Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/tcp_hostcache.c
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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 __FBSDID("$FreeBSD$"); 70 71 #include "opt_inet6.h" 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/hash.h> 76 #include <sys/jail.h> 77 #include <sys/kernel.h> 78 #include <sys/lock.h> 79 #include <sys/mutex.h> 80 #include <sys/malloc.h> 81 #include <sys/proc.h> 82 #include <sys/sbuf.h> 83 #include <sys/smr.h> 84 #include <sys/socket.h> 85 #include <sys/socketvar.h> 86 #include <sys/sysctl.h> 87 88 #include <net/vnet.h> 89 90 #include <netinet/in.h> 91 #include <netinet/in_pcb.h> 92 #include <netinet/tcp.h> 93 #include <netinet/tcp_var.h> 94 95 #include <vm/uma.h> 96 97 struct hc_head { 98 CK_SLIST_HEAD(hc_qhead, hc_metrics) hch_bucket; 99 u_int hch_length; 100 struct mtx hch_mtx; 101 }; 102 103 struct hc_metrics { 104 /* housekeeping */ 105 CK_SLIST_ENTRY(hc_metrics) rmx_q; 106 struct in_addr ip4; /* IP address */ 107 struct in6_addr ip6; /* IP6 address */ 108 uint32_t ip6_zoneid; /* IPv6 scope zone id */ 109 /* endpoint specific values for tcp */ 110 uint32_t rmx_mtu; /* MTU for this path */ 111 uint32_t rmx_ssthresh; /* outbound gateway buffer limit */ 112 uint32_t rmx_rtt; /* estimated round trip time */ 113 uint32_t rmx_rttvar; /* estimated rtt variance */ 114 uint32_t rmx_cwnd; /* congestion window */ 115 uint32_t rmx_sendpipe; /* outbound delay-bandwidth product */ 116 uint32_t rmx_recvpipe; /* inbound delay-bandwidth product */ 117 /* TCP hostcache internal data */ 118 int rmx_expire; /* lifetime for object */ 119 #ifdef TCP_HC_COUNTERS 120 u_long rmx_hits; /* number of hits */ 121 u_long rmx_updates; /* number of updates */ 122 #endif 123 }; 124 125 struct tcp_hostcache { 126 struct hc_head *hashbase; 127 uma_zone_t zone; 128 smr_t smr; 129 u_int hashsize; 130 u_int hashmask; 131 u_int hashsalt; 132 u_int bucket_limit; 133 u_int cache_count; 134 u_int cache_limit; 135 int expire; 136 int prune; 137 int purgeall; 138 }; 139 140 /* Arbitrary values */ 141 #define TCP_HOSTCACHE_HASHSIZE 512 142 #define TCP_HOSTCACHE_BUCKETLIMIT 30 143 #define TCP_HOSTCACHE_EXPIRE 60*60 /* one hour */ 144 #define TCP_HOSTCACHE_PRUNE 5*60 /* every 5 minutes */ 145 146 VNET_DEFINE_STATIC(struct tcp_hostcache, tcp_hostcache); 147 #define V_tcp_hostcache VNET(tcp_hostcache) 148 149 VNET_DEFINE_STATIC(struct callout, tcp_hc_callout); 150 #define V_tcp_hc_callout VNET(tcp_hc_callout) 151 152 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *); 153 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS); 154 static int sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS); 155 static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS); 156 static void tcp_hc_purge_internal(int); 157 static void tcp_hc_purge(void *); 158 159 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, 160 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 161 "TCP Host cache"); 162 163 VNET_DEFINE(int, tcp_use_hostcache) = 1; 164 #define V_tcp_use_hostcache VNET(tcp_use_hostcache) 165 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW, 166 &VNET_NAME(tcp_use_hostcache), 0, 167 "Enable the TCP hostcache"); 168 169 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN, 170 &VNET_NAME(tcp_hostcache.cache_limit), 