net/ipv4/tcp_metrics.c

   1 #include <linux/rcupdate.h>
   2 #include <linux/spinlock.h>
   3 #include <linux/jiffies.h>
   4 #include <linux/module.h>
   5 #include <linux/cache.h>
   6 #include <linux/slab.h>
   7 #include <linux/init.h>
   8 #include <linux/tcp.h>
   9 #include <linux/hash.h>
  10 #include <linux/tcp_metrics.h>
  11 #include <linux/vmalloc.h>
  12
  13 #include <net/inet_connection_sock.h>
  14 #include <net/net_namespace.h>
  15 #include <net/request_sock.h>
  16 #include <net/inetpeer.h>
  17 #include <net/sock.h>
  18 #include <net/ipv6.h>
  19 #include <net/dst.h>
  20 #include <net/tcp.h>
  21 #include <net/genetlink.h>
  22
  23 int sysctl_tcp_nometrics_save __read_mostly;
  24
  25 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
  26                                                    const struct inetpeer_addr *daddr,
  27                                                    struct net *net, unsigned int hash);
  28
  29 struct tcp_fastopen_metrics {
  30         u16     mss;
  31         u16     syn_loss:10;            /* Recurring Fast Open SYN losses */
  32         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
  33         struct  tcp_fastopen_cookie     cookie;
  34 };
  35
  36 struct tcp_metrics_block {
  37         struct tcp_metrics_block __rcu  *tcpm_next;
  38         struct inetpeer_addr            tcpm_saddr;
  39         struct inetpeer_addr            tcpm_daddr;
  40         unsigned long                   tcpm_stamp;
  41         u32                             tcpm_ts;
  42         u32                             tcpm_ts_stamp;
  43         u32                             tcpm_lock;
  44         u32                             tcpm_vals[TCP_METRIC_MAX + 1];
  45         struct tcp_fastopen_metrics     tcpm_fastopen;
  46
  47         struct rcu_head                 rcu_head;
  48 };
  49
  50 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  51                               enum tcp_metric_index idx)
  52 {
  53         return tm->tcpm_lock & (1 << idx);
  54 }
  55
  56 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
  57                           enum tcp_metric_index idx)
  58 {
  59         return tm->tcpm_vals[idx];
  60 }
  61
  62 static u32 tcp_metric_get_jiffies(struct tcp_metrics_block *tm,
  63                                   enum tcp_metric_index idx)
  64 {
  65         return msecs_to_jiffies(tm->tcpm_vals[idx]);
  66 }
  67
  68 static void tcp_metric_set(struct tcp_metrics_block *tm,
  69                            enum tcp_metric_index idx,
  70                            u32 val)
  71 {
  72         tm->tcpm_vals[idx] = val;
  73 }
  74
  75 static void tcp_metric_set_msecs(struct tcp_metrics_block *tm,
  76                                  enum tcp_metric_index idx,
  77                                  u32 val)
  78 {
  79         tm->tcpm_vals[idx] = jiffies_to_msecs(val);
  80 }
  81
  82 static bool addr_same(const struct inetpeer_addr *a,
  83                       const struct inetpeer_addr *b)
  84 {
  85         const struct in6_addr *a6, *b6;
  86
  87         if (a->family != b->family)
  88                 return false;
  89         if (a->family == AF_INET)
  90                 return a->addr.a4 == b->addr.a4;
  91
  92         a6 = (const struct in6_addr *) &a->addr.a6[0];
  93         b6 = (const struct in6_addr *) &b->addr.a6[0];
  94
  95         return ipv6_addr_equal(a6, b6);
  96 }
  97
  98 struct tcpm_hash_bucket {
  99         struct tcp_metrics_block __rcu  *chain;
 100 };
 101
 102 static DEFINE_SPINLOCK(tcp_metrics_lock);
 103
 104 static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst,
 105                           bool fastopen_clear)
 106 {
 107         u32 val;
 108
 109         tm->tcpm_stamp = jiffies;
 110
 111         val = 0;
 112         if (dst_metric_locked(dst, RTAX_RTT))
 113                 val |= 1 << TCP_METRIC_RTT;
 114         if (dst_metric_locked(dst, RTAX_RTTVAR))
 115                 val |= 1 << TCP_METRIC_RTTVAR;
 116         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 117                 val |= 1 << TCP_METRIC_SSTHRESH;
 118         if (dst_metric_locked(dst, RTAX_CWND))
 119                 val |= 1 << TCP_METRIC_CWND;
 120         if (dst_metric_locked(dst, RTAX_REORDERING))
 121                 val |= 1 << TCP_METRIC_REORDERING;
 122         tm->tcpm_lock = val;
 123
 124         tm->tcpm_vals[TCP_METRIC_RTT] = dst_metric_raw(dst, RTAX_RTT);
 125         tm->tcpm_vals[TCP_METRIC_RTTVAR] = dst_metric_raw(dst, RTAX_RTTVAR);
 126         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
 127         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
 128         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 129         tm->tcpm_ts = 0;
 130         tm->tcpm_ts_stamp = 0;
 131         if (fastopen_clear) {
 132                 tm->tcpm_fastopen.mss = 0;
 133                 tm->tcpm_fastopen.syn_loss = 0;
 134                 tm->tcpm_fastopen.cookie.len = 0;
 135         }
 136 }
 137
 138 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 139
 140 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 141 {
 142         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 143                 tcpm_suck_dst(tm, dst, false);
 144 }
 145
 146 #define TCP_METRICS_RECLAIM_DEPTH       5
 147 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 148
 149 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 150                                           struct inetpeer_addr *saddr,
 151                                           struct inetpeer_addr *daddr,
 152                                           unsigned int hash)
 153 {
 154         struct tcp_metrics_block *tm;
 155         struct net *net;
 156         bool reclaim = false;
 157
 158         spin_lock_bh(&tcp_metrics_lock);
 159         net = dev_net(dst->dev);
 160
 161         /* While waiting for the spin-lock the cache might have been populated
 162          * with this entry and so we have to check again.
