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TOMOYO Linux Cross Reference
Linux/net/ipv4/tcp_metrics.c

Version: ~ [ linux-5.6-rc1 ] ~ [ linux-5.5.2 ] ~ [ linux-5.4.17 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.102 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.170 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.213 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.213 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 #include <linux/rcupdate.h>
  2 #include <linux/spinlock.h>
  3 #include <linux/jiffies.h>
  4 #include <linux/module.h>
  5 #include <linux/cache.h>
  6 #include <linux/slab.h>
  7 #include <linux/init.h>
  8 #include <linux/tcp.h>
  9 #include <linux/hash.h>
 10 #include <linux/tcp_metrics.h>
 11 #include <linux/vmalloc.h>
 12 
 13 #include <net/inet_connection_sock.h>
 14 #include <net/net_namespace.h>
 15 #include <net/request_sock.h>
 16 #include <net/inetpeer.h>
 17 #include <net/sock.h>
 18 #include <net/ipv6.h>
 19 #include <net/dst.h>
 20 #include <net/tcp.h>
 21 #include <net/genetlink.h>
 22 
 23 int sysctl_tcp_nometrics_save __read_mostly;
 24 
 25 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 26                                                    const struct inetpeer_addr *daddr,
 27                                                    struct net *net, unsigned int hash);
 28 
 29 struct tcp_fastopen_metrics {
 30         u16     mss;
 31         u16     syn_loss:10,            /* Recurring Fast Open SYN losses */
 32                 try_exp:2;              /* Request w/ exp. option (once) */
 33         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
 34         struct  tcp_fastopen_cookie     cookie;
 35 };
 36 
 37 /* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
 38  * Kernel only stores RTT and RTTVAR in usec resolution
 39  */
 40 #define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)
 41 
 42 struct tcp_metrics_block {
 43         struct tcp_metrics_block __rcu  *tcpm_next;
 44         possible_net_t                  tcpm_net;
 45         struct inetpeer_addr            tcpm_saddr;
 46         struct inetpeer_addr            tcpm_daddr;
 47         unsigned long                   tcpm_stamp;
 48         u32                             tcpm_ts;
 49         u32                             tcpm_ts_stamp;
 50         u32                             tcpm_lock;
 51         u32                             tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
 52         struct tcp_fastopen_metrics     tcpm_fastopen;
 53 
 54         struct rcu_head                 rcu_head;
 55 };
 56 
 57 static inline struct net *tm_net(struct tcp_metrics_block *tm)
 58 {
 59         return read_pnet(&tm->tcpm_net);
 60 }
 61 
 62 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
 63                               enum tcp_metric_index idx)
 64 {
 65         return tm->tcpm_lock & (1 << idx);
 66 }
 67 
 68 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
 69                           enum tcp_metric_index idx)
 70 {
 71         return tm->tcpm_vals[idx];
 72 }
 73 
 74 static void tcp_metric_set(struct tcp_metrics_block *tm,
 75                            enum tcp_metric_index idx,
 76                            u32 val)
 77 {
 78         tm->tcpm_vals[idx] = val;
 79 }
 80 
 81 static bool addr_same(const struct inetpeer_addr *a,
 82                       const struct inetpeer_addr *b)
 83 {
 84         return inetpeer_addr_cmp(a, b) == 0;
 85 }
 86 
 87 struct tcpm_hash_bucket {
 88         struct tcp_metrics_block __rcu  *chain;
 89 };
 90 
 91 static struct tcpm_hash_bucket  *tcp_metrics_hash __read_mostly;
 92 static unsigned int             tcp_metrics_hash_log __read_mostly;
 93 
 94 static DEFINE_SPINLOCK(tcp_metrics_lock);
 95 
 96 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
 97                           const struct dst_entry *dst,
 98                           bool fastopen_clear)
 99 {
100         u32 msval;
101         u32 val;
102 
103         tm->tcpm_stamp = jiffies;
104 
105         val = 0;
106         if (dst_metric_locked(dst, RTAX_RTT))
107                 val |= 1 << TCP_METRIC_RTT;
108         if (dst_metric_locked(dst, RTAX_RTTVAR))
109                 val |= 1 << TCP_METRIC_RTTVAR;
110         if (dst_metric_locked(dst, RTAX_SSTHRESH))
111                 val |= 1 << TCP_METRIC_SSTHRESH;
112         if (dst_metric_locked(dst, RTAX_CWND))
113                 val |= 1 << TCP_METRIC_CWND;
114         if (dst_metric_locked(dst, RTAX_REORDERING))
115                 val |= 1 << TCP_METRIC_REORDERING;
116         tm->tcpm_lock = val;
117 
118         msval = dst_metric_raw(dst, RTAX_RTT);
119         tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
120 
121         msval = dst_metric_raw(dst, RTAX_RTTVAR);