0, 171 "Overall entry limit for hostcache"); 172 173 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN, 174 &VNET_NAME(tcp_hostcache.hashsize), 0, 175 "Size of TCP hostcache hashtable"); 176 177 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit, 178 CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0, 179 "Per-bucket hash limit for hostcache"); 180 181 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD, 182 &VNET_NAME(tcp_hostcache.cache_count), 0, 183 "Current number of entries in hostcache"); 184 185 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW, 186 &VNET_NAME(tcp_hostcache.expire), 0, 187 "Expire time of TCP hostcache entries"); 188 189 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW, 190 &VNET_NAME(tcp_hostcache.prune), 0, 191 "Time between purge runs"); 192 193 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW, 194 &VNET_NAME(tcp_hostcache.purgeall), 0, 195 "Expire all entries on next purge run"); 196 197 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list, 198 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE, 199 0, 0, sysctl_tcp_hc_list, "A", 200 "List of all hostcache entries"); 201 202 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, histo, 203 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE, 204 0, 0, sysctl_tcp_hc_histo, "A", 205 "Print a histogram of hostcache hashbucket utilization"); 206 207 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow, 208 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 209 NULL, 0, sysctl_tcp_hc_purgenow, "I", 210 "Immediately purge all entries"); 211 212 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache"); 213 214 /* Use jenkins_hash32(), as in other parts of the tcp stack */ 215 #define HOSTCACHE_HASH(inc) \ 216 ((inc)->inc_flags & INC_ISIPV6) ? \ 217 (jenkins_hash32((inc)->inc6_faddr.s6_addr32, 4, \ 218 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask) \ 219 : \ 220 (jenkins_hash32(&(inc)->inc_faddr.s_addr, 1, \ 221 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask) 222 223 #define THC_LOCK(h) mtx_lock(&(h)->hch_mtx) 224 #define THC_UNLOCK(h) mtx_unlock(&(h)->hch_mtx) 225 226 void 227 tcp_hc_init(void) 228 { 229 u_int cache_limit; 230 int i; 231 232 /* 233 * Initialize hostcache structures. 234 */ 235 atomic_store_int(&V_tcp_hostcache.cache_count, 0); 236 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; 237 V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT; 238 V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE; 239 V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE; 240 V_tcp_hostcache.hashsalt = arc4random(); 241 242 TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize", 243 &V_tcp_hostcache.hashsize); 244 if (!powerof2(V_tcp_hostcache.hashsize)) { 245 printf("WARNING: hostcache hash size is not a power of 2.\n"); 246 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */ 247 } 248 V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1; 249 250 TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit", 251 &V_tcp_hostcache.bucket_limit); 252 253 cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit; 254 V_tcp_hostcache.cache_limit = cache_limit; 255 TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit", 256 &V_tcp_hostcache.cache_limit); 257 if (V_tcp_hostcache.cache_limit > cache_limit) 258 V_tcp_hostcache.cache_limit = cache_limit; 259 260 /* 261 * Allocate the hash table. 