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|
/* $NetBSD: pktqueue.c,v 1.22 2023/05/28 08:09:34 andvar Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Mindaugas Rasiukevicius.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* The packet queue (pktqueue) interface is a lockless IP input queue
* which also abstracts and handles network ISR scheduling. It provides
* a mechanism to enable receiver-side packet steering (RPS).
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: pktqueue.c,v 1.22 2023/05/28 08:09:34 andvar Exp $");
#ifdef _KERNEL_OPT
#include "opt_net_mpsafe.h"
#endif
#include <sys/param.h>
#include <sys/types.h>
#include <sys/atomic.h>
#include <sys/cpu.h>
#include <sys/pcq.h>
#include <sys/intr.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/percpu.h>
#include <sys/xcall.h>
#include <sys/once.h>
#include <sys/queue.h>
#include <sys/rwlock.h>
#include <net/pktqueue.h>
#include <net/rss_config.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
struct pktqueue {
/*
* The lock used for a barrier mechanism. The barrier counter,
* as well as the drop counter, are managed atomically though.
* Ensure this group is in a separate cache line.
*/
union {
struct {
kmutex_t pq_lock;
volatile u_int pq_barrier;
};
uint8_t _pad[COHERENCY_UNIT];
};
/* The size of the queue, counters and the interrupt handler. */
u_int pq_maxlen;
percpu_t * pq_counters;
void * pq_sih;
/* The per-CPU queues. */
struct percpu * pq_pcq; /* struct pcq * */
/* The linkage on the list of all pktqueues. */
LIST_ENTRY(pktqueue) pq_list;
};
/* The counters of the packet queue. */
#define PQCNT_ENQUEUE 0
#define PQCNT_DEQUEUE 1
#define PQCNT_DROP 2
#define PQCNT_NCOUNTERS 3
typedef struct {
uint64_t count[PQCNT_NCOUNTERS];
} pktq_counters_t;
/* Special marker value used by pktq_barrier() mechanism. */
#define PKTQ_MARKER ((void *)(~0ULL))
/*
* This is a list of all pktqueues. This list is used by
* pktq_ifdetach() to issue a barrier on every pktqueue.
*
* The r/w lock is acquired for writing in pktq_create() and
* pktq_destroy(), and for reading in pktq_ifdetach().
*
* This list is not performance critical, and will seldom be
* accessed.
*/
static LIST_HEAD(, pktqueue) pktqueue_list __read_mostly;
static krwlock_t pktqueue_list_lock __read_mostly;
static once_t pktqueue_list_init_once __read_mostly;
static int
pktqueue_list_init(void)
{
LIST_INIT(&pktqueue_list);
rw_init(&pktqueue_list_lock);
return 0;
}
static void
pktq_init_cpu(void *vqp, void *vpq, struct cpu_info *ci)
{
struct pcq **qp = vqp;
struct pktqueue *pq = vpq;
*qp = pcq_create(pq->pq_maxlen, KM_SLEEP);
}
static void
pktq_fini_cpu(void *vqp, void *vpq, struct cpu_info *ci)
{
struct pcq **qp = vqp, *q = *qp;
KASSERT(pcq_peek(q) == NULL);
pcq_destroy(q);
*qp = NULL; /* paranoia */
}
static struct pcq *
pktq_pcq(struct pktqueue *pq, struct cpu_info *ci)
{
struct pcq **qp, *q;
/*
* As long as preemption is disabled, the xcall to swap percpu
* buffers can't complete, so it is safe to read the pointer.