 163          */
 164         tm = __tcp_get_metrics(saddr, daddr, net, hash);
 165         if (tm == TCP_METRICS_RECLAIM_PTR) {
 166                 reclaim = true;
 167                 tm = NULL;
 168         }
 169         if (tm) {
 170                 tcpm_check_stamp(tm, dst);
 171                 goto out_unlock;
 172         }
 173
 174         if (unlikely(reclaim)) {
 175                 struct tcp_metrics_block *oldest;
 176
 177                 oldest = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain);
 178                 for (tm = rcu_dereference(oldest->tcpm_next); tm;
 179                      tm = rcu_dereference(tm->tcpm_next)) {
 180                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 181                                 oldest = tm;
 182                 }
 183                 tm = oldest;
 184         } else {
 185                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 186                 if (!tm)
 187                         goto out_unlock;
 188         }
 189         tm->tcpm_saddr = *saddr;
 190         tm->tcpm_daddr = *daddr;
 191
 192         tcpm_suck_dst(tm, dst, true);
 193
 194         if (likely(!reclaim)) {
 195                 tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
 196                 rcu_assign_pointer(net->ipv4.tcp_metrics_hash[hash].chain, tm);
 197         }
 198
 199 out_unlock:
 200         spin_unlock_bh(&tcp_metrics_lock);
 201         return tm;
 202 }
 203
 204 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 205 {
 206         if (tm)
 207                 return tm;
 208         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 209                 return TCP_METRICS_RECLAIM_PTR;
 210         return NULL;
 211 }
 212
 213 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 214                                                    const struct inetpeer_addr *daddr,
 215                                                    struct net *net, unsigned int hash)
 216 {
 217         struct tcp_metrics_block *tm;
 218         int depth = 0;
 219
 220         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 221              tm = rcu_dereference(tm->tcpm_next)) {
 222                 if (addr_same(&tm->tcpm_saddr, saddr) &&
 223                     addr_same(&tm->tcpm_daddr, daddr))
 224                         break;
 225                 depth++;
 226         }
 227         return tcp_get_encode(tm, depth);
 228 }
 229
 230 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 231                                                        struct dst_entry *dst)
 232 {
 233         struct tcp_metrics_block *tm;
 234         struct inetpeer_addr saddr, daddr;
 235         unsigned int hash;
 236         struct net *net;
 237
 238         saddr.family = req->rsk_ops->family;
 239         daddr.family = req->rsk_ops->family;
 240         switch (daddr.family) {
 241         case AF_INET:
 242                 saddr.addr.a4 = inet_rsk(req)->ir_loc_addr;
 243                 daddr.addr.a4 = inet_rsk(req)->ir_rmt_addr;
 244                 hash = (__force unsigned int) daddr.addr.a4;
 245                 break;
 246 #if IS_ENABLED(CONFIG_IPV6)
 247         case AF_INET6:
 248                 *(struct in6_addr *)saddr.addr.a6 = inet_rsk(req)->ir_v6_loc_addr;
 249                 *(struct in6_addr *)daddr.addr.a6 = inet_rsk(req)->ir_v6_rmt_addr;
 250                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 251                 break;
 252 #endif
 253         default:
 254                 return NULL;
 255         }
 256
 257         net = dev_net(dst->dev);
 258         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 259
 260         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 261              tm = rcu_dereference(tm->tcpm_next)) {
 262                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 263                     addr_same(&tm->tcpm_daddr, &daddr))
 264                         break;
 265         }
 266         tcpm_check_stamp(tm, dst);
 267         return tm;
 268 }
 269
 270 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 271 {
 272         struct tcp_metrics_block *tm;
 273         struct inetpeer_addr saddr, daddr;
 274         unsigned int hash;
 275         struct net *net;
 276
 277         saddr.family = tw->tw_family;
 278         daddr.family = tw->tw_family;
