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         if (a->family != b->family)
  85                 return false;
  86         if (a->family == AF_INET)
  87                 return a->addr.a4 == b->addr.a4;
  88         return ipv6_addr_equal(&a->addr.in6, &b->addr.in6);
  89 }
  90
  91 struct tcpm_hash_bucket {
  92         struct tcp_metrics_block __rcu  *chain;
  93 };
  94
  95 static struct tcpm_hash_bucket  *tcp_metrics_hash __read_mostly;
  96 static unsigned int             tcp_metrics_hash_log __read_mostly;
  97
  98 static DEFINE_SPINLOCK(tcp_metrics_lock);
  99
 100 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
 101                           const struct dst_entry *dst,
 102                           bool fastopen_clear)
 103 {
 104         u32 msval;
 105         u32 val;
 106
 107         tm->tcpm_stamp = jiffies;
 108
 109         val = 0;
 110         if (dst_metric_locked(dst, RTAX_RTT))
 111                 val |= 1 << TCP_METRIC_RTT;
 112         if (dst_metric_locked(dst, RTAX_RTTVAR))
 113                 val |= 1 << TCP_METRIC_RTTVAR;
 114         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 115                 val |= 1 << TCP_METRIC_SSTHRESH;
 116         if (dst_metric_locked(dst, RTAX_CWND))
 117                 val |= 1 << TCP_METRIC_CWND;
 118         if (dst_metric_locked(dst, RTAX_REORDERING))
 119                 val |= 1 << TCP_METRIC_REORDERING;
 120         tm->tcpm_lock = val;
 121
 122         msval = dst_metric_raw(dst, RTAX_RTT);
 123         tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
 124
 125         msval = dst_metric_raw(dst, RTAX_RTTVAR);
 126         tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
 127         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
 128         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
 129         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 130         tm->tcpm_ts = 0;
 131         tm->tcpm_ts_stamp = 0;
 132         if (fastopen_clear) {
 133                 tm->tcpm_fastopen.mss = 0;
 134                 tm->tcpm_fastopen.syn_loss = 0;
 135                 tm->tcpm_fastopen.try_exp = 0;
 136                 tm->tcpm_fastopen.cookie.exp = false;
 137                 tm->tcpm_fastopen.cookie.len = 0;
 138         }
 139 }
 140
 141 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 142
 143 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 144 {
 145         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 146                 tcpm_suck_dst(tm, dst, false);
 147 }
 148
 149 #define TCP_METRICS_RECLAIM_DEPTH       5
 150 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 151
 152 #define deref_locked(p) \
 153         rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
 154
 155 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 156                                           struct inetpeer_addr *saddr,
 157                                           struct inetpeer_addr *daddr,
 158                                           unsigned int hash)
 159 {
 160         struct tcp_metrics_block *tm;
 161         struct net *net;
 162         bool reclaim = false;
 163
 164         spin_lock_bh(&tcp_metrics_lock);
 165         net = dev_net(dst->dev);
 166
 167         /* While waiting for the spin-lock the cache might have been populated
 168          * with this entry and so we have to check again.