122         tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
123         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
124         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
125         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
126         tm->tcpm_ts = 0;
127         tm->tcpm_ts_stamp = 0;
128         if (fastopen_clear) {
129                 tm->tcpm_fastopen.mss = 0;
130                 tm->tcpm_fastopen.syn_loss = 0;
131                 tm->tcpm_fastopen.try_exp = 0;
132                 tm->tcpm_fastopen.cookie.exp = false;
133                 tm->tcpm_fastopen.cookie.len = 0;
134         }
135 }
136 
137 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
138 
139 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
140 {
141         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
142                 tcpm_suck_dst(tm, dst, false);
143 }
144 
145 #define TCP_METRICS_RECLAIM_DEPTH       5
146 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
147 
148 #define deref_locked(p) \
149         rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
150 
151 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
152                                           struct inetpeer_addr *saddr,
153                                           struct inetpeer_addr *daddr,
154                                           unsigned int hash)
155 {
156         struct tcp_metrics_block *tm;
157         struct net *net;
158         bool reclaim = false;
159 
160         spin_lock_bh(&tcp_metrics_lock);
161         net = dev_net(dst->dev);
162 
163         /* While waiting for the spin-lock the cache might have been populated
164          * with this entry and so we have to check again.
165          */
166         tm = __tcp_get_metrics(saddr, daddr, net, hash);
167         if (tm == TCP_METRICS_RECLAIM_PTR) {
168                 reclaim = true;
169                 tm = NULL;
170         }
171         if (tm) {
172                 tcpm_check_stamp(tm, dst);
173                 goto out_unlock;
174         }
175 
176         if (unlikely(reclaim)) {
177                 struct tcp_metrics_block *oldest;
178 
179                 oldest = deref_locked(tcp_metrics_hash[hash].chain);
180                 for (tm = deref_locked(oldest->tcpm_next); tm;
181                      tm = deref_locked(tm->tcpm_next)) {
182                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
183                                 oldest = tm;
184                 }
185                 tm = oldest;
186         } else {
187                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
188                 if (!tm)
189                         goto out_unlock;
190         }
191         write_pnet(&tm->tcpm_net, net);
192         tm->tcpm_saddr = *saddr;
193         tm->tcpm_daddr = *daddr;
194 
195         tcpm_suck_dst(tm, dst, true);
196 
197         if (likely(!reclaim)) {
198                 tm->tcpm_next = tcp_metrics_hash[hash].chain;
199                 rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
200         }
201 
202 out_unlock:
203         spin_unlock_bh(&tcp_metrics_lock);
204         return tm;
205 }
206 
207 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
208 {
209         if (tm)
210                 return tm;
211         if (depth > TCP_METRICS_RECLAIM_DEPTH)
212                 return TCP_METRICS_RECLAIM_PTR;
213         return NULL;
214 }
215 
216 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
217                                                    const struct inetpeer_addr *daddr,
218                                                    struct net *net, unsigned int hash)
219 {
220         struct tcp_metrics_block *tm;
221         int depth = 0;
222 
223         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
224              tm = rcu_dereference(tm->tcpm_next)) {
225                 if (addr_same(&tm->tcpm_saddr, saddr) &&
226                     addr_same(&tm->tcpm_daddr, daddr) &&
227                     net_eq(tm_net(tm), net))
228                         break;
229                 depth++;
230         }
231         return tcp_get_encode(tm, depth);
232 }
233 
234 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
235                                                        struct dst_entry *dst)
236 {
237         struct tcp_metrics_block *tm;
238         struct inetpeer_addr saddr, daddr;
239         unsigned int hash;
240         struct net *net;
241 
242         saddr.family = req->rsk_ops->family;
243         daddr.family = req->rsk_ops->family;
244         switch (daddr.family) {
245         case AF_INET:
246                 inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
247                 inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
248                 hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
