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sys/netinet/tcp_hostcache.c

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    1 /*-
    2  * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. The name of the author may not be used to endorse or promote
   14  *    products derived from this software without specific prior written
   15  *    permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 /*
   31  * The tcp_hostcache moves the tcp-specific cached metrics from the routing
   32  * table to a dedicated structure indexed by the remote IP address.  It keeps
   33  * information on the measured TCP parameters of past TCP sessions to allow
   34  * better initial start values to be used with later connections to/from the
   35  * same source.  Depending on the network parameters (delay, bandwidth, max
   36  * MTU, congestion window) between local and remote sites, this can lead to
   37  * significant speed-ups for new TCP connections after the first one.
   38  *
   39  * Due to the tcp_hostcache, all TCP-specific metrics information in the
   40  * routing table have been removed.  The inpcb no longer keeps a pointer to
   41  * the routing entry, and protocol-initiated route cloning has been removed
   42  * as well.  With these changes, the routing table has gone back to being
   43  * more lightwight and only carries information related to packet forwarding.
   44  *
   45  * tcp_hostcache is designed for multiple concurrent access in SMP
   46  * environments and high contention.  All bucket rows have their own lock and
   47  * thus multiple lookups and modifies can be done at the same time as long as
   48  * they are in different bucket rows.  If a request for insertion of a new
   49  * record can't be satisfied, it simply returns an empty structure.  Nobody
   50  * and nothing outside of tcp_hostcache.c will ever point directly to any
   51  * entry in the tcp_hostcache.  All communication is done in an
   52  * object-oriented way and only functions of tcp_hostcache will manipulate
   53  * hostcache entries.  Otherwise, we are unable to achieve good behaviour in
   54  * concurrent access situations.  Since tcp_hostcache is only caching
   55  * information, there are no fatal consequences if we either can't satisfy
   56  * any particular request or have to drop/overwrite an existing entry because
   57  * of bucket limit memory constrains.
   58  */
   59 
   60 /*
   61  * Many thanks to jlemon for basic structure of tcp_syncache which is being
   62  * followed here.
   63  */
   64 
   65 #include <sys/cdefs.h>
   66 __FBSDID("$FreeBSD: releng/8.1/sys/netinet/tcp_hostcache.c 207695 2010-05-06 06:44:19Z bz $");
   67 
   68 #include "opt_inet6.h"
   69 
   70 #include <sys/param.h>
   71 #include <sys/systm.h>
   72 #include <sys/kernel.h>
   73 #include <sys/lock.h>
   74 #include <sys/mutex.h>
   75 #include <sys/malloc.h>
   76 #include <sys/socket.h>
   77 #include <sys/socketvar.h>
   78 #include <sys/sysctl.h>
   79 
   80 #include <net/if.h>
   81 #include <net/route.h>
   82 #include <net/vnet.h>
   83 
   84 #include <netinet/in.h>
   85 #include <netinet/in_systm.h>
   86 #include <netinet/ip.h>
   87 #include <netinet/in_var.h>
   88 #include <netinet/in_pcb.h>
   89 #include <netinet/ip_var.h>
   90 #ifdef INET6
   91 #include <netinet/ip6.h>
   92 #include <netinet6/ip6_var.h>
   93 #endif
   94 #include <netinet/tcp.h>
   95 #include <netinet/tcp_var.h>
   96 #include <netinet/tcp_hostcache.h>
   97 #ifdef INET6
   98 #include <netinet6/tcp6_var.h>
   99 #endif
  100 
  101 #include <vm/uma.h>
  102 
  103 /* Arbitrary values */
  104 #define TCP_HOSTCACHE_HASHSIZE          512
  105 #define TCP_HOSTCACHE_BUCKETLIMIT       30
  106 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
  107 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
  108 
  109 static VNET_DEFINE(struct tcp_hostcache, tcp_hostcache);
  110 #define V_tcp_hostcache         VNET(tcp_hostcache)
  111 
  112 static VNET_DEFINE(struct callout, tcp_hc_callout);
  113 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
  114 
  115 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
  116 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
  117 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
  118 static void tcp_hc_purge_internal(int);
  119 static void tcp_hc_purge(void *);
  120 
  121 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0,
  122     "TCP Host cache");
  123 
  124 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN,
  125     &VNET_NAME(tcp_hostcache.cache_limit), 0,
  126     "Overall entry limit for hostcache");
  127 
  128 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN,
  129     &VNET_NAME(tcp_hostcache.hashsize), 0,
  130     "Size of TCP hostcache hashtable");
  131 
  132 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
  133     CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
  134     "Per-bucket hash limit for hostcache");
  135 
  136 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD,
  137      &VNET_NAME(tcp_hostcache.cache_count), 0,
  138     "Current number of entries in hostcache");
  139 