 169          */
 170         tm = __tcp_get_metrics(saddr, daddr, net, hash);
 171         if (tm == TCP_METRICS_RECLAIM_PTR) {
 172                 reclaim = true;
 173                 tm = NULL;
 174         }
 175         if (tm) {
 176                 tcpm_check_stamp(tm, dst);
 177                 goto out_unlock;
 178         }
 179
 180         if (unlikely(reclaim)) {
 181                 struct tcp_metrics_block *oldest;
 182
 183                 oldest = deref_locked(tcp_metrics_hash[hash].chain);
 184                 for (tm = deref_locked(oldest->tcpm_next); tm;
 185                      tm = deref_locked(tm->tcpm_next)) {
 186                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 187                                 oldest = tm;
 188                 }
 189                 tm = oldest;
 190         } else {
 191                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 192                 if (!tm)
 193                         goto out_unlock;
 194         }
 195         write_pnet(&tm->tcpm_net, net);
 196         tm->tcpm_saddr = *saddr;
 197         tm->tcpm_daddr = *daddr;
 198
 199         tcpm_suck_dst(tm, dst, true);
 200
 201         if (likely(!reclaim)) {
 202                 tm->tcpm_next = tcp_metrics_hash[hash].chain;
 203                 rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
 204         }
 205
 206 out_unlock:
 207         spin_unlock_bh(&tcp_metrics_lock);
 208         return tm;
 209 }
 210
 211 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 212 {
 213         if (tm)
 214                 return tm;
 215         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 216                 return TCP_METRICS_RECLAIM_PTR;
 217         return NULL;
 218 }
 219
 220 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 221                                                    const struct inetpeer_addr *daddr,
 222                                                    struct net *net, unsigned int hash)
 223 {
 224         struct tcp_metrics_block *tm;
 225         int depth = 0;
 226
 227         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 228              tm = rcu_dereference(tm->tcpm_next)) {
 229                 if (addr_same(&tm->tcpm_saddr, saddr) &&
 230                     addr_same(&tm->tcpm_daddr, daddr) &&
 231                     net_eq(tm_net(tm), net))
 232                         break;
 233                 depth++;
 234         }
 235         return tcp_get_encode(tm, depth);
 236 }
 237
 238 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 239                                                        struct dst_entry *dst)
 240 {
 241         struct tcp_metrics_block *tm;
 242         struct inetpeer_addr saddr, daddr;
 243         unsigned int hash;
 244         struct net *net;
 245
 246         saddr.family = req->rsk_ops->family;
 247         daddr.family = req->rsk_ops->family;
 248         switch (daddr.family) {
 249         case AF_INET:
 250                 inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
 251                 inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
 252                 hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
 253                 break;
 254 #if IS_ENABLED(CONFIG_IPV6)
 255         case AF_INET6:
 256                 inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
 257                 inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
 258                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 259                 break;
 260 #endif
 261         default:
 262                 return NULL;
 263         }
 264
 265         net = dev_net(dst->dev);
 266         hash ^= net_hash_mix(net);
 267         hash = hash_32(hash, tcp_metrics_hash_log);
 268
 269         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 270              tm = rcu_dereference(tm->tcpm_next)) {
 271                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 272                     addr_same(&tm->tcpm_daddr, &daddr) &&
 273                     net_eq(tm_net(tm), net))
 274                         break;
 275         }
 276         tcpm_check_stamp(tm, dst);
 277         return tm;
 278 }
 279
 280 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 281 {
 282         struct tcp_metrics_block *tm;
 283         struct inetpeer_addr saddr, daddr;
 284         unsigned int hash;
 285         struct net *net;
 286
 287         if (tw->tw_family == AF_INET) {
 288                 inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
 289                 inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
 290                 hash = ipv4_addr_hash(tw->tw_daddr);
 291         }
 292 #if IS_ENABLED(CONFIG_IPV6)
 293         else if (tw->tw_family == AF_INET6) {
 294                 if (ipv6_addr_v4mapped(&tw->tw_v6_daddr)) {
 295                         inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
 296                         inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
 297                         hash = ipv4_addr_hash(tw->tw_daddr);
 298                 } else {
 299                         inetpeer_set_addr_v6(&saddr, &tw->tw_v6_rcv_saddr);
 300                         inetpeer_set_addr_v6(&daddr, &tw->tw_v6_daddr);
 301                         hash = ipv6_addr_hash(&tw->tw_v6_daddr);
 302                 }
 303         }
 304 #endif
 305         else
 306                 return NULL;
 307
 308         net = twsk_net(tw);
 309         hash ^= net_hash_mix(net);
 310         hash = hash_32(hash, tcp_metrics_hash_log);
 311
 312         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 313              tm = rcu_dereference(tm->tcpm_next)) {
 314                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 315                     addr_same(&tm->tcpm_daddr, &daddr) &&
 316                     net_eq(tm_net(tm), net))
 317                         break;
 318         }
 319         return tm;
 320 }
 321
 322 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 323                                                  struct dst_entry *dst,
 324                                                  bool create)
 325 {
 326         struct tcp_metrics_block *tm;
 327         struct inetpeer_addr saddr, daddr;
 328         unsigned int hash;
 329         struct net *net;
 330
 331         if (sk->sk_family == AF_INET) {
 332                 inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 333                 inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 334                 hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 335         }
 336 #if IS_ENABLED(CONFIG_IPV6)
 337         else if (sk->sk_family == AF_INET6) {
 338                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
 339                         inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 340                         inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 341                         hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 342                 } else {
 343                         inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
 344                         inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
 345                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 346                 }
 347         }
 348 #endif
 349         else
 350                 return NULL;
 351
 352         net = dev_net(dst->dev);
 353         hash ^= net_hash_mix(net);
 354         hash = hash_32(hash, tcp_metrics_hash_log);
 355
 356         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 357         if (tm == TCP_METRICS_RECLAIM_PTR)
 358                 tm = NULL;
 359         if (!tm && create)
 360                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 361         else
 362                 tcpm_check_stamp(tm, dst);
 363
 364         return tm;
 365 }
 366
 367 /* Save metrics learned by this TCP session.  This function is called
 368  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 369  * or goes from LAST-ACK to CLOSE.