249                 break;
250 #if IS_ENABLED(CONFIG_IPV6)
251         case AF_INET6:
252                 inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
253                 inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
254                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
255                 break;
256 #endif
257         default:
258                 return NULL;
259         }
260 
261         net = dev_net(dst->dev);
262         hash ^= net_hash_mix(net);
263         hash = hash_32(hash, tcp_metrics_hash_log);
264 
265         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
266              tm = rcu_dereference(tm->tcpm_next)) {
267                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
268                     addr_same(&tm->tcpm_daddr, &daddr) &&
269                     net_eq(tm_net(tm), net))
270                         break;
271         }
272         tcpm_check_stamp(tm, dst);
273         return tm;
274 }
275 
276 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
277 {
278         struct tcp_metrics_block *tm;
279         struct inetpeer_addr saddr, daddr;
280         unsigned int hash;
281         struct net *net;
282 
283         if (tw->tw_family == AF_INET) {
284                 inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
285                 inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
286                 hash = ipv4_addr_hash(tw->tw_daddr);
287         }
288 #if IS_ENABLED(CONFIG_IPV6)
289         else if (tw->tw_family == AF_INET6) {
290                 if (ipv6_addr_v4mapped(&tw->tw_v6_daddr)) {
291                         inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
292                         inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
293                         hash = ipv4_addr_hash(tw->tw_daddr);
294                 } else {
295                         inetpeer_set_addr_v6(&saddr, &tw->tw_v6_rcv_saddr);
296                         inetpeer_set_addr_v6(&daddr, &tw->tw_v6_daddr);
297                         hash = ipv6_addr_hash(&tw->tw_v6_daddr);
298                 }
299         }
300 #endif
301         else
302                 return NULL;
303 
304         net = twsk_net(tw);
305         hash ^= net_hash_mix(net);
306         hash = hash_32(hash, tcp_metrics_hash_log);
307 
308         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
309              tm = rcu_dereference(tm->tcpm_next)) {
310                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
311                     addr_same(&tm->tcpm_daddr, &daddr) &&
312                     net_eq(tm_net(tm), net))
313                         break;
314         }
315         return tm;
316 }
317 
318 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
319                                                  struct dst_entry *dst,
320                                                  bool create)
321 {
322         struct tcp_metrics_block *tm;
323         struct inetpeer_addr saddr, daddr;
324         unsigned int hash;
325         struct net *net;
326 
327         if (sk->sk_family == AF_INET) {
328                 inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
329                 inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
330                 hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
331         }
332 #if IS_ENABLED(CONFIG_IPV6)
333         else if (sk->sk_family == AF_INET6) {
334                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
335                         inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
336                         inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
337                         hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
338                 } else {
339                         inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
340                         inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
341                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
342                 }
343         }
344 #endif
345         else
346                 return NULL;
347 
348         net = dev_net(dst->dev);
349         hash ^= net_hash_mix(net);
350         hash = hash_32(hash, tcp_metrics_hash_log);
351 
352         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
353         if (tm == TCP_METRICS_RECLAIM_PTR)
354                 tm = NULL;
355         if (!tm && create)
356                 tm = tcpm_new(dst, &saddr, &daddr, hash);
357         else
358                 tcpm_check_stamp(tm, dst);
359 
360         return tm;
361 }
362 
363 /* Save metrics learned by this TCP session.  This function is called
364  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
365  * or goes from LAST-ACK to CLOSE.
