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                 try_exp:2;              /* Request w/ exp. option (once) */
  33         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
  34         struct  tcp_fastopen_cookie     cookie;
  35 };
  36
  37 /* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
  38  * Kernel only stores RTT and RTTVAR in usec resolution
  39  */
  40 #define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)
  41
  42 struct tcp_metrics_block {
  43         struct tcp_metrics_block __rcu  *tcpm_next;
  44         possible_net_t                  tcpm_net;
  45         struct inetpeer_addr            tcpm_saddr;
  46         struct inetpeer_addr            tcpm_daddr;
  47         unsigned long                   tcpm_stamp;
  48         u32                             tcpm_ts;
  49         u32                             tcpm_ts_stamp;
  50         u32                             tcpm_lock;
  51         u32                             tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
  52         struct tcp_fastopen_metrics     tcpm_fastopen;
  53
  54         struct rcu_head                 rcu_head;
  55 };
  56
  57 static inline struct net *tm_net(struct tcp_metrics_block *tm)
  58 {
  59         return read_pnet(&tm->tcpm_net);
  60 }
  61
  62 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  63                               enum tcp_metric_index idx)
  64 {
  65         return tm->tcpm_lock & (1 << idx);
  66 }
  67
  68 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
  69                           enum tcp_metric_index idx)
  70 {
  71         return tm->tcpm_vals[idx];
  72 }
  73
  74 static void tcp_metric_set(struct tcp_metrics_block *tm,
  75                            enum tcp_metric_index idx,
  76                            u32 val)
  77 {
  78         tm->tcpm_vals[idx] = val;
  79 }
  80
  81 static bool addr_same(const struct inetpeer_addr *a,
  82                       const struct inetpeer_addr *b)
  83 {
  84         return inetpeer_addr_cmp(a, b) == 0;
  85 }
  86
  87 struct tcpm_hash_bucket {
  88         struct tcp_metrics_block __rcu  *chain;
  89 };
  90
  91 static struct tcpm_hash_bucket  *tcp_metrics_hash __read_mostly;
  92 static unsigned int             tcp_metrics_hash_log __read_mostly;
  93
  94 static DEFINE_SPINLOCK(tcp_metrics_lock);
  95
  96 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
  97                           const struct dst_entry *dst,
  98                           bool fastopen_clear)
  99 {
 100         u32 msval;
 101         u32 val;
 102
 103         tm->tcpm_stamp = jiffies;
 104
 105         val = 0;
 106         if (dst_metric_locked(dst, RTAX_RTT))
 107                 val |= 1 << TCP_METRIC_RTT;
 108         if (dst_metric_locked(dst, RTAX_RTTVAR))
 109                 val |= 1 << TCP_METRIC_RTTVAR;
 110         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 111                 val |= 1 << TCP_METRIC_SSTHRESH;
 112         if (dst_metric_locked(dst, RTAX_CWND))
 113                 val |= 1 << TCP_METRIC_CWND;
 114         if (dst_metric_locked(dst, RTAX_REORDERING))
 115                 val |= 1 << TCP_METRIC_REORDERING;
 116         tm->tcpm_lock = val;
 117
 118         msval = dst_metric_raw(dst, RTAX_RTT);
 119         tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
 120
 121         msval = dst_metric_raw(dst, RTAX_RTTVAR);
 122         tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
 123         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
 124         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
 125         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 126         tm->tcpm_ts = 0;
 127         tm->tcpm_ts_stamp = 0;
 128         if (fastopen_clear) {
 129                 tm->tcpm_fastopen.mss = 0;
 130                 tm->tcpm_fastopen.syn_loss = 0;
 131                 tm->tcpm_fastopen.try_exp = 0;
 132                 tm->tcpm_fastopen.cookie.exp = false;
 133                 tm->tcpm_fastopen.cookie.len = 0;
 134         }
 135 }
 136
 137 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 138
 139 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 140 {
 141         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 142                 tcpm_suck_dst(tm, dst, false);
 143 }
 144
 145 #define TCP_METRICS_RECLAIM_DEPTH       5
 146 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 147
 148 #define deref_locked(p) \
 149         rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
 150
 151 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 152                                           struct inetpeer_addr *saddr,
 153                                           struct inetpeer_addr *daddr,
 154                                           unsigned int hash)
 155 {
 156         struct tcp_metrics_block *tm;
 157         struct net *net;
 158         bool reclaim = false;
 159
 160         spin_lock_bh(&tcp_metrics_lock);
 161         net = dev_net(dst->dev);
 162
 163         /* While waiting for the spin-lock the cache might have been populated
 164          * with this entry and so we have to check again.