 370  */
 371 void tcp_update_metrics(struct sock *sk)
 372 {
 373         const struct inet_connection_sock *icsk = inet_csk(sk);
 374         struct dst_entry *dst = __sk_dst_get(sk);
 375         struct tcp_sock *tp = tcp_sk(sk);
 376         struct tcp_metrics_block *tm;
 377         unsigned long rtt;
 378         u32 val;
 379         int m;
 380
 381         if (sysctl_tcp_nometrics_save || !dst)
 382                 return;
 383
 384         if (dst->flags & DST_HOST)
 385                 dst_confirm(dst);
 386
 387         rcu_read_lock();
 388         if (icsk->icsk_backoff || !tp->srtt_us) {
 389                 /* This session failed to estimate rtt. Why?
 390                  * Probably, no packets returned in time.  Reset our
 391                  * results.
 392                  */
 393                 tm = tcp_get_metrics(sk, dst, false);
 394                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 395                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 396                 goto out_unlock;
 397         } else
 398                 tm = tcp_get_metrics(sk, dst, true);
 399
 400         if (!tm)
 401                 goto out_unlock;
 402
 403         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 404         m = rtt - tp->srtt_us;
 405
 406         /* If newly calculated rtt larger than stored one, store new
 407          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 408          * always better than underestimation.
 409          */
 410         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 411                 if (m <= 0)
 412                         rtt = tp->srtt_us;
 413                 else
 414                         rtt -= (m >> 3);
 415                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
 416         }
 417
 418         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 419                 unsigned long var;
 420
 421                 if (m < 0)
 422                         m = -m;
 423
 424                 /* Scale deviation to rttvar fixed point */
 425                 m >>= 1;
 426                 if (m < tp->mdev_us)
 427                         m = tp->mdev_us;
 428
 429                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
 430                 if (m >= var)
 431                         var = m;
 432                 else
 433                         var -= (var - m) >> 2;
 434
 435                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
 436         }
 437
 438         if (tcp_in_initial_slowstart(tp)) {
 439                 /* Slow start still did not finish. */
 440                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 441                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 442                         if (val && (tp->snd_cwnd >> 1) > val)
 443                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 444                                                tp->snd_cwnd >> 1);
 445                 }
 446                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 447                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 448                         if (tp->snd_cwnd > val)
 449                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 450                                                tp->snd_cwnd);
 451                 }
 452         } else if (!tcp_in_slow_start(tp) &&
 453                    icsk->icsk_ca_state == TCP_CA_Open) {
 454                 /* Cong. avoidance phase, cwnd is reliable. */
 455                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 456                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 457                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 458                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 459                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 460                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 461                 }
 462         } else {
 463                 /* Else slow start did not finish, cwnd is non-sense,
 464                  * ssthresh may be also invalid.
