sys/netinet/tcp_hostcache.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
   5  * Copyright (c) 2021 Gleb Smirnoff <glebius@FreeBSD.org>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote
  17  *    products derived from this software without specific prior written
  18  *    permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 /*
  34  * The tcp_hostcache moves the tcp-specific cached metrics from the routing
  35  * table to a dedicated structure indexed by the remote IP address.  It keeps
  36  * information on the measured TCP parameters of past TCP sessions to allow
  37  * better initial start values to be used with later connections to/from the
  38  * same source.  Depending on the network parameters (delay, max MTU,
  39  * congestion window) between local and remote sites, this can lead to
  40  * significant speed-ups for new TCP connections after the first one.
  41  *
  42  * Due to the tcp_hostcache, all TCP-specific metrics information in the
  43  * routing table have been removed.  The inpcb no longer keeps a pointer to
  44  * the routing entry, and protocol-initiated route cloning has been removed
  45  * as well.  With these changes, the routing table has gone back to being
  46  * more lightwight and only carries information related to packet forwarding.
  47  *
  48  * tcp_hostcache is designed for multiple concurrent access in SMP
  49  * environments and high contention.  It is a straight hash.  Each bucket row
  50  * is protected by its own lock for modification.  Readers are protected by
  51  * SMR.  This puts certain restrictions on writers, e.g. a writer shall only
  52  * insert a fully populated entry into a row.  Writer can't reuse least used
  53  * entry if a hash is full.  Value updates for an entry shall be atomic.
  54  *
  55  * TCP stack(s) communication with tcp_hostcache() is done via KBI functions
  56  * tcp_hc_*() and the hc_metrics_lite structure.
  57  *
  58  * Since tcp_hostcache is only caching information, there are no fatal
  59  * consequences if we either can't allocate a new entry or have to drop
  60  * an existing entry, or return somewhat stale information.
  61  */
  62
  63 /*
  64  * Many thanks to jlemon for basic structure of tcp_syncache which is being
  65  * followed here.
  66  */
  67
  68 #include <sys/cdefs.h>
  69 #include "opt_inet6.h"
  70
  71 #include <sys/param.h>
  72 #include <sys/systm.h>
  73 #include <sys/hash.h>
  74 #include <sys/jail.h>
  75 #include <sys/kernel.h>
  76 #include <sys/lock.h>
  77 #include <sys/mutex.h>
  78 #include <sys/malloc.h>
  79 #include <sys/proc.h>
  80 #include <sys/sbuf.h>
  81 #include <sys/smr.h>
  82 #include <sys/socket.h>
  83 #include <sys/sysctl.h>
  84
  85 #include <net/vnet.h>
  86
  87 #include <netinet/in.h>
  88 #include <netinet/in_pcb.h>
  89 #include <netinet/tcp.h>
  90 #include <netinet/tcp_var.h>
  91
  92 #include <vm/uma.h>
  93
  94 struct hc_head {
  95         CK_SLIST_HEAD(hc_qhead, hc_metrics) hch_bucket;
  96         u_int           hch_length;
  97         struct mtx      hch_mtx;
  98 };
  99
 100 struct hc_metrics {
 101         /* housekeeping */
 102         CK_SLIST_ENTRY(hc_metrics) rmx_q;
 103         struct          in_addr ip4;    /* IP address */
 104         struct          in6_addr ip6;   /* IP6 address */
 105         uint32_t        ip6_zoneid;     /* IPv6 scope zone id */
 106         /* endpoint specific values for tcp */
 107         uint32_t        rmx_mtu;        /* MTU for this path */
 108         uint32_t        rmx_ssthresh;   /* outbound gateway buffer limit */
 109         uint32_t        rmx_rtt;        /* estimated round trip time */
 110         uint32_t        rmx_rttvar;     /* estimated rtt variance */
 111         uint32_t        rmx_cwnd;       /* congestion window */
 112         uint32_t        rmx_sendpipe;   /* outbound delay-bandwidth product */
 113         uint32_t        rmx_recvpipe;   /* inbound delay-bandwidth product */
 114         /* TCP hostcache internal data */
 115         int             rmx_expire;     /* lifetime for object */
 116 #ifdef  TCP_HC_COUNTERS
 117         u_long          rmx_hits;       /* number of hits */
 118         u_long          rmx_updates;    /* number of updates */
 119 #endif
 120 };
 121
 122 struct tcp_hostcache {
 123         struct hc_head  *hashbase;
 124         uma_zone_t      zone;
 125         smr_t           smr;
 126         u_int           hashsize;
 127         u_int           hashmask;
 128         u_int           hashsalt;
 129         u_int           bucket_limit;
 130         u_int           cache_count;
 131         u_int           cache_limit;
 132         int             expire;
 133         int             prune;
 134         int             purgeall;
 135 };
 136
 137 /* Arbitrary values */
 138 #define TCP_HOSTCACHE_HASHSIZE          512
 139 #define TCP_HOSTCACHE_BUCKETLIMIT       30
 140 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
 141 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
 142
 143 VNET_DEFINE_STATIC(struct tcp_hostcache, tcp_hostcache);
