net/ipv4/tcp_metrics.c

   1 #include <linux/rcupdate.h>
   2 #include <linux/spinlock.h>
   3 #include <linux/jiffies.h>
   4 #include <linux/module.h>
   5 #include <linux/cache.h>
   6 #include <linux/slab.h>
   7 #include <linux/init.h>
   8 #include <linux/tcp.h>
   9 #include <linux/hash.h>
  10 #include <linux/tcp_metrics.h>
  11 #include <linux/vmalloc.h>
  12
  13 #include <net/inet_connection_sock.h>
  14 #include <net/net_namespace.h>
  15 #include <net/request_sock.h>
  16 #include <net/inetpeer.h>
  17 #include <net/sock.h>
  18 #include <net/ipv6.h>
  19 #include <net/dst.h>
  20 #include <net/tcp.h>
  21 #include <net/genetlink.h>
  22
  23 int sysctl_tcp_nometrics_save __read_mostly;
  24
  25 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
  26                                                    const struct inetpeer_addr *daddr,
  27                                                    struct net *net, unsigned int hash);
  28
  29 struct tcp_fastopen_metrics {
  30         u16     mss;
  31         u16     syn_loss:10;            /* Recurring Fast Open SYN losses */
  32         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
  33         struct  tcp_fastopen_cookie     cookie;
  34 };
  35
  36 /* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
  37  * Kernel only stores RTT and RTTVAR in usec resolution
  38  */
  39 #define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)
  40
  41 struct tcp_metrics_block {
  42         struct tcp_metrics_block __rcu  *tcpm_next;
  43         possible_net_t                  tcpm_net;
  44         struct inetpeer_addr            tcpm_saddr;
  45         struct inetpeer_addr            tcpm_daddr;
  46         unsigned long                   tcpm_stamp;
  47         u32                             tcpm_ts;
  48         u32                             tcpm_ts_stamp;
  49         u32                             tcpm_lock;
  50         u32                             tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
  51         struct tcp_fastopen_metrics     tcpm_fastopen;
  52
  53         struct rcu_head                 rcu_head;
  54 };
  55
  56 static inline struct net *tm_net(struct tcp_metrics_block *tm)
  57 {
  58         return read_pnet(&tm->tcpm_net);
  59 }
  60
  61 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  62                               enum tcp_metric_index idx)
  63 {
  64         return tm->tcpm_lock & (1 << idx);
  65 }
  66
  67 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
  68                           enum tcp_metric_index idx)
  69 {
  70         return tm->tcpm_vals[idx];
  71 }
  72
  73 static void tcp_metric_set(struct tcp_metrics_block *tm,
  74                            enum tcp_metric_index idx,
  75                            u32 val)
  76 {
  77         tm->tcpm_vals[idx] = val;
  78 }
  79
  80 static bool addr_same(const struct inetpeer_addr *a,
  81                       const struct inetpeer_addr *b)
  82 {
  83         const struct in6_addr *a6, *b6;
  84
  85         if (a->family != b->family)
  86                 return false;
  87         if (a->family == AF_INET)
  88                 return a->addr.a4 == b->addr.a4;
  89
  90         a6 = (const struct in6_addr *) &a->addr.a6[0];
  91         b6 = (const struct in6_addr *) &b->addr.a6[0];
  92
  93         return ipv6_addr_equal(a6, b6);
  94 }
  95
  96 struct tcpm_hash_bucket {
  97         struct tcp_metrics_block __rcu  *chain;
  98 };
  99
 100 static DEFINE_SPINLOCK(tcp_metrics_lock);
 101
 102 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
 103                           const struct dst_entry *dst,
 104                           bool fastopen_clear)
 105 {
 106         u32 msval;
 107         u32 val;
 108
 109         tm->tcpm_stamp = jiffies;
 110
 111         val = 0;
 112         if (dst_metric_locked(dst, RTAX_RTT))
 113                 val |= 1 << TCP_METRIC_RTT;
 114         if (dst_metric_locked(dst, RTAX_RTTVAR))
 115                 val |= 1 << TCP_METRIC_RTTVAR;
 116         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 117                 val |= 1 << TCP_METRIC_SSTHRESH;
 118         if (dst_metric_locked(dst, RTAX_CWND))
 119                 val |= 1 << TCP_METRIC_CWND;
 120         if (dst_metric_locked(dst, RTAX_REORDERING))
 121                 val |= 1 << TCP_METRIC_REORDERING;
 122         tm->tcpm_lock = val;
 123
 124         msval = dst_metric_raw(dst, RTAX_RTT);
 125         tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
 126
 127         msval = dst_metric_raw(dst, RTAX_RTTVAR);
 128         tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
 129         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
 130         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
 131         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 132         tm->tcpm_ts = 0;
 133         tm->tcpm_ts_stamp = 0;
 134         if (fastopen_clear) {
 135                 tm->tcpm_fastopen.mss = 0;
 136                 tm->tcpm_fastopen.syn_loss = 0;
 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 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 153                                           struct inetpeer_addr *saddr,
 154                                           struct inetpeer_addr *daddr,
 155                                           unsigned int hash)
 156 {
 157         struct tcp_metrics_block *tm;
 158         struct net *net;
 159         bool reclaim = false;
 160
 161         spin_lock_bh(&tcp_metrics_lock);
 162         net = dev_net(dst->dev);
 163
 164         /* While waiting for the spin-lock the cache might have been populated
 165          * with this entry and so we have to check again.