 165          */
 166         tm = __tcp_get_metrics(saddr, daddr, net, hash);
 167         if (tm == TCP_METRICS_RECLAIM_PTR) {
 168                 reclaim = true;
 169                 tm = NULL;
 170         }
 171         if (tm) {
 172                 tcpm_check_stamp(tm, dst);
 173                 goto out_unlock;
 174         }
 175
 176         if (unlikely(reclaim)) {
 177                 struct tcp_metrics_block *oldest;
 178
 179                 oldest = deref_locked(tcp_metrics_hash[hash].chain);
 180                 for (tm = deref_locked(oldest->tcpm_next); tm;
 181                      tm = deref_locked(tm->tcpm_next)) {
 182                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 183                                 oldest = tm;
 184                 }
 185                 tm = oldest;
 186         } else {
 187                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 188                 if (!tm)
 189                         goto out_unlock;
 190         }
 191         write_pnet(&tm->tcpm_net, net);
 192         tm->tcpm_saddr = *saddr;
 193         tm->tcpm_daddr = *daddr;
 194
 195         tcpm_suck_dst(tm, dst, true);
 196
 197         if (likely(!reclaim)) {
 198                 tm->tcpm_next = tcp_metrics_hash[hash].chain;
 199                 rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
 200         }
 201
 202 out_unlock:
 203         spin_unlock_bh(&tcp_metrics_lock);
 204         return tm;
 205 }
 206
 207 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 208 {
 209         if (tm)
 210                 return tm;
 211         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 212                 return TCP_METRICS_RECLAIM_PTR;
 213         return NULL;
 214 }
 215
 216 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 217                                                    const struct inetpeer_addr *daddr,
 218                                                    struct net *net, unsigned int hash)
 219 {
 220         struct tcp_metrics_block *tm;
 221         int depth = 0;
 222
 223         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 224              tm = rcu_dereference(tm->tcpm_next)) {
 225                 if (addr_same(&tm->tcpm_saddr, saddr) &&
 226                     addr_same(&tm->tcpm_daddr, daddr) &&
 227                     net_eq(tm_net(tm), net))
 228                         break;
 229                 depth++;
 230         }
 231         return tcp_get_encode(tm, depth);
 232 }
 233
 234 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 235                                                        struct dst_entry *dst)
 236 {
 237         struct tcp_metrics_block *tm;
 238         struct inetpeer_addr saddr, daddr;
 239         unsigned int hash;
 240         struct net *net;
 241
 242         saddr.family = req->rsk_ops->family;
 243         daddr.family = req->rsk_ops->family;
 244         switch (daddr.family) {
 245         case AF_INET:
 246                 inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
 247                 inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
 248                 hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
 249                 break;
 250 #if IS_ENABLED(CONFIG_IPV6)
 251         case AF_INET6:
 252                 inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
 253                 inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
 254                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 255                 break;
 256 #endif
 257         default:
 258                 return NULL;
 259         }
 260
 261         net = dev_net(dst->dev);
 262         hash ^= net_hash_mix(net);
 263         hash = hash_32(hash, tcp_metrics_hash_log);
 264
 265         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 266              tm = rcu_dereference(tm->tcpm_next)) {
 267                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 268                     addr_same(&tm->tcpm_daddr, &daddr) &&
 269                     net_eq(tm_net(tm), net))
 270                         break;
 271         }
 272         tcpm_check_stamp(tm, dst);
 273         return tm;
 274 }
 275
 276 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 277 {
 278         struct tcp_metrics_block *tm;
 279         struct inetpeer_addr saddr, daddr;
 280         unsigned int hash;
 281         struct net *net;
 282
 283         if (tw->tw_family == AF_INET) {
 284                 inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
 285                 inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
 286                 hash = ipv4_addr_hash(tw->tw_daddr);
 287         }
 288 #if IS_ENABLED(CONFIG_IPV6)
 289         else if (tw->tw_family == AF_INET6) {
 290                 if (ipv6_addr_v4mapped(&tw->tw_v6_daddr)) {
 291                         inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
 292                         inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
 293                         hash = ipv4_addr_hash(tw->tw_daddr);
 294                 } else {
 295                         inetpeer_set_addr_v6(&saddr, &tw->tw_v6_rcv_saddr);
 296                         inetpeer_set_addr_v6(&daddr, &tw->tw_v6_daddr);
 297                         hash = ipv6_addr_hash(&tw->tw_v6_daddr);
 298                 }
 299         }
 300 #endif
 301         else
 302                 return NULL;
 303
 304         net = twsk_net(tw);
 305         hash ^= net_hash_mix(net);
 306         hash = hash_32(hash, tcp_metrics_hash_log);
 307
 308         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 309              tm = rcu_dereference(tm->tcpm_next)) {
 310                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 311                     addr_same(&tm->tcpm_daddr, &daddr) &&
 312                     net_eq(tm_net(tm), net))
 313                         break;
 314         }
 315         return tm;
 316 }
 317
 318 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 319                                                  struct dst_entry *dst,
