kernel/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                 saddr.addr.a4 = inet_rsk(req)->ir_loc_addr;
 251                 daddr.addr.a4 = inet_rsk(req)->ir_rmt_addr;
 252                 hash = (__force unsigned int) daddr.addr.a4;
 253                 break;
 254 #if IS_ENABLED(CONFIG_IPV6)
 255         case AF_INET6:
 256                 saddr.addr.in6 = inet_rsk(req)->ir_v6_loc_addr;
 257                 daddr.addr.in6 = 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                 saddr.family = AF_INET;
 289                 saddr.addr.a4 = tw->tw_rcv_saddr;
 290                 daddr.family = AF_INET;
 291                 daddr.addr.a4 = tw->tw_daddr;
 292                 hash = (__force unsigned int) daddr.addr.a4;
 293         }
 294 #if IS_ENABLED(CONFIG_IPV6)
 295         else if (tw->tw_family == AF_INET6) {
 296                 if (ipv6_addr_v4mapped(&tw->tw_v6_daddr)) {
 297                         saddr.family = AF_INET;
 298                         saddr.addr.a4 = tw->tw_rcv_saddr;
 299                         daddr.family = AF_INET;
 300                         daddr.addr.a4 = tw->tw_daddr;
 301                         hash = (__force unsigned int) daddr.addr.a4;
 302                 } else {
 303                         saddr.family = AF_INET6;
 304                         saddr.addr.in6 = tw->tw_v6_rcv_saddr;
 305                         daddr.family = AF_INET6;
 306                         daddr.addr.in6 = tw->tw_v6_daddr;
 307                         hash = ipv6_addr_hash(&tw->tw_v6_daddr);
 308                 }
 309         }
 310 #endif
 311         else
 312                 return NULL;
 313
 314         net = twsk_net(tw);
 315         hash ^= net_hash_mix(net);
 316         hash = hash_32(hash, tcp_metrics_hash_log);
 317
 318         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 319              tm = rcu_dereference(tm->tcpm_next)) {
 320                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 321                     addr_same(&tm->tcpm_daddr, &daddr) &&
 322                     net_eq(tm_net(tm), net))
 323                         break;
 324         }
 325         return tm;
 326 }
 327
 328 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 329                                                  struct dst_entry *dst,
 330                                                  bool create)
 331 {
 332         struct tcp_metrics_block *tm;
 333         struct inetpeer_addr saddr, daddr;
 334         unsigned int hash;
 335         struct net *net;
 336
 337         if (sk->sk_family == AF_INET) {
 338                 saddr.family = AF_INET;
 339                 saddr.addr.a4 = inet_sk(sk)->inet_saddr;
 340                 daddr.family = AF_INET;
 341                 daddr.addr.a4 = inet_sk(sk)->inet_daddr;
 342                 hash = (__force unsigned int) daddr.addr.a4;
 343         }
 344 #if IS_ENABLED(CONFIG_IPV6)
 345         else if (sk->sk_family == AF_INET6) {
 346                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
 347                         saddr.family = AF_INET;
 348                         saddr.addr.a4 = inet_sk(sk)->inet_saddr;
 349                         daddr.family = AF_INET;
 350                         daddr.addr.a4 = inet_sk(sk)->inet_daddr;
 351                         hash = (__force unsigned int) daddr.addr.a4;
 352                 } else {
 353                         saddr.family = AF_INET6;
 354                         saddr.addr.in6 = sk->sk_v6_rcv_saddr;
 355                         daddr.family = AF_INET6;
 356                         daddr.addr.in6 = sk->sk_v6_daddr;
 357                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 358                 }
 359         }
 360 #endif
 361         else
 362                 return NULL;
 363
 364         net = dev_net(dst->dev);
 365         hash ^= net_hash_mix(net);
 366         hash = hash_32(hash, tcp_metrics_hash_log);
 367
 368         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 369         if (tm == TCP_METRICS_RECLAIM_PTR)
 370                 tm = NULL;
 371         if (!tm && create)
 372                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 373         else
 374                 tcpm_check_stamp(tm, dst);
 375
 376         return tm;
 377 }
 378
 379 /* Save metrics learned by this TCP session.  This function is called
 380  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 381  * or goes from LAST-ACK to CLOSE.