 166          */
 167         tm = __tcp_get_metrics(saddr, daddr, net, hash);
 168         if (tm == TCP_METRICS_RECLAIM_PTR) {
 169                 reclaim = true;
 170                 tm = NULL;
 171         }
 172         if (tm) {
 173                 tcpm_check_stamp(tm, dst);
 174                 goto out_unlock;
 175         }
 176
 177         if (unlikely(reclaim)) {
 178                 struct tcp_metrics_block *oldest;
 179
 180                 oldest = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain);
 181                 for (tm = rcu_dereference(oldest->tcpm_next); tm;
 182                      tm = rcu_dereference(tm->tcpm_next)) {
 183                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 184                                 oldest = tm;
 185                 }
 186                 tm = oldest;
 187         } else {
 188                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 189                 if (!tm)
 190                         goto out_unlock;
 191         }
 192         write_pnet(&tm->tcpm_net, net);
 193         tm->tcpm_saddr = *saddr;
 194         tm->tcpm_daddr = *daddr;
 195
 196         tcpm_suck_dst(tm, dst, true);
 197
 198         if (likely(!reclaim)) {
 199                 tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
 200                 rcu_assign_pointer(net->ipv4.tcp_metrics_hash[hash].chain, tm);
 201         }
 202
 203 out_unlock:
 204         spin_unlock_bh(&tcp_metrics_lock);
 205         return tm;
 206 }
 207
 208 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 209 {
 210         if (tm)
 211                 return tm;
 212         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 213                 return TCP_METRICS_RECLAIM_PTR;
 214         return NULL;
 215 }
 216
 217 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 218                                                    const struct inetpeer_addr *daddr,
 219                                                    struct net *net, unsigned int hash)
 220 {
 221         struct tcp_metrics_block *tm;
 222         int depth = 0;
 223
 224         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 225              tm = rcu_dereference(tm->tcpm_next)) {
 226                 if (addr_same(&tm->tcpm_saddr, saddr) &&
 227                     addr_same(&tm->tcpm_daddr, daddr) &&
 228                     net_eq(tm_net(tm), net))
 229                         break;
 230                 depth++;
 231         }
 232         return tcp_get_encode(tm, depth);
 233 }
 234
 235 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 236                                                        struct dst_entry *dst)
 237 {
 238         struct tcp_metrics_block *tm;
 239         struct inetpeer_addr saddr, daddr;
 240         unsigned int hash;
 241         struct net *net;
 242
 243         saddr.family = req->rsk_ops->family;
 244         daddr.family = req->rsk_ops->family;
 245         switch (daddr.family) {
 246         case AF_INET:
 247                 saddr.addr.a4 = inet_rsk(req)->ir_loc_addr;
 248                 daddr.addr.a4 = inet_rsk(req)->ir_rmt_addr;
 249                 hash = (__force unsigned int) daddr.addr.a4;
 250                 break;
 251 #if IS_ENABLED(CONFIG_IPV6)
 252         case AF_INET6:
 253                 *(struct in6_addr *)saddr.addr.a6 = inet_rsk(req)->ir_v6_loc_addr;
 254                 *(struct in6_addr *)daddr.addr.a6 = inet_rsk(req)->ir_v6_rmt_addr;
 255                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 256                 break;
 257 #endif
 258         default:
 259                 return NULL;
 260         }
 261
 262         net = dev_net(dst->dev);
 263         hash ^= net_hash_mix(net);
 264         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 265
 266         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 267              tm = rcu_dereference(tm->tcpm_next)) {
 268                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 269                     addr_same(&tm->tcpm_daddr, &daddr) &&
 270                     net_eq(tm_net(tm), net))
 271                         break;
 272         }
 273         tcpm_check_stamp(tm, dst);
 274         return tm;
 275 }
 276
 277 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 278 {
 279         struct tcp_metrics_block *tm;
 280         struct inetpeer_addr saddr, daddr;
 281         unsigned int hash;
 282         struct net *net;
 283
 284         if (tw->tw_family == AF_INET) {
 285                 saddr.family = AF_INET;
 286                 saddr.addr.a4 = tw->tw_rcv_saddr;
 287                 daddr.family = AF_INET;
 288                 daddr.addr.a4 = tw->tw_daddr;
 289                 hash = (__force unsigned int) daddr.addr.a4;
 290         }
 291 #if IS_ENABLED(CONFIG_IPV6)
 292         else if (tw->tw_family == AF_INET6) {
 293                 if (ipv6_addr_v4mapped(&tw->tw_v6_daddr)) {
 294                         saddr.family = AF_INET;
 295                         saddr.addr.a4 = tw->tw_rcv_saddr;
