = NULL;
  	npwp->nw_len = 0;
  	nwsp->nws_pendingbits &= ~(1 << proto);
  	NWS_UNLOCK(nwsp);
  	while ((m = local_npw.nw_head) != NULL) {
  		local_npw.nw_head = m->m_nextpkt;
  		m->m_nextpkt = NULL;
  		if (local_npw.nw_head == NULL)
  			local_npw.nw_tail = NULL;
  		local_npw.nw_len--;
  		VNET_ASSERT(m->m_pkthdr.rcvif != NULL,
  		    ("%s:%d rcvif == NULL: m=%p", __func__, __LINE__, m));
  		CURVNET_SET(m->m_pkthdr.rcvif->if_vnet);
  		netisr_proto[proto].np_handler(m);
  		CURVNET_RESTORE();
  	}
  	KASSERT(local_npw.nw_len == 0,
  	    ("%s(%u): len %u", __func__, proto, local_npw.nw_len));
  	if (netisr_proto[proto].np_drainedcpu)
  		netisr_proto[proto].np_drainedcpu(nwsp->nws_cpu);
  	NWS_LOCK(nwsp);
  	npwp->nw_handled += handled;
  	return (handled);
  }
  
  /*
   * SWI handler for netisr -- processes packets in a set of workstreams that
   * it owns, woken up by calls to NWS_SIGNAL().  If this workstream is already
   * being direct dispatched, go back to sleep and wait for the dispatching
   * thread to wake us up again.
   */
  static void
  swi_net(void *arg)
  {
  #ifdef NETISR_LOCKING
  	struct rm_priotracker tracker;
  #endif
  	struct netisr_workstream *nwsp;
  	u_int bits, prot;
  
  	nwsp = arg;
  
  #ifdef DEVICE_POLLING
  	KASSERT(nws_count == 1,
  	    ("%s: device_polling but nws_count != 1", __func__));
  	netisr_poll();
  #endif
  #ifdef NETISR_LOCKING
  	NETISR_RLOCK(&tracker);
  #endif
  	NWS_LOCK(nwsp);
  	KASSERT(!(nwsp->nws_flags & NWS_RUNNING), ("swi_net: running"));
  	if (nwsp->nws_flags & NWS_DISPATCHING)
  		goto out;
  	nwsp->nws_flags |= NWS_RUNNING;
  	nwsp->nws_flags &= ~NWS_SCHEDULED;
  	while ((bits = nwsp->nws_pendingbits) != 0) {
  		while ((prot = ffs(bits)) != 0) {
  			prot--;
  			bits &= ~(1 << prot);
  			(void)netisr_process_workstream_proto(nwsp, prot);
  		}
  	}
  	nwsp->nws_flags &= ~NWS_RUNNING;
  out:
  	NWS_UNLOCK(nwsp);
  #ifdef NETISR_LOCKING
  	NETISR_RUNLOCK(&tracker);
  #endif
  #ifdef DEVICE_POLLING
  	netisr_pollmore();
  #endif
  }
  
  static int
  netisr_queue_workstream(struct netisr_workstream *nwsp, u_int proto,
      struct netisr_work *npwp, struct mbuf *m, int *dosignalp)
  {
  
  	NWS_LOCK_ASSERT(nwsp);
  
  	*dosignalp = 0;
  	if (npwp->nw_len < npwp->nw_qlimit) {
  		m->m_nextpkt = NULL;
  		if (npwp->nw_head == NULL) {
  			npwp->nw_head = m;
  			npwp->nw_tail = m;
  		} else {
  			npwp->nw_tail->m_nextpkt = m;
  			npwp->nw_tail = m;
  		}
  		npwp->nw_len++;
  		if (npwp->nw_len > npwp->nw_watermark)
  			npwp->nw_watermark = npwp->nw_len;
  
  		/*
  		 * We must set the bit regardless of NWS_RUNNING, so that
  		 * swi_net() keeps calling netisr_process_workstream_proto().
  		 */
  		nwsp->nws_pendingbits |= (1 << proto);
  		if (!(nwsp->nws_flags & 
  		    (NWS_RUNNING | NWS_DISPATCHING | NWS_SCHEDULED))) {
  			nwsp->nws_flags |= NWS_SCHEDULED;
  			*dosignalp = 1;	/* Defer until unlocked. */
  		}
  		npwp->nw_queued++;
  		return (0);
  	} else {
  		m_freem(m);
  		npwp->nw_qdrops++;
  		return (ENOBUFS);
  	}
  }
  
  static int
  netisr_queue_internal(u_int proto, struct mbuf *m, u_int cpuid)
  {
  	struct netisr_workstream *nwsp;
  	struct netisr_work *npwp;
  	int dosignal, error;
  