  140 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW,
  141     &VNET_NAME(tcp_hostcache.expire), 0,
  142     "Expire time of TCP hostcache entries");
  143 
  144 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_RW,
  145     &VNET_NAME(tcp_hostcache.prune), 0,
  146     "Time between purge runs");
  147 
  148 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW,
  149     &VNET_NAME(tcp_hostcache.purgeall), 0,
  150     "Expire all entires on next purge run");
  151 
  152 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
  153     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
  154     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
  155 
  156 
  157 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
  158 
  159 #define HOSTCACHE_HASH(ip) \
  160         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
  161           V_tcp_hostcache.hashmask)
  162 
  163 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
  164 #define HOSTCACHE_HASH6(ip6)                            \
  165         (((ip6)->s6_addr32[0] ^                         \
  166           (ip6)->s6_addr32[1] ^                         \
  167           (ip6)->s6_addr32[2] ^                         \
  168           (ip6)->s6_addr32[3]) &                        \
  169          V_tcp_hostcache.hashmask)
  170 
  171 #define THC_LOCK(lp)            mtx_lock(lp)
  172 #define THC_UNLOCK(lp)          mtx_unlock(lp)
  173 
  174 void
  175 tcp_hc_init(void)
  176 {
  177         int i;
  178 
  179         /*
  180          * Initialize hostcache structures.
  181          */
  182         V_tcp_hostcache.cache_count = 0;
  183         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
  184         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
  185         V_tcp_hostcache.cache_limit =
  186             V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
  187         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
  188         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
  189 
  190         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
  191             &V_tcp_hostcache.hashsize);
  192         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
  193             &V_tcp_hostcache.cache_limit);
  194         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
  195             &V_tcp_hostcache.bucket_limit);
  196         if (!powerof2(V_tcp_hostcache.hashsize)) {
  197                 printf("WARNING: hostcache hash size is not a power of 2.\n");
  198                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
  199         }
  200         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
  201 
  202         /*
  203          * Allocate the hash table.
  204          */
  205         V_tcp_hostcache.hashbase = (struct hc_head *)
  206             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
  207                    M_HOSTCACHE, M_WAITOK | M_ZERO);
  208 
  209         /*
  210          * Initialize the hash buckets.
  211          */
  212         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  213                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
  214                 V_tcp_hostcache.hashbase[i].hch_length = 0;
  215                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
  216                           NULL, MTX_DEF);
  217         }
  218 
  219         /*
  220          * Allocate the hostcache entries.
  221          */
  222         V_tcp_hostcache.zone =
  223             uma_zcreate("hostcache", sizeof(struct hc_metrics),
  224             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
  225         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
  226 
  227         /*
  228          * Set up periodic cache cleanup.
  229          */
  230         callout_init(&V_tcp_hc_callout, CALLOUT_MPSAFE);
  231         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
  232             tcp_hc_purge, curvnet);
  233 }
  234 
  235 #ifdef VIMAGE
  236 void
  237 tcp_hc_destroy(void)
  238 {
  239         int i;
  240 
  241         callout_drain(&V_tcp_hc_callout);
  242 
  243         /* Purge all hc entries. */
  244         tcp_hc_purge_internal(1);
  245 
  246         /* Free the uma zone and the allocated hash table. */
  247         uma_zdestroy(V_tcp_hostcache.zone);
  248 
  249         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
  250                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
  251         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
  252 }
  253 #endif
  254 
  255 /*
  256  * Internal function: look up an entry in the hostcache or return NULL.
  257  *
  258  * If an entry has been returned, the caller becomes responsible for
  259  * unlocking the bucket row after he is done reading/modifying the entry.
  260  */
  261 static struct hc_metrics *
  262 tcp_hc_lookup(struct in_conninfo *inc)
  263 {
  264         int hash;
  265         struct hc_head *hc_head;
  266         struct hc_metrics *hc_entry;
  267 
  268         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
  269 
  270         /*
  271          * Hash the foreign ip address.