262 */ 263 V_tcp_hostcache.hashbase = (struct hc_head *) 264 malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head), 265 M_HOSTCACHE, M_WAITOK | M_ZERO); 266 267 /* 268 * Initialize the hash buckets. 269 */ 270 for (i = 0; i < V_tcp_hostcache.hashsize; i++) { 271 CK_SLIST_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket); 272 V_tcp_hostcache.hashbase[i].hch_length = 0; 273 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry", 274 NULL, MTX_DEF); 275 } 276 277 /* 278 * Allocate the hostcache entries. 279 */ 280 V_tcp_hostcache.zone = 281 uma_zcreate("hostcache", sizeof(struct hc_metrics), 282 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_SMR); 283 uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit); 284 V_tcp_hostcache.smr = uma_zone_get_smr(V_tcp_hostcache.zone); 285 286 /* 287 * Set up periodic cache cleanup. 288 */ 289 callout_init(&V_tcp_hc_callout, 1); 290 callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz, 291 tcp_hc_purge, curvnet); 292 } 293 294 #ifdef VIMAGE 295 void 296 tcp_hc_destroy(void) 297 { 298 int i; 299 300 callout_drain(&V_tcp_hc_callout); 301 302 /* Purge all hc entries. */ 303 tcp_hc_purge_internal(1); 304 305 /* Free the uma zone and the allocated hash table. */ 306 uma_zdestroy(V_tcp_hostcache.zone); 307 308 for (i = 0; i < V_tcp_hostcache.hashsize; i++) 309 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx); 310 free(V_tcp_hostcache.hashbase, M_HOSTCACHE); 311 } 312 #endif 313 314 /* 315 * Internal function: compare cache entry to a connection. 316 */ 317 static bool 318 tcp_hc_cmp(struct hc_metrics *hc_entry, struct in_conninfo *inc) 319 { 320 321 if (inc->inc_flags & INC_ISIPV6) { 322 /* XXX: check ip6_zoneid */ 323 if (memcmp(&inc->inc6_faddr, &hc_entry->ip6, 324 sizeof(inc->inc6_faddr)) == 0) 325 return (true); 326 } else { 327 if (memcmp(&inc->inc_faddr, &hc_entry->ip4, 328 sizeof(inc->inc_faddr)) == 0) 329 return (true); 330 } 331 332 return (false); 333 } 334 335 /* 336 * Internal function: look up an entry in the hostcache for read. 337 * On success returns in SMR section. 338 */ 339 static struct hc_metrics * 340 tcp_hc_lookup(struct in_conninfo *inc) 341 { 342 struct hc_head *hc_head; 343 struct hc_metrics *hc_entry; 344 345 KASSERT(inc != NULL, ("%s: NULL in_conninfo", __func__)); 346 347 hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)]; 348 349 /* 350 * Iterate through entries in bucket row looking for a match. 351 */ 352 smr_enter(V_tcp_hostcache.smr); 353 CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) 354 if (tcp_hc_cmp(hc_entry, inc)) 355 break; 356 357 if (hc_entry != NULL) { 358 if (atomic_load_int(&hc_entry->rmx_expire) != 359 V_tcp_hostcache.expire) 360 atomic_store_int(&hc_entry->rmx_expire, 361 V_tcp_hostcache.expire); 362 #ifdef TCP_HC_COUNTERS 363 hc_entry->rmx_hits++; 364 #endif 365 } else 366 smr_exit(V_tcp_hostcache.smr); 367 368 return (hc_entry); 369 } 370 371 /* 372 * External function: look up an entry in the hostcache and fill out the 373 * supplied TCP metrics structure. Fills in NULL when no entry was found or 374 * a value is not set. 375 */ 376 void 377 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite) 378 { 379 struct hc_metrics *hc_entry; 380 381 if (!V_tcp_use_hostcache) { 382 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite)); 383 return; 384 } 385 386 /* 387 * Find the right bucket. 