 382  */
 383 void tcp_update_metrics(struct sock *sk)
 384 {
 385         const struct inet_connection_sock *icsk = inet_csk(sk);
 386         struct dst_entry *dst = __sk_dst_get(sk);
 387         struct tcp_sock *tp = tcp_sk(sk);
 388         struct tcp_metrics_block *tm;
 389         unsigned long rtt;
 390         u32 val;
 391         int m;
 392
 393         if (sysctl_tcp_nometrics_save || !dst)
 394                 return;
 395
 396         if (dst->flags & DST_HOST)
 397                 dst_confirm(dst);
 398
 399         rcu_read_lock();
 400         if (icsk->icsk_backoff || !tp->srtt_us) {
 401                 /* This session failed to estimate rtt. Why?
 402                  * Probably, no packets returned in time.  Reset our
 403                  * results.
 404                  */
 405                 tm = tcp_get_metrics(sk, dst, false);
 406                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 407                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 408                 goto out_unlock;
 409         } else
 410                 tm = tcp_get_metrics(sk, dst, true);
 411
 412         if (!tm)
 413                 goto out_unlock;
 414
 415         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 416         m = rtt - tp->srtt_us;
 417
 418         /* If newly calculated rtt larger than stored one, store new
 419          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 420          * always better than underestimation.
 421          */
 422         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 423                 if (m <= 0)
 424                         rtt = tp->srtt_us;
 425                 else
 426                         rtt -= (m >> 3);
 427                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
 428         }
 429
 430         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 431                 unsigned long var;
 432
 433                 if (m < 0)
 434                         m = -m;
 435
 436                 /* Scale deviation to rttvar fixed point */
 437                 m >>= 1;
 438                 if (m < tp->mdev_us)
 439                         m = tp->mdev_us;
 440
 441                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
 442                 if (m >= var)
 443                         var = m;
 444                 else
 445                         var -= (var - m) >> 2;
 446
 447                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
 448         }
 449
 450         if (tcp_in_initial_slowstart(tp)) {
 451                 /* Slow start still did not finish. */
 452                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 453                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 454                         if (val && (tp->snd_cwnd >> 1) > val)
 455                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 456                                                tp->snd_cwnd >> 1);
 457                 }
 458                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 459                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 460                         if (tp->snd_cwnd > val)
 461                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 462                                                tp->snd_cwnd);
 463                 }
 464         } else if (tp->snd_cwnd > tp->snd_ssthresh &&
 465                    icsk->icsk_ca_state == TCP_CA_Open) {
 466                 /* Cong. avoidance phase, cwnd is reliable. */
 467                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 468                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 469                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 470                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 471                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 472                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 473                 }
 474         } else {
 475                 /* Else slow start did not finish, cwnd is non-sense,
 476                  * ssthresh may be also invalid.
 477                  */
 478                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 479                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 480                         tcp_metric_set(tm, TCP_METRIC_CWND,
 481                                        (val + tp->snd_ssthresh) >> 1);
 482                 }
 483                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 484                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 485                         if (val && tp->snd_ssthresh > val)
 486                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 487                                                tp->snd_ssthresh);
 488                 }
 489                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 490                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 491                         if (val < tp->reordering &&
 492                             tp->reordering != sysctl_tcp_reordering)
 493                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 494                                                tp->reordering);
 495                 }
 496         }
 497         tm->tcpm_stamp = jiffies;
 498 out_unlock:
 499         rcu_read_unlock();
 500 }
 501
 502 /* Initialize metrics on socket. */
 503
 504 void tcp_init_metrics(struct sock *sk)
 505 {
 506         struct dst_entry *dst = __sk_dst_get(sk);
 507         struct tcp_sock *tp = tcp_sk(sk);
 508         struct tcp_metrics_block *tm;
 509         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 510
 511         if (!dst)
 512                 goto reset;
 513
 514         dst_confirm(dst);
 515
 516         rcu_read_lock();
 517         tm = tcp_get_metrics(sk, dst, true);
 518         if (!tm) {
 519                 rcu_read_unlock();
 520                 goto reset;
 521         }
 522
 523         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 524                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 525
 526         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 527         if (val) {
 528                 tp->snd_ssthresh = val;
 529                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 530                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 531         } else {
 532                 /* ssthresh may have been reduced unnecessarily during.