*/
KASSERT(kpreempt_disabled());
qp = percpu_getptr_remote(pq->pq_pcq, ci);
q = *qp;
return q;
}
pktqueue_t *
pktq_create(size_t maxlen, void (*intrh)(void *), void *sc)
{
const u_int sflags = SOFTINT_NET | SOFTINT_MPSAFE | SOFTINT_RCPU;
pktqueue_t *pq;
percpu_t *pc;
void *sih;
RUN_ONCE(&pktqueue_list_init_once, pktqueue_list_init);
pc = percpu_alloc(sizeof(pktq_counters_t));
if ((sih = softint_establish(sflags, intrh, sc)) == NULL) {
percpu_free(pc, sizeof(pktq_counters_t));
return NULL;
}
pq = kmem_zalloc(sizeof(*pq), KM_SLEEP);
mutex_init(&pq->pq_lock, MUTEX_DEFAULT, IPL_NONE);
pq->pq_maxlen = maxlen;
pq->pq_counters = pc;
pq->pq_sih = sih;
pq->pq_pcq = percpu_create(sizeof(struct pcq *),
pktq_init_cpu, pktq_fini_cpu, pq);
rw_enter(&pktqueue_list_lock, RW_WRITER);
LIST_INSERT_HEAD(&pktqueue_list, pq, pq_list);
rw_exit(&pktqueue_list_lock);
return pq;
}
void
pktq_destroy(pktqueue_t *pq)
{
KASSERT(pktqueue_list_init_once.o_status == ONCE_DONE);
rw_enter(&pktqueue_list_lock, RW_WRITER);
LIST_REMOVE(pq, pq_list);
rw_exit(&pktqueue_list_lock);
percpu_free(pq->pq_pcq, sizeof(struct pcq *));
percpu_free(pq->pq_counters, sizeof(pktq_counters_t));
softint_disestablish(pq->pq_sih);
mutex_destroy(&pq->pq_lock);
kmem_free(pq, sizeof(*pq));
}
/*
* - pktq_inc_counter: increment the counter given an ID.
* - pktq_collect_counts: handler to sum up the counts from each CPU.
* - pktq_getcount: return the effective count given an ID.
*/
static inline void
pktq_inc_count(pktqueue_t *pq, u_int i)
{
percpu_t *pc = pq->pq_counters;
pktq_counters_t *c;
c = percpu_getref(pc);
c->count[i]++;
percpu_putref(pc);
}
static void
pktq_collect_counts(void *mem, void *arg, struct cpu_info *ci)
{
const pktq_counters_t *c = mem;
pktq_counters_t *sum = arg;
int s = splnet();
for (u_int i = 0; i < PQCNT_NCOUNTERS; i++) {
sum->count[i] += c->count[i];
}
splx(s);
}
static uint64_t
pktq_get_count(pktqueue_t *pq, pktq_count_t c)
{
pktq_counters_t sum;
if (c != PKTQ_MAXLEN) {
memset(&sum, 0, sizeof(sum));
percpu_foreach_xcall(pq->pq_counters,
XC_HIGHPRI_IPL(IPL_SOFTNET), pktq_collect_counts, &sum);
}
switch (c) {
case PKTQ_NITEMS:
return sum.count[PQCNT_ENQUEUE] - sum.count[PQCNT_DEQUEUE];
case PKTQ_DROPS:
return sum.count[PQCNT_DROP];
case PKTQ_MAXLEN:
return pq->pq_maxlen;
}
return 0;
}
uint32_t
pktq_rps_hash(const pktq_rps_hash_func_t *funcp, const struct mbuf *m)
{
pktq_rps_hash_func_t func = atomic_load_relaxed(funcp);
KASSERT(func != NULL);
return (*func)(m);
}
static uint32_t
pktq_rps_hash_zero(const struct mbuf *m __unused)
{
return 0;
}
static uint32_t
pktq_rps_hash_curcpu(const struct mbuf *m __unused)
{
return cpu_index(curcpu());
}
static uint32_t
pktq_rps_hash_toeplitz(const struct mbuf *m)
{
struct ip *ip;
/*
* Disable UDP port - IP fragments aren't currently being handled
* and so we end up with a mix of 2-tuple and 4-tuple
* traffic.
*/
const u_int flag = RSS_TOEPLITZ_USE_TCP_PORT;
/* glance IP version */
if ((m->m_flags & M_PKTHDR) == 0)
return 0;
ip = mtod(m, struct ip *);
if (ip->ip_v == IPVERSION) {
if (__predict_false(m->m_len < sizeof(struct ip)))
return 0;
return rss_toeplitz_hash_from_mbuf_ipv4(m, flag);
} else if (ip->ip_v == 6) {
if (__predict_false(m->m_len < sizeof(struct ip6_hdr)))
return 0;
return rss_toeplitz_hash_from_mbuf_ipv6(m, flag);
}
return 0;
}
/*
* toeplitz without curcpu.
* Generally, this has better performance than toeplitz.