388 */ 389 hc_entry = tcp_hc_lookup(inc); 390 391 /* 392 * If we don't have an existing object. 393 */ 394 if (hc_entry == NULL) { 395 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite)); 396 return; 397 } 398 399 hc_metrics_lite->rmx_mtu = atomic_load_32(&hc_entry->rmx_mtu); 400 hc_metrics_lite->rmx_ssthresh = atomic_load_32(&hc_entry->rmx_ssthresh); 401 hc_metrics_lite->rmx_rtt = atomic_load_32(&hc_entry->rmx_rtt); 402 hc_metrics_lite->rmx_rttvar = atomic_load_32(&hc_entry->rmx_rttvar); 403 hc_metrics_lite->rmx_cwnd = atomic_load_32(&hc_entry->rmx_cwnd); 404 hc_metrics_lite->rmx_sendpipe = atomic_load_32(&hc_entry->rmx_sendpipe); 405 hc_metrics_lite->rmx_recvpipe = atomic_load_32(&hc_entry->rmx_recvpipe); 406 407 smr_exit(V_tcp_hostcache.smr); 408 } 409 410 /* 411 * External function: look up an entry in the hostcache and return the 412 * discovered path MTU. Returns 0 if no entry is found or value is not 413 * set. 414 */ 415 uint32_t 416 tcp_hc_getmtu(struct in_conninfo *inc) 417 { 418 struct hc_metrics *hc_entry; 419 uint32_t mtu; 420 421 if (!V_tcp_use_hostcache) 422 return (0); 423 424 hc_entry = tcp_hc_lookup(inc); 425 if (hc_entry == NULL) { 426 return (0); 427 } 428 429 mtu = atomic_load_32(&hc_entry->rmx_mtu); 430 smr_exit(V_tcp_hostcache.smr); 431 432 return (mtu); 433 } 434 435 /* 436 * External function: update the MTU value of an entry in the hostcache. 437 * Creates a new entry if none was found. 438 */ 439 void 440 tcp_hc_updatemtu(struct in_conninfo *inc, uint32_t mtu) 441 { 442 struct hc_metrics_lite hcml = { .rmx_mtu = mtu }; 443 444 return (tcp_hc_update(inc, &hcml)); 445 } 446 447 /* 448 * External function: update the TCP metrics of an entry in the hostcache. 449 * Creates a new entry if none was found. 450 */ 451 void 452 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml) 453 { 454 struct hc_head *hc_head; 455 struct hc_metrics *hc_entry, *hc_prev; 456 uint32_t v; 457 bool new; 458 459 if (!V_tcp_use_hostcache) 460 return; 461 462 hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)]; 463 hc_prev = NULL; 464 465 THC_LOCK(hc_head); 466 CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) { 467 if (tcp_hc_cmp(hc_entry, inc)) 468 break; 469 if (CK_SLIST_NEXT(hc_entry, rmx_q) != NULL) 470 hc_prev = hc_entry; 471 } 472 473 if (hc_entry != NULL) { 474 if (atomic_load_int(&hc_entry->rmx_expire) != 475 V_tcp_hostcache.expire) 476 atomic_store_int(&hc_entry->rmx_expire, 477 V_tcp_hostcache.expire); 478 #ifdef TCP_HC_COUNTERS 479 hc_entry->rmx_updates++; 480 #endif 481 new = false; 482 } else { 483 /* 484 * Try to allocate a new entry. If the bucket limit is 485 * reached, delete the least-used element, located at the end 486 * of the CK_SLIST. During lookup we saved the pointer to 487 * the second to last element, in case if list has at least 2 488 * elements. This will allow to delete last element without 489 * extra traversal. 490 * 491 * Give up if the row is empty. 