 465                  */
 466                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 467                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 468                         tcp_metric_set(tm, TCP_METRIC_CWND,
 469                                        (val + tp->snd_ssthresh) >> 1);
 470                 }
 471                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 472                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 473                         if (val && tp->snd_ssthresh > val)
 474                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 475                                                tp->snd_ssthresh);
 476                 }
 477                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 478                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 479                         if (val < tp->reordering &&
 480                             tp->reordering != sysctl_tcp_reordering)
 481                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 482                                                tp->reordering);
 483                 }
 484         }
 485         tm->tcpm_stamp = jiffies;
 486 out_unlock:
 487         rcu_read_unlock();
 488 }
 489
 490 /* Initialize metrics on socket. */
 491
 492 void tcp_init_metrics(struct sock *sk)
 493 {
 494         struct dst_entry *dst = __sk_dst_get(sk);
 495         struct tcp_sock *tp = tcp_sk(sk);
 496         struct tcp_metrics_block *tm;
 497         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 498
 499         if (!dst)
 500                 goto reset;
 501
 502         dst_confirm(dst);
 503
 504         rcu_read_lock();
 505         tm = tcp_get_metrics(sk, dst, true);
 506         if (!tm) {
 507                 rcu_read_unlock();
 508                 goto reset;
 509         }
 510
 511         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 512                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 513
 514         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 515         if (val) {
 516                 tp->snd_ssthresh = val;
 517                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 518                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 519         } else {
 520                 /* ssthresh may have been reduced unnecessarily during.
 521                  * 3WHS. Restore it back to its initial default.
 522                  */
 523                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 524         }
 525         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 526         if (val && tp->reordering != val) {
 527                 tcp_disable_fack(tp);
 528                 tcp_disable_early_retrans(tp);
 529                 tp->reordering = val;
 530         }
 531
 532         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 533         rcu_read_unlock();
 534 reset:
 535         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 536          * to seed the RTO for later data packets because SYN packets are
 537          * small. Use the per-dst cached values to seed the RTO but keep
 538          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 539          * Later the RTO will be updated immediately upon obtaining the first
 540          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 541          * influences the first RTO but not later RTT estimation.
 542          *
 543          * But if RTT is not available from the SYN (due to retransmits or
 544          * syn cookies) or the cache, force a conservative 3secs timeout.
 545          *
 546          * A bit of theory. RTT is time passed after "normal" sized packet
 547          * is sent until it is ACKed. In normal circumstances sending small
 548          * packets force peer to delay ACKs and calculation is correct too.
 549          * The algorithm is adaptive and, provided we follow specs, it
 550          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 551          * tricks sort of "quick acks" for time long enough to decrease RTT
 552          * to low value, and then abruptly stops to do it and starts to delay
 553          * ACKs, wait for troubles.
 554          */
 555         if (crtt > tp->srtt_us) {
 556                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 557                 crtt /= 8 * USEC_PER_MSEC;
 558                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 559         } else if (tp->srtt_us == 0) {
 560                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 561                  * 3WHS. This is most likely due to retransmission,
 562                  * including spurious one. Reset the RTO back to 3secs
 563                  * from the more aggressive 1sec to avoid more spurious
 564                  * retransmission.
 565                  */
 566                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 567                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 568
 569                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 570         }
 571         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 572          * retransmitted. In light of RFC6298 more aggressive 1sec
 573          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 574          * retransmission has occurred.
 575          */
 576         if (tp->total_retrans > 1)
 577                 tp->snd_cwnd = 1;
 578         else
 579                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 580         tp->snd_cwnd_stamp = tcp_time_stamp;
 581 }
 582
 583 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
 584                         bool paws_check, bool timestamps)
 585 {
 586         struct tcp_metrics_block *tm;
 587         bool ret;
 588
 589         if (!dst)
 590                 return false;
 591
 592         rcu_read_lock();
 593         tm = __tcp_get_metrics_req(req, dst);
 594         if (paws_check) {
 595                 if (tm &&
 596                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 597                     ((s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW ||
 598                      !timestamps))
 599                         ret = false;
 600                 else
 601                         ret = true;
 602         } else {
 603                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 604                         ret = true;
 605                 else
 606                         ret = false;
 607         }
 608         rcu_read_unlock();
 609
 610         return ret;
 611 }
 612 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 613
 614 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 615 {
 616         struct tcp_metrics_block *tm;
 617
 618         rcu_read_lock();
 619         tm = tcp_get_metrics(sk, dst, true);
 620         if (tm) {
 621                 struct tcp_sock *tp = tcp_sk(sk);
 622
 623                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 624                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 625                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 626                 }
 627         }
 628         rcu_read_unlock();
 629 }
 630 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 631
 632 /* VJ's idea. Save last timestamp seen from this destination and hold
 633  * it at least for normal timewait interval to use for duplicate
 634  * segment detection in subsequent connections, before they enter
 635  * synchronized state.