 144 #define V_tcp_hostcache         VNET(tcp_hostcache)
 145
 146 VNET_DEFINE_STATIC(struct callout, tcp_hc_callout);
 147 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
 148
 149 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
 150 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
 151 static int sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS);
 152 static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS);
 153 static void tcp_hc_purge_internal(int);
 154 static void tcp_hc_purge(void *);
 155
 156 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache,
 157     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
 158     "TCP Host cache");
 159
 160 VNET_DEFINE(int, tcp_use_hostcache) = 1;
 161 #define V_tcp_use_hostcache  VNET(tcp_use_hostcache)
 162 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
 163     &VNET_NAME(tcp_use_hostcache), 0,
 164     "Enable the TCP hostcache");
 165
 166 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN,
 167     &VNET_NAME(tcp_hostcache.cache_limit), 0,
 168     "Overall entry limit for hostcache");
 169
 170 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN,
 171     &VNET_NAME(tcp_hostcache.hashsize), 0,
 172     "Size of TCP hostcache hashtable");
 173
 174 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
 175     CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
 176     "Per-bucket hash limit for hostcache");
 177
 178 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD,
 179     &VNET_NAME(tcp_hostcache.cache_count), 0,
 180     "Current number of entries in hostcache");
 181
 182 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW,
 183     &VNET_NAME(tcp_hostcache.expire), 0,
 184     "Expire time of TCP hostcache entries");
 185
 186 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW,
 187     &VNET_NAME(tcp_hostcache.prune), 0,
 188     "Time between purge runs");
 189
 190 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW,
 191     &VNET_NAME(tcp_hostcache.purgeall), 0,
 192     "Expire all entries on next purge run");
 193
 194 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 195     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE,
 196     0, 0, sysctl_tcp_hc_list, "A",
 197     "List of all hostcache entries");
 198
 199 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, histo,
 200     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE,
 201     0, 0, sysctl_tcp_hc_histo, "A",
 202     "Print a histogram of hostcache hashbucket utilization");
 203
 204 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
 205     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
 206     NULL, 0, sysctl_tcp_hc_purgenow, "I",
 207     "Immediately purge all entries");
 208
 209 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 210
 211 /* Use jenkins_hash32(), as in other parts of the tcp stack */
 212 #define HOSTCACHE_HASH(inc)                                             \
 213         ((inc)->inc_flags & INC_ISIPV6) ?                               \
 214                 (jenkins_hash32((inc)->inc6_faddr.s6_addr32, 4,         \
 215                 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask)   \
 216         :                                                               \
 217                 (jenkins_hash32(&(inc)->inc_faddr.s_addr, 1,            \
 218                 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask)
 219
 220 #define THC_LOCK(h)             mtx_lock(&(h)->hch_mtx)
 221 #define THC_UNLOCK(h)           mtx_unlock(&(h)->hch_mtx)
 222
 223 void
 224 tcp_hc_init(void)
 225 {
 226         u_int cache_limit;
 227         int i;
 228
 229         /*
 230          * Initialize hostcache structures.
 231          */
 232         atomic_store_int(&V_tcp_hostcache.cache_count, 0);
 233         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 234         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 235         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 236         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
 237         V_tcp_hostcache.hashsalt = arc4random();
 238
 239         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 240             &V_tcp_hostcache.hashsize);
 241         if (!powerof2(V_tcp_hostcache.hashsize)) {
 242                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 243                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
 244         }
 245         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
 246
 247         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 248             &V_tcp_hostcache.bucket_limit);
 249
 250         cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
 251         V_tcp_hostcache.cache_limit = cache_limit;
 252         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 253             &V_tcp_hostcache.cache_limit);
 254         if (V_tcp_hostcache.cache_limit > cache_limit)
 255                 V_tcp_hostcache.cache_limit = cache_limit;
 256
 257         /*
 258          * Allocate the hash table.