 320                                                  bool create)
 321 {
 322         struct tcp_metrics_block *tm;
 323         struct inetpeer_addr saddr, daddr;
 324         unsigned int hash;
 325         struct net *net;
 326
 327         if (sk->sk_family == AF_INET) {
 328                 inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 329                 inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 330                 hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 331         }
 332 #if IS_ENABLED(CONFIG_IPV6)
 333         else if (sk->sk_family == AF_INET6) {
 334                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
 335                         inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 336                         inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 337                         hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 338                 } else {
 339                         inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
 340                         inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
 341                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 342                 }
 343         }
 344 #endif
 345         else
 346                 return NULL;
 347
 348         net = dev_net(dst->dev);
 349         hash ^= net_hash_mix(net);
 350         hash = hash_32(hash, tcp_metrics_hash_log);
 351
 352         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 353         if (tm == TCP_METRICS_RECLAIM_PTR)
 354                 tm = NULL;
 355         if (!tm && create)
 356                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 357         else
 358                 tcpm_check_stamp(tm, dst);
 359
 360         return tm;
 361 }
 362
 363 /* Save metrics learned by this TCP session.  This function is called
 364  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 365  * or goes from LAST-ACK to CLOSE.
 366  */
 367 void tcp_update_metrics(struct sock *sk)
 368 {
 369         const struct inet_connection_sock *icsk = inet_csk(sk);
 370         struct dst_entry *dst = __sk_dst_get(sk);
 371         struct tcp_sock *tp = tcp_sk(sk);
 372         struct tcp_metrics_block *tm;
 373         unsigned long rtt;
 374         u32 val;
 375         int m;
 376
 377         if (sysctl_tcp_nometrics_save || !dst)
 378                 return;
 379
 380         if (dst->flags & DST_HOST)
 381                 dst_confirm(dst);
 382
 383         rcu_read_lock();
 384         if (icsk->icsk_backoff || !tp->srtt_us) {
 385                 /* This session failed to estimate rtt. Why?
 386                  * Probably, no packets returned in time.  Reset our
 387                  * results.
 388                  */
 389                 tm = tcp_get_metrics(sk, dst, false);
 390                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 391                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 392                 goto out_unlock;
 393         } else
 394                 tm = tcp_get_metrics(sk, dst, true);
 395
 396         if (!tm)
 397                 goto out_unlock;
 398
 399         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 400         m = rtt - tp->srtt_us;
 401
 402         /* If newly calculated rtt larger than stored one, store new
 403          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 404          * always better than underestimation.
 405          */
 406         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 407                 if (m <= 0)
 408                         rtt = tp->srtt_us;
 409                 else
 410                         rtt -= (m >> 3);
 411                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
 412         }
 413
 414         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 415                 unsigned long var;
 416
 417                 if (m < 0)
 418                         m = -m;
 419
 420                 /* Scale deviation to rttvar fixed point */
 421                 m >>= 1;
 422                 if (m < tp->mdev_us)
 423                         m = tp->mdev_us;
 424
 425                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
 426                 if (m >= var)
 427                         var = m;
 428                 else
 429                         var -= (var - m) >> 2;
 430
 431                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
 432         }
 433
 434         if (tcp_in_initial_slowstart(tp)) {
 435                 /* Slow start still did not finish. */
 436                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 437                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 438                         if (val && (tp->snd_cwnd >> 1) > val)
 439                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 440                                                tp->snd_cwnd >> 1);
 441                 }
 442                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 443                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 444                         if (tp->snd_cwnd > val)
 445                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 446                                                tp->snd_cwnd);
 447                 }
 448         } else if (!tcp_in_slow_start(tp) &&
 449                    icsk->icsk_ca_state == TCP_CA_Open) {
 450                 /* Cong. avoidance phase, cwnd is reliable. */
 451                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 452                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 453                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 454                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 455                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 456                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 457                 }
 458         } else {
 459                 /* Else slow start did not finish, cwnd is non-sense,
 460                  * ssthresh may be also invalid.