 279         switch (daddr.family) {
 280         case AF_INET:
 281                 saddr.addr.a4 = tw->tw_rcv_saddr;
 282                 daddr.addr.a4 = tw->tw_daddr;
 283                 hash = (__force unsigned int) daddr.addr.a4;
 284                 break;
 285 #if IS_ENABLED(CONFIG_IPV6)
 286         case AF_INET6:
 287                 *(struct in6_addr *)saddr.addr.a6 = tw->tw_v6_rcv_saddr;
 288                 *(struct in6_addr *)daddr.addr.a6 = tw->tw_v6_daddr;
 289                 hash = ipv6_addr_hash(&tw->tw_v6_daddr);
 290                 break;
 291 #endif
 292         default:
 293                 return NULL;
 294         }
 295
 296         net = twsk_net(tw);
 297         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 298
 299         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 300              tm = rcu_dereference(tm->tcpm_next)) {
 301                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 302                     addr_same(&tm->tcpm_daddr, &daddr))
 303                         break;
 304         }
 305         return tm;
 306 }
 307
 308 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 309                                                  struct dst_entry *dst,
 310                                                  bool create)
 311 {
 312         struct tcp_metrics_block *tm;
 313         struct inetpeer_addr saddr, daddr;
 314         unsigned int hash;
 315         struct net *net;
 316
 317         saddr.family = sk->sk_family;
 318         daddr.family = sk->sk_family;
 319         switch (daddr.family) {
 320         case AF_INET:
 321                 saddr.addr.a4 = inet_sk(sk)->inet_saddr;
 322                 daddr.addr.a4 = inet_sk(sk)->inet_daddr;
 323                 hash = (__force unsigned int) daddr.addr.a4;
 324                 break;
 325 #if IS_ENABLED(CONFIG_IPV6)
 326         case AF_INET6:
 327                 *(struct in6_addr *)saddr.addr.a6 = sk->sk_v6_rcv_saddr;
 328                 *(struct in6_addr *)daddr.addr.a6 = sk->sk_v6_daddr;
 329                 hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 330                 break;
 331 #endif
 332         default:
 333                 return NULL;
 334         }
 335
 336         net = dev_net(dst->dev);
 337         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 338
 339         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 340         if (tm == TCP_METRICS_RECLAIM_PTR)
 341                 tm = NULL;
 342         if (!tm && create)
 343                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 344         else
 345                 tcpm_check_stamp(tm, dst);
 346
 347         return tm;
 348 }
 349
 350 /* Save metrics learned by this TCP session.  This function is called
 351  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 352  * or goes from LAST-ACK to CLOSE.
 353  */
 354 void tcp_update_metrics(struct sock *sk)
 355 {
 356         const struct inet_connection_sock *icsk = inet_csk(sk);
 357         struct dst_entry *dst = __sk_dst_get(sk);
 358         struct tcp_sock *tp = tcp_sk(sk);
 359         struct tcp_metrics_block *tm;
 360         unsigned long rtt;
 361         u32 val;
 362         int m;
 363
 364         if (sysctl_tcp_nometrics_save || !dst)
 365                 return;
 366
 367         if (dst->flags & DST_HOST)
 368                 dst_confirm(dst);
 369
 370         rcu_read_lock();
 371         if (icsk->icsk_backoff || !tp->srtt) {
 372                 /* This session failed to estimate rtt. Why?
 373                  * Probably, no packets returned in time.  Reset our
 374                  * results.
 375                  */
 376                 tm = tcp_get_metrics(sk, dst, false);
 377                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 378                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 379                 goto out_unlock;
 380         } else
 381                 tm = tcp_get_metrics(sk, dst, true);
 382
 383         if (!tm)
 384                 goto out_unlock;
 385
 386         rtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
 387         m = rtt - tp->srtt;
 388
 389         /* If newly calculated rtt larger than stored one, store new
 390          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 391          * always better than underestimation.