  #ifdef NETISR_LOCKING
  	NETISR_LOCK_ASSERT();
  #endif
  	KASSERT(cpuid <= mp_maxid, ("%s: cpuid too big (%u, %u)", __func__,
  	    cpuid, mp_maxid));
  	KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__, cpuid));
  
  	dosignal = 0;
  	error = 0;
  	nwsp = DPCPU_ID_PTR(cpuid, nws);
  	npwp = &nwsp->nws_work[proto];
  	NWS_LOCK(nwsp);
  	error = netisr_queue_workstream(nwsp, proto, npwp, m, &dosignal);
  	NWS_UNLOCK(nwsp);
  	if (dosignal)
  		NWS_SIGNAL(nwsp);
  	return (error);
  }
  
  int
  netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m)
  {
  #ifdef NETISR_LOCKING
  	struct rm_priotracker tracker;
  #endif
  	u_int cpuid;
  	int error;
  
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s: invalid proto %u", __func__, proto));
  
  #ifdef NETISR_LOCKING
  	NETISR_RLOCK(&tracker);
  #endif
  	KASSERT(netisr_proto[proto].np_handler != NULL,
  	    ("%s: invalid proto %u", __func__, proto));
  
  	m = netisr_select_cpuid(&netisr_proto[proto], NETISR_DISPATCH_DEFERRED,
  	    source, m, &cpuid);
  	if (m != NULL) {
  		KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__,
  		    cpuid));
  		error = netisr_queue_internal(proto, m, cpuid);
  	} else
  		error = ENOBUFS;
  #ifdef NETISR_LOCKING
  	NETISR_RUNLOCK(&tracker);
  #endif
  	return (error);
  }
  
  int
  netisr_queue(u_int proto, struct mbuf *m)
  {
  
  	return (netisr_queue_src(proto, 0, m));
  }
  
  /*
   * Dispatch a packet for netisr processing; direct dispatch is permitted by
   * calling context.
   */
  int
  netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m)
  {
  #ifdef NETISR_LOCKING
  	struct rm_priotracker tracker;
  #endif
  	struct netisr_workstream *nwsp;
  	struct netisr_proto *npp;
  	struct netisr_work *npwp;
  	int dosignal, error;
  	u_int cpuid, dispatch_policy;
  
  	KASSERT(proto < NETISR_MAXPROT,
  	    ("%s: invalid proto %u", __func__, proto));
  #ifdef NETISR_LOCKING
  	NETISR_RLOCK(&tracker);
  #endif
  	npp = &netisr_proto[proto];
  	KASSERT(npp->np_handler != NULL, ("%s: invalid proto %u", __func__,
  	    proto));
  
  	dispatch_policy = netisr_get_dispatch(npp);
  	if (dispatch_policy == NETISR_DISPATCH_DEFERRED)
  		return (netisr_queue_src(proto, source, m));
  
  	/*
  	 * If direct dispatch is forced, then unconditionally dispatch
  	 * without a formal CPU selection.  Borrow the current CPU's stats,
  	 * even if there's no worker on it.  In this case we don't update
  	 * nws_flags because all netisr processing will be source ordered due
  	 * to always being forced to directly dispatch.
  	 */
  	if (dispatch_policy == NETISR_DISPATCH_DIRECT) {
  		nwsp = DPCPU_PTR(nws);
  		npwp = &nwsp->nws_work[proto];
  		npwp->nw_dispatched++;
  		npwp->nw_handled++;
  		netisr_proto[proto].np_handler(m);
  		error = 0;
  		goto out_unlock;
  	}
  
  	KASSERT(dispatch_policy == NETISR_DISPATCH_HYBRID,
  	    ("%s: unknown dispatch policy (%u)", __func__, dispatch_policy));
  