 461                  */
 462                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 463                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 464                         tcp_metric_set(tm, TCP_METRIC_CWND,
 465                                        (val + tp->snd_ssthresh) >> 1);
 466                 }
 467                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 468                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 469                         if (val && tp->snd_ssthresh > val)
 470                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 471                                                tp->snd_ssthresh);
 472                 }
 473                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 474                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 475                         if (val < tp->reordering &&
 476                             tp->reordering != sysctl_tcp_reordering)
 477                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 478                                                tp->reordering);
 479                 }
 480         }
 481         tm->tcpm_stamp = jiffies;
 482 out_unlock:
 483         rcu_read_unlock();
 484 }
 485
 486 /* Initialize metrics on socket. */
 487
 488 void tcp_init_metrics(struct sock *sk)
 489 {
 490         struct dst_entry *dst = __sk_dst_get(sk);
 491         struct tcp_sock *tp = tcp_sk(sk);
 492         struct tcp_metrics_block *tm;
 493         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 494
 495         if (!dst)
 496                 goto reset;
 497
 498         dst_confirm(dst);
 499
 500         rcu_read_lock();
 501         tm = tcp_get_metrics(sk, dst, true);
 502         if (!tm) {
 503                 rcu_read_unlock();
 504                 goto reset;
 505         }
 506
 507         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 508                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 509
 510         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 511         if (val) {
 512                 tp->snd_ssthresh = val;
 513                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 514                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 515         } else {
 516                 /* ssthresh may have been reduced unnecessarily during.
 517                  * 3WHS. Restore it back to its initial default.
 518                  */
 519                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 520         }
 521         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 522         if (val && tp->reordering != val) {
 523                 tcp_disable_fack(tp);
 524                 tcp_disable_early_retrans(tp);
 525                 tp->reordering = val;
 526         }
 527
 528         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 529         rcu_read_unlock();
 530 reset:
 531         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 532          * to seed the RTO for later data packets because SYN packets are
 533          * small. Use the per-dst cached values to seed the RTO but keep
 534          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 535          * Later the RTO will be updated immediately upon obtaining the first
 536          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 537          * influences the first RTO but not later RTT estimation.
 538          *
 539          * But if RTT is not available from the SYN (due to retransmits or
 540          * syn cookies) or the cache, force a conservative 3secs timeout.
 541          *
 542          * A bit of theory. RTT is time passed after "normal" sized packet
 543          * is sent until it is ACKed. In normal circumstances sending small
 544          * packets force peer to delay ACKs and calculation is correct too.
 545          * The algorithm is adaptive and, provided we follow specs, it
 546          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 547          * tricks sort of "quick acks" for time long enough to decrease RTT
 548          * to low value, and then abruptly stops to do it and starts to delay
 549          * ACKs, wait for troubles.
 550          */
 551         if (crtt > tp->srtt_us) {
 552                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 553                 crtt /= 8 * USEC_PER_SEC / HZ;
 554                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 555         } else if (tp->srtt_us == 0) {
 556                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 557                  * 3WHS. This is most likely due to retransmission,
 558                  * including spurious one. Reset the RTO back to 3secs
 559                  * from the more aggressive 1sec to avoid more spurious
 560                  * retransmission.
 561                  */
 562                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 563                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 564
 565                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 566         }
 567         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 568          * retransmitted. In light of RFC6298 more aggressive 1sec
 569          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 570          * retransmission has occurred.