 296                         daddr.family = AF_INET;
 297                         daddr.addr.a4 = tw->tw_daddr;
 298                         hash = (__force unsigned int) daddr.addr.a4;
 299                 } else {
 300                         saddr.family = AF_INET6;
 301                         *(struct in6_addr *)saddr.addr.a6 = tw->tw_v6_rcv_saddr;
 302                         daddr.family = AF_INET6;
 303                         *(struct in6_addr *)daddr.addr.a6 = tw->tw_v6_daddr;
 304                         hash = ipv6_addr_hash(&tw->tw_v6_daddr);
 305                 }
 306         }
 307 #endif
 308         else
 309                 return NULL;
 310
 311         net = twsk_net(tw);
 312         hash ^= net_hash_mix(net);
 313         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 314
 315         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 316              tm = rcu_dereference(tm->tcpm_next)) {
 317                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 318                     addr_same(&tm->tcpm_daddr, &daddr) &&
 319                     net_eq(tm_net(tm), net))
 320                         break;
 321         }
 322         return tm;
 323 }
 324
 325 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 326                                                  struct dst_entry *dst,
 327                                                  bool create)
 328 {
 329         struct tcp_metrics_block *tm;
 330         struct inetpeer_addr saddr, daddr;
 331         unsigned int hash;
 332         struct net *net;
 333
 334         if (sk->sk_family == AF_INET) {
 335                 saddr.family = AF_INET;
 336                 saddr.addr.a4 = inet_sk(sk)->inet_saddr;
 337                 daddr.family = AF_INET;
 338                 daddr.addr.a4 = inet_sk(sk)->inet_daddr;
 339                 hash = (__force unsigned int) daddr.addr.a4;
 340         }
 341 #if IS_ENABLED(CONFIG_IPV6)
 342         else if (sk->sk_family == AF_INET6) {
 343                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
 344                         saddr.family = AF_INET;
 345                         saddr.addr.a4 = inet_sk(sk)->inet_saddr;
 346                         daddr.family = AF_INET;
 347                         daddr.addr.a4 = inet_sk(sk)->inet_daddr;
 348                         hash = (__force unsigned int) daddr.addr.a4;
 349                 } else {
 350                         saddr.family = AF_INET6;
 351                         *(struct in6_addr *)saddr.addr.a6 = sk->sk_v6_rcv_saddr;
 352                         daddr.family = AF_INET6;
 353                         *(struct in6_addr *)daddr.addr.a6 = sk->sk_v6_daddr;
 354                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 355                 }
 356         }
 357 #endif
 358         else
 359                 return NULL;
 360
 361         net = dev_net(dst->dev);
 362         hash ^= net_hash_mix(net);
 363         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 364
 365         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 366         if (tm == TCP_METRICS_RECLAIM_PTR)
 367                 tm = NULL;
 368         if (!tm && create)
 369                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 370         else
 371                 tcpm_check_stamp(tm, dst);
 372
 373         return tm;
 374 }
 375
 376 /* Save metrics learned by this TCP session.  This function is called
 377  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 378  * or goes from LAST-ACK to CLOSE.
 379  */
 380 void tcp_update_metrics(struct sock *sk)
 381 {
 382         const struct inet_connection_sock *icsk = inet_csk(sk);
 383         struct dst_entry *dst = __sk_dst_get(sk);
 384         struct tcp_sock *tp = tcp_sk(sk);
 385         struct tcp_metrics_block *tm;
 386         unsigned long rtt;
 387         u32 val;
 388         int m;
 389
 390         if (sysctl_tcp_nometrics_save || !dst)
 391                 return;
 392
 393         if (dst->flags & DST_HOST)
 394                 dst_confirm(dst);
 395
 396         rcu_read_lock();
 397         if (icsk->icsk_backoff || !tp->srtt_us) {
 398                 /* This session failed to estimate rtt. Why?
 399                  * Probably, no packets returned in time.  Reset our
 400                  * results.
 401                  */
 402                 tm = tcp_get_metrics(sk, dst, false);
 403                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 404                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 405                 goto out_unlock;
 406         } else
 407                 tm = tcp_get_metrics(sk, dst, true);
 408
 409         if (!tm)
 410                 goto out_unlock;
 411
 412         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 413         m = rtt - tp->srtt_us;
 414
 415         /* If newly calculated rtt larger than stored one, store new
 416          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 417          * always better than underestimation.