  272          */
  273         if (inc->inc_flags & INC_ISIPV6)
  274                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  275         else
  276                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  277 
  278         hc_head = &V_tcp_hostcache.hashbase[hash];
  279 
  280         /*
  281          * Acquire lock for this bucket row; we release the lock if we don't
  282          * find an entry, otherwise the caller has to unlock after he is
  283          * done.
  284          */
  285         THC_LOCK(&hc_head->hch_mtx);
  286 
  287         /*
  288          * Iterate through entries in bucket row looking for a match.
  289          */
  290         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
  291                 if (inc->inc_flags & INC_ISIPV6) {
  292                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
  293                             sizeof(inc->inc6_faddr)) == 0)
  294                                 return hc_entry;
  295                 } else {
  296                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
  297                             sizeof(inc->inc_faddr)) == 0)
  298                                 return hc_entry;
  299                 }
  300         }
  301 
  302         /*
  303          * We were unsuccessful and didn't find anything.
  304          */
  305         THC_UNLOCK(&hc_head->hch_mtx);
  306         return NULL;
  307 }
  308 
  309 /*
  310  * Internal function: insert an entry into the hostcache or return NULL if
  311  * unable to allocate a new one.
  312  *
  313  * If an entry has been returned, the caller becomes responsible for
  314  * unlocking the bucket row after he is done reading/modifying the entry.
  315  */
  316 static struct hc_metrics *
  317 tcp_hc_insert(struct in_conninfo *inc)
  318 {
  319         int hash;
  320         struct hc_head *hc_head;
  321         struct hc_metrics *hc_entry;
  322 
  323         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
  324 
  325         /*
  326          * Hash the foreign ip address.
  327          */
  328         if (inc->inc_flags & INC_ISIPV6)
  329                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  330         else
  331                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  332 
  333         hc_head = &V_tcp_hostcache.hashbase[hash];
  334 
  335         /*
  336          * Acquire lock for this bucket row; we release the lock if we don't
  337          * find an entry, otherwise the caller has to unlock after he is
  338          * done.
  339          */
  340         THC_LOCK(&hc_head->hch_mtx);
  341 
  342         /*
  343          * If the bucket limit is reached, reuse the least-used element.
  344          */
  345         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
  346             V_tcp_hostcache.cache_count >= V_tcp_hostcache.cache_limit) {
  347                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
  348                 /*
  349                  * At first we were dropping the last element, just to
  350                  * reacquire it in the next two lines again, which isn't very
  351                  * efficient.  Instead just reuse the least used element.
  352                  * We may drop something that is still "in-use" but we can be
  353                  * "lossy".
  354                  * Just give up if this bucket row is empty and we don't have
  355                  * anything to replace.
  356                  */
  357                 if (hc_entry == NULL) {
  358                         THC_UNLOCK(&hc_head->hch_mtx);
  359                         return NULL;
  360                 }
  361                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
  362                 V_tcp_hostcache.hashbase[hash].hch_length--;
  363                 V_tcp_hostcache.cache_count--;
  364                 TCPSTAT_INC(tcps_hc_bucketoverflow);
  365 #if 0
  366                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
  367 #endif
  368         } else {
  369                 /*
  370                  * Allocate a new entry, or balk if not possible.
  371                  */
  372                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
  373                 if (hc_entry == NULL) {
  374                         THC_UNLOCK(&hc_head->hch_mtx);
  375                         return NULL;
  376                 }
  377         }
  378 
  379         /*
  380          * Initialize basic information of hostcache entry.
  381          */
  382         bzero(hc_entry, sizeof(*hc_entry));
  383         if (inc->inc_flags & INC_ISIPV6)
  384                 bcopy(&inc->inc6_faddr, &hc_entry->ip6, sizeof(hc_entry->ip6));
  385         else
  386                 hc_entry->ip4 = inc->inc_faddr;
  387         hc_entry->rmx_head = hc_head;
  388         hc_entry->rmx_expire = V_tcp_hostcache.expire;
  389 
  390         /*
  391          * Put it upfront.
  392          */
  393         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
  394         V_tcp_hostcache.hashbase[hash].hch_length++;
  395         V_tcp_hostcache.cache_count++;
  396         TCPSTAT_INC(tcps_hc_added);
  397 
  398         return hc_entry;
  399 }
  400 
  401 /*
  402  * External function: look up an entry in the hostcache and fill out the
  403  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
  404  * a value is not set.