 571          */
 572         if (tp->total_retrans > 1)
 573                 tp->snd_cwnd = 1;
 574         else
 575                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 576         tp->snd_cwnd_stamp = tcp_time_stamp;
 577 }
 578
 579 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
 580                         bool paws_check, bool timestamps)
 581 {
 582         struct tcp_metrics_block *tm;
 583         bool ret;
 584
 585         if (!dst)
 586                 return false;
 587
 588         rcu_read_lock();
 589         tm = __tcp_get_metrics_req(req, dst);
 590         if (paws_check) {
 591                 if (tm &&
 592                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 593                     ((s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW ||
 594                      !timestamps))
 595                         ret = false;
 596                 else
 597                         ret = true;
 598         } else {
 599                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 600                         ret = true;
 601                 else
 602                         ret = false;
 603         }
 604         rcu_read_unlock();
 605
 606         return ret;
 607 }
 608 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 609
 610 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 611 {
 612         struct tcp_metrics_block *tm;
 613
 614         rcu_read_lock();
 615         tm = tcp_get_metrics(sk, dst, true);
 616         if (tm) {
 617                 struct tcp_sock *tp = tcp_sk(sk);
 618
 619                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 620                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 621                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 622                 }
 623         }
 624         rcu_read_unlock();
 625 }
 626 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 627
 628 /* VJ's idea. Save last timestamp seen from this destination and hold
 629  * it at least for normal timewait interval to use for duplicate
 630  * segment detection in subsequent connections, before they enter
 631  * synchronized state.
 632  */
 633 bool tcp_remember_stamp(struct sock *sk)
 634 {
 635         struct dst_entry *dst = __sk_dst_get(sk);
 636         bool ret = false;
 637
 638         if (dst) {
 639                 struct tcp_metrics_block *tm;
 640
 641                 rcu_read_lock();
 642                 tm = tcp_get_metrics(sk, dst, true);
 643                 if (tm) {
 644                         struct tcp_sock *tp = tcp_sk(sk);
 645
 646                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 647                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 648                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 649                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 650                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 651                         }
 652                         ret = true;
 653                 }
 654                 rcu_read_unlock();
 655         }
 656         return ret;
 657 }
 658
 659 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 660 {
 661         struct tcp_metrics_block *tm;
 662         bool ret = false;
 663
 664         rcu_read_lock();
 665         tm = __tcp_get_metrics_tw(tw);
 666         if (tm) {
 667                 const struct tcp_timewait_sock *tcptw;
 668                 struct sock *sk = (struct sock *) tw;
 669
 670                 tcptw = tcp_twsk(sk);
 671                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 672                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 673                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 674                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 675                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 676                 }
 677                 ret = true;
 678         }
 679         rcu_read_unlock();
 680
 681         return ret;
 682 }
 683
 684 static DEFINE_SEQLOCK(fastopen_seqlock);
 685
 686 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 687                             struct tcp_fastopen_cookie *cookie,
 688                             int *syn_loss, unsigned long *last_syn_loss)
 689 {
 690         struct tcp_metrics_block *tm;
 691
 692         rcu_read_lock();
 693         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 694         if (tm) {
 695                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 696                 unsigned int seq;
 697
 698                 do {
 699                         seq = read_seqbegin(&fastopen_seqlock);
 700                         if (tfom->mss)
 701                                 *mss = tfom->mss;
 702                         *cookie = tfom->cookie;
 703                         if (cookie->len <= 0 && tfom->try_exp == 1)
 704                                 cookie->exp = true;
 705                         *syn_loss = tfom->syn_loss;
 706                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 707                 } while (read_seqretry(&fastopen_seqlock, seq));
 708         }
 709         rcu_read_unlock();
 710 }
 711
 712 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 713                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
 714                             u16 try_exp)
 715 {
 716         struct dst_entry *dst = __sk_dst_get(sk);
 717         struct tcp_metrics_block *tm;
 718
 719         if (!dst)
 720                 return;
 721         rcu_read_lock();
 722         tm = tcp_get_metrics(sk, dst, true);
 723         if (tm) {
 724                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 725
 726                 write_seqlock_bh(&fastopen_seqlock);
 727                 if (mss)