492 */ 493 if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit || 494 atomic_load_int(&V_tcp_hostcache.cache_count) >= 495 V_tcp_hostcache.cache_limit) { 496 if (hc_prev != NULL) { 497 hc_entry = CK_SLIST_NEXT(hc_prev, rmx_q); 498 KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL, 499 ("%s: %p is not one to last", 500 __func__, hc_prev)); 501 CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q); 502 } else if ((hc_entry = 503 CK_SLIST_FIRST(&hc_head->hch_bucket)) != NULL) { 504 KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL, 505 ("%s: %p is not the only element", 506 __func__, hc_entry)); 507 CK_SLIST_REMOVE_HEAD(&hc_head->hch_bucket, 508 rmx_q); 509 } else { 510 THC_UNLOCK(hc_head); 511 return; 512 } 513 KASSERT(hc_head->hch_length > 0 && 514 hc_head->hch_length <= V_tcp_hostcache.bucket_limit, 515 ("tcp_hostcache: bucket length violated at %p", 516 hc_head)); 517 hc_head->hch_length--; 518 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1); 519 TCPSTAT_INC(tcps_hc_bucketoverflow); 520 uma_zfree_smr(V_tcp_hostcache.zone, hc_entry); 521 } 522 523 /* 524 * Allocate a new entry, or balk if not possible. 525 */ 526 hc_entry = uma_zalloc_smr(V_tcp_hostcache.zone, M_NOWAIT); 527 if (hc_entry == NULL) { 528 THC_UNLOCK(hc_head); 529 return; 530 } 531 532 /* 533 * Initialize basic information of hostcache entry. 534 */ 535 bzero(hc_entry, sizeof(*hc_entry)); 536 if (inc->inc_flags & INC_ISIPV6) { 537 hc_entry->ip6 = inc->inc6_faddr; 538 hc_entry->ip6_zoneid = inc->inc6_zoneid; 539 } else 540 hc_entry->ip4 = inc->inc_faddr; 541 hc_entry->rmx_expire = V_tcp_hostcache.expire; 542 new = true; 543 } 544 545 /* 546 * Fill in data. Use atomics, since an existing entry is 547 * accessible by readers in SMR section. 548 */ 549 if (hcml->rmx_mtu != 0) { 550 atomic_store_32(&hc_entry->rmx_mtu, hcml->rmx_mtu); 551 } 552 if (hcml->rmx_rtt != 0) { 553 if (hc_entry->rmx_rtt == 0) 554 v = hcml->rmx_rtt; 555 else 556 v = ((uint64_t)hc_entry->rmx_rtt + 557 (uint64_t)hcml->rmx_rtt) / 2; 558 atomic_store_32(&hc_entry->rmx_rtt, v); 559 TCPSTAT_INC(tcps_cachedrtt); 560 } 561 if (hcml->rmx_rttvar != 0) { 562 if (hc_entry->rmx_rttvar == 0) 563 v = hcml->rmx_rttvar; 564 else 565 v = ((uint64_t)hc_entry->rmx_rttvar + 566 (uint64_t)hcml->rmx_rttvar) / 2; 567 atomic_store_32(&hc_entry->rmx_rttvar, v); 568 TCPSTAT_INC(tcps_cachedrttvar); 569 } 570 if (hcml->rmx_ssthresh != 0) { 571 if (hc_entry->rmx_ssthresh == 0) 572 v = hcml->rmx_ssthresh; 573 else 574 v = (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2; 575 atomic_store_32(&hc_entry->rmx_ssthresh, v); 576 TCPSTAT_INC(tcps_cachedssthresh); 577 } 578 if (hcml->rmx_cwnd != 0) { 579 if (hc_entry->rmx_cwnd == 0) 580 v = hcml->rmx_cwnd; 581 else 582 v = ((uint64_t)hc_entry->rmx_cwnd + 583 (uint64_t)hcml->rmx_cwnd) / 2; 584 atomic_store_32(&hc_entry->rmx_cwnd, v); 585 /* TCPSTAT_INC(tcps_cachedcwnd); */ 586 } 587 if (hcml->rmx_sendpipe != 0) { 588 if (hc_entry->rmx_sendpipe == 0) 589 v = hcml->rmx_sendpipe; 590 else 591 v = ((uint64_t)hc_entry->rmx_sendpipe + 592 (uint64_t)hcml->rmx_sendpipe) /2; 593 atomic_store_32(&hc_entry->rmx_sendpipe, v); 594 /* TCPSTAT_INC(tcps_cachedsendpipe); */ 595 } 596 if (hcml->rmx_recvpipe != 0) { 597 if (hc_entry->rmx_recvpipe == 0) 598 v = hcml->rmx_recvpipe; 599 else 600 v = ((uint64_t)hc_entry->rmx_recvpipe + 601 (uint64_t)hcml->rmx_recvpipe) /2; 602 atomic_store_32(&hc_entry->rmx_recvpipe, v); 603 /* TCPSTAT_INC(tcps_cachedrecvpipe); */ 604 } 605 606 /* 607 * Put it upfront. 