366  */
367 void tcp_update_metrics(struct sock *sk)
368 {
369         const struct inet_connection_sock *icsk = inet_csk(sk);
370         struct dst_entry *dst = __sk_dst_get(sk);
371         struct tcp_sock *tp = tcp_sk(sk);
372         struct net *net = sock_net(sk);
373         struct tcp_metrics_block *tm;
374         unsigned long rtt;
375         u32 val;
376         int m;
377 
378         if (sysctl_tcp_nometrics_save || !dst)
379                 return;
380 
381         if (dst->flags & DST_HOST)
382                 dst_confirm(dst);
383 
384         rcu_read_lock();
385         if (icsk->icsk_backoff || !tp->srtt_us) {
386                 /* This session failed to estimate rtt. Why?
387                  * Probably, no packets returned in time.  Reset our
388                  * results.
389                  */
390                 tm = tcp_get_metrics(sk, dst, false);
391                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
392                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
393                 goto out_unlock;
394         } else
395                 tm = tcp_get_metrics(sk, dst, true);
396 
397         if (!tm)
398                 goto out_unlock;
399 
400         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
401         m = rtt - tp->srtt_us;
402 
403         /* If newly calculated rtt larger than stored one, store new
404          * one. Otherwise, use EWMA. Remember, rtt overestimation is
405          * always better than underestimation.
406          */
407         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
408                 if (m <= 0)
409                         rtt = tp->srtt_us;
410                 else
411                         rtt -= (m >> 3);
412                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
413         }
414 
415         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
416                 unsigned long var;
417 
418                 if (m < 0)
419                         m = -m;
420 
421                 /* Scale deviation to rttvar fixed point */
422                 m >>= 1;
423                 if (m < tp->mdev_us)
424                         m = tp->mdev_us;
425 
426                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
427                 if (m >= var)
428                         var = m;
429                 else
430                         var -= (var - m) >> 2;
431 
432                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
433         }
434 
435         if (tcp_in_initial_slowstart(tp)) {
436                 /* Slow start still did not finish. */
437                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
438                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
439                         if (val && (tp->snd_cwnd >> 1) > val)
440                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
441                                                tp->snd_cwnd >> 1);
442                 }
443                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
444                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
445                         if (tp->snd_cwnd > val)
446                                 tcp_metric_set(tm, TCP_METRIC_CWND,
447                                                tp->snd_cwnd);
448                 }
449         } else if (!tcp_in_slow_start(tp) &&
450                    icsk->icsk_ca_state == TCP_CA_Open) {
451                 /* Cong. avoidance phase, cwnd is reliable. */
452                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
453                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
454                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
455                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
456                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
457                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
458                 }
459         } else {
460                 /* Else slow start did not finish, cwnd is non-sense,
461                  * ssthresh may be also invalid.
462                  */
463                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
464                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
465                         tcp_metric_set(tm, TCP_METRIC_CWND,
466                                        (val + tp->snd_ssthresh) >> 1);
467                 }
468                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
469                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
470                         if (val && tp->snd_ssthresh > val)
471                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
472                                                tp->snd_ssthresh);
473                 }
474                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
475                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
476                         if (val < tp->reordering &&
477                             tp->reordering != net->ipv4.sysctl_tcp_reordering)
478                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
479                                                tp->reordering);
480                 }
481         }
482         tm->tcpm_stamp = jiffies;
483 out_unlock:
484         rcu_read_unlock();
485 }
486 
487 /* Initialize metrics on socket. */
488 
489 void tcp_init_metrics(struct sock *sk)
490 {
491         struct dst_entry *dst = __sk_dst_get(sk);
492         struct tcp_sock *tp = tcp_sk(sk);
493         struct tcp_metrics_block *tm;
494         u32 val, crtt = 0; /* cached RTT scaled by 8 */
495 
496         if (!dst)
497                 goto reset;
498 
499         dst_confirm(dst);
500 
501         rcu_read_lock();
502         tm = tcp_get_metrics(sk, dst, true);
503         if (!tm) {
504                 rcu_read_unlock();
505                 goto reset;
506         }
507 
508         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
509                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
510 
511         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
512         if (val) {
513                 tp->snd_ssthresh = val;
514                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
515                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
516         } else {
517                 /* ssthresh may have been reduced unnecessarily during.
