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ip_reass: retire ipreass_slowtimo() in favor of per-slot callout
o Retire global always running ipreass_slowtimo(). o Instead use one callout entry per hash slot. The per-slot callout would be scheduled only if a slot has entries, and would be driven by TTL of the very last entry. o Make net.inet.ip.fragttl read/write and document it. o Retire IPFRAGTTL, which used to be meaningful only with PR_SLOWTIMO. Differential revision: https://reviews.freebsd.org/D36275
This commit is contained in:
Gleb Smirnoff
parent
e599810ded
commit
a30cb31589
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@ -28,7 +28,7 @@
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.\" From: @(#)inet.4 8.1 (Berkeley) 6/5/93
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.\" $FreeBSD$
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.\"
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.Dd August 1, 2022
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.Dd September 8, 2022
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.Dt INET 4
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.Os
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.Sh NAME
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@ -186,6 +186,8 @@ Defaults to off.
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.It Va fragpackets
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Integer: Current number of IPv4 fragment reassembly queue entries
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for the VNET (read-only).
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.It Va fragttl
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Integer: time to live for IPv4 packet fragments in the per-VNET reassemby queue.
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.It Va loopback_prefixlen
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Integer: prefix length of the address space reserved for loopback purposes.
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The default is 8, meaning that 127.0.0.0/8 is reserved for loopback,
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@ -210,7 +210,6 @@ struct ip_timestamp {
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*/
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#define MAXTTL 255 /* maximum time to live (seconds) */
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#define IPDEFTTL 64 /* default ttl, from RFC 1340 */
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#define IPFRAGTTL 60 /* time to live for frags, slowhz */
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#define IPTTLDEC 1 /* subtracted when forwarding */
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#define IP_MSS 576 /* default maximum segment size */
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@ -75,6 +75,10 @@ SYSCTL_DECL(_net_inet_ip);
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struct ipqbucket {
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TAILQ_HEAD(ipqhead, ipq) head;
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struct mtx lock;
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struct callout timer;
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#ifdef VIMAGE
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struct vnet *vnet;
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#endif
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int count;
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};
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@ -87,6 +91,7 @@ VNET_DEFINE_STATIC(uint32_t, ipq_hashseed);
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#define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock)
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#define IPQ_UNLOCK(i) mtx_unlock(&V_ipq[i].lock)
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#define IPQ_LOCK_ASSERT(i) mtx_assert(&V_ipq[i].lock, MA_OWNED)
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#define IPQ_BUCKET_LOCK_ASSERT(b) mtx_assert(&(b)->lock, MA_OWNED)
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VNET_DEFINE_STATIC(int, ipreass_maxbucketsize);
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#define V_ipreass_maxbucketsize VNET(ipreass_maxbucketsize)
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@ -98,10 +103,13 @@ void ipreass_destroy(void);
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#endif
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static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS);
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static int sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS);
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static int sysctl_fragttl(SYSCTL_HANDLER_ARGS);
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static void ipreass_zone_change(void *);
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static void ipreass_drain_tomax(void);
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static void ipq_free(struct ipqbucket *, struct ipq *);
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static struct ipq * ipq_reuse(int);
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static void ipreass_callout(void *);
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static void ipreass_reschedule(struct ipqbucket *);
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static inline void
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ipq_timeout(struct ipqbucket *bucket, struct ipq *fp)
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@ -117,6 +125,7 @@ ipq_drop(struct ipqbucket *bucket, struct ipq *fp)
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IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
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ipq_free(bucket, fp);
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ipreass_reschedule(bucket);
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}
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/*
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@ -167,9 +176,11 @@ SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragbucketsize,
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sysctl_maxfragbucketsize, "I",
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"Maximum number of IPv4 fragment reassembly queue entries per bucket");
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static u_int ipfragttl = IPFRAGTTL / 2;
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SYSCTL_UINT(_net_inet_ip, OID_AUTO, fragttl, CTLFLAG_RD, &ipfragttl,
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IPFRAGTTL / 2, "IP fragment life time on reassembly queue");
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VNET_DEFINE_STATIC(u_int, ipfragttl) = 30;
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#define V_ipfragttl VNET(ipfragttl)
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SYSCTL_PROC(_net_inet_ip, OID_AUTO, fragttl, CTLTYPE_INT | CTLFLAG_RW |
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CTLFLAG_MPSAFE | CTLFLAG_VNET, NULL, 0, sysctl_fragttl, "IU",
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"IP fragment life time on reassembly queue (seconds)");
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/*
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* Take incoming datagram fragment and try to reassemble it into
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@ -311,7 +322,7 @@ ip_reass(struct mbuf *m)
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V_ipq[hash].count++;
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fp->ipq_nfrags = 1;
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atomic_add_int(&nfrags, 1);
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fp->ipq_ttl = IPFRAGTTL;