 728                         tfom->mss = mss;
 729                 if (cookie && cookie->len > 0)
 730                         tfom->cookie = *cookie;
 731                 else if (try_exp > tfom->try_exp &&
 732                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
 733                         tfom->try_exp = try_exp;
 734                 if (syn_lost) {
 735                         ++tfom->syn_loss;
 736                         tfom->last_syn_loss = jiffies;
 737                 } else
 738                         tfom->syn_loss = 0;
 739                 write_sequnlock_bh(&fastopen_seqlock);
 740         }
 741         rcu_read_unlock();
 742 }
 743
 744 static struct genl_family tcp_metrics_nl_family = {
 745         .id             = GENL_ID_GENERATE,
 746         .hdrsize        = 0,
 747         .name           = TCP_METRICS_GENL_NAME,
 748         .version        = TCP_METRICS_GENL_VERSION,
 749         .maxattr        = TCP_METRICS_ATTR_MAX,
 750         .netnsok        = true,
 751 };
 752
 753 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 754         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 755         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 756                                             .len = sizeof(struct in6_addr), },
 757         /* Following attributes are not received for GET/DEL,
 758          * we keep them for reference
 759          */
 760 #if 0
 761         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 762         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 763         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 764         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 765         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 766         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 767         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 768         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 769                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 770 #endif
 771 };
 772
 773 /* Add attributes, caller cancels its header on failure */
 774 static int tcp_metrics_fill_info(struct sk_buff *msg,
 775                                  struct tcp_metrics_block *tm)
 776 {
 777         struct nlattr *nest;
 778         int i;
 779
 780         switch (tm->tcpm_daddr.family) {
 781         case AF_INET:
 782                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 783                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
 784                         goto nla_put_failure;
 785                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 786                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
 787                         goto nla_put_failure;
 788                 break;
 789         case AF_INET6:
 790                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
 791                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
 792                         goto nla_put_failure;
 793                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
 794                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
 795                         goto nla_put_failure;
 796                 break;
 797         default:
 798                 return -EAFNOSUPPORT;
 799         }
 800
 801         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 802                           jiffies - tm->tcpm_stamp) < 0)
 803                 goto nla_put_failure;
 804         if (tm->tcpm_ts_stamp) {
 805                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 806                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 807                         goto nla_put_failure;
 808                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 809                                 tm->tcpm_ts) < 0)
 810                         goto nla_put_failure;
 811         }
 812
 813         {
 814                 int n = 0;
 815
 816                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 817                 if (!nest)
 818                         goto nla_put_failure;
 819                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 820                         u32 val = tm->tcpm_vals[i];
 821
 822                         if (!val)
 823                                 continue;
 824                         if (i == TCP_METRIC_RTT) {
 825                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 826                                                 val) < 0)
 827                                         goto nla_put_failure;
 828                                 n++;
 829                                 val = max(val / 1000, 1U);
 830                         }
 831                         if (i == TCP_METRIC_RTTVAR) {
 832                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 833                                                 val) < 0)
 834                                         goto nla_put_failure;
 835                                 n++;
 836                                 val = max(val / 1000, 1U);
 837                         }
 838                         if (nla_put_u32(msg, i + 1, val) < 0)
 839                                 goto nla_put_failure;
 840                         n++;
 841                 }
 842                 if (n)
 843                         nla_nest_end(msg, nest);
 844                 else
 845                         nla_nest_cancel(msg, nest);
 846         }
 847
 848         {
 849                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 850                 unsigned int seq;
 851
 852                 do {
 853                         seq = read_seqbegin(&fastopen_seqlock);
 854                         tfom_copy[0] = tm->tcpm_fastopen;
 855                 } while (read_seqretry(&fastopen_seqlock, seq));