518                  * 3WHS. Restore it back to its initial default.
519                  */
520                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
521         }
522         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
523         if (val && tp->reordering != val) {
524                 tcp_disable_fack(tp);
525                 tcp_disable_early_retrans(tp);
526                 tp->reordering = val;
527         }
528 
529         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
530         rcu_read_unlock();
531 reset:
532         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
533          * to seed the RTO for later data packets because SYN packets are
534          * small. Use the per-dst cached values to seed the RTO but keep
535          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
536          * Later the RTO will be updated immediately upon obtaining the first
537          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
538          * influences the first RTO but not later RTT estimation.
539          *
540          * But if RTT is not available from the SYN (due to retransmits or
541          * syn cookies) or the cache, force a conservative 3secs timeout.
542          *
543          * A bit of theory. RTT is time passed after "normal" sized packet
544          * is sent until it is ACKed. In normal circumstances sending small
545          * packets force peer to delay ACKs and calculation is correct too.
546          * The algorithm is adaptive and, provided we follow specs, it
547          * NEVER underestimate RTT. BUT! If peer tries to make some clever
548          * tricks sort of "quick acks" for time long enough to decrease RTT
549          * to low value, and then abruptly stops to do it and starts to delay
550          * ACKs, wait for troubles.
551          */
552         if (crtt > tp->srtt_us) {
553                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
554                 crtt /= 8 * USEC_PER_SEC / HZ;
555                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
556         } else if (tp->srtt_us == 0) {
557                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
558                  * 3WHS. This is most likely due to retransmission,
559                  * including spurious one. Reset the RTO back to 3secs
560                  * from the more aggressive 1sec to avoid more spurious
561                  * retransmission.
562                  */
563                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
564                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
565 
566                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
567         }
568         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
569          * retransmitted. In light of RFC6298 more aggressive 1sec
570          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
571          * retransmission has occurred.
572          */
573         if (tp->total_retrans > 1)
574                 tp->snd_cwnd = 1;
575         else
576                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
577         tp->snd_cwnd_stamp = tcp_time_stamp;
578 }
579 
580 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
581                         bool paws_check, bool timestamps)
582 {
583         struct tcp_metrics_block *tm;
584         bool ret;
585 
586         if (!dst)
587                 return false;
588 
589         rcu_read_lock();
590         tm = __tcp_get_metrics_req(req, dst);
591         if (paws_check) {
592                 if (tm &&
593                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
594                     ((s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW ||
595                      !timestamps))
596                         ret = false;
597                 else
598                         ret = true;
599         } else {
600                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
601                         ret = true;
602                 else
603                         ret = false;
604         }
605         rcu_read_unlock();
606 
607         return ret;
608 }
609 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
610 
611 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
612 {
613         struct tcp_metrics_block *tm;
614 
615         rcu_read_lock();
616         tm = tcp_get_metrics(sk, dst, true);
617         if (tm) {
618                 struct tcp_sock *tp = tcp_sk(sk);
619 
620                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
621                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
622                         tp->rx_opt.ts_recent = tm->tcpm_ts;
623                 }
624         }
625         rcu_read_unlock();
626 }
627 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
628 
629 /* VJ's idea. Save last timestamp seen from this destination and hold
630  * it at least for normal timewait interval to use for duplicate
631  * segment detection in subsequent connections, before they enter
632  * synchronized state.