 392          */
 393         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 394                 if (m <= 0)
 395                         rtt = tp->srtt;
 396                 else
 397                         rtt -= (m >> 3);
 398                 tcp_metric_set_msecs(tm, TCP_METRIC_RTT, rtt);
 399         }
 400
 401         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 402                 unsigned long var;
 403
 404                 if (m < 0)
 405                         m = -m;
 406
 407                 /* Scale deviation to rttvar fixed point */
 408                 m >>= 1;
 409                 if (m < tp->mdev)
 410                         m = tp->mdev;
 411
 412                 var = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
 413                 if (m >= var)
 414                         var = m;
 415                 else
 416                         var -= (var - m) >> 2;
 417
 418                 tcp_metric_set_msecs(tm, TCP_METRIC_RTTVAR, var);
 419         }
 420
 421         if (tcp_in_initial_slowstart(tp)) {
 422                 /* Slow start still did not finish. */
 423                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 424                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 425                         if (val && (tp->snd_cwnd >> 1) > val)
 426                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 427                                                tp->snd_cwnd >> 1);
 428                 }
 429                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 430                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 431                         if (tp->snd_cwnd > val)
 432                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 433                                                tp->snd_cwnd);
 434                 }
 435         } else if (tp->snd_cwnd > tp->snd_ssthresh &&
 436                    icsk->icsk_ca_state == TCP_CA_Open) {
 437                 /* Cong. avoidance phase, cwnd is reliable. */
 438                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 439                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 440                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 441                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 442                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 443                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 444                 }
 445         } else {
 446                 /* Else slow start did not finish, cwnd is non-sense,
 447                  * ssthresh may be also invalid.
 448                  */
 449                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 450                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 451                         tcp_metric_set(tm, TCP_METRIC_CWND,
 452                                        (val + tp->snd_ssthresh) >> 1);
 453                 }
 454                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 455                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 456                         if (val && tp->snd_ssthresh > val)
 457                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 458                                                tp->snd_ssthresh);
 459                 }
 460                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 461                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 462                         if (val < tp->reordering &&
 463                             tp->reordering != sysctl_tcp_reordering)
 464                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 465                                                tp->reordering);
 466                 }
 467         }
 468         tm->tcpm_stamp = jiffies;
 469 out_unlock:
 470         rcu_read_unlock();
 471 }
 472
 473 /* Initialize metrics on socket. */
 474
 475 void tcp_init_metrics(struct sock *sk)
 476 {
 477         struct dst_entry *dst = __sk_dst_get(sk);
 478         struct tcp_sock *tp = tcp_sk(sk);
 479         struct tcp_metrics_block *tm;
 480         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 481
 482         if (dst == NULL)
 483                 goto reset;
 484
 485         dst_confirm(dst);
 486
 487         rcu_read_lock();
 488         tm = tcp_get_metrics(sk, dst, true);
 489         if (!tm) {
 490                 rcu_read_unlock();
 491                 goto reset;
 492         }
 493
 494         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 495                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 496
 497         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 498         if (val) {
 499                 tp->snd_ssthresh = val;
 500                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 501                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 502         } else {
 503                 /* ssthresh may have been reduced unnecessarily during.
 504                  * 3WHS. Restore it back to its initial default.
 505                  */
 506                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 507         }
 508         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 509         if (val && tp->reordering != val) {
 510                 tcp_disable_fack(tp);
 511                 tcp_disable_early_retrans(tp);
 512                 tp->reordering = val;
 513         }
 514
 515         crtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
 516         rcu_read_unlock();
 517 reset:
 518         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 519          * to seed the RTO for later data packets because SYN packets are
 520          * small. Use the per-dst cached values to seed the RTO but keep
 521          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 522          * Later the RTO will be updated immediately upon obtaining the first
 523          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 524          * influences the first RTO but not later RTT estimation.
 525          *
 526          * But if RTT is not available from the SYN (due to retransmits or
 527          * syn cookies) or the cache, force a conservative 3secs timeout.
 528          *
 529          * A bit of theory. RTT is time passed after "normal" sized packet
 530          * is sent until it is ACKed. In normal circumstances sending small
 531          * packets force peer to delay ACKs and calculation is correct too.
 532          * The algorithm is adaptive and, provided we follow specs, it
 533          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 534          * tricks sort of "quick acks" for time long enough to decrease RTT
 535          * to low value, and then abruptly stops to do it and starts to delay
 536          * ACKs, wait for troubles.
 537          */
 538         if (crtt > tp->srtt) {
 539                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 540                 crtt >>= 3;
 541                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 542         } else if (tp->srtt == 0) {
 543                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 544                  * 3WHS. This is most likely due to retransmission,
 545                  * including spurious one. Reset the RTO back to 3secs
 546                  * from the more aggressive 1sec to avoid more spurious
 547                  * retransmission.
 548                  */
 549                 tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
 550                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 551         }
 552         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 553          * retransmitted. In light of RFC6298 more aggressive 1sec
 554          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 555          * retransmission has occurred.