 418          */
 419         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 420                 if (m <= 0)
 421                         rtt = tp->srtt_us;
 422                 else
 423                         rtt -= (m >> 3);
 424                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
 425         }
 426
 427         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 428                 unsigned long var;
 429
 430                 if (m < 0)
 431                         m = -m;
 432
 433                 /* Scale deviation to rttvar fixed point */
 434                 m >>= 1;
 435                 if (m < tp->mdev_us)
 436                         m = tp->mdev_us;
 437
 438                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
 439                 if (m >= var)
 440                         var = m;
 441                 else
 442                         var -= (var - m) >> 2;
 443
 444                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
 445         }
 446
 447         if (tcp_in_initial_slowstart(tp)) {
 448                 /* Slow start still did not finish. */
 449                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 450                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 451                         if (val && (tp->snd_cwnd >> 1) > val)
 452                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 453                                                tp->snd_cwnd >> 1);
 454                 }
 455                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 456                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 457                         if (tp->snd_cwnd > val)
 458                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 459                                                tp->snd_cwnd);
 460                 }
 461         } else if (tp->snd_cwnd > tp->snd_ssthresh &&
 462                    icsk->icsk_ca_state == TCP_CA_Open) {
 463                 /* Cong. avoidance phase, cwnd is reliable. */
 464                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 465                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 466                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 467                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 468                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 469                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 470                 }
 471         } else {
 472                 /* Else slow start did not finish, cwnd is non-sense,
 473                  * ssthresh may be also invalid.
 474                  */
 475                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 476                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 477                         tcp_metric_set(tm, TCP_METRIC_CWND,
 478                                        (val + tp->snd_ssthresh) >> 1);
 479                 }
 480                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 481                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 482                         if (val && tp->snd_ssthresh > val)
 483                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 484                                                tp->snd_ssthresh);
 485                 }
 486                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 487                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 488                         if (val < tp->reordering &&
 489                             tp->reordering != sysctl_tcp_reordering)
 490                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 491                                                tp->reordering);
 492                 }
 493         }
 494         tm->tcpm_stamp = jiffies;
 495 out_unlock:
 496         rcu_read_unlock();
 497 }
 498
 499 /* Initialize metrics on socket. */
 500
 501 void tcp_init_metrics(struct sock *sk)
 502 {
 503         struct dst_entry *dst = __sk_dst_get(sk);
 504         struct tcp_sock *tp = tcp_sk(sk);
 505         struct tcp_metrics_block *tm;
 506         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 507
 508         if (dst == NULL)
 509                 goto reset;
 510
 511         dst_confirm(dst);
 512
 513         rcu_read_lock();
 514         tm = tcp_get_metrics(sk, dst, true);
 515         if (!tm) {
 516                 rcu_read_unlock();
 517                 goto reset;
 518         }
 519
 520         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 521                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 522
 523         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 524         if (val) {
 525                 tp->snd_ssthresh = val;
 526                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 527                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 528         } else {
 529                 /* ssthresh may have been reduced unnecessarily during.
 530                  * 3WHS. Restore it back to its initial default.
 531                  */
 532                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 533         }
 534         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 535         if (val && tp->reordering != val) {
 536                 tcp_disable_fack(tp);
 537                 tcp_disable_early_retrans(tp);
 538                 tp->reordering = val;
 539         }
 540
 541         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 542         rcu_read_unlock();
 543 reset:
 544         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 545          * to seed the RTO for later data packets because SYN packets are
 546          * small. Use the per-dst cached values to seed the RTO but keep
 547          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 548          * Later the RTO will be updated immediately upon obtaining the first
 549          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 550          * influences the first RTO but not later RTT estimation.
 551          *
 552          * But if RTT is not available from the SYN (due to retransmits or
 553          * syn cookies) or the cache, force a conservative 3secs timeout.
 554          *
 555          * A bit of theory. RTT is time passed after "normal" sized packet
 556          * is sent until it is ACKed. In normal circumstances sending small
 557          * packets force peer to delay ACKs and calculation is correct too.
 558          * The algorithm is adaptive and, provided we follow specs, it
 559          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 560          * tricks sort of "quick acks" for time long enough to decrease RTT
 561          * to low value, and then abruptly stops to do it and starts to delay
 562          * ACKs, wait for troubles.
 563          */
 564         if (crtt > tp->srtt_us) {
 565                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 566                 crtt /= 8 * USEC_PER_MSEC;
 567                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 568         } else if (tp->srtt_us == 0) {
 569                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 570                  * 3WHS. This is most likely due to retransmission,
 571                  * including spurious one. Reset the RTO back to 3secs
 572                  * from the more aggressive 1sec to avoid more spurious
 573                  * retransmission.
 574                  */
 575                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 576                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 577
 578                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 579         }
 580         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 581          * retransmitted. In light of RFC6298 more aggressive 1sec
 582          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 583          * retransmission has occurred.