633  */
634 bool tcp_remember_stamp(struct sock *sk)
635 {
636         struct dst_entry *dst = __sk_dst_get(sk);
637         bool ret = false;
638 
639         if (dst) {
640                 struct tcp_metrics_block *tm;
641 
642                 rcu_read_lock();
643                 tm = tcp_get_metrics(sk, dst, true);
644                 if (tm) {
645                         struct tcp_sock *tp = tcp_sk(sk);
646 
647                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
648                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
649                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
650                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
651                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
652                         }
653                         ret = true;
654                 }
655                 rcu_read_unlock();
656         }
657         return ret;
658 }
659 
660 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
661 {
662         struct tcp_metrics_block *tm;
663         bool ret = false;
664 
665         rcu_read_lock();
666         tm = __tcp_get_metrics_tw(tw);
667         if (tm) {
668                 const struct tcp_timewait_sock *tcptw;
669                 struct sock *sk = (struct sock *) tw;
670 
671                 tcptw = tcp_twsk(sk);
672                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
673                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
674                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
675                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
676                         tm->tcpm_ts        = tcptw->tw_ts_recent;
677                 }
678                 ret = true;
679         }
680         rcu_read_unlock();
681 
682         return ret;
683 }
684 
685 static DEFINE_SEQLOCK(fastopen_seqlock);
686 
687 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
688                             struct tcp_fastopen_cookie *cookie,
689                             int *syn_loss, unsigned long *last_syn_loss)
690 {
691         struct tcp_metrics_block *tm;
692 
693         rcu_read_lock();
694         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
695         if (tm) {
696                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
697                 unsigned int seq;
698 
699                 do {
700                         seq = read_seqbegin(&fastopen_seqlock);
701                         if (tfom->mss)
702                                 *mss = tfom->mss;
703                         *cookie = tfom->cookie;
704                         if (cookie->len <= 0 && tfom->try_exp == 1)
705                                 cookie->exp = true;
706                         *syn_loss = tfom->syn_loss;
707                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
708                 } while (read_seqretry(&fastopen_seqlock, seq));
709         }
710         rcu_read_unlock();
711 }
712 
713 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
714                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
715                             u16 try_exp)
716 {
717         struct dst_entry *dst = __sk_dst_get(sk);
718         struct tcp_metrics_block *tm;
719 
720         if (!dst)
721                 return;
722         rcu_read_lock();
723         tm = tcp_get_metrics(sk, dst, true);
724         if (tm) {
725                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
726 
727                 write_seqlock_bh(&fastopen_seqlock);
728                 if (mss)
729                         tfom->mss = mss;
730                 if (cookie && cookie->len > 0)
731                         tfom->cookie = *cookie;
732                 else if (try_exp > tfom->try_exp &&
733                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
734                         tfom->try_exp = try_exp;
735                 if (syn_lost) {
736                         ++tfom->syn_loss;
737                         tfom->last_syn_loss = jiffies;
738                 } else
739                         tfom->syn_loss = 0;
740                 write_sequnlock_bh(&fastopen_seqlock);
741         }
742         rcu_read_unlock();
743 }
744 
745 static struct genl_family tcp_metrics_nl_family = {
746         .id             = GENL_ID_GENERATE,
747         .hdrsize        = 0,
748         .name           = TCP_METRICS_GENL_NAME,
749         .version        = TCP_METRICS_GENL_VERSION,
750         .maxattr        = TCP_METRICS_ATTR_MAX,
751         .netnsok        = true,
752 };
753 
754 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
755         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
756         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
757                                             .len = sizeof(struct in6_addr), },
758         /* Following attributes are not received for GET/DEL,
759          * we keep them for reference
760          */
761 #if 0
762         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
763         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
764         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
765         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
766         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
767         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
768         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
769         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