 636  */
 637 bool tcp_remember_stamp(struct sock *sk)
 638 {
 639         struct dst_entry *dst = __sk_dst_get(sk);
 640         bool ret = false;
 641
 642         if (dst) {
 643                 struct tcp_metrics_block *tm;
 644
 645                 rcu_read_lock();
 646                 tm = tcp_get_metrics(sk, dst, true);
 647                 if (tm) {
 648                         struct tcp_sock *tp = tcp_sk(sk);
 649
 650                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 651                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 652                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 653                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 654                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 655                         }
 656                         ret = true;
 657                 }
 658                 rcu_read_unlock();
 659         }
 660         return ret;
 661 }
 662
 663 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 664 {
 665         struct tcp_metrics_block *tm;
 666         bool ret = false;
 667
 668         rcu_read_lock();
 669         tm = __tcp_get_metrics_tw(tw);
 670         if (tm) {
 671                 const struct tcp_timewait_sock *tcptw;
 672                 struct sock *sk = (struct sock *) tw;
 673
 674                 tcptw = tcp_twsk(sk);
 675                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 676                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 677                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 678                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 679                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 680                 }
 681                 ret = true;
 682         }
 683         rcu_read_unlock();
 684
 685         return ret;
 686 }
 687
 688 static DEFINE_SEQLOCK(fastopen_seqlock);
 689
 690 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 691                             struct tcp_fastopen_cookie *cookie,
 692                             int *syn_loss, unsigned long *last_syn_loss)
 693 {
 694         struct tcp_metrics_block *tm;
 695
 696         rcu_read_lock();
 697         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 698         if (tm) {
 699                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 700                 unsigned int seq;
 701
 702                 do {
 703                         seq = read_seqbegin(&fastopen_seqlock);
 704                         if (tfom->mss)
 705                                 *mss = tfom->mss;
 706                         *cookie = tfom->cookie;
 707                         if (cookie->len <= 0 && tfom->try_exp == 1)
 708                                 cookie->exp = true;
 709                         *syn_loss = tfom->syn_loss;
 710                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 711                 } while (read_seqretry(&fastopen_seqlock, seq));
 712         }
 713         rcu_read_unlock();
 714 }
 715
 716 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 717                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
 718                             u16 try_exp)
 719 {
 720         struct dst_entry *dst = __sk_dst_get(sk);
 721         struct tcp_metrics_block *tm;
 722
 723         if (!dst)
 724                 return;
 725         rcu_read_lock();
 726         tm = tcp_get_metrics(sk, dst, true);
 727         if (tm) {
 728                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 729
 730                 write_seqlock_bh(&fastopen_seqlock);
 731                 if (mss)
 732                         tfom->mss = mss;
 733                 if (cookie && cookie->len > 0)
 734                         tfom->cookie = *cookie;
 735                 else if (try_exp > tfom->try_exp &&
 736                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
 737                         tfom->try_exp = try_exp;
 738                 if (syn_lost) {
 739                         ++tfom->syn_loss;
 740                         tfom->last_syn_loss = jiffies;
 741                 } else
 742                         tfom->syn_loss = 0;
 743                 write_sequnlock_bh(&fastopen_seqlock);
 744         }
 745         rcu_read_unlock();
 746 }
 747
 748 static struct genl_family tcp_metrics_nl_family = {
 749         .id             = GENL_ID_GENERATE,
 750         .hdrsize        = 0,
 751         .name           = TCP_METRICS_GENL_NAME,
 752         .version        = TCP_METRICS_GENL_VERSION,
 753         .maxattr        = TCP_METRICS_ATTR_MAX,
 754         .netnsok        = true,
 755 };
 756
 757 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 758         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 759         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 760                                             .len = sizeof(struct in6_addr), },
 761         /* Following attributes are not received for GET/DEL,
 762          * we keep them for reference
 763          */
 764 #if 0