*/
static uint32_t
pktq_rps_hash_toeplitz_othercpus(const struct mbuf *m)
{
uint32_t hash;
if (ncpu == 1)
return 0;
hash = pktq_rps_hash_toeplitz(m);
hash %= ncpu - 1;
if (hash >= cpu_index(curcpu()))
return hash + 1;
else
return hash;
}
static struct pktq_rps_hash_table {
const char* prh_type;
pktq_rps_hash_func_t prh_func;
} const pktq_rps_hash_tab[] = {
{ "zero", pktq_rps_hash_zero },
{ "curcpu", pktq_rps_hash_curcpu },
{ "toeplitz", pktq_rps_hash_toeplitz },
{ "toeplitz-othercpus", pktq_rps_hash_toeplitz_othercpus },
};
const pktq_rps_hash_func_t pktq_rps_hash_default =
#ifdef NET_MPSAFE
pktq_rps_hash_curcpu;
#else
pktq_rps_hash_zero;
#endif
static const char *
pktq_get_rps_hash_type(pktq_rps_hash_func_t func)
{
for (int i = 0; i < __arraycount(pktq_rps_hash_tab); i++) {
if (func == pktq_rps_hash_tab[i].prh_func) {
return pktq_rps_hash_tab[i].prh_type;
}
}
return NULL;
}
static int
pktq_set_rps_hash_type(pktq_rps_hash_func_t *func, const char *type)
{
if (strcmp(type, pktq_get_rps_hash_type(*func)) == 0)
return 0;
for (int i = 0; i < __arraycount(pktq_rps_hash_tab); i++) {
if (strcmp(type, pktq_rps_hash_tab[i].prh_type) == 0) {
atomic_store_relaxed(func, pktq_rps_hash_tab[i].prh_func);
return 0;
}
}
return ENOENT;
}
int
sysctl_pktq_rps_hash_handler(SYSCTLFN_ARGS)
{
struct sysctlnode node;
pktq_rps_hash_func_t *func;
int error;
char type[PKTQ_RPS_HASH_NAME_LEN];
node = *rnode;
func = node.sysctl_data;
strlcpy(type, pktq_get_rps_hash_type(*func), PKTQ_RPS_HASH_NAME_LEN);
node.sysctl_data = &type;
node.sysctl_size = sizeof(type);
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return error;
error = pktq_set_rps_hash_type(func, type);
return error;
}
/*
* pktq_enqueue: inject the packet into the end of the queue.
*
* => Must be called from the interrupt or with the preemption disabled.
* => Consumes the packet and returns true on success.
* => Returns false on failure; caller is responsible to free the packet.
*/
bool
pktq_enqueue(pktqueue_t *pq, struct mbuf *m, const u_int hash __unused)
{
#if defined(_RUMPKERNEL) || defined(_RUMP_NATIVE_ABI)
struct cpu_info *ci = curcpu();
#else
struct cpu_info *ci = cpu_lookup(hash % ncpu);
#endif
KASSERT(kpreempt_disabled());
if (__predict_false(!pcq_put(pktq_pcq(pq, ci), m))) {
pktq_inc_count(pq, PQCNT_DROP);
return false;
}
softint_schedule_cpu(pq->pq_sih, ci);
pktq_inc_count(pq, PQCNT_ENQUEUE);
return true;
}
/*
* pktq_dequeue: take a packet from the queue.
*
* => Must be called with preemption disabled.
* => Must ensure there are not concurrent dequeue calls.
*/
struct mbuf *
pktq_dequeue(pktqueue_t *pq)
{
struct cpu_info *ci = curcpu();
struct mbuf *m;
KASSERT(kpreempt_disabled());
m = pcq_get(pktq_pcq(pq, ci));
if (__predict_false(m == PKTQ_MARKER)) {
/* Note the marker entry. */
atomic_inc_uint(&pq->pq_barrier);
/* Get the next queue entry. */
m = pcq_get(pktq_pcq(pq, ci));
/*
* There can only be one barrier operation pending
* on a pktqueue at any given time, so we can assert
* that the next item is not a marker.
*/
KASSERT(m != PKTQ_MARKER);
}
if (__predict_true(m != NULL)) {
pktq_inc_count(pq, PQCNT_DEQUEUE);
}
return m;
}
/*
* pktq_barrier: waits for a grace period when all packets enqueued at
* the moment of calling this routine will be processed. This is used
* to ensure that e.g. packets referencing some interface were drained.
