Move files to match FreeBSD layout

1 files changed, 1172 insertions, 0 deletions

diff --git a/freebsd/sys/net/netisr.c b/freebsd/sys/net/netisr.c
new file mode 100644
index 00000000..4d34953a
--- /dev/null
+++ b/freebsd/sys/net/netisr.c
@@ -0,0 +1,1172 @@
+#include <freebsd/machine/rtems-bsd-config.h>
+
+/*-
+ * Copyright (c) 2007-2009 Robert N. M. Watson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <freebsd/sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ * 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 with the registered handler, or passed to a
+ * kernel software interrupt (SWI) thread for deferred dispatch.  Callers
+ * will generally select one or the other based on:
+ *
+ * - Might directly dispatching a netisr handler lead to code reentrance or
+ *   lock recursion, such as entering the socket code from the socket code.
+ * - Might 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 a varying role in
+ * identifying flows, assigning work to CPUs, etc.  These are described in
+ * detail in netisr.h.
+ */
+
+#include <freebsd/local/opt_ddb.h>
+#include <freebsd/local/opt_device_polling.h>
+
+#include <freebsd/sys/param.h>
+#include <freebsd/sys/bus.h>
+#include <freebsd/sys/kernel.h>
+#include <freebsd/sys/kthread.h>
+#include <freebsd/sys/interrupt.h>
+#include <freebsd/sys/lock.h>
+#include <freebsd/sys/mbuf.h>
+#include <freebsd/sys/mutex.h>
+#include <freebsd/sys/pcpu.h>
+#include <freebsd/sys/proc.h>
+#include <freebsd/sys/rmlock.h>
+#include <freebsd/sys/sched.h>
+#include <freebsd/sys/smp.h>
+#include <freebsd/sys/socket.h>
+#include <freebsd/sys/sysctl.h>
+#include <freebsd/sys/systm.h>
+
+#ifdef DDB
+#include <freebsd/ddb/ddb.h>
+#endif
+
+#include <freebsd/net/if.h>
+#include <freebsd/net/if_var.h>
+#include <freebsd/net/netisr.h>
+#include <freebsd/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 np 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 a 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 */
+
+SYSCTL_NODE(_net, OID_AUTO, isr, CTLFLAG_RW, 0, "netisr");
+
+/*-
+ * Three direct dispatch policies are supported:
+ *
+ * - Always defer: all work is scheduled for a netisr, regardless of context.
+ *   (!direct)
+ *
+ * - Hybrid: if the executing context allows direct dispatch, and we're
+ *   running on the CPU the work would be done on, then direct dispatch if it
+ *   wouldn't violate ordering constraints on the workstream.
+ *   (direct && !direct_force)
+ *
+ * - Always direct: if the executing context allows direct dispatch, always
+ *   direct dispatch.  (direct && direct_force)
+ *
+ * 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.
+ */
+static int	netisr_direct_force = 1;	/* Always direct dispatch. */
+TUNABLE_INT("net.isr.direct_force", &netisr_direct_force);
+SYSCTL_INT(_net_isr, OID_AUTO, direct_force, CTLFLAG_RW,
+    &netisr_direct_force, 0, "Force direct dispatch");
+
+static int	netisr_direct = 1;	/* Enable direct dispatch. */
+TUNABLE_INT("net.isr.direct", &netisr_direct);
+SYSCTL_INT(_net_isr, OID_AUTO, direct, CTLFLAG_RW,
+    &netisr_direct, 0, "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_RD,
+    &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_RD,
+    &netisr_bindthreads, 0, "Bind netisr threads to CPUs.");
+
+/*
+ * Limit per-workstream queues 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_INT(_net_isr, OID_AUTO, maxqlimit, CTLFLAG_RD,
+    &netisr_maxqlimit, 0,
+    "Maximum netisr per-protocol, per-CPU queue depth.");
+
+/*
+ * The default per-workstream 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_INT(_net_isr, OID_AUTO, defaultqlimit, CTLFLAG_RD,
+    &netisr_defaultqlimit, 0,
+    "Default netisr per-protocol, per-CPU queue limit if not set by protocol");
+
+/*
+ * Each protocol is described by a struct netisr_proto, which holds all
+ * global per-protocol information.  This data structure is set up by
+ * netisr_register(), and derived from the public struct netisr_handler.
+ */
+struct netisr_proto {
+	const char	*np_name;	/* Character string protocol name. */
+	netisr_handler_t *np_handler;	/* Protocol handler. */
+	netisr_m2flow_t	*np_m2flow;	/* Query flow for untagged packet. */
+	netisr_m2cpuid_t *np_m2cpuid;	/* Query CPU to process packet on. */
+	netisr_drainedcpu_t *np_drainedcpu; /* Callback when drained a queue. */
+	u_int		 np_qlimit;	/* Maximum per-CPU queue depth. */
+	u_int		 np_policy;	/* Work placement policy. */
+};
+
+#define	NETISR_MAXPROT		16		/* Compile-time limit. */
+
+/*
+ * The np array describes all registered protocols, indexed by protocol
+ * number.