 556          */
 557         if (tp->total_retrans > 1)
 558                 tp->snd_cwnd = 1;
 559         else
 560                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 561         tp->snd_cwnd_stamp = tcp_time_stamp;
 562 }
 563
 564 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check)
 565 {
 566         struct tcp_metrics_block *tm;
 567         bool ret;
 568
 569         if (!dst)
 570                 return false;
 571
 572         rcu_read_lock();
 573         tm = __tcp_get_metrics_req(req, dst);
 574         if (paws_check) {
 575                 if (tm &&
 576                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 577                     (s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW)
 578                         ret = false;
 579                 else
 580                         ret = true;
 581         } else {
 582                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 583                         ret = true;
 584                 else
 585                         ret = false;
 586         }
 587         rcu_read_unlock();
 588
 589         return ret;
 590 }
 591 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 592
 593 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 594 {
 595         struct tcp_metrics_block *tm;
 596
 597         rcu_read_lock();
 598         tm = tcp_get_metrics(sk, dst, true);
 599         if (tm) {
 600                 struct tcp_sock *tp = tcp_sk(sk);
 601
 602                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 603                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 604                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 605                 }
 606         }
 607         rcu_read_unlock();
 608 }
 609 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 610
 611 /* VJ's idea. Save last timestamp seen from this destination and hold
 612  * it at least for normal timewait interval to use for duplicate
 613  * segment detection in subsequent connections, before they enter
 614  * synchronized state.
 615  */
 616 bool tcp_remember_stamp(struct sock *sk)
 617 {
 618         struct dst_entry *dst = __sk_dst_get(sk);
 619         bool ret = false;
 620
 621         if (dst) {
 622                 struct tcp_metrics_block *tm;
 623
 624                 rcu_read_lock();
 625                 tm = tcp_get_metrics(sk, dst, true);
 626                 if (tm) {
 627                         struct tcp_sock *tp = tcp_sk(sk);
 628
 629                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 630                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 631                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 632                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 633                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 634                         }
 635                         ret = true;
 636                 }
 637                 rcu_read_unlock();
 638         }
 639         return ret;
 640 }
 641
 642 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 643 {
 644         struct tcp_metrics_block *tm;
 645         bool ret = false;
 646
 647         rcu_read_lock();
 648         tm = __tcp_get_metrics_tw(tw);
 649         if (tm) {
 650                 const struct tcp_timewait_sock *tcptw;
 651                 struct sock *sk = (struct sock *) tw;
 652
 653                 tcptw = tcp_twsk(sk);
 654                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 655                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 656                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 657                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 658                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 659                 }
 660                 ret = true;
 661         }
 662         rcu_read_unlock();
 663
 664         return ret;
 665 }
 666
 667 static DEFINE_SEQLOCK(fastopen_seqlock);
 668
 669 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 670                             struct tcp_fastopen_cookie *cookie,
 671                             int *syn_loss, unsigned long *last_syn_loss)
 672 {
 673         struct tcp_metrics_block *tm;
 674
 675         rcu_read_lock();
 676         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 677         if (tm) {
 678                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 679                 unsigned int seq;
 680
 681                 do {
 682                         seq = read_seqbegin(&fastopen_seqlock);
 683                         if (tfom->mss)
 684                                 *mss = tfom->mss;
 685                         *cookie = tfom->cookie;
 686                         *syn_loss = tfom->syn_loss;
 687                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 688                 } while (read_seqretry(&fastopen_seqlock, seq));
 689         }
 690         rcu_read_unlock();
 691 }
 692
 693 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 694                             struct tcp_fastopen_cookie *cookie, bool syn_lost)
 695 {
 696         struct dst_entry *dst = __sk_dst_get(sk);
 697         struct tcp_metrics_block *tm;
 698
 699         if (!dst)
 700                 return;
 701         rcu_read_lock();
 702         tm = tcp_get_metrics(sk, dst, true);
 703         if (tm) {
 704                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 705
 706                 write_seqlock_bh(&fastopen_seqlock);
 707                 if (mss)
 708                         tfom->mss = mss;
 709                 if (cookie && cookie->len > 0)
 710                         tfom->cookie = *cookie;