770                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
771 #endif
772 };
773 
774 /* Add attributes, caller cancels its header on failure */
775 static int tcp_metrics_fill_info(struct sk_buff *msg,
776                                  struct tcp_metrics_block *tm)
777 {
778         struct nlattr *nest;
779         int i;
780 
781         switch (tm->tcpm_daddr.family) {
782         case AF_INET:
783                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
784                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
785                         goto nla_put_failure;
786                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
787                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
788                         goto nla_put_failure;
789                 break;
790         case AF_INET6:
791                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
792                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
793                         goto nla_put_failure;
794                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
795                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
796                         goto nla_put_failure;
797                 break;
798         default:
799                 return -EAFNOSUPPORT;
800         }
801 
802         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
803                           jiffies - tm->tcpm_stamp,
804                           TCP_METRICS_ATTR_PAD) < 0)
805                 goto nla_put_failure;
806         if (tm->tcpm_ts_stamp) {
807                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
808                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
809                         goto nla_put_failure;
810                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
811                                 tm->tcpm_ts) < 0)
812                         goto nla_put_failure;
813         }
814 
815         {
816                 int n = 0;
817 
818                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
819                 if (!nest)
820                         goto nla_put_failure;
821                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
822                         u32 val = tm->tcpm_vals[i];
823 
824                         if (!val)
825                                 continue;
826                         if (i == TCP_METRIC_RTT) {
827                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
828                                                 val) < 0)
829                                         goto nla_put_failure;
830                                 n++;
831                                 val = max(val / 1000, 1U);
832                         }
833                         if (i == TCP_METRIC_RTTVAR) {
834                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
835                                                 val) < 0)
836                                         goto nla_put_failure;
837                                 n++;
838                                 val = max(val / 1000, 1U);
839                         }
840                         if (nla_put_u32(msg, i + 1, val) < 0)
841                                 goto nla_put_failure;
842                         n++;
843                 }
844                 if (n)
845                         nla_nest_end(msg, nest);
846                 else
847                         nla_nest_cancel(msg, nest);
848         }
849 
850         {
851                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
852                 unsigned int seq;
853 
854                 do {
855                         seq = read_seqbegin(&fastopen_seqlock);
856                         tfom_copy[0] = tm->tcpm_fastopen;
857                 } while (read_seqretry(&fastopen_seqlock, seq));
858 
859                 tfom = tfom_copy;
860                 if (tfom->mss &&
861                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
862                                 tfom->mss) < 0)
863                         goto nla_put_failure;
864                 if (tfom->syn_loss &&
865                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
866                                 tfom->syn_loss) < 0 ||
867                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
868                                 jiffies - tfom->last_syn_loss,
869                                 TCP_METRICS_ATTR_PAD) < 0))
870                         goto nla_put_failure;
871                 if (tfom->cookie.len > 0 &&
872                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
873                             tfom->cookie.len, tfom->cookie.val) < 0)
874                         goto nla_put_failure;
875         }
876 
877         return 0;
878 
879 nla_put_failure:
880         return -EMSGSIZE;
881 }
882 
883 static int tcp_metrics_dump_info(struct sk_buff *skb,
884                                  struct netlink_callback *cb,
885                                  struct tcp_metrics_block *tm)
886 {
887         void *hdr;
888 
889         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
890                           &tcp_metrics_nl_family, NLM_F_MULTI,
891                           TCP_METRICS_CMD_GET);
892         if (!hdr)
893                 return -EMSGSIZE;
894 
895         if (tcp_metrics_fill_info(skb, tm) < 0)
896                 goto nla_put_failure;
897 
898         genlmsg_end(skb, hdr);