 856
 857                 tfom = tfom_copy;
 858                 if (tfom->mss &&
 859                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 860                                 tfom->mss) < 0)
 861                         goto nla_put_failure;
 862                 if (tfom->syn_loss &&
 863                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 864                                 tfom->syn_loss) < 0 ||
 865                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 866                                 jiffies - tfom->last_syn_loss) < 0))
 867                         goto nla_put_failure;
 868                 if (tfom->cookie.len > 0 &&
 869                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 870                             tfom->cookie.len, tfom->cookie.val) < 0)
 871                         goto nla_put_failure;
 872         }
 873
 874         return 0;
 875
 876 nla_put_failure:
 877         return -EMSGSIZE;
 878 }
 879
 880 static int tcp_metrics_dump_info(struct sk_buff *skb,
 881                                  struct netlink_callback *cb,
 882                                  struct tcp_metrics_block *tm)
 883 {
 884         void *hdr;
 885
 886         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 887                           &tcp_metrics_nl_family, NLM_F_MULTI,
 888                           TCP_METRICS_CMD_GET);
 889         if (!hdr)
 890                 return -EMSGSIZE;
 891
 892         if (tcp_metrics_fill_info(skb, tm) < 0)
 893                 goto nla_put_failure;
 894
 895         genlmsg_end(skb, hdr);
 896         return 0;
 897
 898 nla_put_failure:
 899         genlmsg_cancel(skb, hdr);
 900         return -EMSGSIZE;
 901 }
 902
 903 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 904                                struct netlink_callback *cb)
 905 {
 906         struct net *net = sock_net(skb->sk);
 907         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 908         unsigned int row, s_row = cb->args[0];
 909         int s_col = cb->args[1], col = s_col;
 910
 911         for (row = s_row; row < max_rows; row++, s_col = 0) {
 912                 struct tcp_metrics_block *tm;
 913                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
 914
 915                 rcu_read_lock();
 916                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 917                      tm = rcu_dereference(tm->tcpm_next), col++) {
 918                         if (!net_eq(tm_net(tm), net))
 919                                 continue;
 920                         if (col < s_col)
 921                                 continue;
 922                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 923                                 rcu_read_unlock();
 924                                 goto done;
 925                         }
 926                 }
 927                 rcu_read_unlock();
 928         }
 929
 930 done:
 931         cb->args[0] = row;
 932         cb->args[1] = col;
 933         return skb->len;
 934 }
 935
 936 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 937                            unsigned int *hash, int optional, int v4, int v6)
 938 {
 939         struct nlattr *a;
 940
 941         a = info->attrs[v4];
 942         if (a) {
 943                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
 944                 if (hash)
 945                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
 946                 return 0;
 947         }
 948         a = info->attrs[v6];
 949         if (a) {
 950                 struct in6_addr in6;
 951
 952                 if (nla_len(a) != sizeof(struct in6_addr))
 953                         return -EINVAL;
 954                 in6 = nla_get_in6_addr(a);
 955                 inetpeer_set_addr_v6(addr, &in6);
 956                 if (hash)
 957                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
 958                 return 0;
 959         }
 960         return optional ? 1 : -EAFNOSUPPORT;
 961 }
 962
 963 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 964                          unsigned int *hash, int optional)
 965 {
 966         return __parse_nl_addr(info, addr, hash, optional,
 967                                TCP_METRICS_ATTR_ADDR_IPV4,
 968                                TCP_METRICS_ATTR_ADDR_IPV6);
 969 }
 970
 971 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 972 {
 973         return __parse_nl_addr(info, addr, NULL, 0,
 974                                TCP_METRICS_ATTR_SADDR_IPV4,
 975                                TCP_METRICS_ATTR_SADDR_IPV6);
 976 }
 977
 978 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 979 {
 980         struct tcp_metrics_block *tm;
 981         struct inetpeer_addr saddr, daddr;
 982         unsigned int hash;
 983         struct sk_buff *msg;
 984         struct net *net = genl_info_net(info);
 985         void *reply;
 986         int ret;
 987         bool src = true;
 988
 989         ret = parse_nl_addr(info, &daddr, &hash, 0);
 990         if (ret < 0)
 991                 return ret;
 992
 993         ret = parse_nl_saddr(info, &saddr);
 994         if (ret < 0)
 995                 src = false;
 996
 997         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 998         if (!msg)
 999                 return -ENOMEM;
1000
1001         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
1002                                   info->genlhdr->cmd);
1003         if (!reply)
1004                 goto nla_put_failure;
1005
1006         hash ^= net_hash_mix(net);
1007         hash = hash_32(hash, tcp_metrics_hash_log);
1008         ret = -ESRCH;
1009         rcu_read_lock();
1010         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
1011              tm = rcu_dereference(tm->tcpm_next)) {