 259          */
 260         V_tcp_hostcache.hashbase = (struct hc_head *)
 261             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
 262                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 263
 264         /*
 265          * Initialize the hash buckets.
 266          */
 267         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 268                 CK_SLIST_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
 269                 V_tcp_hostcache.hashbase[i].hch_length = 0;
 270                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 271                           NULL, MTX_DEF);
 272         }
 273
 274         /*
 275          * Allocate the hostcache entries.
 276          */
 277         V_tcp_hostcache.zone =
 278             uma_zcreate("hostcache", sizeof(struct hc_metrics),
 279             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_SMR);
 280         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
 281         V_tcp_hostcache.smr = uma_zone_get_smr(V_tcp_hostcache.zone);
 282
 283         /*
 284          * Set up periodic cache cleanup.
 285          */
 286         callout_init(&V_tcp_hc_callout, 1);
 287         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 288             tcp_hc_purge, curvnet);
 289 }
 290
 291 #ifdef VIMAGE
 292 void
 293 tcp_hc_destroy(void)
 294 {
 295         int i;
 296
 297         callout_drain(&V_tcp_hc_callout);
 298
 299         /* Purge all hc entries. */
 300         tcp_hc_purge_internal(1);
 301
 302         /* Free the uma zone and the allocated hash table. */
 303         uma_zdestroy(V_tcp_hostcache.zone);
 304
 305         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
 306                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
 307         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
 308 }
 309 #endif
 310
 311 /*
 312  * Internal function: compare cache entry to a connection.
 313  */
 314 static bool
 315 tcp_hc_cmp(struct hc_metrics *hc_entry, struct in_conninfo *inc)
 316 {
 317
 318         if (inc->inc_flags & INC_ISIPV6) {
 319                 /* XXX: check ip6_zoneid */
 320                 if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 321                     sizeof(inc->inc6_faddr)) == 0)
 322                         return (true);
 323         } else {
 324                 if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 325                     sizeof(inc->inc_faddr)) == 0)
 326                         return (true);
 327         }
 328
 329         return (false);
 330 }
 331
 332 /*
 333  * Internal function: look up an entry in the hostcache for read.
 334  * On success returns in SMR section.
 335  */
 336 static struct hc_metrics *
 337 tcp_hc_lookup(struct in_conninfo *inc)
 338 {
 339         struct hc_head *hc_head;
 340         struct hc_metrics *hc_entry;
 341
 342         KASSERT(inc != NULL, ("%s: NULL in_conninfo", __func__));
 343
 344         hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
 345
 346         /*
 347          * Iterate through entries in bucket row looking for a match.
 348          */
 349         smr_enter(V_tcp_hostcache.smr);
 350         CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q)
 351                 if (tcp_hc_cmp(hc_entry, inc))
 352                         break;
 353
 354         if (hc_entry != NULL) {
 355                 if (atomic_load_int(&hc_entry->rmx_expire) !=
 356                     V_tcp_hostcache.expire)
 357                         atomic_store_int(&hc_entry->rmx_expire,
 358                             V_tcp_hostcache.expire);
 359 #ifdef  TCP_HC_COUNTERS
 360                 hc_entry->rmx_hits++;
 361 #endif
 362         } else
 363                 smr_exit(V_tcp_hostcache.smr);
 364
 365         return (hc_entry);
 366 }
 367
 368 /*
 369  * External function: look up an entry in the hostcache and fill out the
 370  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
 371  * a value is not set.
 372  */
 373 void
 374 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 375 {
 376         struct hc_metrics *hc_entry;
 377
 378         if (!V_tcp_use_hostcache) {
 379                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 380                 return;
 381         }
 382
 383         /*
 384          * Find the right bucket.
 385          */
 386         hc_entry = tcp_hc_lookup(inc);
 387
 388         /*
 389          * If we don't have an existing object.