 711                 if (syn_lost) {
 712                         ++tfom->syn_loss;
 713                         tfom->last_syn_loss = jiffies;
 714                 } else
 715                         tfom->syn_loss = 0;
 716                 write_sequnlock_bh(&fastopen_seqlock);
 717         }
 718         rcu_read_unlock();
 719 }
 720
 721 static struct genl_family tcp_metrics_nl_family = {
 722         .id             = GENL_ID_GENERATE,
 723         .hdrsize        = 0,
 724         .name           = TCP_METRICS_GENL_NAME,
 725         .version        = TCP_METRICS_GENL_VERSION,
 726         .maxattr        = TCP_METRICS_ATTR_MAX,
 727         .netnsok        = true,
 728 };
 729
 730 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 731         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 732         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 733                                             .len = sizeof(struct in6_addr), },
 734         /* Following attributes are not received for GET/DEL,
 735          * we keep them for reference
 736          */
 737 #if 0
 738         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 739         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 740         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 741         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 742         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 743         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 744         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 745         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 746                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 747 #endif
 748 };
 749
 750 /* Add attributes, caller cancels its header on failure */
 751 static int tcp_metrics_fill_info(struct sk_buff *msg,
 752                                  struct tcp_metrics_block *tm)
 753 {
 754         struct nlattr *nest;
 755         int i;
 756
 757         switch (tm->tcpm_daddr.family) {
 758         case AF_INET:
 759                 if (nla_put_be32(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 760                                 tm->tcpm_daddr.addr.a4) < 0)
 761                         goto nla_put_failure;
 762                 if (nla_put_be32(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 763                                 tm->tcpm_saddr.addr.a4) < 0)
 764                         goto nla_put_failure;
 765                 break;
 766         case AF_INET6:
 767                 if (nla_put(msg, TCP_METRICS_ATTR_ADDR_IPV6, 16,
 768                             tm->tcpm_daddr.addr.a6) < 0)
 769                         goto nla_put_failure;
 770                 if (nla_put(msg, TCP_METRICS_ATTR_SADDR_IPV6, 16,
 771                             tm->tcpm_saddr.addr.a6) < 0)
 772                         goto nla_put_failure;
 773                 break;
 774         default:
 775                 return -EAFNOSUPPORT;
 776         }
 777
 778         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 779                           jiffies - tm->tcpm_stamp) < 0)
 780                 goto nla_put_failure;
 781         if (tm->tcpm_ts_stamp) {
 782                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 783                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 784                         goto nla_put_failure;
 785                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 786                                 tm->tcpm_ts) < 0)
 787                         goto nla_put_failure;
 788         }
 789
 790         {
 791                 int n = 0;
 792
 793                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 794                 if (!nest)
 795                         goto nla_put_failure;
 796                 for (i = 0; i < TCP_METRIC_MAX + 1; i++) {
 797                         if (!tm->tcpm_vals[i])
 798                                 continue;
 799                         if (nla_put_u32(msg, i + 1, tm->tcpm_vals[i]) < 0)
 800                                 goto nla_put_failure;
 801                         n++;
 802                 }
 803                 if (n)
 804                         nla_nest_end(msg, nest);
 805                 else
 806                         nla_nest_cancel(msg, nest);
 807         }
 808
 809         {
 810                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 811                 unsigned int seq;
 812
 813                 do {
 814                         seq = read_seqbegin(&fastopen_seqlock);
 815                         tfom_copy[0] = tm->tcpm_fastopen;
 816                 } while (read_seqretry(&fastopen_seqlock, seq));
 817
 818                 tfom = tfom_copy;
 819                 if (tfom->mss &&
 820                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 821                                 tfom->mss) < 0)
 822                         goto nla_put_failure;
 823                 if (tfom->syn_loss &&
 824                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 825                                 tfom->syn_loss) < 0 ||
 826                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 827                                 jiffies - tfom->last_syn_loss) < 0))
 828                         goto nla_put_failure;
 829                 if (tfom->cookie.len > 0 &&
 830                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 831                             tfom->cookie.len, tfom->cookie.val) < 0)
 832                         goto nla_put_failure;
 833         }
 834
 835         return 0;
 836
 837 nla_put_failure:
 838         return -EMSGSIZE;
 839 }