1012                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1013                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1014                     net_eq(tm_net(tm), net)) {
1015                         ret = tcp_metrics_fill_info(msg, tm);
1016                         break;
1017                 }
1018         }
1019         rcu_read_unlock();
1020         if (ret < 0)
1021                 goto out_free;
1022
1023         genlmsg_end(msg, reply);
1024         return genlmsg_reply(msg, info);
1025
1026 nla_put_failure:
1027         ret = -EMSGSIZE;
1028
1029 out_free:
1030         nlmsg_free(msg);
1031         return ret;
1032 }
1033
1034 static void tcp_metrics_flush_all(struct net *net)
1035 {
1036         unsigned int max_rows = 1U << tcp_metrics_hash_log;
1037         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
1038         struct tcp_metrics_block *tm;
1039         unsigned int row;
1040
1041         for (row = 0; row < max_rows; row++, hb++) {
1042                 struct tcp_metrics_block __rcu **pp;
1043                 spin_lock_bh(&tcp_metrics_lock);
1044                 pp = &hb->chain;
1045                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1046                         if (net_eq(tm_net(tm), net)) {
1047                                 *pp = tm->tcpm_next;
1048                                 kfree_rcu(tm, rcu_head);
1049                         } else {
1050                                 pp = &tm->tcpm_next;
1051                         }
1052                 }
1053                 spin_unlock_bh(&tcp_metrics_lock);
1054         }
1055 }
1056
1057 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
1058 {
1059         struct tcpm_hash_bucket *hb;
1060         struct tcp_metrics_block *tm;
1061         struct tcp_metrics_block __rcu **pp;
1062         struct inetpeer_addr saddr, daddr;
1063         unsigned int hash;
1064         struct net *net = genl_info_net(info);
1065         int ret;
1066         bool src = true, found = false;
1067
1068         ret = parse_nl_addr(info, &daddr, &hash, 1);
1069         if (ret < 0)
1070                 return ret;
1071         if (ret > 0) {
1072                 tcp_metrics_flush_all(net);
1073                 return 0;
1074         }
1075         ret = parse_nl_saddr(info, &saddr);
1076         if (ret < 0)
1077                 src = false;
1078
1079         hash ^= net_hash_mix(net);
1080         hash = hash_32(hash, tcp_metrics_hash_log);
1081         hb = tcp_metrics_hash + hash;
1082         pp = &hb->chain;
1083         spin_lock_bh(&tcp_metrics_lock);
1084         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1085                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1086                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1087                     net_eq(tm_net(tm), net)) {
1088                         *pp = tm->tcpm_next;
1089                         kfree_rcu(tm, rcu_head);
1090                         found = true;
1091                 } else {
1092                         pp = &tm->tcpm_next;
1093                 }
1094         }
1095         spin_unlock_bh(&tcp_metrics_lock);
1096         if (!found)
1097                 return -ESRCH;
1098         return 0;
1099 }
1100
1101 static const struct genl_ops tcp_metrics_nl_ops[] = {
1102         {
1103                 .cmd = TCP_METRICS_CMD_GET,
1104                 .doit = tcp_metrics_nl_cmd_get,
1105                 .dumpit = tcp_metrics_nl_dump,
1106                 .policy = tcp_metrics_nl_policy,
1107         },
1108         {
1109                 .cmd = TCP_METRICS_CMD_DEL,
1110                 .doit = tcp_metrics_nl_cmd_del,
1111                 .policy = tcp_metrics_nl_policy,
1112                 .flags = GENL_ADMIN_PERM,
1113         },
1114 };
1115
1116 static unsigned int tcpmhash_entries;
1117 static int __init set_tcpmhash_entries(char *str)
1118 {
1119         ssize_t ret;
1120
1121         if (!str)
1122                 return 0;
1123
1124         ret = kstrtouint(str, 0, &tcpmhash_entries);
1125         if (ret)
1126                 return 0;
1127
1128         return 1;
1129 }
1130 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1131
1132 static int __net_init tcp_net_metrics_init(struct net *net)
1133 {
1134         size_t size;
1135         unsigned int slots;
1136
1137         if (!net_eq(net, &init_net))
1138                 return 0;
1139
1140         slots = tcpmhash_entries;
1141         if (!slots) {
1142                 if (totalram_pages >= 128 * 1024)
1143                         slots = 16 * 1024;
1144                 else
1145                         slots = 8 * 1024;
1146         }
1147
1148         tcp_metrics_hash_log = order_base_2(slots);
1149         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1150
1151         tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1152         if (!tcp_metrics_hash)
1153                 tcp_metrics_hash = vzalloc(size);
1154
1155         if (!tcp_metrics_hash)
1156                 return -ENOMEM;
1157
1158         return 0;
1159 }
1160
1161 static void __net_exit tcp_net_metrics_exit(struct net *net)
1162 {
1163         tcp_metrics_flush_all(net);
1164 }
1165
1166 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1167         .init   =       tcp_net_metrics_init,
1168         .exit   =       tcp_net_metrics_exit,
1169 };
1170
1171 void __init tcp_metrics_init(void)
1172 {
1173         int ret;
1174
1175         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1176         if (ret < 0)
1177                 panic("Could not allocate the tcp_metrics hash table\n");
1178
1179         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1180                                             tcp_metrics_nl_ops);
1181         if (ret < 0)
1182                 panic("Could not register tcp_metrics generic netlink\n");
1183 }