 765         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 766         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 767         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 768         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 769         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 770         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 771         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 772         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 773                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 774 #endif
 775 };
 776
 777 /* Add attributes, caller cancels its header on failure */
 778 static int tcp_metrics_fill_info(struct sk_buff *msg,
 779                                  struct tcp_metrics_block *tm)
 780 {
 781         struct nlattr *nest;
 782         int i;
 783
 784         switch (tm->tcpm_daddr.family) {
 785         case AF_INET:
 786                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 787                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
 788                         goto nla_put_failure;
 789                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 790                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
 791                         goto nla_put_failure;
 792                 break;
 793         case AF_INET6:
 794                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
 795                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
 796                         goto nla_put_failure;
 797                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
 798                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
 799                         goto nla_put_failure;
 800                 break;
 801         default:
 802                 return -EAFNOSUPPORT;
 803         }
 804
 805         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 806                           jiffies - tm->tcpm_stamp) < 0)
 807                 goto nla_put_failure;
 808         if (tm->tcpm_ts_stamp) {
 809                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 810                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 811                         goto nla_put_failure;
 812                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 813                                 tm->tcpm_ts) < 0)
 814                         goto nla_put_failure;
 815         }
 816
 817         {
 818                 int n = 0;
 819
 820                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 821                 if (!nest)
 822                         goto nla_put_failure;
 823                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 824                         u32 val = tm->tcpm_vals[i];
 825
 826                         if (!val)
 827                                 continue;
 828                         if (i == TCP_METRIC_RTT) {
 829                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 830                                                 val) < 0)
 831                                         goto nla_put_failure;
 832                                 n++;
 833                                 val = max(val / 1000, 1U);
 834                         }
 835                         if (i == TCP_METRIC_RTTVAR) {
 836                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 837                                                 val) < 0)
 838                                         goto nla_put_failure;
 839                                 n++;
 840                                 val = max(val / 1000, 1U);
 841                         }
 842                         if (nla_put_u32(msg, i + 1, val) < 0)
 843                                 goto nla_put_failure;
 844                         n++;
 845                 }
 846                 if (n)
 847                         nla_nest_end(msg, nest);
 848                 else
 849                         nla_nest_cancel(msg, nest);
 850         }
 851
 852         {
 853                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 854                 unsigned int seq;
 855
 856                 do {
 857                         seq = read_seqbegin(&fastopen_seqlock);
 858                         tfom_copy[0] = tm->tcpm_fastopen;
 859                 } while (read_seqretry(&fastopen_seqlock, seq));
 860
 861                 tfom = tfom_copy;
 862                 if (tfom->mss &&
 863                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 864                                 tfom->mss) < 0)
 865                         goto nla_put_failure;
 866                 if (tfom->syn_loss &&
 867                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 868                                 tfom->syn_loss) < 0 ||
 869                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 870                                 jiffies - tfom->last_syn_loss) < 0))
 871                         goto nla_put_failure;
 872                 if (tfom->cookie.len > 0 &&
 873                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 874                             tfom->cookie.len, tfom->cookie.val) < 0)
 875                         goto nla_put_failure;
 876         }
 877
 878         return 0;
 879
 880 nla_put_failure:
 881         return -EMSGSIZE;
 882 }
 883
 884 static int tcp_metrics_dump_info(struct sk_buff *skb,
 885                                  struct netlink_callback *cb,