 840
 841 static int tcp_metrics_dump_info(struct sk_buff *skb,
 842                                  struct netlink_callback *cb,
 843                                  struct tcp_metrics_block *tm)
 844 {
 845         void *hdr;
 846
 847         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 848                           &tcp_metrics_nl_family, NLM_F_MULTI,
 849                           TCP_METRICS_CMD_GET);
 850         if (!hdr)
 851                 return -EMSGSIZE;
 852
 853         if (tcp_metrics_fill_info(skb, tm) < 0)
 854                 goto nla_put_failure;
 855
 856         return genlmsg_end(skb, hdr);
 857
 858 nla_put_failure:
 859         genlmsg_cancel(skb, hdr);
 860         return -EMSGSIZE;
 861 }
 862
 863 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 864                                struct netlink_callback *cb)
 865 {
 866         struct net *net = sock_net(skb->sk);
 867         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 868         unsigned int row, s_row = cb->args[0];
 869         int s_col = cb->args[1], col = s_col;
 870
 871         for (row = s_row; row < max_rows; row++, s_col = 0) {
 872                 struct tcp_metrics_block *tm;
 873                 struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash + row;
 874
 875                 rcu_read_lock();
 876                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 877                      tm = rcu_dereference(tm->tcpm_next), col++) {
 878                         if (col < s_col)
 879                                 continue;
 880                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 881                                 rcu_read_unlock();
 882                                 goto done;
 883                         }
 884                 }
 885                 rcu_read_unlock();
 886         }
 887
 888 done:
 889         cb->args[0] = row;
 890         cb->args[1] = col;
 891         return skb->len;
 892 }
 893
 894 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 895                            unsigned int *hash, int optional, int v4, int v6)
 896 {
 897         struct nlattr *a;
 898
 899         a = info->attrs[v4];
 900         if (a) {
 901                 addr->family = AF_INET;
 902                 addr->addr.a4 = nla_get_be32(a);
 903                 if (hash)
 904                         *hash = (__force unsigned int) addr->addr.a4;
 905                 return 0;
 906         }
 907         a = info->attrs[v6];
 908         if (a) {
 909                 if (nla_len(a) != sizeof(struct in6_addr))
 910                         return -EINVAL;
 911                 addr->family = AF_INET6;
 912                 memcpy(addr->addr.a6, nla_data(a), sizeof(addr->addr.a6));
 913                 if (hash)
 914                         *hash = ipv6_addr_hash((struct in6_addr *) addr->addr.a6);
 915                 return 0;
 916         }
 917         return optional ? 1 : -EAFNOSUPPORT;
 918 }
 919
 920 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 921                          unsigned int *hash, int optional)
 922 {
 923         return __parse_nl_addr(info, addr, hash, optional,
 924                                TCP_METRICS_ATTR_ADDR_IPV4,
 925                                TCP_METRICS_ATTR_ADDR_IPV6);
 926 }
 927
 928 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 929 {
 930         return __parse_nl_addr(info, addr, NULL, 0,
 931                                TCP_METRICS_ATTR_SADDR_IPV4,
 932                                TCP_METRICS_ATTR_SADDR_IPV6);
 933 }
 934
 935 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 936 {
 937         struct tcp_metrics_block *tm;
 938         struct inetpeer_addr saddr, daddr;
 939         unsigned int hash;
 940         struct sk_buff *msg;
 941         struct net *net = genl_info_net(info);
 942         void *reply;
 943         int ret;
 944         bool src = true;
 945
 946         ret = parse_nl_addr(info, &daddr, &hash, 0);
 947         if (ret < 0)
 948                 return ret;
 949
 950         ret = parse_nl_saddr(info, &saddr);
 951         if (ret < 0)
 952                 src = false;
 953
 954         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 955         if (!msg)
 956                 return -ENOMEM;
 957
 958         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 959                                   info->genlhdr->cmd);
 960         if (!reply)
 961                 goto nla_put_failure;
 962
 963         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 964         ret = -ESRCH;
 965         rcu_read_lock();
 966         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 967              tm = rcu_dereference(tm->tcpm_next)) {
 968                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 969                     (!src || addr_same(&tm->tcpm_saddr, &saddr))) {
 970                         ret = tcp_metrics_fill_info(msg, tm);
 971                         break;
 972                 }
 973         }
 974         rcu_read_unlock();
 975         if (ret < 0)
 976                 goto out_free;
 977
 978         genlmsg_end(msg, reply);
 979         return genlmsg_reply(msg, info);
 980
 981 nla_put_failure:
 982         ret = -EMSGSIZE;
 983
 984 out_free:
 985         nlmsg_free(msg);
 986         return ret;
 987 }
 988
 989 #define deref_locked_genl(p)    \
 990         rcu_dereference_protected(p, lockdep_genl_is_held() && \
 991                                      lockdep_is_held(&tcp_metrics_lock))
 992
 993 #define deref_genl(p)   rcu_dereference_protected(p, lockdep_genl_is_held())
 994
 995 static int tcp_metrics_flush_all(struct net *net)
 996 {