 390          */
 391         if (hc_entry == NULL) {
 392                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 393                 return;
 394         }
 395
 396         hc_metrics_lite->rmx_mtu = atomic_load_32(&hc_entry->rmx_mtu);
 397         hc_metrics_lite->rmx_ssthresh = atomic_load_32(&hc_entry->rmx_ssthresh);
 398         hc_metrics_lite->rmx_rtt = atomic_load_32(&hc_entry->rmx_rtt);
 399         hc_metrics_lite->rmx_rttvar = atomic_load_32(&hc_entry->rmx_rttvar);
 400         hc_metrics_lite->rmx_cwnd = atomic_load_32(&hc_entry->rmx_cwnd);
 401         hc_metrics_lite->rmx_sendpipe = atomic_load_32(&hc_entry->rmx_sendpipe);
 402         hc_metrics_lite->rmx_recvpipe = atomic_load_32(&hc_entry->rmx_recvpipe);
 403
 404         smr_exit(V_tcp_hostcache.smr);
 405 }
 406
 407 /*
 408  * External function: look up an entry in the hostcache and return the
 409  * discovered path MTU.  Returns 0 if no entry is found or value is not
 410  * set.
 411  */
 412 uint32_t
 413 tcp_hc_getmtu(struct in_conninfo *inc)
 414 {
 415         struct hc_metrics *hc_entry;
 416         uint32_t mtu;
 417
 418         if (!V_tcp_use_hostcache)
 419                 return (0);
 420
 421         hc_entry = tcp_hc_lookup(inc);
 422         if (hc_entry == NULL) {
 423                 return (0);
 424         }
 425
 426         mtu = atomic_load_32(&hc_entry->rmx_mtu);
 427         smr_exit(V_tcp_hostcache.smr);
 428
 429         return (mtu);
 430 }
 431
 432 /*
 433  * External function: update the MTU value of an entry in the hostcache.
 434  * Creates a new entry if none was found.
 435  */
 436 void
 437 tcp_hc_updatemtu(struct in_conninfo *inc, uint32_t mtu)
 438 {
 439         struct hc_metrics_lite hcml = { .rmx_mtu = mtu };
 440
 441         return (tcp_hc_update(inc, &hcml));
 442 }
 443
 444 /*
 445  * External function: update the TCP metrics of an entry in the hostcache.
 446  * Creates a new entry if none was found.
 447  */
 448 void
 449 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 450 {
 451         struct hc_head *hc_head;
 452         struct hc_metrics *hc_entry, *hc_prev;
 453         uint32_t v;
 454         bool new;
 455
 456         if (!V_tcp_use_hostcache)
 457                 return;
 458
 459         hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
 460         hc_prev = NULL;
 461
 462         THC_LOCK(hc_head);
 463         CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 464                 if (tcp_hc_cmp(hc_entry, inc))
 465                         break;
 466                 if (CK_SLIST_NEXT(hc_entry, rmx_q) != NULL)
 467                         hc_prev = hc_entry;
 468         }
 469
 470         if (hc_entry != NULL) {
 471                 if (atomic_load_int(&hc_entry->rmx_expire) !=
 472                     V_tcp_hostcache.expire)
 473                         atomic_store_int(&hc_entry->rmx_expire,
 474                             V_tcp_hostcache.expire);
 475 #ifdef  TCP_HC_COUNTERS
 476                 hc_entry->rmx_updates++;
 477 #endif
 478                 new = false;
 479         } else {
 480                 /*
 481                  * Try to allocate a new entry.  If the bucket limit is
 482                  * reached, delete the least-used element, located at the end
 483                  * of the CK_SLIST.  During lookup we saved the pointer to
 484                  * the second to last element, in case if list has at least 2
 485                  * elements.  This will allow to delete last element without
 486                  * extra traversal.
 487                  *
 488                  * Give up if the row is empty.
 489                  */
 490                 if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
 491                     atomic_load_int(&V_tcp_hostcache.cache_count) >=
 492                     V_tcp_hostcache.cache_limit) {
 493                         if (hc_prev != NULL) {
 494                                 hc_entry = CK_SLIST_NEXT(hc_prev, rmx_q);
 495                                 KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL,
 496                                     ("%s: %p is not one to last",
 497                                     __func__, hc_prev));
 498                                 CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
 499                         } else if ((hc_entry =
 500                             CK_SLIST_FIRST(&hc_head->hch_bucket)) != NULL) {
 501                                 KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL,
 502                                     ("%s: %p is not the only element",
 503                                     __func__, hc_entry));
 504                                 CK_SLIST_REMOVE_HEAD(&hc_head->hch_bucket,
 505                                     rmx_q);
 506                         } else {
 507                                 THC_UNLOCK(hc_head);
 508                                 return;
 509                         }
 510                         KASSERT(hc_head->hch_length > 0 &&
 511                             hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
 512                             ("tcp_hostcache: bucket length violated at %p",
 513                             hc_head));
 514                         hc_head->hch_length--;
 515                         atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
 516                         TCPSTAT_INC(tcps_hc_bucketoverflow);
 517                         uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
 518                 }
 519
 520                 /*
 521                  * Allocate a new entry, or balk if not possible.