  405  */
  406 void
  407 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
  408 {
  409         struct hc_metrics *hc_entry;
  410 
  411         /*
  412          * Find the right bucket.
  413          */
  414         hc_entry = tcp_hc_lookup(inc);
  415 
  416         /*
  417          * If we don't have an existing object.
  418          */
  419         if (hc_entry == NULL) {
  420                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
  421                 return;
  422         }
  423         hc_entry->rmx_hits++;
  424         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  425 
  426         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
  427         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
  428         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
  429         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
  430         hc_metrics_lite->rmx_bandwidth = hc_entry->rmx_bandwidth;
  431         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
  432         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
  433         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
  434 
  435         /*
  436          * Unlock bucket row.
  437          */
  438         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  439 }
  440 
  441 /*
  442  * External function: look up an entry in the hostcache and return the
  443  * discovered path MTU.  Returns NULL if no entry is found or value is not
  444  * set.
  445  */
  446 u_long
  447 tcp_hc_getmtu(struct in_conninfo *inc)
  448 {
  449         struct hc_metrics *hc_entry;
  450         u_long mtu;
  451 
  452         hc_entry = tcp_hc_lookup(inc);
  453         if (hc_entry == NULL) {
  454                 return 0;
  455         }
  456         hc_entry->rmx_hits++;
  457         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  458 
  459         mtu = hc_entry->rmx_mtu;
  460         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  461         return mtu;
  462 }
  463 
  464 /*
  465  * External function: update the MTU value of an entry in the hostcache.
  466  * Creates a new entry if none was found.
  467  */
  468 void
  469 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
  470 {
  471         struct hc_metrics *hc_entry;
  472 
  473         /*
  474          * Find the right bucket.
  475          */
  476         hc_entry = tcp_hc_lookup(inc);
  477 
  478         /*
  479          * If we don't have an existing object, try to insert a new one.
  480          */
  481         if (hc_entry == NULL) {
  482                 hc_entry = tcp_hc_insert(inc);
  483                 if (hc_entry == NULL)
  484                         return;
  485         }
  486         hc_entry->rmx_updates++;
  487         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  488 
  489         hc_entry->rmx_mtu = mtu;
  490 
  491         /*
  492          * Put it upfront so we find it faster next time.
  493          */
  494         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  495         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  496 
  497         /*
  498          * Unlock bucket row.
  499          */
  500         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  501 }
  502 
  503 /*
  504  * External function: update the TCP metrics of an entry in the hostcache.
  505  * Creates a new entry if none was found.
  506  */
  507 void
  508 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
  509 {
  510         struct hc_metrics *hc_entry;
  511 
  512         hc_entry = tcp_hc_lookup(inc);
  513         if (hc_entry == NULL) {
  514                 hc_entry = tcp_hc_insert(inc);
  515                 if (hc_entry == NULL)
  516                         return;
  517         }
  518         hc_entry->rmx_updates++;
  519         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  520 
  521         if (hcml->rmx_rtt != 0) {
  522                 if (hc_entry->rmx_rtt == 0)
  523                         hc_entry->rmx_rtt = hcml->rmx_rtt;
  524                 else
  525                         hc_entry->rmx_rtt =
  526                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
  527                 TCPSTAT_INC(tcps_cachedrtt);
  528         }
  529         if (hcml->rmx_rttvar != 0) {
  530                 if (hc_entry->rmx_rttvar == 0)
  531                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
  532                 else
  533                         hc_entry->rmx_rttvar =
  534                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
  535                 TCPSTAT_INC(tcps_cachedrttvar);
  536         }
  537         if (hcml->rmx_ssthresh != 0) {
  538                 if (hc_entry->rmx_ssthresh == 0)
  539                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
  540                 else
  541                         hc_entry->rmx_ssthresh =
  542                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
  543                 TCPSTAT_INC(tcps_cachedssthresh);
  544         }
  545         if (hcml->rmx_bandwidth != 0) {
  546                 if (hc_entry->rmx_bandwidth == 0)
  547                         hc_entry->rmx_bandwidth = hcml->rmx_bandwidth;
  548                 else
  549                         hc_entry->rmx_bandwidth =
  550                             (hc_entry->rmx_bandwidth + hcml->rmx_bandwidth) / 2;
  551                 /* TCPSTAT_INC(tcps_cachedbandwidth); */
  552         }
  553         if (hcml->rmx_cwnd != 0) {
  554                 if (hc_entry->rmx_cwnd == 0)
  555                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
  556                 else
  557                         hc_entry->rmx_cwnd =
  558                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
  559                 /* TCPSTAT_INC(tcps_cachedcwnd); */
  560         }
  561         if (hcml->rmx_sendpipe != 0) {
  562                 if (hc_entry->rmx_sendpipe == 0)
  563                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
  564                 else
  565                         hc_entry->rmx_sendpipe =
  566                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
  567                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
  568         }
  569         if (hcml->rmx_recvpipe != 0) {
  570                 if (hc_entry->rmx_recvpipe == 0)
  571                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
  572                 else
  573                         hc_entry->rmx_recvpipe =
  574                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
  575                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
  576         }
  577 
  578         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  579         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  580         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  581 }
  582 
  583 /*
  584  * Sysctl function: prints the list and values of all hostcache entries in
  585  * unsorted order.