 997         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 998         struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash;
 999         struct tcp_metrics_block *tm;
1000         unsigned int row;
1001
1002         for (row = 0; row < max_rows; row++, hb++) {
1003                 spin_lock_bh(&tcp_metrics_lock);
1004                 tm = deref_locked_genl(hb->chain);
1005                 if (tm)
1006                         hb->chain = NULL;
1007                 spin_unlock_bh(&tcp_metrics_lock);
1008                 while (tm) {
1009                         struct tcp_metrics_block *next;
1010
1011                         next = deref_genl(tm->tcpm_next);
1012                         kfree_rcu(tm, rcu_head);
1013                         tm = next;
1014                 }
1015         }
1016         return 0;
1017 }
1018
1019 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
1020 {
1021         struct tcpm_hash_bucket *hb;
1022         struct tcp_metrics_block *tm;
1023         struct tcp_metrics_block __rcu **pp;
1024         struct inetpeer_addr saddr, daddr;
1025         unsigned int hash;
1026         struct net *net = genl_info_net(info);
1027         int ret;
1028         bool src = true, found = false;
1029
1030         ret = parse_nl_addr(info, &daddr, &hash, 1);
1031         if (ret < 0)
1032                 return ret;
1033         if (ret > 0)
1034                 return tcp_metrics_flush_all(net);
1035         ret = parse_nl_saddr(info, &saddr);
1036         if (ret < 0)
1037                 src = false;
1038
1039         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
1040         hb = net->ipv4.tcp_metrics_hash + hash;
1041         pp = &hb->chain;
1042         spin_lock_bh(&tcp_metrics_lock);
1043         for (tm = deref_locked_genl(*pp); tm; tm = deref_locked_genl(*pp)) {
1044                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1045                     (!src || addr_same(&tm->tcpm_saddr, &saddr))) {
1046                         *pp = tm->tcpm_next;
1047                         kfree_rcu(tm, rcu_head);
1048                         found = true;
1049                 } else {
1050                         pp = &tm->tcpm_next;
1051                 }
1052         }
1053         spin_unlock_bh(&tcp_metrics_lock);
1054         if (!found)
1055                 return -ESRCH;
1056         return 0;
1057 }
1058
1059 static const struct genl_ops tcp_metrics_nl_ops[] = {
1060         {
1061                 .cmd = TCP_METRICS_CMD_GET,
1062                 .doit = tcp_metrics_nl_cmd_get,
1063                 .dumpit = tcp_metrics_nl_dump,
1064                 .policy = tcp_metrics_nl_policy,
1065                 .flags = GENL_ADMIN_PERM,
1066         },
1067         {
1068                 .cmd = TCP_METRICS_CMD_DEL,
1069                 .doit = tcp_metrics_nl_cmd_del,
1070                 .policy = tcp_metrics_nl_policy,
1071                 .flags = GENL_ADMIN_PERM,
1072         },
1073 };
1074
1075 static unsigned int tcpmhash_entries;
1076 static int __init set_tcpmhash_entries(char *str)
1077 {
1078         ssize_t ret;
1079
1080         if (!str)
1081                 return 0;
1082
1083         ret = kstrtouint(str, 0, &tcpmhash_entries);
1084         if (ret)
1085                 return 0;
1086
1087         return 1;
1088 }
1089 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1090
1091 static int __net_init tcp_net_metrics_init(struct net *net)
1092 {
1093         size_t size;
1094         unsigned int slots;
1095
1096         slots = tcpmhash_entries;
1097         if (!slots) {
1098                 if (totalram_pages >= 128 * 1024)
1099                         slots = 16 * 1024;
1100                 else
1101                         slots = 8 * 1024;
1102         }
1103
1104         net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
1105         size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
1106
1107         net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1108         if (!net->ipv4.tcp_metrics_hash)
1109                 net->ipv4.tcp_metrics_hash = vzalloc(size);
1110
1111         if (!net->ipv4.tcp_metrics_hash)
1112                 return -ENOMEM;
1113
1114         return 0;
1115 }
1116
1117 static void __net_exit tcp_net_metrics_exit(struct net *net)
1118 {
1119         unsigned int i;
1120
1121         for (i = 0; i < (1U << net->ipv4.tcp_metrics_hash_log) ; i++) {
1122                 struct tcp_metrics_block *tm, *next;
1123
1124                 tm = rcu_dereference_protected(net->ipv4.tcp_metrics_hash[i].chain, 1);
1125                 while (tm) {
1126                         next = rcu_dereference_protected(tm->tcpm_next, 1);
1127                         kfree(tm);
1128                         tm = next;
1129                 }
1130         }
1131         if (is_vmalloc_addr(net->ipv4.tcp_metrics_hash))
1132                 vfree(net->ipv4.tcp_metrics_hash);
1133         else
1134                 kfree(net->ipv4.tcp_metrics_hash);
1135 }
1136
1137 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1138         .init   =       tcp_net_metrics_init,
1139         .exit   =       tcp_net_metrics_exit,
1140 };
1141
1142 void __init tcp_metrics_init(void)
1143 {
1144         int ret;
1145
1146         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1147         if (ret < 0)
1148                 goto cleanup;
1149         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1150                                             tcp_metrics_nl_ops);
1151         if (ret < 0)
1152                 goto cleanup_subsys;
1153         return;
1154
1155 cleanup_subsys:
1156         unregister_pernet_subsys(&tcp_net_metrics_ops);
1157
1158 cleanup:
1159         return;
1160 }