 522                  */
 523                 hc_entry = uma_zalloc_smr(V_tcp_hostcache.zone, M_NOWAIT);
 524                 if (hc_entry == NULL) {
 525                         THC_UNLOCK(hc_head);
 526                         return;
 527                 }
 528
 529                 /*
 530                  * Initialize basic information of hostcache entry.
 531                  */
 532                 bzero(hc_entry, sizeof(*hc_entry));
 533                 if (inc->inc_flags & INC_ISIPV6) {
 534                         hc_entry->ip6 = inc->inc6_faddr;
 535                         hc_entry->ip6_zoneid = inc->inc6_zoneid;
 536                 } else
 537                         hc_entry->ip4 = inc->inc_faddr;
 538                 hc_entry->rmx_expire = V_tcp_hostcache.expire;
 539                 new = true;
 540         }
 541
 542         /*
 543          * Fill in data.  Use atomics, since an existing entry is
 544          * accessible by readers in SMR section.
 545          */
 546         if (hcml->rmx_mtu != 0) {
 547                 atomic_store_32(&hc_entry->rmx_mtu, hcml->rmx_mtu);
 548         }
 549         if (hcml->rmx_rtt != 0) {
 550                 if (hc_entry->rmx_rtt == 0)
 551                         v = hcml->rmx_rtt;
 552                 else
 553                         v = ((uint64_t)hc_entry->rmx_rtt +
 554                             (uint64_t)hcml->rmx_rtt) / 2;
 555                 atomic_store_32(&hc_entry->rmx_rtt, v);
 556                 TCPSTAT_INC(tcps_cachedrtt);
 557         }
 558         if (hcml->rmx_rttvar != 0) {
 559                 if (hc_entry->rmx_rttvar == 0)
 560                         v = hcml->rmx_rttvar;
 561                 else
 562                         v = ((uint64_t)hc_entry->rmx_rttvar +
 563                             (uint64_t)hcml->rmx_rttvar) / 2;
 564                 atomic_store_32(&hc_entry->rmx_rttvar, v);
 565                 TCPSTAT_INC(tcps_cachedrttvar);
 566         }
 567         if (hcml->rmx_ssthresh != 0) {
 568                 if (hc_entry->rmx_ssthresh == 0)
 569                         v = hcml->rmx_ssthresh;
 570                 else
 571                         v = (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 572                 atomic_store_32(&hc_entry->rmx_ssthresh, v);
 573                 TCPSTAT_INC(tcps_cachedssthresh);
 574         }
 575         if (hcml->rmx_cwnd != 0) {
 576                 if (hc_entry->rmx_cwnd == 0)
 577                         v = hcml->rmx_cwnd;
 578                 else
 579                         v = ((uint64_t)hc_entry->rmx_cwnd +
 580                             (uint64_t)hcml->rmx_cwnd) / 2;
 581                 atomic_store_32(&hc_entry->rmx_cwnd, v);
 582                 /* TCPSTAT_INC(tcps_cachedcwnd); */
 583         }
 584         if (hcml->rmx_sendpipe != 0) {
 585                 if (hc_entry->rmx_sendpipe == 0)
 586                         v = hcml->rmx_sendpipe;
 587                 else
 588                         v = ((uint64_t)hc_entry->rmx_sendpipe +
 589                             (uint64_t)hcml->rmx_sendpipe) /2;
 590                 atomic_store_32(&hc_entry->rmx_sendpipe, v);
 591                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
 592         }
 593         if (hcml->rmx_recvpipe != 0) {
 594                 if (hc_entry->rmx_recvpipe == 0)
 595                         v = hcml->rmx_recvpipe;
 596                 else
 597                         v = ((uint64_t)hc_entry->rmx_recvpipe +
 598                             (uint64_t)hcml->rmx_recvpipe) /2;
 599                 atomic_store_32(&hc_entry->rmx_recvpipe, v);
 600                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
 601         }
 602
 603         /*
 604          * Put it upfront.