 584          */
 585         if (tp->total_retrans > 1)
 586                 tp->snd_cwnd = 1;
 587         else
 588                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 589         tp->snd_cwnd_stamp = tcp_time_stamp;
 590 }
 591
 592 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
 593                         bool paws_check, bool timestamps)
 594 {
 595         struct tcp_metrics_block *tm;
 596         bool ret;
 597
 598         if (!dst)
 599                 return false;
 600
 601         rcu_read_lock();
 602         tm = __tcp_get_metrics_req(req, dst);
 603         if (paws_check) {
 604                 if (tm &&
 605                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 606                     ((s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW ||
 607                      !timestamps))
 608                         ret = false;
 609                 else
 610                         ret = true;
 611         } else {
 612                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 613                         ret = true;
 614                 else
 615                         ret = false;
 616         }
 617         rcu_read_unlock();
 618
 619         return ret;
 620 }
 621 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 622
 623 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 624 {
 625         struct tcp_metrics_block *tm;
 626
 627         rcu_read_lock();
 628         tm = tcp_get_metrics(sk, dst, true);
 629         if (tm) {
 630                 struct tcp_sock *tp = tcp_sk(sk);
 631
 632                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 633                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 634                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 635                 }
 636         }
 637         rcu_read_unlock();
 638 }
 639 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 640
 641 /* VJ's idea. Save last timestamp seen from this destination and hold
 642  * it at least for normal timewait interval to use for duplicate
 643  * segment detection in subsequent connections, before they enter
 644  * synchronized state.
 645  */
 646 bool tcp_remember_stamp(struct sock *sk)
 647 {
 648         struct dst_entry *dst = __sk_dst_get(sk);
 649         bool ret = false;
 650
 651         if (dst) {
 652                 struct tcp_metrics_block *tm;
 653
 654                 rcu_read_lock();
 655                 tm = tcp_get_metrics(sk, dst, true);
 656                 if (tm) {
 657                         struct tcp_sock *tp = tcp_sk(sk);
 658
 659                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 660                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 661                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 662                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 663                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 664                         }
 665                         ret = true;
 666                 }
 667                 rcu_read_unlock();
 668         }
 669         return ret;
 670 }
 671
 672 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 673 {
 674         struct tcp_metrics_block *tm;
 675         bool ret = false;
 676
 677         rcu_read_lock();
 678         tm = __tcp_get_metrics_tw(tw);
 679         if (tm) {
 680                 const struct tcp_timewait_sock *tcptw;
 681                 struct sock *sk = (struct sock *) tw;
 682
 683                 tcptw = tcp_twsk(sk);
 684                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 685                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 686                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 687                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 688                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 689                 }
 690                 ret = true;
 691         }
 692         rcu_read_unlock();
 693
 694         return ret;
 695 }
 696
 697 static DEFINE_SEQLOCK(fastopen_seqlock);
 698
 699 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 700                             struct tcp_fastopen_cookie *cookie,
 701                             int *syn_loss, unsigned long *last_syn_loss)
 702 {
 703         struct tcp_metrics_block *tm;
 704
 705         rcu_read_lock();
 706         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 707         if (tm) {
 708                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 709                 unsigned int seq;
 710
 711                 do {
 712                         seq = read_seqbegin(&fastopen_seqlock);
 713                         if (tfom->mss)
 714                                 *mss = tfom->mss;
 715                         *cookie = tfom->cookie;
 716                         *syn_loss = tfom->syn_loss;
 717                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 718                 } while (read_seqretry(&fastopen_seqlock, seq));
 719         }
 720         rcu_read_unlock();
 721 }
 722
 723 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 724                             struct tcp_fastopen_cookie *cookie, bool syn_lost)
 725 {
 726         struct dst_entry *dst = __sk_dst_get(sk);
 727         struct tcp_metrics_block *tm;
 728
 729         if (!dst)
 730                 return;
 731         rcu_read_lock();
 732         tm = tcp_get_metrics(sk, dst, true);
 733         if (tm) {
 734                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 735
 736                 write_seqlock_bh(&fastopen_seqlock);
 737                 if (mss)
 738                         tfom->mss = mss;
 739                 if (cookie && cookie->len > 0)
 740                         tfom->cookie = *cookie;
 741                 if (syn_lost) {
 742                         ++tfom->syn_loss;
 743                         tfom->last_syn_loss = jiffies;