 533                  * 3WHS. Restore it back to its initial default.
 534                  */
 535                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 536         }
 537         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 538         if (val && tp->reordering != val) {
 539                 tcp_disable_fack(tp);
 540                 tcp_disable_early_retrans(tp);
 541                 tp->reordering = val;
 542         }
 543
 544         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 545         rcu_read_unlock();
 546 reset:
 547         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 548          * to seed the RTO for later data packets because SYN packets are
 549          * small. Use the per-dst cached values to seed the RTO but keep
 550          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 551          * Later the RTO will be updated immediately upon obtaining the first
 552          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 553          * influences the first RTO but not later RTT estimation.
 554          *
 555          * But if RTT is not available from the SYN (due to retransmits or
 556          * syn cookies) or the cache, force a conservative 3secs timeout.
 557          *
 558          * A bit of theory. RTT is time passed after "normal" sized packet
 559          * is sent until it is ACKed. In normal circumstances sending small
 560          * packets force peer to delay ACKs and calculation is correct too.
 561          * The algorithm is adaptive and, provided we follow specs, it
 562          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 563          * tricks sort of "quick acks" for time long enough to decrease RTT
 564          * to low value, and then abruptly stops to do it and starts to delay
 565          * ACKs, wait for troubles.
 566          */
 567         if (crtt > tp->srtt_us) {
 568                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 569                 crtt /= 8 * USEC_PER_MSEC;
 570                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 571         } else if (tp->srtt_us == 0) {
 572                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 573                  * 3WHS. This is most likely due to retransmission,
 574                  * including spurious one. Reset the RTO back to 3secs
 575                  * from the more aggressive 1sec to avoid more spurious
 576                  * retransmission.
 577                  */
 578                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 579                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 580
 581                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 582         }
 583         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 584          * retransmitted. In light of RFC6298 more aggressive 1sec
 585          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 586          * retransmission has occurred.
 587          */
 588         if (tp->total_retrans > 1)
 589                 tp->snd_cwnd = 1;
 590         else
 591                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 592         tp->snd_cwnd_stamp = tcp_time_stamp;
 593 }
 594
 595 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
 596                         bool paws_check, bool timestamps)
 597 {
 598         struct tcp_metrics_block *tm;
 599         bool ret;
 600
 601         if (!dst)
 602                 return false;
 603
 604         rcu_read_lock();
 605         tm = __tcp_get_metrics_req(req, dst);
 606         if (paws_check) {
 607                 if (tm &&
 608                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 609                     ((s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW ||
 610                      !timestamps))
 611                         ret = false;
 612                 else
 613                         ret = true;
 614         } else {
 615                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 616                         ret = true;
 617                 else
 618                         ret = false;
 619         }
 620         rcu_read_unlock();
 621
 622         return ret;
 623 }
 624 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 625
 626 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 627 {
 628         struct tcp_metrics_block *tm;
 629
 630         rcu_read_lock();
 631         tm = tcp_get_metrics(sk, dst, true);
 632         if (tm) {
 633                 struct tcp_sock *tp = tcp_sk(sk);
 634
 635                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 636                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 637                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 638                 }
 639         }
 640         rcu_read_unlock();
 641 }
 642 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 643
 644 /* VJ's idea. Save last timestamp seen from this destination and hold
 645  * it at least for normal timewait interval to use for duplicate
 646  * segment detection in subsequent connections, before they enter
 647  * synchronized state.