*/
void
pktq_barrier(pktqueue_t *pq)
{
CPU_INFO_ITERATOR cii;
struct cpu_info *ci;
u_int pending = 0;
mutex_enter(&pq->pq_lock);
KASSERT(pq->pq_barrier == 0);
for (CPU_INFO_FOREACH(cii, ci)) {
struct pcq *q;
kpreempt_disable();
q = pktq_pcq(pq, ci);
kpreempt_enable();
/* If the queue is empty - nothing to do. */
if (pcq_peek(q) == NULL) {
continue;
}
/* Otherwise, put the marker and entry. */
while (!pcq_put(q, PKTQ_MARKER)) {
kpause("pktqsync", false, 1, NULL);
}
kpreempt_disable();
softint_schedule_cpu(pq->pq_sih, ci);
kpreempt_enable();
pending++;
}
/* Wait for each queue to process the markers. */
while (pq->pq_barrier != pending) {
kpause("pktqsync", false, 1, NULL);
}
pq->pq_barrier = 0;
mutex_exit(&pq->pq_lock);
}
/*
* pktq_ifdetach: issue a barrier on all pktqueues when a network
* interface is detached.
*/
void
pktq_ifdetach(void)
{
pktqueue_t *pq;
/* Just in case no pktqueues have been created yet... */
RUN_ONCE(&pktqueue_list_init_once, pktqueue_list_init);
rw_enter(&pktqueue_list_lock, RW_READER);
LIST_FOREACH(pq, &pktqueue_list, pq_list) {
pktq_barrier(pq);
}
rw_exit(&pktqueue_list_lock);
}
/*
* pktq_flush: free mbufs in all queues.
*
* => The caller must ensure there are no concurrent writers or flush calls.
*/
void
pktq_flush(pktqueue_t *pq)
{
CPU_INFO_ITERATOR cii;
struct cpu_info *ci;
struct mbuf *m, *m0 = NULL;
ASSERT_SLEEPABLE();
/*
* Run a dummy softint at IPL_SOFTNET on all CPUs to ensure that any
* already running handler for this pktqueue is no longer running.
*/
xc_barrier(XC_HIGHPRI_IPL(IPL_SOFTNET));
/*
* Acquire the barrier lock. While the caller ensures that
* no explicit pktq_barrier() calls will be issued, this holds
* off any implicit pktq_barrier() calls that would happen
* as the result of pktq_ifdetach().
*/
mutex_enter(&pq->pq_lock);
for (CPU_INFO_FOREACH(cii, ci)) {
struct pcq *q;
kpreempt_disable();
q = pktq_pcq(pq, ci);
kpreempt_enable();
/*
* Pull the packets off the pcq and chain them into
* a list to be freed later.
*/
while ((m = pcq_get(q)) != NULL) {
pktq_inc_count(pq, PQCNT_DEQUEUE);
m->m_nextpkt = m0;
m0 = m;
}
}
mutex_exit(&pq->pq_lock);
/* Free the packets now that the critical section is over. */
while ((m = m0) != NULL) {
m0 = m->m_nextpkt;
m_freem(m);
}
}
static void
pktq_set_maxlen_cpu(void *vpq, void *vqs)
{
struct pktqueue *pq = vpq;
struct pcq **qp, *q, **qs = vqs;
unsigned i = cpu_index(curcpu());
int s;
s = splnet();
qp = percpu_getref(pq->pq_pcq);
q = *qp;
*qp = qs[i];
qs[i] = q;
percpu_putref(pq->pq_pcq);
splx(s);
}
/*
* pktq_set_maxlen: create per-CPU queues using a new size and replace
* the existing queues without losing any packets.
*
* XXX ncpu must remain stable throughout.
*/
int
pktq_set_maxlen(pktqueue_t *pq, size_t maxlen)
{
const u_int slotbytes = ncpu * sizeof(pcq_t *);
pcq_t **qs;
if (!maxlen || maxlen > PCQ_MAXLEN)
return EINVAL;
if (pq->pq_maxlen == maxlen)
return 0;
/* First, allocate the new queues. */
qs = kmem_zalloc(slotbytes, KM_SLEEP);
for (u_int i = 0; i < ncpu; i++) {
qs[i] = pcq_create(maxlen, KM_SLEEP);
}
/*
* Issue an xcall to replace the queue pointers on each CPU.