+ */
+static struct netisr_proto	np[NETISR_MAXPROT];
+
+/*
+ * Protocol-specific work for each workstream is described by struct
+ * netisr_work.  Each work descriptor consists of an mbuf queue and
+ * statistics.
+ */
+struct netisr_work {
+	/*
+	 * Packet queue, linked by m_nextpkt.
+	 */
+	struct mbuf	*nw_head;
+	struct mbuf	*nw_tail;
+	u_int		 nw_len;
+	u_int		 nw_qlimit;
+	u_int		 nw_watermark;
+
+	/*
+	 * Statistics -- written unlocked, but mostly from curcpu.
+	 */
+	u_int64_t	 nw_dispatched; /* Number of direct dispatches. */
+	u_int64_t	 nw_hybrid_dispatched; /* "" hybrid dispatches. */
+	u_int64_t	 nw_qdrops;	/* "" drops. */
+	u_int64_t	 nw_queued;	/* "" enqueues. */
+	u_int64_t	 nw_handled;	/* "" handled in worker. */
+};
+
+/*
+ * Workstreams hold a set of ordered work across each protocol, and are
+ * described by netisr_workstream.  Each workstream is associated with a
+ * worker thread, which in turn is pinned to a CPU.  Work associated with a
+ * workstream can be processd in other threads during direct dispatch;
+ * concurrent processing is prevented by the NWS_RUNNING flag, which
+ * indicates that a thread is already processing the work queue.
+ */
+struct netisr_workstream {
+	struct intr_event *nws_intr_event;	/* Handler for stream. */
+	void		*nws_swi_cookie;	/* swi(9) cookie for stream. */
+	struct mtx	 nws_mtx;		/* Synchronize work. */
+	u_int		 nws_cpu;		/* CPU pinning. */
+	u_int		 nws_flags;		/* Wakeup flags. */
+	u_int		 nws_pendingbits;	/* Scheduled protocols. */
+
+	/*
+	 * Each protocol has per-workstream data.
+	 */
+	struct netisr_work	nws_work[NETISR_MAXPROT];
+} __aligned(CACHE_LINE_SIZE);
+
+/*
+ * Per-CPU workstream data.
+ */
+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_INT(_net_isr, OID_AUTO, numthreads, CTLFLAG_RD,
+    &nws_count, 0, "Number of extant netisr threads.");
+
+/*
+ * Per-workstream flags.
+ */
+#define	NWS_RUNNING	0x00000001	/* Currently running in a thread. */
+#define	NWS_DISPATCHING	0x00000002	/* Currently being direct-dispatched. */
+#define	NWS_SCHEDULED	0x00000004	/* Signal issued. */
+
+/*
+ * 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)
+
+#ifndef __rtems__
+/*
+ * 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]);
+}
+#endif  /* __rtems__ */
+
+/*
+ * The default implementation of -> 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]);
+}
+
+/*
+ * 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(proto < NETISR_MAXPROT,
+	    ("%s(%u, %s): protocol too big", __func__, proto, name));
+
+	/*
+	 * Test that no existing registration exists for this protocol.
+	 */
+	NETISR_WLOCK();
+	KASSERT(np[proto].np_name == NULL,
+	    ("%s(%u, %s): name present", __func__, proto, name));
+	KASSERT(np[proto].np_handler == NULL,
+	    ("%s(%u, %s): handler present", __func__, proto, name));
+
+	np[proto].np_name = name;
+	np[proto].np_handler = nhp->nh_handler;
+	np[proto].np_m2flow = nhp->nh_m2flow;
+	np[proto].np_m2cpuid = nhp->nh_m2cpuid;
+	np[proto].np_drainedcpu = nhp->nh_drainedcpu;
+	if (nhp->nh_qlimit == 0)
+		np[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);
+		np[proto].np_qlimit = netisr_maxqlimit;
+	} else
+		np[proto].np_qlimit = nhp->nh_qlimit;
+	np[proto].np_policy = nhp->nh_policy;
+	for (i = 0; i <= mp_maxid; i++) {
+		if (CPU_ABSENT(i))
+			continue;
+		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
+		bzero(npwp, sizeof(*npwp));
+		npwp->nw_qlimit = np[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(np[proto].np_handler != NULL,
+	    ("%s(%u): protocol not registered for %s", __func__, proto,
+	    name));
+
+	for (i = 0; i <= mp_maxid; i++) {
+		if (CPU_ABSENT(i))
+			continue;
+		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
+		npwp->nw_qdrops = 0;
+	}
+	NETISR_WUNLOCK();
+}
+
+/*
+ * Query the 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(np[proto].np_handler != NULL,
+	    ("%s(%u): protocol not registered for %s", __func__, proto,
+	    name));
+
+	for (i = 0; i <= mp_maxid; i++) {
+		if (CPU_ABSENT(i))
+			continue;
+		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
+		*qdropp += npwp->nw_qdrops;
+	}
+	NETISR_RUNLOCK(&tracker);
+}
+
+/*
+ * Query the current queue limit for per-workstream queues 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(np[proto].np_handler != NULL,
+	    ("%s(%u): protocol not registered for %s", __func__, proto,
+	    name));
+	*qlimitp = np[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(np[proto].np_handler != NULL,
+	    ("%s(%u): protocol not registered for %s", __func__, proto,
+	    name));
+
+	np[proto].np_qlimit = qlimit;
+	for (i = 0; i <= mp_maxid; i++) {
+		if (CPU_ABSENT(i))
+			continue;
+		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(np[proto].np_handler != NULL,
+	    ("%s(%u): protocol not registered for %s", __func__, proto,
+	    name));
+
+	np[proto].np_name = NULL;
+	np[proto].np_handler = NULL;
+	np[proto].np_m2flow = NULL;
+	np[proto].np_m2cpuid = NULL;
+	np[proto].np_qlimit = 0;
+	np[proto].np_policy = 0;
+	for (i = 0; i <= mp_maxid; i++) {
+		if (CPU_ABSENT(i))
+			continue;
+		npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
+		netisr_drain_proto(npwp);
+		bzero(npwp, sizeof(*npwp));
+	}
+	NETISR_WUNLOCK();
+}
+
+/*
+ * 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, uintptr_t source,
+    struct mbuf *m, u_int *cpuidp)
+{
+	struct ifnet *ifp;
+
+	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.