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fp->ipq_expire = time_uptime + V_ipfragttl;
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fp->ipq_p = ip->ip_p;
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fp->ipq_id = ip->ip_id;
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fp->ipq_src = ip->ip_src;
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@ -322,6 +333,12 @@ ip_reass(struct mbuf *m)
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else
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fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
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m->m_nextpkt = NULL;
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if (fp == TAILQ_LAST(head, ipqhead))
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callout_reset_sbt(&V_ipq[hash].timer,
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SBT_1S * V_ipfragttl, SBT_1S, ipreass_callout,
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&V_ipq[hash], 0);
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else
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MPASS(callout_active(&V_ipq[hash].timer));
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goto done;
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} else {
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/*
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@ -509,6 +526,7 @@ ip_reass(struct mbuf *m)
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m->m_pkthdr.rcvif = srcifp;
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}
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IPSTAT_INC(ips_reassembled);
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ipreass_reschedule(&V_ipq[hash]);
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IPQ_UNLOCK(hash);
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#ifdef RSS
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@ -560,44 +578,48 @@ ip_reass(struct mbuf *m)
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}
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/*
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* If a timer expires on a reassembly queue, discard it.
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* Timer expired on a bucket.
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* There should be at least one ipq to be timed out.
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*/
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static struct callout ipreass_callout;
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static void
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ipreass_slowtimo(void *arg __unused)
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ipreass_callout(void *arg)
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{
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VNET_ITERATOR_DECL(vnet_iter);
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struct ipq *fp, *tmp;
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struct ipqbucket *bucket = arg;
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struct ipq *fp;
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if (atomic_load_int(&nfrags) == 0)
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return;
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IPQ_BUCKET_LOCK_ASSERT(bucket);
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MPASS(atomic_load_int(&nfrags) > 0);
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VNET_FOREACH(vnet_iter) {
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CURVNET_SET(vnet_iter);
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for (int i = 0; i < IPREASS_NHASH; i++) {
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if (TAILQ_EMPTY(&V_ipq[i].head))
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continue;
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IPQ_LOCK(i);
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TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, tmp)
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if (--fp->ipq_ttl == 0)
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ipq_timeout(&V_ipq[i], fp);
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IPQ_UNLOCK(i);
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}
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CURVNET_RESTORE();
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CURVNET_SET(bucket->vnet);
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fp = TAILQ_LAST(&bucket->head, ipqhead);
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KASSERT(fp != NULL && fp->ipq_expire >= time_uptime,
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("%s: stray callout on bucket %p", __func__, bucket));
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while (fp != NULL && fp->ipq_expire >= time_uptime) {
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ipq_timeout(bucket, fp);
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fp = TAILQ_LAST(&bucket->head, ipqhead);
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}
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VNET_LIST_RUNLOCK_NOSLEEP();
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callout_reset_sbt(&ipreass_callout, SBT_1MS * 500, SBT_1MS * 10,
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ipreass_slowtimo, NULL, 0);
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ipreass_reschedule(bucket);
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CURVNET_RESTORE();
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}
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static void
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ipreass_timer_init(void *arg __unused)
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ipreass_reschedule(struct ipqbucket *bucket)
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{
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struct ipq *fp;
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callout_init(&ipreass_callout, 1);
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callout_reset_sbt(&ipreass_callout, SBT_1MS * 500, SBT_1MS * 10,
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ipreass_slowtimo, NULL, 0);
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IPQ_BUCKET_LOCK_ASSERT(bucket);
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if ((fp = TAILQ_LAST(&bucket->head, ipqhead)) != NULL) {
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time_t t;
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/* Protect against time_uptime tick. */
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t = fp->ipq_expire - time_uptime;
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t = (t > 0) ? t : 1;
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callout_reset_sbt(&bucket->timer, SBT_1S * t, SBT_1S,
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ipreass_callout, bucket, 0);
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} else
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callout_stop(&bucket->timer);
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}
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static void
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@ -614,7 +636,6 @@ ipreass_drain_vnet(void)
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IPQ_UNLOCK(i);
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}
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}
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SYSINIT(ipreass, SI_SUB_VNET_DONE, SI_ORDER_ANY, ipreass_timer_init, NULL);
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/*
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* Drain off all datagram fragments.