 744                 } else
 745                         tfom->syn_loss = 0;
 746                 write_sequnlock_bh(&fastopen_seqlock);
 747         }
 748         rcu_read_unlock();
 749 }
 750
 751 static struct genl_family tcp_metrics_nl_family = {
 752         .id             = GENL_ID_GENERATE,
 753         .hdrsize        = 0,
 754         .name           = TCP_METRICS_GENL_NAME,
 755         .version        = TCP_METRICS_GENL_VERSION,
 756         .maxattr        = TCP_METRICS_ATTR_MAX,
 757         .netnsok        = true,
 758 };
 759
 760 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 761         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 762         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 763                                             .len = sizeof(struct in6_addr), },
 764         /* Following attributes are not received for GET/DEL,
 765          * we keep them for reference
 766          */
 767 #if 0
 768         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 769         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 770         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 771         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 772         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 773         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 774         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 775         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 776                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 777 #endif
 778 };
 779
 780 /* Add attributes, caller cancels its header on failure */
 781 static int tcp_metrics_fill_info(struct sk_buff *msg,
 782                                  struct tcp_metrics_block *tm)
 783 {
 784         struct nlattr *nest;
 785         int i;
 786
 787         switch (tm->tcpm_daddr.family) {
 788         case AF_INET:
 789                 if (nla_put_be32(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 790                                 tm->tcpm_daddr.addr.a4) < 0)
 791                         goto nla_put_failure;
 792                 if (nla_put_be32(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 793                                 tm->tcpm_saddr.addr.a4) < 0)
 794                         goto nla_put_failure;
 795                 break;
 796         case AF_INET6:
 797                 if (nla_put(msg, TCP_METRICS_ATTR_ADDR_IPV6, 16,
 798                             tm->tcpm_daddr.addr.a6) < 0)
 799                         goto nla_put_failure;
 800                 if (nla_put(msg, TCP_METRICS_ATTR_SADDR_IPV6, 16,
 801                             tm->tcpm_saddr.addr.a6) < 0)
 802                         goto nla_put_failure;
 803                 break;
 804         default:
 805                 return -EAFNOSUPPORT;
 806         }
 807
 808         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 809                           jiffies - tm->tcpm_stamp) < 0)
 810                 goto nla_put_failure;
 811         if (tm->tcpm_ts_stamp) {
 812                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 813                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 814                         goto nla_put_failure;
 815                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 816                                 tm->tcpm_ts) < 0)
 817                         goto nla_put_failure;
 818         }
 819
 820         {
 821                 int n = 0;
 822
 823                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 824                 if (!nest)
 825                         goto nla_put_failure;
 826                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 827                         u32 val = tm->tcpm_vals[i];
 828
 829                         if (!val)
 830                                 continue;
 831                         if (i == TCP_METRIC_RTT) {
 832                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 833                                                 val) < 0)
 834                                         goto nla_put_failure;
 835                                 n++;
 836                                 val = max(val / 1000, 1U);
 837                         }
 838                         if (i == TCP_METRIC_RTTVAR) {
 839                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 840                                                 val) < 0)
 841                                         goto nla_put_failure;
 842                                 n++;
 843                                 val = max(val / 1000, 1U);
 844                         }
 845                         if (nla_put_u32(msg, i + 1, val) < 0)
 846                                 goto nla_put_failure;
 847                         n++;
 848                 }
 849                 if (n)
 850                         nla_nest_end(msg, nest);
 851                 else
 852                         nla_nest_cancel(msg, nest);
 853         }
 854
 855         {
 856                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 857                 unsigned int seq;
 858
 859                 do {
 860                         seq = read_seqbegin(&fastopen_seqlock);
 861                         tfom_copy[0] = tm->tcpm_fastopen;
 862                 } while (read_seqretry(&fastopen_seqlock, seq));
 863
 864                 tfom = tfom_copy;
 865                 if (tfom->mss &&
 866                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 867                                 tfom->mss) < 0)
 868                         goto nla_put_failure;
 869                 if (tfom->syn_loss &&
 870                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 871                                 tfom->syn_loss) < 0 ||
 872                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 873                                 jiffies - tfom->last_syn_loss) < 0))
