/*-
* 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 <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 "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/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>
#include <sys/vimage.h>
#ifdef DDB
#include <ddb/ddb.h>
#endif
#include <net/if.h>
#include <net/if_var.h>
#include <net/netisr.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, indexed by CPU ID.
*/
static struct netisr_workstream nws[MAXCPU];
/*
* Map contiguous values between 0 and nws_count into CPU IDs appropriate for
* indexing the nws[] array. This allows constructions of the form
* nws[nws_array(arbitraryvalue % nws_count)].
*/
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)
/*
* 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 -> 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 < MAXCPU; i++) {
npwp = &nws[i].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 < MAXCPU; i++) {
npwp = &nws[i].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 < MAXCPU; i++) {
npwp = &nws[i].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 < MAXCPU; i++) {
npwp = &nws[i].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 < MAXCPU; i++) {
npwp = &nws[i].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 {
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 < MAXCPU, ("%s: cpuid too big (%u, %u)", __func__,
cpuid, MAXCPU));
dosignal = 0;
error = 0;
nwsp = &nws[cpuid];
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)
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 = &nws[curcpu];
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;
}
sched_pin();
if (cpuid != curcpu)
goto queue_fallback;
nwsp = &nws[cpuid];
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(nws);
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:
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 = &nws[nws_array[0]];
NWS_SIGNAL(nwsp);
}
#endif
static void
netisr_start_swi(u_int cpuid, struct pcpu *pc)
{
char swiname[12];
struct netisr_workstream *nwsp;
int error;
nwsp = &nws[cpuid];
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)
{
KASSERT(curcpu == 0, ("%s: not on CPU 0", __func__));
NETISR_LOCK_INIT();
if (netisr_maxthreads < 1) {
printf("netisr2: forcing maxthreads to 1\n");
netisr_maxthreads = 1;
}
if (netisr_maxthreads > MAXCPU) {
printf("netisr2: forcing maxthreads to %d\n", MAXCPU);
netisr_maxthreads = MAXCPU;
}
if (netisr_defaultqlimit > netisr_maxqlimit) {
printf("netisr2: forcing defaultqlimit to %d\n",
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("netisr2: forcing maxthreads to 1 and bindthreads to "
"0 for device polling\n");
netisr_maxthreads = 1;
netisr_bindthreads = 0;
}
#endif
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;
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);
#ifdef DDB
DB_SHOW_COMMAND(netisr, db_show_netisr)
{
struct netisr_workstream *nwsp;
struct netisr_work *nwp;
int first, proto;
u_int cpu;
db_printf("%3s %6s %5s %5s %5s %8s %8s %8s %8s\n", "CPU", "Proto",
"Len", "WMark", "Max", "Disp", "HDisp", "Drop", "Queue");
for (cpu = 0; cpu < MAXCPU; cpu++) {
nwsp = &nws[cpu];
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 ", cpu);
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