 886                                  struct tcp_metrics_block *tm)
 887 {
 888         void *hdr;
 889
 890         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 891                           &tcp_metrics_nl_family, NLM_F_MULTI,
 892                           TCP_METRICS_CMD_GET);
 893         if (!hdr)
 894                 return -EMSGSIZE;
 895
 896         if (tcp_metrics_fill_info(skb, tm) < 0)
 897                 goto nla_put_failure;
 898
 899         genlmsg_end(skb, hdr);
 900         return 0;
 901
 902 nla_put_failure:
 903         genlmsg_cancel(skb, hdr);
 904         return -EMSGSIZE;
 905 }
 906
 907 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 908                                struct netlink_callback *cb)
 909 {
 910         struct net *net = sock_net(skb->sk);
 911         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 912         unsigned int row, s_row = cb->args[0];
 913         int s_col = cb->args[1], col = s_col;
 914
 915         for (row = s_row; row < max_rows; row++, s_col = 0) {
 916                 struct tcp_metrics_block *tm;
 917                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
 918
 919                 rcu_read_lock();
 920                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 921                      tm = rcu_dereference(tm->tcpm_next), col++) {
 922                         if (!net_eq(tm_net(tm), net))
 923                                 continue;
 924                         if (col < s_col)
 925                                 continue;
 926                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 927                                 rcu_read_unlock();
 928                                 goto done;
 929                         }
 930                 }
 931                 rcu_read_unlock();
 932         }
 933
 934 done:
 935         cb->args[0] = row;
 936         cb->args[1] = col;
 937         return skb->len;
 938 }
 939
 940 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 941                            unsigned int *hash, int optional, int v4, int v6)
 942 {
 943         struct nlattr *a;
 944
 945         a = info->attrs[v4];
 946         if (a) {
 947                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
 948                 if (hash)
 949                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
 950                 return 0;
 951         }
 952         a = info->attrs[v6];
 953         if (a) {
 954                 struct in6_addr in6;
 955
 956                 if (nla_len(a) != sizeof(struct in6_addr))
 957                         return -EINVAL;
 958                 in6 = nla_get_in6_addr(a);
 959                 inetpeer_set_addr_v6(addr, &in6);
 960                 if (hash)
 961                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
 962                 return 0;
 963         }
 964         return optional ? 1 : -EAFNOSUPPORT;
 965 }
 966
 967 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 968                          unsigned int *hash, int optional)
 969 {
 970         return __parse_nl_addr(info, addr, hash, optional,
 971                                TCP_METRICS_ATTR_ADDR_IPV4,
 972                                TCP_METRICS_ATTR_ADDR_IPV6);
 973 }
 974
 975 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 976 {
 977         return __parse_nl_addr(info, addr, NULL, 0,
 978                                TCP_METRICS_ATTR_SADDR_IPV4,
 979                                TCP_METRICS_ATTR_SADDR_IPV6);
 980 }
 981
 982 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 983 {
 984         struct tcp_metrics_block *tm;
 985         struct inetpeer_addr saddr, daddr;
 986         unsigned int hash;
 987         struct sk_buff *msg;
 988         struct net *net = genl_info_net(info);
 989         void *reply;
 990         int ret;
 991         bool src = true;
 992
 993         ret = parse_nl_addr(info, &daddr, &hash, 0);
 994         if (ret < 0)
 995                 return ret;
 996
 997         ret = parse_nl_saddr(info, &saddr);
 998         if (ret < 0)
 999                 src = false;
1000
1001         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
1002         if (!msg)
1003                 return -ENOMEM;
1004
1005         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
1006                                   info->genlhdr->cmd);
1007         if (!reply)
1008                 goto nla_put_failure;
1009
1010         hash ^= net_hash_mix(net);
1011         hash = hash_32(hash, tcp_metrics_hash_log);
1012         ret = -ESRCH;
1013         rcu_read_lock();
1014         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
1015              tm = rcu_dereference(tm->tcpm_next)) {
1016                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1017                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1018                     net_eq(tm_net(tm), net)) {
1019                         ret = tcp_metrics_fill_info(msg, tm);
1020                         break;
1021                 }
1022         }
1023         rcu_read_unlock();
1024         if (ret < 0)
1025                 goto out_free;
1026
1027         genlmsg_end(msg, reply);
1028         return genlmsg_reply(msg, info);
1029
1030 nla_put_failure:
1031         ret = -EMSGSIZE;
1032
1033 out_free:
1034         nlmsg_free(msg);
1035         return ret;
1036 }
1037
1038 static void tcp_metrics_flush_all(struct net *net)
1039 {
1040         unsigned int max_rows = 1U << tcp_metrics_hash_log;
1041         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
1042         struct tcp_metrics_block *tm;
1043         unsigned int row;
1044
1045         for (row = 0; row < max_rows; row++, hb++) {
1046                 struct tcp_metrics_block __rcu **pp;
1047                 spin_lock_bh(&tcp_metrics_lock);
1048                 pp = &hb->chain;
1049                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1050                         if (net_eq(tm_net(tm), net)) {
1051                                 *pp = tm->tcpm_next;
1052                                 kfree_rcu(tm, rcu_head);
1053                         } else {
1054                                 pp = &tm->tcpm_next;
1055                         }
1056                 }
1057                 spin_unlock_bh(&tcp_metrics_lock);
1058         }
1059 }
1060
1061 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
1062 {
1063         struct tcpm_hash_bucket *hb;
1064         struct tcp_metrics_block *tm;
1065         struct tcp_metrics_block __rcu **pp;
1066         struct inetpeer_addr saddr, daddr;
1067         unsigned int hash;
1068         struct net *net = genl_info_net(info);
1069         int ret;
1070         bool src = true, found = false;
1071
1072         ret = parse_nl_addr(info, &daddr, &hash, 1);
1073         if (ret < 0)
1074                 return ret;
1075         if (ret > 0) {
1076                 tcp_metrics_flush_all(net);
1077                 return 0;
1078         }
1079         ret = parse_nl_saddr(info, &saddr);
1080         if (ret < 0)
1081                 src = false;
1082
1083         hash ^= net_hash_mix(net);
1084         hash = hash_32(hash, tcp_metrics_hash_log);
1085         hb = tcp_metrics_hash + hash;
1086         pp = &hb->chain;
1087         spin_lock_bh(&tcp_metrics_lock);
1088         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1089                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1090                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1091                     net_eq(tm_net(tm), net)) {
1092                         *pp = tm->tcpm_next;
1093                         kfree_rcu(tm, rcu_head);
1094                         found = true;
1095                 } else {
1096                         pp = &tm->tcpm_next;
1097                 }
1098         }
1099         spin_unlock_bh(&tcp_metrics_lock);
1100         if (!found)
1101                 return -ESRCH;
1102         return 0;
1103 }
1104
1105 static const struct genl_ops tcp_metrics_nl_ops[] = {
1106         {
1107                 .cmd = TCP_METRICS_CMD_GET,
1108                 .doit = tcp_metrics_nl_cmd_get,
1109                 .dumpit = tcp_metrics_nl_dump,
1110                 .policy = tcp_metrics_nl_policy,
1111         },
1112         {
1113                 .cmd = TCP_METRICS_CMD_DEL,
1114                 .doit = tcp_metrics_nl_cmd_del,
1115                 .policy = tcp_metrics_nl_policy,
1116                 .flags = GENL_ADMIN_PERM,
1117         },
1118 };
1119
1120 static unsigned int tcpmhash_entries;
1121 static int __init set_tcpmhash_entries(char *str)
1122 {
1123         ssize_t ret;
1124
1125         if (!str)
1126                 return 0;
1127
1128         ret = kstrtouint(str, 0, &tcpmhash_entries);
1129         if (ret)
1130                 return 0;
1131
1132         return 1;
1133 }
1134 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1135
1136 static int __net_init tcp_net_metrics_init(struct net *net)
1137 {
1138         size_t size;
1139         unsigned int slots;
1140
1141         if (!net_eq(net, &init_net))
1142                 return 0;
1143
1144         slots = tcpmhash_entries;
1145         if (!slots) {
1146                 if (totalram_pages >= 128 * 1024)
1147                         slots = 16 * 1024;
1148                 else
1149                         slots = 8 * 1024;
1150         }
1151
1152         tcp_metrics_hash_log = order_base_2(slots);
1153         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1154
1155         tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1156         if (!tcp_metrics_hash)
1157                 tcp_metrics_hash = vzalloc(size);
1158
1159         if (!tcp_metrics_hash)
1160                 return -ENOMEM;
1161
1162         return 0;
1163 }
1164
1165 static void __net_exit tcp_net_metrics_exit(struct net *net)
1166 {
1167         tcp_metrics_flush_all(net);
1168 }
1169
1170 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1171         .init   =       tcp_net_metrics_init,
1172         .exit   =       tcp_net_metrics_exit,
1173 };
1174
1175 void __init tcp_metrics_init(void)
1176 {
1177         int ret;
1178
1179         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1180         if (ret < 0)
1181                 panic("Could not allocate the tcp_metrics hash table\n");
1182
1183         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1184                                             tcp_metrics_nl_ops);
1185         if (ret < 0)
1186                 panic("Could not register tcp_metrics generic netlink\n");
1187 }