 648  */
 649 bool tcp_remember_stamp(struct sock *sk)
 650 {
 651         struct dst_entry *dst = __sk_dst_get(sk);
 652         bool ret = false;
 653
 654         if (dst) {
 655                 struct tcp_metrics_block *tm;
 656
 657                 rcu_read_lock();
 658                 tm = tcp_get_metrics(sk, dst, true);
 659                 if (tm) {
 660                         struct tcp_sock *tp = tcp_sk(sk);
 661
 662                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 663                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 664                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 665                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 666                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 667                         }
 668                         ret = true;
 669                 }
 670                 rcu_read_unlock();
 671         }
 672         return ret;
 673 }
 674
 675 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 676 {
 677         struct tcp_metrics_block *tm;
 678         bool ret = false;
 679
 680         rcu_read_lock();
 681         tm = __tcp_get_metrics_tw(tw);
 682         if (tm) {
 683                 const struct tcp_timewait_sock *tcptw;
 684                 struct sock *sk = (struct sock *) tw;
 685
 686                 tcptw = tcp_twsk(sk);
 687                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 688                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 689                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 690                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 691                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 692                 }
 693                 ret = true;
 694         }
 695         rcu_read_unlock();
 696
 697         return ret;
 698 }
 699
 700 static DEFINE_SEQLOCK(fastopen_seqlock);
 701
 702 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 703                             struct tcp_fastopen_cookie *cookie,
 704                             int *syn_loss, unsigned long *last_syn_loss)
 705 {
 706         struct tcp_metrics_block *tm;
 707
 708         rcu_read_lock();
 709         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 710         if (tm) {
 711                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 712                 unsigned int seq;
 713
 714                 do {
 715                         seq = read_seqbegin(&fastopen_seqlock);
 716                         if (tfom->mss)
 717                                 *mss = tfom->mss;
 718                         *cookie = tfom->cookie;
 719                         if (cookie->len <= 0 && tfom->try_exp == 1)
 720                                 cookie->exp = true;
 721                         *syn_loss = tfom->syn_loss;
 722                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 723                 } while (read_seqretry(&fastopen_seqlock, seq));
 724         }
 725         rcu_read_unlock();
 726 }
 727
 728 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 729                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
 730                             u16 try_exp)
 731 {
 732         struct dst_entry *dst = __sk_dst_get(sk);
 733         struct tcp_metrics_block *tm;
 734
 735         if (!dst)
 736                 return;
 737         rcu_read_lock();
 738         tm = tcp_get_metrics(sk, dst, true);
 739         if (tm) {
 740                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 741
 742                 write_seqlock_bh(&fastopen_seqlock);
 743                 if (mss)
 744                         tfom->mss = mss;
 745                 if (cookie && cookie->len > 0)
 746                         tfom->cookie = *cookie;
 747                 else if (try_exp > tfom->try_exp &&
 748                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
 749                         tfom->try_exp = try_exp;
 750                 if (syn_lost) {
 751                         ++tfom->syn_loss;
 752                         tfom->last_syn_loss = jiffies;
 753                 } else
 754                         tfom->syn_loss = 0;
 755                 write_sequnlock_bh(&fastopen_seqlock);
 756         }
 757         rcu_read_unlock();
 758 }
 759
 760 static struct genl_family tcp_metrics_nl_family = {
 761         .id             = GENL_ID_GENERATE,
 762         .hdrsize        = 0,
 763         .name           = TCP_METRICS_GENL_NAME,
 764         .version        = TCP_METRICS_GENL_VERSION,
 765         .maxattr        = TCP_METRICS_ATTR_MAX,
 766         .netnsok        = true,
 767 };
 768
 769 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 770         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 771         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 772                                             .len = sizeof(struct in6_addr), },
 773         /* Following attributes are not received for GET/DEL,
 774          * we keep them for reference
 775          */
 776 #if 0