* This implies all the necessary memory barriers.
*/
mutex_enter(&pq->pq_lock);
xc_wait(xc_broadcast(XC_HIGHPRI, pktq_set_maxlen_cpu, pq, qs));
pq->pq_maxlen = maxlen;
mutex_exit(&pq->pq_lock);
/*
* At this point, the new packets are flowing into the new
* queues. However, the old queues may have some packets
* present which are no longer being processed. We are going
* to re-enqueue them. This may change the order of packet
* arrival, but it is not considered an issue.
*
* There may be in-flight interrupts calling pktq_dequeue()
* which reference the old queues. Issue a barrier to ensure
* that we are going to be the only pcq_get() callers on the
* old queues.
*/
pktq_barrier(pq);
for (u_int i = 0; i < ncpu; i++) {
struct pcq *q;
struct mbuf *m;
kpreempt_disable();
q = pktq_pcq(pq, cpu_lookup(i));
kpreempt_enable();
while ((m = pcq_get(qs[i])) != NULL) {
while (!pcq_put(q, m)) {
kpause("pktqrenq", false, 1, NULL);
}
}
pcq_destroy(qs[i]);
}
/* Well, that was fun. */
kmem_free(qs, slotbytes);
return 0;
}
static int
sysctl_pktq_maxlen(SYSCTLFN_ARGS)
{
struct sysctlnode node = *rnode;
pktqueue_t * const pq = node.sysctl_data;
u_int nmaxlen = pktq_get_count(pq, PKTQ_MAXLEN);
int error;
node.sysctl_data = &nmaxlen;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return error;
return pktq_set_maxlen(pq, nmaxlen);
}
static int
sysctl_pktq_count(SYSCTLFN_ARGS, u_int count_id)
{
struct sysctlnode node = *rnode;
pktqueue_t * const pq = node.sysctl_data;
uint64_t count = pktq_get_count(pq, count_id);
node.sysctl_data = &count;
return sysctl_lookup(SYSCTLFN_CALL(&node));
}
static int
sysctl_pktq_nitems(SYSCTLFN_ARGS)
{
return sysctl_pktq_count(SYSCTLFN_CALL(rnode), PKTQ_NITEMS);
}
static int
sysctl_pktq_drops(SYSCTLFN_ARGS)
{
return sysctl_pktq_count(SYSCTLFN_CALL(rnode), PKTQ_DROPS);
}
/*
* pktqueue_sysctl_setup: set up the sysctl nodes for a pktqueue
* using standardized names at the specified parent node and
* node ID (or CTL_CREATE).
*/
void
pktq_sysctl_setup(pktqueue_t * const pq, struct sysctllog ** const clog,
const struct sysctlnode * const parent_node, const int qid)
{
const struct sysctlnode *rnode = parent_node, *cnode;
KASSERT(pq != NULL);
KASSERT(parent_node != NULL);
KASSERT(qid == CTL_CREATE || qid >= 0);
/* Create the "ifq" node below the parent node. */
sysctl_createv(clog, 0, &rnode, &cnode,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "ifq",
SYSCTL_DESCR("Protocol input queue controls"),
NULL, 0, NULL, 0,
qid, CTL_EOL);
/* Now create the standard child nodes below "ifq". */
rnode = cnode;
sysctl_createv(clog, 0, &rnode, &cnode,
CTLFLAG_PERMANENT,
CTLTYPE_QUAD, "len",
SYSCTL_DESCR("Current input queue length"),
sysctl_pktq_nitems, 0, (void *)pq, 0,
IFQCTL_LEN, CTL_EOL);
sysctl_createv(clog, 0, &rnode, &cnode,
CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
CTLTYPE_INT, "maxlen",
SYSCTL_DESCR("Maximum allowed input queue length"),
sysctl_pktq_maxlen, 0, (void *)pq, 0,
IFQCTL_MAXLEN, CTL_EOL);
sysctl_createv(clog, 0, &rnode, &cnode,
CTLFLAG_PERMANENT,
CTLTYPE_QUAD, "drops",
SYSCTL_DESCR("Packets dropped due to full input queue"),
sysctl_pktq_drops, 0, (void *)pq, 0,
IFQCTL_DROPS, CTL_EOL);
}
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