  	/*
  	 * Otherwise, we execute in a hybrid mode where we will try to direct
  	 * dispatch if we're on the right CPU and the netisr worker isn't
  	 * already running.
  	 */
  	sched_pin();
  	m = netisr_select_cpuid(&netisr_proto[proto], NETISR_DISPATCH_HYBRID,
  	    source, m, &cpuid);
  	if (m == NULL) {
  		error = ENOBUFS;
  		goto out_unpin;
  	}
  	KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__, cpuid));
  	if (cpuid != curcpu)
  		goto queue_fallback;
  	nwsp = DPCPU_PTR(nws);
  	npwp = &nwsp->nws_work[proto];
  
  	/*-
  	 * We are willing to direct dispatch only if three conditions hold:
  	 *
  	 * (1) The netisr worker isn't already running,
  	 * (2) Another thread isn't already directly dispatching, and
  	 * (3) The netisr hasn't already been woken up.
  	 */
  	NWS_LOCK(nwsp);
  	if (nwsp->nws_flags & (NWS_RUNNING | NWS_DISPATCHING | NWS_SCHEDULED)) {
  		error = netisr_queue_workstream(nwsp, proto, npwp, m,
  		    &dosignal);
  		NWS_UNLOCK(nwsp);
  		if (dosignal)
  			NWS_SIGNAL(nwsp);
  		goto out_unpin;
  	}
  
  	/*
  	 * The current thread is now effectively the netisr worker, so set
  	 * the dispatching flag to prevent concurrent processing of the
  	 * stream from another thread (even the netisr worker), which could
  	 * otherwise lead to effective misordering of the stream.
  	 */
  	nwsp->nws_flags |= NWS_DISPATCHING;
  	NWS_UNLOCK(nwsp);
  	netisr_proto[proto].np_handler(m);
  	NWS_LOCK(nwsp);
  	nwsp->nws_flags &= ~NWS_DISPATCHING;
  	npwp->nw_handled++;
  	npwp->nw_hybrid_dispatched++;
  
  	/*
  	 * If other work was enqueued by another thread while we were direct
  	 * dispatching, we need to signal the netisr worker to do that work.
  	 * In the future, we might want to do some of that work in the
  	 * current thread, rather than trigger further context switches.  If
  	 * so, we'll want to establish a reasonable bound on the work done in
  	 * the "borrowed" context.
  	 */
  	if (nwsp->nws_pendingbits != 0) {
  		nwsp->nws_flags |= NWS_SCHEDULED;
  		dosignal = 1;
  	} else
  		dosignal = 0;
  	NWS_UNLOCK(nwsp);
  	if (dosignal)
  		NWS_SIGNAL(nwsp);
  	error = 0;
  	goto out_unpin;
  
  queue_fallback:
  	error = netisr_queue_internal(proto, m, cpuid);
  out_unpin:
  	sched_unpin();
  out_unlock:
  #ifdef NETISR_LOCKING
  	NETISR_RUNLOCK(&tracker);
  #endif
  	return (error);
  }
  
  int
  netisr_dispatch(u_int proto, struct mbuf *m)
  {
  
  	return (netisr_dispatch_src(proto, 0, m));
  }
  
  #ifdef DEVICE_POLLING
  /*
   * Kernel polling borrows a netisr thread to run interface polling in; this
   * function allows kernel polling to request that the netisr thread be
   * scheduled even if no packets are pending for protocols.
   */
  void
  netisr_sched_poll(void)
  {
  	struct netisr_workstream *nwsp;
  
  	nwsp = DPCPU_ID_PTR(nws_array[0], nws);
  	NWS_SIGNAL(nwsp);
  }
  #endif
  
  static void
  netisr_start_swi(u_int cpuid, struct pcpu *pc)
  {
  	char swiname[12];
  	struct netisr_workstream *nwsp;
  	int error;
  