  586  */
  587 static int
  588 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
  589 {
  590         int bufsize;
  591         int linesize = 128;
  592         char *p, *buf;
  593         int len, i, error;
  594         struct hc_metrics *hc_entry;
  595 #ifdef INET6
  596         char ip6buf[INET6_ADDRSTRLEN];
  597 #endif
  598 
  599         bufsize = linesize * (V_tcp_hostcache.cache_count + 1);
  600 
  601         p = buf = (char *)malloc(bufsize, M_TEMP, M_WAITOK|M_ZERO);
  602 
  603         len = snprintf(p, linesize,
  604                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR BANDWIDTH "
  605                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
  606         p += len;
  607 
  608 #define msec(u) (((u) + 500) / 1000)
  609         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  610                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  611                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
  612                               rmx_q) {
  613                         len = snprintf(p, linesize,
  614                             "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu "
  615                             "%4lu %4lu %4i\n",
  616                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
  617 #ifdef INET6
  618                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
  619 #else
  620                                 "IPv6?",
  621 #endif
  622                             hc_entry->rmx_mtu,
  623                             hc_entry->rmx_ssthresh,
  624                             msec(hc_entry->rmx_rtt *
  625                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
  626                             msec(hc_entry->rmx_rttvar *
  627                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
  628                             hc_entry->rmx_bandwidth * 8,
  629                             hc_entry->rmx_cwnd,
  630                             hc_entry->rmx_sendpipe,
  631                             hc_entry->rmx_recvpipe,
  632                             hc_entry->rmx_hits,
  633                             hc_entry->rmx_updates,
  634                             hc_entry->rmx_expire);
  635                         p += len;
  636                 }
  637                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  638         }
  639 #undef msec
  640         error = SYSCTL_OUT(req, buf, p - buf);
  641         free(buf, M_TEMP);
  642         return(error);
  643 }
  644 
  645 /*
  646  * Caller has to make sure the curvnet is set properly.
  647  */
  648 static void
  649 tcp_hc_purge_internal(int all)
  650 {
  651         struct hc_metrics *hc_entry, *hc_next;
  652         int i;
  653 
  654         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  655                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  656                 TAILQ_FOREACH_SAFE(hc_entry,
  657                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
  658                         if (all || hc_entry->rmx_expire <= 0) {
  659                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
  660                                               hc_entry, rmx_q);
  661                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
  662                                 V_tcp_hostcache.hashbase[i].hch_length--;
  663                                 V_tcp_hostcache.cache_count--;
  664                         } else
  665                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
  666                 }
  667                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  668         }
  669 }
  670 
  671 /*
  672  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
  673  * periodically from the callout.
  674  */
  675 static void
  676 tcp_hc_purge(void *arg)
  677 {
  678         CURVNET_SET((struct vnet *) arg);
  679         int all = 0;
  680 
  681         if (V_tcp_hostcache.purgeall) {
  682                 all = 1;
  683                 V_tcp_hostcache.purgeall = 0;
  684         }
  685 
  686         tcp_hc_purge_internal(all);
  687 
  688         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
  689             tcp_hc_purge, arg);
  690         CURVNET_RESTORE();
  691 }

Cache object: 7d8046a6300f401eb8f5e89dec7ed42d


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