608 */ 609 if (new) { 610 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q); 611 hc_head->hch_length++; 612 KASSERT(hc_head->hch_length <= V_tcp_hostcache.bucket_limit, 613 ("tcp_hostcache: bucket length too high at %p", hc_head)); 614 atomic_add_int(&V_tcp_hostcache.cache_count, 1); 615 TCPSTAT_INC(tcps_hc_added); 616 } else if (hc_entry != CK_SLIST_FIRST(&hc_head->hch_bucket)) { 617 KASSERT(CK_SLIST_NEXT(hc_prev, rmx_q) == hc_entry, 618 ("%s: %p next is not %p", __func__, hc_prev, hc_entry)); 619 CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q); 620 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q); 621 } 622 THC_UNLOCK(hc_head); 623 } 624 625 /* 626 * Sysctl function: prints the list and values of all hostcache entries in 627 * unsorted order. 628 */ 629 static int 630 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS) 631 { 632 const int linesize = 128; 633 struct sbuf sb; 634 int i, error, len; 635 struct hc_metrics *hc_entry; 636 char ip4buf[INET_ADDRSTRLEN]; 637 #ifdef INET6 638 char ip6buf[INET6_ADDRSTRLEN]; 639 #endif 640 641 if (jailed_without_vnet(curthread->td_ucred) != 0) 642 return (EPERM); 643 644 /* Optimize Buffer length query by sbin/sysctl */ 645 if (req->oldptr == NULL) { 646 len = (atomic_load_int(&V_tcp_hostcache.cache_count) + 1) * 647 linesize; 648 return (SYSCTL_OUT(req, NULL, len)); 649 } 650 651 error = sysctl_wire_old_buffer(req, 0); 652 if (error != 0) { 653 return(error); 654 } 655 656 /* Use a buffer sized for one full bucket */ 657 sbuf_new_for_sysctl(&sb, NULL, V_tcp_hostcache.bucket_limit * 658 linesize, req); 659 660 sbuf_printf(&sb, 661 "\nIP address MTU SSTRESH RTT RTTVAR " 662 " CWND SENDPIPE RECVPIPE " 663 #ifdef TCP_HC_COUNTERS 664 "HITS UPD " 665 #endif 666 "EXP\n"); 667 sbuf_drain(&sb); 668 669 #define msec(u) (((u) + 500) / 1000) 670 for (i = 0; i < V_tcp_hostcache.hashsize; i++) { 671 THC_LOCK(&V_tcp_hostcache.hashbase[i]); 672 CK_SLIST_FOREACH(hc_entry, 673 &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q) { 674 sbuf_printf(&sb, 675 "%-15s %5u %8u %6lums %6lums %8u %8u %8u " 676 #ifdef TCP_HC_COUNTERS 677 "%4lu %4lu " 678 #endif 679 "%4i\n", 680 hc_entry->ip4.s_addr ? 681 inet_ntoa_r(hc_entry->ip4, ip4buf) : 682 #ifdef INET6 683 ip6_sprintf(ip6buf, &hc_entry->ip6), 684 #else 685 "IPv6?", 686 #endif 687 hc_entry->rmx_mtu, 688 hc_entry->rmx_ssthresh, 689 msec((u_long)hc_entry->rmx_rtt * 690 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))), 691 msec((u_long)hc_entry->rmx_rttvar * 692 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))), 693 hc_entry->rmx_cwnd, 694 hc_entry->rmx_sendpipe, 695 hc_entry->rmx_recvpipe, 696 #ifdef TCP_HC_COUNTERS 697 hc_entry->rmx_hits, 698 hc_entry->rmx_updates, 699 #endif 700 hc_entry->rmx_expire); 701 } 702 THC_UNLOCK(&V_tcp_hostcache.hashbase[i]); 703 sbuf_drain(&sb); 704 } 705 #undef msec 706 error = sbuf_finish(&sb); 707 sbuf_delete(&sb); 708 return(error); 709 } 710 711 /* 712 * Sysctl function: prints a histogram of the hostcache hashbucket 713 * utilization. 