  	KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__, cpuid));
  
  	nwsp = DPCPU_ID_PTR(cpuid, nws);
  	mtx_init(&nwsp->nws_mtx, "netisr_mtx", NULL, MTX_DEF);
  	nwsp->nws_cpu = cpuid;
  	snprintf(swiname, sizeof(swiname), "netisr %u", cpuid);
  	error = swi_add(&nwsp->nws_intr_event, swiname, swi_net, nwsp,
  	    SWI_NET, INTR_MPSAFE, &nwsp->nws_swi_cookie);
  	if (error)
  		panic("%s: swi_add %d", __func__, error);
  	pc->pc_netisr = nwsp->nws_intr_event;
  	if (netisr_bindthreads) {
  		error = intr_event_bind(nwsp->nws_intr_event, cpuid);
  		if (error != 0)
  			printf("%s: cpu %u: intr_event_bind: %d", __func__,
  			    cpuid, error);
  	}
  	NETISR_WLOCK();
  	nws_array[nws_count] = nwsp->nws_cpu;
  	nws_count++;
  	NETISR_WUNLOCK();
  }
  
  /*
   * Initialize the netisr subsystem.  We rely on BSS and static initialization
   * of most fields in global data structures.
   *
   * Start a worker thread for the boot CPU so that we can support network
   * traffic immediately in case the network stack is used before additional
   * CPUs are started (for example, diskless boot).
   */
  static void
  netisr_init(void *arg)
  {
  	char tmp[NETISR_DISPATCH_POLICY_MAXSTR];
  	u_int dispatch_policy;
  	int error;
  
  	KASSERT(curcpu == 0, ("%s: not on CPU 0", __func__));
  
  	NETISR_LOCK_INIT();
  	if (netisr_maxthreads < 1)
  		netisr_maxthreads = 1;
  	if (netisr_maxthreads > mp_ncpus) {
  		printf("netisr_init: forcing maxthreads from %d to %d\n",
  		    netisr_maxthreads, mp_ncpus);
  		netisr_maxthreads = mp_ncpus;
  	}
  	if (netisr_defaultqlimit > netisr_maxqlimit) {
  		printf("netisr_init: forcing defaultqlimit from %d to %d\n",
  		    netisr_defaultqlimit, netisr_maxqlimit);
  		netisr_defaultqlimit = netisr_maxqlimit;
  	}
  #ifdef DEVICE_POLLING
  	/*
  	 * The device polling code is not yet aware of how to deal with
  	 * multiple netisr threads, so for the time being compiling in device
  	 * polling disables parallel netisr workers.
  	 */
  	if (netisr_maxthreads != 1 || netisr_bindthreads != 0) {
  		printf("netisr_init: forcing maxthreads to 1 and "
  		    "bindthreads to 0 for device polling\n");
  		netisr_maxthreads = 1;
  		netisr_bindthreads = 0;
  	}
  #endif
  
  	if (TUNABLE_STR_FETCH("net.isr.dispatch", tmp, sizeof(tmp))) {
  		error = netisr_dispatch_policy_from_str(tmp,
  		    &dispatch_policy);
  		if (error == 0 && dispatch_policy == NETISR_DISPATCH_DEFAULT)
  			error = EINVAL;
  		if (error == 0) {
  			netisr_dispatch_policy = dispatch_policy;
  			netisr_dispatch_policy_compat();
  		} else
  			printf(
  			    "%s: invalid dispatch policy %s, using default\n",
  			    __func__, tmp);
  	}
  
  	netisr_start_swi(curcpu, pcpu_find(curcpu));
  }
  SYSINIT(netisr_init, SI_SUB_SOFTINTR, SI_ORDER_FIRST, netisr_init, NULL);
  
  /*
   * Start worker threads for additional CPUs.  No attempt to gracefully handle
   * work reassignment, we don't yet support dynamic reconfiguration.
   */
  static void
  netisr_start(void *arg)
  {
  	struct pcpu *pc;
  
  	STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
  		if (nws_count >= netisr_maxthreads)
  			break;
  		/* XXXRW: Is skipping absent CPUs still required here? */
  		if (CPU_ABSENT(pc->pc_cpuid))
  			continue;
  		/* Worker will already be present for boot CPU. */
  		if (pc->pc_netisr != NULL)
  			continue;
  		netisr_start_swi(pc->pc_cpuid, pc);
  	}
  }
  SYSINIT(netisr_start, SI_SUB_SMP, SI_ORDER_MIDDLE, netisr_start, NULL);
  