 874                         goto nla_put_failure;
 875                 if (tfom->cookie.len > 0 &&
 876                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 877                             tfom->cookie.len, tfom->cookie.val) < 0)
 878                         goto nla_put_failure;
 879         }
 880
 881         return 0;
 882
 883 nla_put_failure:
 884         return -EMSGSIZE;
 885 }
 886
 887 static int tcp_metrics_dump_info(struct sk_buff *skb,
 888                                  struct netlink_callback *cb,
 889                                  struct tcp_metrics_block *tm)
 890 {
 891         void *hdr;
 892
 893         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 894                           &tcp_metrics_nl_family, NLM_F_MULTI,
 895                           TCP_METRICS_CMD_GET);
 896         if (!hdr)
 897                 return -EMSGSIZE;
 898
 899         if (tcp_metrics_fill_info(skb, tm) < 0)
 900                 goto nla_put_failure;
 901
 902         genlmsg_end(skb, hdr);
 903         return 0;
 904
 905 nla_put_failure:
 906         genlmsg_cancel(skb, hdr);
 907         return -EMSGSIZE;
 908 }
 909
 910 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 911                                struct netlink_callback *cb)
 912 {
 913         struct net *net = sock_net(skb->sk);
 914         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 915         unsigned int row, s_row = cb->args[0];
 916         int s_col = cb->args[1], col = s_col;
 917
 918         for (row = s_row; row < max_rows; row++, s_col = 0) {
 919                 struct tcp_metrics_block *tm;
 920                 struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash + row;
 921
 922                 rcu_read_lock();
 923                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 924                      tm = rcu_dereference(tm->tcpm_next), col++) {
 925                         if (!net_eq(tm_net(tm), net))
 926                                 continue;
 927                         if (col < s_col)
 928                                 continue;
 929                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 930                                 rcu_read_unlock();
 931                                 goto done;
 932                         }
 933                 }
 934                 rcu_read_unlock();
 935         }
 936
 937 done:
 938         cb->args[0] = row;
 939         cb->args[1] = col;
 940         return skb->len;
 941 }
 942
 943 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 944                            unsigned int *hash, int optional, int v4, int v6)
 945 {
 946         struct nlattr *a;
 947
 948         a = info->attrs[v4];
 949         if (a) {
 950                 addr->family = AF_INET;
 951                 addr->addr.a4 = nla_get_be32(a);
 952                 if (hash)
 953                         *hash = (__force unsigned int) addr->addr.a4;
 954                 return 0;
 955         }
 956         a = info->attrs[v6];
 957         if (a) {
 958                 if (nla_len(a) != sizeof(struct in6_addr))
 959                         return -EINVAL;
 960                 addr->family = AF_INET6;
 961                 memcpy(addr->addr.a6, nla_data(a), sizeof(addr->addr.a6));
 962                 if (hash)
 963                         *hash = ipv6_addr_hash((struct in6_addr *) addr->addr.a6);
 964                 return 0;
 965         }
 966         return optional ? 1 : -EAFNOSUPPORT;
 967 }
 968
 969 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 970                          unsigned int *hash, int optional)
 971 {
 972         return __parse_nl_addr(info, addr, hash, optional,
 973                                TCP_METRICS_ATTR_ADDR_IPV4,
 974                                TCP_METRICS_ATTR_ADDR_IPV6);
 975 }
 976
 977 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 978 {
 979         return __parse_nl_addr(info, addr, NULL, 0,
 980                                TCP_METRICS_ATTR_SADDR_IPV4,
 981                                TCP_METRICS_ATTR_SADDR_IPV6);
 982 }
 983
 984 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 985 {
 986         struct tcp_metrics_block *tm;
 987         struct inetpeer_addr saddr, daddr;
 988         unsigned int hash;
 989         struct sk_buff *msg;
 990         struct net *net = genl_info_net(info);
 991         void *reply;
 992         int ret;
 993         bool src = true;
 994
 995         ret = parse_nl_addr(info, &daddr, &hash, 0);
 996         if (ret < 0)
 997                 return ret;
 998
 999         ret = parse_nl_saddr(info, &saddr);
1000         if (ret < 0)
1001                 src = false;
1002
1003         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
1004         if (!msg)
1005                 return -ENOMEM;
1006
1007         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
1008                                   info->genlhdr->cmd);
1009         if (!reply)
1010                 goto nla_put_failure;
1011
1012         hash ^= net_hash_mix(net);
1013         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
1014         ret = -ESRCH;
1015         rcu_read_lock();
1016         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
1017              tm = rcu_dereference(tm->tcpm_next)) {
1018                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1019                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1020                     net_eq(tm_net(tm), net)) {
1021                         ret = tcp_metrics_fill_info(msg, tm);
1022                         break;
1023                 }
1024         }
1025         rcu_read_unlock();
1026         if (ret < 0)
1027                 goto out_free;
1028
1029         genlmsg_end(msg, reply);
1030         return genlmsg_reply(msg, info);
1031
1032 nla_put_failure:
1033         ret = -EMSGSIZE;
1034
1035 out_free:
1036         nlmsg_free(msg);