 777         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 778         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 779         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 780         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 781         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 782         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 783         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 784         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 785                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 786 #endif
 787 };
 788
 789 /* Add attributes, caller cancels its header on failure */
 790 static int tcp_metrics_fill_info(struct sk_buff *msg,
 791                                  struct tcp_metrics_block *tm)
 792 {
 793         struct nlattr *nest;
 794         int i;
 795
 796         switch (tm->tcpm_daddr.family) {
 797         case AF_INET:
 798                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 799                                     tm->tcpm_daddr.addr.a4) < 0)
 800                         goto nla_put_failure;
 801                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 802                                     tm->tcpm_saddr.addr.a4) < 0)
 803                         goto nla_put_failure;
 804                 break;
 805         case AF_INET6:
 806                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
 807                                      &tm->tcpm_daddr.addr.in6) < 0)
 808                         goto nla_put_failure;
 809                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
 810                                      &tm->tcpm_saddr.addr.in6) < 0)
 811                         goto nla_put_failure;
 812                 break;
 813         default:
 814                 return -EAFNOSUPPORT;
 815         }
 816
 817         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 818                           jiffies - tm->tcpm_stamp) < 0)
 819                 goto nla_put_failure;
 820         if (tm->tcpm_ts_stamp) {
 821                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 822                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 823                         goto nla_put_failure;
 824                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 825                                 tm->tcpm_ts) < 0)
 826                         goto nla_put_failure;
 827         }
 828
 829         {
 830                 int n = 0;
 831
 832                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 833                 if (!nest)
 834                         goto nla_put_failure;
 835                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 836                         u32 val = tm->tcpm_vals[i];
 837
 838                         if (!val)
 839                                 continue;
 840                         if (i == TCP_METRIC_RTT) {
 841                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 842                                                 val) < 0)
 843                                         goto nla_put_failure;
 844                                 n++;
 845                                 val = max(val / 1000, 1U);
 846                         }
 847                         if (i == TCP_METRIC_RTTVAR) {
 848                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 849                                                 val) < 0)
 850                                         goto nla_put_failure;
 851                                 n++;
 852                                 val = max(val / 1000, 1U);
 853                         }
 854                         if (nla_put_u32(msg, i + 1, val) < 0)
 855                                 goto nla_put_failure;
 856                         n++;
 857                 }
 858                 if (n)
 859                         nla_nest_end(msg, nest);
 860                 else
 861                         nla_nest_cancel(msg, nest);
 862         }
 863
 864         {
 865                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 866                 unsigned int seq;
 867
 868                 do {
 869                         seq = read_seqbegin(&fastopen_seqlock);
 870                         tfom_copy[0] = tm->tcpm_fastopen;
 871                 } while (read_seqretry(&fastopen_seqlock, seq));
 872
 873                 tfom = tfom_copy;
 874                 if (tfom->mss &&
 875                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 876                                 tfom->mss) < 0)
 877                         goto nla_put_failure;
 878                 if (tfom->syn_loss &&
 879                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 880                                 tfom->syn_loss) < 0 ||
 881                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 882                                 jiffies - tfom->last_syn_loss) < 0))
 883                         goto nla_put_failure;
 884                 if (tfom->cookie.len > 0 &&
 885                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 886                             tfom->cookie.len, tfom->cookie.val) < 0)
 887                         goto nla_put_failure;
 888         }
 889
 890         return 0;
 891
 892 nla_put_failure:
 893         return -EMSGSIZE;
 894 }
 895
 896 static int tcp_metrics_dump_info(struct sk_buff *skb,