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@ -644,7 +665,11 @@ ipreass_vnet_init(void)
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TAILQ_INIT(&V_ipq[i].head);
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mtx_init(&V_ipq[i].lock, "IP reassembly", NULL,
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MTX_DEF | MTX_DUPOK);
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callout_init_mtx(&V_ipq[i].timer, &V_ipq[i].lock, 0);
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V_ipq[i].count = 0;
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#ifdef VIMAGE
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V_ipq[i].vnet = curvnet;
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#endif
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}
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V_ipq_hashseed = arc4random();
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V_maxfragsperpacket = 16;
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@ -745,6 +770,7 @@ ipreass_drain_tomax(void)
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while (V_ipq[i].count > V_ipreass_maxbucketsize &&
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(fp = TAILQ_LAST(&V_ipq[i].head, ipqhead)) != NULL)
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ipq_timeout(&V_ipq[i], fp);
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ipreass_reschedule(&V_ipq[i]);
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IPQ_UNLOCK(i);
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}
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@ -759,8 +785,10 @@ ipreass_drain_tomax(void)
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for (int i = 0; i < IPREASS_NHASH; i++) {
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IPQ_LOCK(i);
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fp = TAILQ_LAST(&V_ipq[i].head, ipqhead);
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if (fp != NULL)
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if (fp != NULL) {
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ipq_timeout(&V_ipq[i], fp);
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ipreass_reschedule(&V_ipq[i]);
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}
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IPQ_UNLOCK(i);
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}
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}
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@ -854,6 +882,7 @@ ipq_reuse(int start)
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}
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TAILQ_REMOVE(&V_ipq[bucket].head, fp, ipq_list);
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V_ipq[bucket].count--;
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ipreass_reschedule(&V_ipq[bucket]);
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if (bucket != start)
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IPQ_UNLOCK(bucket);
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break;
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@ -902,3 +931,24 @@ sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)
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ipreass_drain_tomax();
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return (0);
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}
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/*
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* Get or set the IP fragment time to live.
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*/
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static int
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sysctl_fragttl(SYSCTL_HANDLER_ARGS)
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{
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u_int ttl;
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int error;
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ttl = V_ipfragttl;
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error = sysctl_handle_int(oidp, &ttl, 0, req);
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if (error || !req->newptr)
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return (error);
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if (ttl < 1 || ttl > MAXTTL)
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return (EINVAL);
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atomic_store_int(&V_ipfragttl, ttl);
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return (0);
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}
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@ -56,18 +56,18 @@ struct ipovly {
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/*
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* Ip reassembly queue structure. Each fragment
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* being reassembled is attached to one of these structures.
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* They are timed out after ipq_ttl drops to 0, and may also
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* be reclaimed if memory becomes tight.
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* They are timed out after net.inet.ip.fragttl seconds, and may also be
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* reclaimed if memory becomes tight.
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*/
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struct ipq {
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TAILQ_ENTRY(ipq) ipq_list; /* to other reass headers */
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u_char ipq_ttl; /* time for reass q to live */
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time_t ipq_expire; /* time_uptime when ipq expires */
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u_char ipq_nfrags; /* # frags in this packet */
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u_char ipq_p; /* protocol of this fragment */
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u_short ipq_id; /* sequence id for reassembly */
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int ipq_maxoff; /* total length of packet */
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struct mbuf *ipq_frags; /* to ip headers of fragments */
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struct in_addr ipq_src,ipq_dst;
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u_char ipq_nfrags; /* # frags in this packet */
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struct label *ipq_label; /* MAC label */
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};
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#endif /* _KERNEL */
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