1037         return ret;
1038 }
1039
1040 #define deref_locked_genl(p)    \
1041         rcu_dereference_protected(p, lockdep_genl_is_held() && \
1042                                      lockdep_is_held(&tcp_metrics_lock))
1043
1044 #define deref_genl(p)   rcu_dereference_protected(p, lockdep_genl_is_held())
1045
1046 static int tcp_metrics_flush_all(struct net *net)
1047 {
1048         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
1049         struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash;
1050         struct tcp_metrics_block *tm;
1051         unsigned int row;
1052
1053         for (row = 0; row < max_rows; row++, hb++) {
1054                 spin_lock_bh(&tcp_metrics_lock);
1055                 tm = deref_locked_genl(hb->chain);
1056                 if (tm)
1057                         hb->chain = NULL;
1058                 spin_unlock_bh(&tcp_metrics_lock);
1059                 while (tm) {
1060                         struct tcp_metrics_block *next;
1061
1062                         next = deref_genl(tm->tcpm_next);
1063                         kfree_rcu(tm, rcu_head);
1064                         tm = next;
1065                 }
1066         }
1067         return 0;
1068 }
1069
1070 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
1071 {
1072         struct tcpm_hash_bucket *hb;
1073         struct tcp_metrics_block *tm;
1074         struct tcp_metrics_block __rcu **pp;
1075         struct inetpeer_addr saddr, daddr;
1076         unsigned int hash;
1077         struct net *net = genl_info_net(info);
1078         int ret;
1079         bool src = true, found = false;
1080
1081         ret = parse_nl_addr(info, &daddr, &hash, 1);
1082         if (ret < 0)
1083                 return ret;
1084         if (ret > 0)
1085                 return tcp_metrics_flush_all(net);
1086         ret = parse_nl_saddr(info, &saddr);
1087         if (ret < 0)
1088                 src = false;
1089
1090         hash ^= net_hash_mix(net);
1091         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
1092         hb = net->ipv4.tcp_metrics_hash + hash;
1093         pp = &hb->chain;
1094         spin_lock_bh(&tcp_metrics_lock);
1095         for (tm = deref_locked_genl(*pp); tm; tm = deref_locked_genl(*pp)) {
1096                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1097                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1098                     net_eq(tm_net(tm), net)) {
1099                         *pp = tm->tcpm_next;
1100                         kfree_rcu(tm, rcu_head);
1101                         found = true;
1102                 } else {
1103                         pp = &tm->tcpm_next;
1104                 }
1105         }
1106         spin_unlock_bh(&tcp_metrics_lock);
1107         if (!found)
1108                 return -ESRCH;
1109         return 0;
1110 }
1111
1112 static const struct genl_ops tcp_metrics_nl_ops[] = {
1113         {
1114                 .cmd = TCP_METRICS_CMD_GET,
1115                 .doit = tcp_metrics_nl_cmd_get,
1116                 .dumpit = tcp_metrics_nl_dump,
1117                 .policy = tcp_metrics_nl_policy,
1118         },
1119         {
1120                 .cmd = TCP_METRICS_CMD_DEL,
1121                 .doit = tcp_metrics_nl_cmd_del,
1122                 .policy = tcp_metrics_nl_policy,
1123                 .flags = GENL_ADMIN_PERM,
1124         },
1125 };
1126
1127 static unsigned int tcpmhash_entries;
1128 static int __init set_tcpmhash_entries(char *str)
1129 {
1130         ssize_t ret;
1131
1132         if (!str)
1133                 return 0;
1134
1135         ret = kstrtouint(str, 0, &tcpmhash_entries);
1136         if (ret)
1137                 return 0;
1138
1139         return 1;
1140 }
1141 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1142
1143 static int __net_init tcp_net_metrics_init(struct net *net)
1144 {
1145         size_t size;
1146         unsigned int slots;
1147
1148         slots = tcpmhash_entries;
1149         if (!slots) {
1150                 if (totalram_pages >= 128 * 1024)
1151                         slots = 16 * 1024;
1152                 else
1153                         slots = 8 * 1024;
1154         }
1155
1156         net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
1157         size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
1158
1159         net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1160         if (!net->ipv4.tcp_metrics_hash)
1161                 net->ipv4.tcp_metrics_hash = vzalloc(size);
1162
1163         if (!net->ipv4.tcp_metrics_hash)
1164                 return -ENOMEM;
1165
1166         return 0;
1167 }
1168
1169 static void __net_exit tcp_net_metrics_exit(struct net *net)
1170 {
1171         unsigned int i;
1172
1173         for (i = 0; i < (1U << net->ipv4.tcp_metrics_hash_log) ; i++) {
1174                 struct tcp_metrics_block *tm, *next;
1175
1176                 tm = rcu_dereference_protected(net->ipv4.tcp_metrics_hash[i].chain, 1);
1177                 while (tm) {
1178                         next = rcu_dereference_protected(tm->tcpm_next, 1);
1179                         kfree(tm);
1180                         tm = next;
1181                 }
1182         }
1183         kvfree(net->ipv4.tcp_metrics_hash);
1184 }
1185
1186 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1187         .init   =       tcp_net_metrics_init,
1188         .exit   =       tcp_net_metrics_exit,
1189 };
1190
1191 void __init tcp_metrics_init(void)
1192 {
1193         int ret;
1194
1195         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1196         if (ret < 0)
1197                 panic("Could not allocate the tcp_metrics hash table\n");
1198
1199         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1200                                             tcp_metrics_nl_ops);
1201         if (ret < 0)
1202                 panic("Could not register tcp_metrics generic netlink\n");
1203 }