 897                                  struct netlink_callback *cb,
 898                                  struct tcp_metrics_block *tm)
 899 {
 900         void *hdr;
 901
 902         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 903                           &tcp_metrics_nl_family, NLM_F_MULTI,
 904                           TCP_METRICS_CMD_GET);
 905         if (!hdr)
 906                 return -EMSGSIZE;
 907
 908         if (tcp_metrics_fill_info(skb, tm) < 0)
 909                 goto nla_put_failure;
 910
 911         genlmsg_end(skb, hdr);
 912         return 0;
 913
 914 nla_put_failure:
 915         genlmsg_cancel(skb, hdr);
 916         return -EMSGSIZE;
 917 }
 918
 919 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 920                                struct netlink_callback *cb)
 921 {
 922         struct net *net = sock_net(skb->sk);
 923         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 924         unsigned int row, s_row = cb->args[0];
 925         int s_col = cb->args[1], col = s_col;
 926
 927         for (row = s_row; row < max_rows; row++, s_col = 0) {
 928                 struct tcp_metrics_block *tm;
 929                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
 930
 931                 rcu_read_lock();
 932                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 933                      tm = rcu_dereference(tm->tcpm_next), col++) {
 934                         if (!net_eq(tm_net(tm), net))
 935                                 continue;
 936                         if (col < s_col)
 937                                 continue;
 938                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 939                                 rcu_read_unlock();
 940                                 goto done;
 941                         }
 942                 }
 943                 rcu_read_unlock();
 944         }
 945
 946 done:
 947         cb->args[0] = row;
 948         cb->args[1] = col;
 949         return skb->len;
 950 }
 951
 952 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 953                            unsigned int *hash, int optional, int v4, int v6)
 954 {
 955         struct nlattr *a;
 956
 957         a = info->attrs[v4];
 958         if (a) {
 959                 addr->family = AF_INET;
 960                 addr->addr.a4 = nla_get_in_addr(a);
 961                 if (hash)
 962                         *hash = (__force unsigned int) addr->addr.a4;
 963                 return 0;
 964         }
 965         a = info->attrs[v6];
 966         if (a) {
 967                 if (nla_len(a) != sizeof(struct in6_addr))
 968                         return -EINVAL;
 969                 addr->family = AF_INET6;
 970                 addr->addr.in6 = nla_get_in6_addr(a);
 971                 if (hash)
 972                         *hash = ipv6_addr_hash(&addr->addr.in6);
 973                 return 0;
 974         }
 975         return optional ? 1 : -EAFNOSUPPORT;
 976 }
 977
 978 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 979                          unsigned int *hash, int optional)
 980 {
 981         return __parse_nl_addr(info, addr, hash, optional,
 982                                TCP_METRICS_ATTR_ADDR_IPV4,
 983                                TCP_METRICS_ATTR_ADDR_IPV6);
 984 }
 985
 986 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 987 {
 988         return __parse_nl_addr(info, addr, NULL, 0,
 989                                TCP_METRICS_ATTR_SADDR_IPV4,
 990                                TCP_METRICS_ATTR_SADDR_IPV6);
 991 }
 992
 993 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 994 {
 995         struct tcp_metrics_block *tm;
 996         struct inetpeer_addr saddr, daddr;
 997         unsigned int hash;
 998         struct sk_buff *msg;
 999         struct net *net = genl_info_net(info);
1000         void *reply;
1001         int ret;
1002         bool src = true;
1003
1004         ret = parse_nl_addr(info, &daddr, &hash, 0);
1005         if (ret < 0)
1006                 return ret;
1007
1008         ret = parse_nl_saddr(info, &saddr);
1009         if (ret < 0)
1010                 src = false;
1011
1012         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
1013         if (!msg)
1014                 return -ENOMEM;
1015
1016         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
1017                                   info->genlhdr->cmd);
1018         if (!reply)
1019                 goto nla_put_failure;
1020
1021         hash ^= net_hash_mix(net);
1022         hash = hash_32(hash, tcp_metrics_hash_log);
1023         ret = -ESRCH;
1024         rcu_read_lock();
1025         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
1026              tm = rcu_dereference(tm->tcpm_next)) {
1027                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1028                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1029                     net_eq(tm_net(tm), net)) {
1030                         ret = tcp_metrics_fill_info(msg, tm);
1031                         break;
1032                 }
1033         }
1034         rcu_read_unlock();
1035         if (ret < 0)
1036                 goto out_free;
1037
1038         genlmsg_end(msg, reply);
1039         return genlmsg_reply(msg, info);
1040
1041 nla_put_failure:
1042         ret = -EMSGSIZE;