+	 */
+	switch (npp->np_policy) {
+	case NETISR_POLICY_CPU:
+		return (npp->np_m2cpuid(m, source, cpuidp));
+
+	case 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);
+		}
+		/* FALLTHROUGH */
+
+	case NETISR_POLICY_SOURCE:
+		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);
+
+	default:
+		panic("%s: invalid policy %u for %s", __func__,
+		    npp->np_policy, npp->np_name);
+	}
+}
+
+/*
+ * 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);
+		CURVNET_SET(m->m_pkthdr.rcvif->if_vnet);
+		np[proto].np_handler(m);
+		CURVNET_RESTORE();
+	}
+	KASSERT(local_npw.nw_len == 0,
+	    ("%s(%u): len %u", __func__, proto, local_npw.nw_len));
+	if (np[proto].np_drainedcpu)
+		np[proto].np_drainedcpu(nwsp->nws_cpu);
+	NWS_LOCK(nwsp);
+	npwp->nw_handled += handled;
+	return (handled);
+}
+
+/*
+ * SWI handler for netisr -- processes prackets 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;
+		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(np[proto].np_handler != NULL,
+	    ("%s: invalid proto %u", __func__, proto));
+
+	m = netisr_select_cpuid(&np[proto], 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 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_work *npwp;
+	int dosignal, error;
+	u_int cpuid;
+
+	/*
+	 * If direct dispatch is entirely disabled, fall back on queueing.
+	 */
+	if (!netisr_direct)
+		return (netisr_queue_src(proto, source, m));
+
+	KASSERT(proto < NETISR_MAXPROT,
+	    ("%s: invalid proto %u", __func__, proto));
+#ifdef NETISR_LOCKING
+	NETISR_RLOCK(&tracker);
+#endif
+	KASSERT(np[proto].np_handler != NULL,
+	    ("%s: invalid proto %u", __func__, proto));
+
+	/*
+	 * 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 (netisr_direct_force) {
+		nwsp = DPCPU_PTR(nws);
+		npwp = &nwsp->nws_work[proto];
+		npwp->nw_dispatched++;
+		npwp->nw_handled++;
+		np[proto].np_handler(m);
+		error = 0;
+		goto out_unlock;
+	}
+
+	/*
+	 * 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.
+	 */
+	m = netisr_select_cpuid(&np[proto], source, m, &cpuid);
+	if (m == NULL) {
+		error = ENOBUFS;
+		goto out_unlock;
+	}
+	KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__, cpuid));
+#ifndef __rtems__
+	sched_pin();
+#endif  /* __rtems__ */
+	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);
+	np[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:
+#ifndef __rtems__
+	sched_unpin();
+#endif  /* __rtems__ */
+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);
+#ifndef __rtems__
+	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);
+	}
+#endif
+	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)
+{
+
+	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
+
+#ifndef __rtems__
+	netisr_start_swi(curcpu, pcpu_find(curcpu));
+#else /* __rtems__ */
+	netisr_start_swi(0, NULL);
+#endif /* __rtems__ */
+}
+SYSINIT(netisr_init, SI_SUB_SOFTINTR, SI_ORDER_FIRST, netisr_init, NULL);
+
+#ifndef __rtems__
+/*
+ * 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;
+
+	SLIST_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);
+#endif /* __rtems__ */
+
+#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");
+	for (cpuid = 0; cpuid <= mp_maxid; cpuid++) {
+		if (CPU_ABSENT(cpuid))
+			continue;
+		nwsp = DPCPU_ID_PTR(cpuid, nws);
+		if (nwsp->nws_intr_event == NULL)
+			continue;
+		first = 1;
+		for (proto = 0; proto < NETISR_MAXPROT; proto++) {
+			if (np[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",
+			    np[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