  /*
   * Sysctl monitoring for netisr: query a list of registered protocols.
   */
  static int
  sysctl_netisr_proto(SYSCTL_HANDLER_ARGS)
  {
  	struct rm_priotracker tracker;
  	struct sysctl_netisr_proto *snpp, *snp_array;
  	struct netisr_proto *npp;
  	u_int counter, proto;
  	int error;
  
  	if (req->newptr != NULL)
  		return (EINVAL);
  	snp_array = malloc(sizeof(*snp_array) * NETISR_MAXPROT, M_TEMP,
  	    M_ZERO | M_WAITOK);
  	counter = 0;
  	NETISR_RLOCK(&tracker);
  	for (proto = 0; proto < NETISR_MAXPROT; proto++) {
  		npp = &netisr_proto[proto];
  		if (npp->np_name == NULL)
  			continue;
  		snpp = &snp_array[counter];
  		snpp->snp_version = sizeof(*snpp);
  		strlcpy(snpp->snp_name, npp->np_name, NETISR_NAMEMAXLEN);
  		snpp->snp_proto = proto;
  		snpp->snp_qlimit = npp->np_qlimit;
  		snpp->snp_policy = npp->np_policy;
  		snpp->snp_dispatch = npp->np_dispatch;
  		if (npp->np_m2flow != NULL)
  			snpp->snp_flags |= NETISR_SNP_FLAGS_M2FLOW;
  		if (npp->np_m2cpuid != NULL)
  			snpp->snp_flags |= NETISR_SNP_FLAGS_M2CPUID;
  		if (npp->np_drainedcpu != NULL)
  			snpp->snp_flags |= NETISR_SNP_FLAGS_DRAINEDCPU;
  		counter++;
  	}
  	NETISR_RUNLOCK(&tracker);
  	KASSERT(counter <= NETISR_MAXPROT,
  	    ("sysctl_netisr_proto: counter too big (%d)", counter));
  	error = SYSCTL_OUT(req, snp_array, sizeof(*snp_array) * counter);
  	free(snp_array, M_TEMP);
  	return (error);
  }
  
  SYSCTL_PROC(_net_isr, OID_AUTO, proto,
      CTLFLAG_RD|CTLTYPE_STRUCT|CTLFLAG_MPSAFE, 0, 0, sysctl_netisr_proto,
      "S,sysctl_netisr_proto",
      "Return list of protocols registered with netisr");
  
  /*
   * Sysctl monitoring for netisr: query a list of workstreams.
   */
  static int
  sysctl_netisr_workstream(SYSCTL_HANDLER_ARGS)
  {
  	struct rm_priotracker tracker;
  	struct sysctl_netisr_workstream *snwsp, *snws_array;
  	struct netisr_workstream *nwsp;
  	u_int counter, cpuid;
  	int error;
  
  	if (req->newptr != NULL)
  		return (EINVAL);
  	snws_array = malloc(sizeof(*snws_array) * MAXCPU, M_TEMP,
  	    M_ZERO | M_WAITOK);
  	counter = 0;
  	NETISR_RLOCK(&tracker);
  	CPU_FOREACH(cpuid) {
  		nwsp = DPCPU_ID_PTR(cpuid, nws);
  		if (nwsp->nws_intr_event == NULL)
  			continue;
  		NWS_LOCK(nwsp);
  		snwsp = &snws_array[counter];
  		snwsp->snws_version = sizeof(*snwsp);
  
  		/*
  		 * For now, we equate workstream IDs and CPU IDs in the
  		 * kernel, but expose them independently to userspace in case
  		 * that assumption changes in the future.
  		 */
  		snwsp->snws_wsid = cpuid;
  		snwsp->snws_cpu = cpuid;
  		if (nwsp->nws_intr_event != NULL)
  			snwsp->snws_flags |= NETISR_SNWS_FLAGS_INTR;
  		NWS_UNLOCK(nwsp);
  		counter++;
  	}
  	NETISR_RUNLOCK(&tracker);
  	KASSERT(counter <= MAXCPU,
  	    ("sysctl_netisr_workstream: counter too big (%d)", counter));
  	error = SYSCTL_OUT(req, snws_array, sizeof(*snws_array) * counter);
  	free(snws_array, M_TEMP);
  	return (error);
  }
  
  SYSCTL_PROC(_net_isr, OID_AUTO, workstream,
      CTLFLAG_RD|CTLTYPE_STRUCT|CTLFLAG_MPSAFE, 0, 0, sysctl_netisr_workstream,
      "S,sysctl_netisr_workstream",
      "Return list of workstreams implemented by netisr");
  