 605          */
 606         if (new) {
 607                 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 608                 hc_head->hch_length++;
 609                 KASSERT(hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
 610                     ("tcp_hostcache: bucket length too high at %p", hc_head));
 611                 atomic_add_int(&V_tcp_hostcache.cache_count, 1);
 612                 TCPSTAT_INC(tcps_hc_added);
 613         } else if (hc_entry != CK_SLIST_FIRST(&hc_head->hch_bucket)) {
 614                 KASSERT(CK_SLIST_NEXT(hc_prev, rmx_q) == hc_entry,
 615                     ("%s: %p next is not %p", __func__, hc_prev, hc_entry));
 616                 CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
 617                 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 618         }
 619         THC_UNLOCK(hc_head);
 620 }
 621
 622 /*
 623  * Sysctl function: prints the list and values of all hostcache entries in
 624  * unsorted order.
 625  */
 626 static int
 627 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 628 {
 629         const int linesize = 128;
 630         struct sbuf sb;
 631         int i, error, len;
 632         struct hc_metrics *hc_entry;
 633         char ip4buf[INET_ADDRSTRLEN];
 634 #ifdef INET6
 635         char ip6buf[INET6_ADDRSTRLEN];
 636 #endif
 637
 638         if (jailed_without_vnet(curthread->td_ucred) != 0)
 639                 return (EPERM);
 640
 641         /* Optimize Buffer length query by sbin/sysctl */
 642         if (req->oldptr == NULL) {
 643                 len = (atomic_load_int(&V_tcp_hostcache.cache_count) + 1) *
 644                         linesize;
 645                 return (SYSCTL_OUT(req, NULL, len));
 646         }
 647
 648         error = sysctl_wire_old_buffer(req, 0);
 649         if (error != 0) {
 650                 return(error);
 651         }
 652
 653         /* Use a buffer sized for one full bucket */
 654         sbuf_new_for_sysctl(&sb, NULL, V_tcp_hostcache.bucket_limit *
 655                 linesize, req);
 656
 657         sbuf_printf(&sb,
 658                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR "
 659                 "    CWND SENDPIPE RECVPIPE "
 660 #ifdef  TCP_HC_COUNTERS
 661                 "HITS  UPD  "
 662 #endif
 663                 "EXP\n");
 664         sbuf_drain(&sb);
 665
 666 #define msec(u) (((u) + 500) / 1000)
 667         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 668                 THC_LOCK(&V_tcp_hostcache.hashbase[i]);
 669                 CK_SLIST_FOREACH(hc_entry,
 670                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q) {
 671                         sbuf_printf(&sb,
 672                             "%-15s %5u %8u %6lums %6lums %8u %8u %8u "
 673 #ifdef  TCP_HC_COUNTERS
 674                             "%4lu %4lu "
 675 #endif
 676                             "%4i\n",
 677                             hc_entry->ip4.s_addr ?
 678                                 inet_ntoa_r(hc_entry->ip4, ip4buf) :
 679 #ifdef INET6
 680                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 681 #else
 682                                 "IPv6?",
 683 #endif
 684                             hc_entry->rmx_mtu,
 685                             hc_entry->rmx_ssthresh,
 686                             msec((u_long)hc_entry->rmx_rtt *
 687                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 688                             msec((u_long)hc_entry->rmx_rttvar *
 689                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
 690                             hc_entry->rmx_cwnd,
 691                             hc_entry->rmx_sendpipe,
 692                             hc_entry->rmx_recvpipe,
 693 #ifdef  TCP_HC_COUNTERS
 694                             hc_entry->rmx_hits,
 695                             hc_entry->rmx_updates,
 696 #endif
 697                             hc_entry->rmx_expire);
 698                 }
 699                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i]);
 700                 sbuf_drain(&sb);
 701         }
 702 #undef msec
 703         error = sbuf_finish(&sb);
 704         sbuf_delete(&sb);
 705         return(error);
 706 }
 707
 708 /*
 709  * Sysctl function: prints a histogram of the hostcache hashbucket
 710  * utilization.