1043
1044 out_free:
1045         nlmsg_free(msg);
1046         return ret;
1047 }
1048
1049 static void tcp_metrics_flush_all(struct net *net)
1050 {
1051         unsigned int max_rows = 1U << tcp_metrics_hash_log;
1052         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
1053         struct tcp_metrics_block *tm;
1054         unsigned int row;
1055
1056         for (row = 0; row < max_rows; row++, hb++) {
1057                 struct tcp_metrics_block __rcu **pp;
1058                 spin_lock_bh(&tcp_metrics_lock);
1059                 pp = &hb->chain;
1060                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1061                         if (net_eq(tm_net(tm), net)) {
1062                                 *pp = tm->tcpm_next;
1063                                 kfree_rcu(tm, rcu_head);
1064                         } else {
1065                                 pp = &tm->tcpm_next;
1066                         }
1067                 }
1068                 spin_unlock_bh(&tcp_metrics_lock);
1069         }
1070 }
1071
1072 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
1073 {
1074         struct tcpm_hash_bucket *hb;
1075         struct tcp_metrics_block *tm;
1076         struct tcp_metrics_block __rcu **pp;
1077         struct inetpeer_addr saddr, daddr;
1078         unsigned int hash;
1079         struct net *net = genl_info_net(info);
1080         int ret;
1081         bool src = true, found = false;
1082
1083         ret = parse_nl_addr(info, &daddr, &hash, 1);
1084         if (ret < 0)
1085                 return ret;
1086         if (ret > 0) {
1087                 tcp_metrics_flush_all(net);
1088                 return 0;
1089         }
1090         ret = parse_nl_saddr(info, &saddr);
1091         if (ret < 0)
1092                 src = false;
1093
1094         hash ^= net_hash_mix(net);
1095         hash = hash_32(hash, tcp_metrics_hash_log);
1096         hb = tcp_metrics_hash + hash;
1097         pp = &hb->chain;
1098         spin_lock_bh(&tcp_metrics_lock);
1099         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1100                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1101                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1102                     net_eq(tm_net(tm), net)) {
1103                         *pp = tm->tcpm_next;
1104                         kfree_rcu(tm, rcu_head);
1105                         found = true;
1106                 } else {
1107                         pp = &tm->tcpm_next;
1108                 }
1109         }
1110         spin_unlock_bh(&tcp_metrics_lock);
1111         if (!found)
1112                 return -ESRCH;
1113         return 0;
1114 }
1115
1116 static const struct genl_ops tcp_metrics_nl_ops[] = {
1117         {
1118                 .cmd = TCP_METRICS_CMD_GET,
1119                 .doit = tcp_metrics_nl_cmd_get,
1120                 .dumpit = tcp_metrics_nl_dump,
1121                 .policy = tcp_metrics_nl_policy,
1122         },
1123         {
1124                 .cmd = TCP_METRICS_CMD_DEL,
1125                 .doit = tcp_metrics_nl_cmd_del,
1126                 .policy = tcp_metrics_nl_policy,
1127                 .flags = GENL_ADMIN_PERM,
1128         },
1129 };
1130
1131 static unsigned int tcpmhash_entries;
1132 static int __init set_tcpmhash_entries(char *str)
1133 {
1134         ssize_t ret;
1135
1136         if (!str)
1137                 return 0;
1138
1139         ret = kstrtouint(str, 0, &tcpmhash_entries);
1140         if (ret)
1141                 return 0;
1142
1143         return 1;
1144 }
1145 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1146
1147 static int __net_init tcp_net_metrics_init(struct net *net)
1148 {
1149         size_t size;
1150         unsigned int slots;
1151
1152         if (!net_eq(net, &init_net))
1153                 return 0;
1154
1155         slots = tcpmhash_entries;
1156         if (!slots) {
1157                 if (totalram_pages >= 128 * 1024)
1158                         slots = 16 * 1024;
1159                 else
1160                         slots = 8 * 1024;
1161         }
1162
1163         tcp_metrics_hash_log = order_base_2(slots);
1164         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1165
1166         tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1167         if (!tcp_metrics_hash)
1168                 tcp_metrics_hash = vzalloc(size);
1169
1170         if (!tcp_metrics_hash)
1171                 return -ENOMEM;
1172
1173         return 0;
1174 }
1175
1176 static void __net_exit tcp_net_metrics_exit(struct net *net)
1177 {
1178         tcp_metrics_flush_all(net);
1179 }
1180
1181 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1182         .init   =       tcp_net_metrics_init,
1183         .exit   =       tcp_net_metrics_exit,
1184 };
1185
1186 void __init tcp_metrics_init(void)
1187 {
1188         int ret;
1189
1190         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1191         if (ret < 0)
1192                 panic("Could not allocate the tcp_metrics hash table\n");
1193
1194         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1195                                             tcp_metrics_nl_ops);
1196         if (ret < 0)
1197                 panic("Could not register tcp_metrics generic netlink\n");
1198 }