714 */ 715 static int 716 sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS) 717 { 718 const int linesize = 50; 719 struct sbuf sb; 720 int i, error; 721 int *histo; 722 u_int hch_length; 723 724 if (jailed_without_vnet(curthread->td_ucred) != 0) 725 return (EPERM); 726 727 histo = (int *)malloc(sizeof(int) * (V_tcp_hostcache.bucket_limit + 1), 728 M_TEMP, M_NOWAIT|M_ZERO); 729 if (histo == NULL) 730 return(ENOMEM); 731 732 for (i = 0; i < V_tcp_hostcache.hashsize; i++) { 733 hch_length = V_tcp_hostcache.hashbase[i].hch_length; 734 KASSERT(hch_length <= V_tcp_hostcache.bucket_limit, 735 ("tcp_hostcache: bucket limit exceeded at %u: %u", 736 i, hch_length)); 737 histo[hch_length]++; 738 } 739 740 /* Use a buffer for 16 lines */ 741 sbuf_new_for_sysctl(&sb, NULL, 16 * linesize, req); 742 743 sbuf_printf(&sb, "\nLength\tCount\n"); 744 for (i = 0; i <= V_tcp_hostcache.bucket_limit; i++) { 745 sbuf_printf(&sb, "%u\t%u\n", i, histo[i]); 746 } 747 error = sbuf_finish(&sb); 748 sbuf_delete(&sb); 749 free(histo, M_TEMP); 750 return(error); 751 } 752 753 /* 754 * Caller has to make sure the curvnet is set properly. 755 */ 756 static void 757 tcp_hc_purge_internal(int all) 758 { 759 struct hc_head *head; 760 struct hc_metrics *hc_entry, *hc_next, *hc_prev; 761 int i; 762 763 for (i = 0; i < V_tcp_hostcache.hashsize; i++) { 764 head = &V_tcp_hostcache.hashbase[i]; 765 hc_prev = NULL; 766 THC_LOCK(head); 767 CK_SLIST_FOREACH_SAFE(hc_entry, &head->hch_bucket, rmx_q, 768 hc_next) { 769 KASSERT(head->hch_length > 0 && head->hch_length <= 770 V_tcp_hostcache.bucket_limit, ("tcp_hostcache: " 771 "bucket length out of range at %u: %u", i, 772 head->hch_length)); 773 if (all || 774 atomic_load_int(&hc_entry->rmx_expire) <= 0) { 775 if (hc_prev != NULL) { 776 KASSERT(hc_entry == 777 CK_SLIST_NEXT(hc_prev, rmx_q), 778 ("%s: %p is not next to %p", 779 __func__, hc_entry, hc_prev)); 780 CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q); 781 } else { 782 KASSERT(hc_entry == 783 CK_SLIST_FIRST(&head->hch_bucket), 784 ("%s: %p is not first", 785 __func__, hc_entry)); 786 CK_SLIST_REMOVE_HEAD(&head->hch_bucket, 787 rmx_q); 788 } 789 uma_zfree_smr(V_tcp_hostcache.zone, hc_entry); 790 head->hch_length--; 791 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1); 792 } else { 793 atomic_subtract_int(&hc_entry->rmx_expire, 794 V_tcp_hostcache.prune); 795 hc_prev = hc_entry; 796 } 797 } 798 THC_UNLOCK(head); 799 } 800 } 801 802 /* 803 * Expire and purge (old|all) entries in the tcp_hostcache. Runs 804 * periodically from the callout. 805 */ 806 static void 807 tcp_hc_purge(void *arg) 808 { 809 CURVNET_SET((struct vnet *) arg); 810 int all = 0; 811 812 if (V_tcp_hostcache.purgeall) { 813 if (V_tcp_hostcache.purgeall == 2) 814 V_tcp_hostcache.hashsalt = arc4random(); 815 all = 1; 816 V_tcp_hostcache.purgeall = 0; 817 } 818 819 tcp_hc_purge_internal(all); 820 821 callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz, 822 tcp_hc_purge, arg); 823 CURVNET_RESTORE(); 824 } 825 826 /* 827 * Expire and purge all entries in hostcache immediately. 828 */ 829 static int 830 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS) 831 { 832 int error, val; 833 834 val = 0; 835 error = sysctl_handle_int(oidp, &val, 0, req); 836 if (error || !req->newptr) 837 return (error); 838 839 if (val == 2) 840 V_tcp_hostcache.hashsalt = arc4random(); 841 tcp_hc_purge_internal(1); 842 843 callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz, 844 tcp_hc_purge, curvnet); 845 846 return (0); 847 }
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