 711  */
 712 static int
 713 sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS)
 714 {
 715         const int linesize = 50;
 716         struct sbuf sb;
 717         int i, error;
 718         int *histo;
 719         u_int hch_length;
 720
 721         if (jailed_without_vnet(curthread->td_ucred) != 0)
 722                 return (EPERM);
 723
 724         histo = (int *)malloc(sizeof(int) * (V_tcp_hostcache.bucket_limit + 1),
 725                         M_TEMP, M_NOWAIT|M_ZERO);
 726         if (histo == NULL)
 727                 return(ENOMEM);
 728
 729         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 730                 hch_length = V_tcp_hostcache.hashbase[i].hch_length;
 731                 KASSERT(hch_length <= V_tcp_hostcache.bucket_limit,
 732                     ("tcp_hostcache: bucket limit exceeded at %u: %u",
 733                     i, hch_length));
 734                 histo[hch_length]++;
 735         }
 736
 737         /* Use a buffer for 16 lines */
 738         sbuf_new_for_sysctl(&sb, NULL, 16 * linesize, req);
 739
 740         sbuf_printf(&sb, "\nLength\tCount\n");
 741         for (i = 0; i <= V_tcp_hostcache.bucket_limit; i++) {
 742                 sbuf_printf(&sb, "%u\t%u\n", i, histo[i]);
 743         }
 744         error = sbuf_finish(&sb);
 745         sbuf_delete(&sb);
 746         free(histo, M_TEMP);
 747         return(error);
 748 }
 749
 750 /*
 751  * Caller has to make sure the curvnet is set properly.
 752  */
 753 static void
 754 tcp_hc_purge_internal(int all)
 755 {
 756         struct hc_head *head;
 757         struct hc_metrics *hc_entry, *hc_next, *hc_prev;
 758         int i;
 759
 760         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 761                 head = &V_tcp_hostcache.hashbase[i];
 762                 hc_prev = NULL;
 763                 THC_LOCK(head);
 764                 CK_SLIST_FOREACH_SAFE(hc_entry, &head->hch_bucket, rmx_q,
 765                     hc_next) {
 766                         KASSERT(head->hch_length > 0 && head->hch_length <=
 767                             V_tcp_hostcache.bucket_limit, ("tcp_hostcache: "
 768                             "bucket length out of range at %u: %u", i,
 769                             head->hch_length));
 770                         if (all ||
 771                             atomic_load_int(&hc_entry->rmx_expire) <= 0) {
 772                                 if (hc_prev != NULL) {
 773                                         KASSERT(hc_entry ==
 774                                             CK_SLIST_NEXT(hc_prev, rmx_q),
 775                                             ("%s: %p is not next to %p",
 776                                             __func__, hc_entry, hc_prev));
 777                                         CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
 778                                 } else {
 779                                         KASSERT(hc_entry ==
 780                                             CK_SLIST_FIRST(&head->hch_bucket),
 781                                             ("%s: %p is not first",
 782                                             __func__, hc_entry));
 783                                         CK_SLIST_REMOVE_HEAD(&head->hch_bucket,
 784                                             rmx_q);
 785                                 }
 786                                 uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
 787                                 head->hch_length--;
 788                                 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
 789                         } else {
 790                                 atomic_subtract_int(&hc_entry->rmx_expire,
 791                                     V_tcp_hostcache.prune);
 792                                 hc_prev = hc_entry;
 793                         }
 794                 }
 795                 THC_UNLOCK(head);
 796         }
 797 }
 798
 799 /*
 800  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
 801  * periodically from the callout.
 802  */
 803 static void
 804 tcp_hc_purge(void *arg)
 805 {
 806         CURVNET_SET((struct vnet *) arg);
 807         int all = 0;
 808
 809         if (V_tcp_hostcache.purgeall) {
 810                 if (V_tcp_hostcache.purgeall == 2)
 811                         V_tcp_hostcache.hashsalt = arc4random();
 812                 all = 1;
 813                 V_tcp_hostcache.purgeall = 0;
 814         }
 815
 816         tcp_hc_purge_internal(all);
 817
 818         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 819             tcp_hc_purge, arg);
 820         CURVNET_RESTORE();
 821 }
 822
 823 /*
 824  * Expire and purge all entries in hostcache immediately.
 825  */
 826 static int
 827 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)
 828 {
 829         int error, val;
 830
 831         val = 0;
 832         error = sysctl_handle_int(oidp, &val, 0, req);
 833         if (error || !req->newptr)
 834                 return (error);
 835
 836         if (val == 2)
 837                 V_tcp_hostcache.hashsalt = arc4random();
 838         tcp_hc_purge_internal(1);
 839
 840         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 841             tcp_hc_purge, curvnet);
 842
 843         return (0);
 844 }