  /*
   * Sysctl monitoring for netisr: query per-protocol data across all
   * workstreams.
   */
  static int
  sysctl_netisr_work(SYSCTL_HANDLER_ARGS)
  {
  	struct rm_priotracker tracker;
  	struct sysctl_netisr_work *snwp, *snw_array;
  	struct netisr_workstream *nwsp;
  	struct netisr_proto *npp;
  	struct netisr_work *nwp;
  	u_int counter, cpuid, proto;
  	int error;
  
  	if (req->newptr != NULL)
  		return (EINVAL);
  	snw_array = malloc(sizeof(*snw_array) * MAXCPU * NETISR_MAXPROT,
  	    M_TEMP, M_ZERO | M_WAITOK);
  	counter = 0;
  	NETISR_RLOCK(&tracker);
  	CPU_FOREACH(cpuid) {
  		nwsp = DPCPU_ID_PTR(cpuid, nws);
  		if (nwsp->nws_intr_event == NULL)
  			continue;
  		NWS_LOCK(nwsp);
  		for (proto = 0; proto < NETISR_MAXPROT; proto++) {
  			npp = &netisr_proto[proto];
  			if (npp->np_name == NULL)
  				continue;
  			nwp = &nwsp->nws_work[proto];
  			snwp = &snw_array[counter];
  			snwp->snw_version = sizeof(*snwp);
  			snwp->snw_wsid = cpuid;		/* See comment above. */
  			snwp->snw_proto = proto;
  			snwp->snw_len = nwp->nw_len;
  			snwp->snw_watermark = nwp->nw_watermark;
  			snwp->snw_dispatched = nwp->nw_dispatched;
  			snwp->snw_hybrid_dispatched =
  			    nwp->nw_hybrid_dispatched;
  			snwp->snw_qdrops = nwp->nw_qdrops;
  			snwp->snw_queued = nwp->nw_queued;
  			snwp->snw_handled = nwp->nw_handled;
  			counter++;
  		}
  		NWS_UNLOCK(nwsp);
  	}
  	KASSERT(counter <= MAXCPU * NETISR_MAXPROT,
  	    ("sysctl_netisr_work: counter too big (%d)", counter));
  	NETISR_RUNLOCK(&tracker);
  	error = SYSCTL_OUT(req, snw_array, sizeof(*snw_array) * counter);
  	free(snw_array, M_TEMP);
  	return (error);
  }
  
  SYSCTL_PROC(_net_isr, OID_AUTO, work,
      CTLFLAG_RD|CTLTYPE_STRUCT|CTLFLAG_MPSAFE, 0, 0, sysctl_netisr_work,
      "S,sysctl_netisr_work",
      "Return list of per-workstream, per-protocol work in netisr");
  
  #ifdef DDB
  DB_SHOW_COMMAND(netisr, db_show_netisr)
  {
  	struct netisr_workstream *nwsp;
  	struct netisr_work *nwp;
  	int first, proto;
  	u_int cpuid;
  
  	db_printf("%3s %6s %5s %5s %5s %8s %8s %8s %8s\n", "CPU", "Proto",
  	    "Len", "WMark", "Max", "Disp", "HDisp", "Drop", "Queue");
  	CPU_FOREACH(cpuid) {
  		nwsp = DPCPU_ID_PTR(cpuid, nws);
  		if (nwsp->nws_intr_event == NULL)
  			continue;
  		first = 1;
  		for (proto = 0; proto < NETISR_MAXPROT; proto++) {
  			if (netisr_proto[proto].np_handler == NULL)
  				continue;
  			nwp = &nwsp->nws_work[proto];
  			if (first) {
  				db_printf("%3d ", cpuid);
  				first = 0;
  			} else
  				db_printf("%3s ", "");
  			db_printf(
  			    "%6s %5d %5d %5d %8ju %8ju %8ju %8ju\n",
  			    netisr_proto[proto].np_name, nwp->nw_len,
  			    nwp->nw_watermark, nwp->nw_qlimit,
  			    nwp->nw_dispatched, nwp->nw_hybrid_dispatched,
  			    nwp->nw_qdrops, nwp->nw_queued);
  		}
  	}
  }
  #endif
  