899         return 0;
900 
901 nla_put_failure:
902         genlmsg_cancel(skb, hdr);
903         return -EMSGSIZE;
904 }
905 
906 static int tcp_metrics_nl_dump(struct sk_buff *skb,
907                                struct netlink_callback *cb)
908 {
909         struct net *net = sock_net(skb->sk);
910         unsigned int max_rows = 1U << tcp_metrics_hash_log;
911         unsigned int row, s_row = cb->args[0];
912         int s_col = cb->args[1], col = s_col;
913 
914         for (row = s_row; row < max_rows; row++, s_col = 0) {
915                 struct tcp_metrics_block *tm;
916                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
917 
918                 rcu_read_lock();
919                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
920                      tm = rcu_dereference(tm->tcpm_next), col++) {
921                         if (!net_eq(tm_net(tm), net))
922                                 continue;
923                         if (col < s_col)
924                                 continue;
925                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
926                                 rcu_read_unlock();
927                                 goto done;
928                         }
929                 }
930                 rcu_read_unlock();
931         }
932 
933 done:
934         cb->args[0] = row;
935         cb->args[1] = col;
936         return skb->len;
937 }
938 
939 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
940                            unsigned int *hash, int optional, int v4, int v6)
941 {
942         struct nlattr *a;
943 
944         a = info->attrs[v4];
945         if (a) {
946                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
947                 if (hash)
948                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
949                 return 0;
950         }
951         a = info->attrs[v6];
952         if (a) {
953                 struct in6_addr in6;
954 
955                 if (nla_len(a) != sizeof(struct in6_addr))
956                         return -EINVAL;
957                 in6 = nla_get_in6_addr(a);
958                 inetpeer_set_addr_v6(addr, &in6);
959                 if (hash)
960                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
961                 return 0;
962         }
963         return optional ? 1 : -EAFNOSUPPORT;
964 }
965 
966 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
967                          unsigned int *hash, int optional)
968 {
969         return __parse_nl_addr(info, addr, hash, optional,
970                                TCP_METRICS_ATTR_ADDR_IPV4,
971                                TCP_METRICS_ATTR_ADDR_IPV6);
972 }
973 
974 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
975 {
976         return __parse_nl_addr(info, addr, NULL, 0,
977                                TCP_METRICS_ATTR_SADDR_IPV4,
978                                TCP_METRICS_ATTR_SADDR_IPV6);
979 }
980 
981 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
982 {
983         struct tcp_metrics_block *tm;
984         struct inetpeer_addr saddr, daddr;
985         unsigned int hash;
986         struct sk_buff *msg;
987         struct net *net = genl_info_net(info);
988         void *reply;
989         int ret;
990         bool src = true;
991 
992         ret = parse_nl_addr(info, &daddr, &hash, 0);
993         if (ret < 0)
994                 return ret;
995 
996         ret = parse_nl_saddr(info, &saddr);
997         if (ret < 0)
998                 src = false;
999 
1000         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
1001         if (!msg)
1002                 return -ENOMEM;
1003 
1004         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
1005                                   info->genlhdr->cmd);
1006         if (!reply)
1007                 goto nla_put_failure;
1008 
1009         hash ^= net_hash_mix(net);
1010         hash = hash_32(hash, tcp_metrics_hash_log);
1011         ret = -ESRCH;
1012         rcu_read_lock();
1013         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
1014              tm = rcu_dereference(tm->tcpm_next)) {
1015                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1016                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1017                     net_eq(tm_net(tm), net)) {
1018                         ret = tcp_metrics_fill_info(msg, tm);
1019                         break;
1020                 }
1021         }
1022         rcu_read_unlock();
1023         if (ret < 0)
1024                 goto out_free;
1025 
1026         genlmsg_end(msg, reply);
1027         return genlmsg_reply(msg, info);
1028 
1029 nla_put_failure:
1030         ret = -EMSGSIZE;
1031 
1032 out_free:
1033         nlmsg_free(msg);
1034         return ret;
1035 }
1036 
1037 static void tcp_metrics_flush_all(struct net *net)
1038 {
1039         unsigned int max_rows = 1U << tcp_metrics_hash_log;
1040         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
1041         struct tcp_metrics_block *tm;
1042         unsigned int row;
1043 
1044         for (row = 0; row < max_rows; row++, hb++) {
1045                 struct tcp_metrics_block __rcu **pp;
1046                 spin_lock_bh(&tcp_metrics_lock);
1047                 pp = &hb->chain;
1048                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1049                         if (net_eq(tm_net(tm), net)) {
1050                                 *pp = tm->tcpm_next;
1051                                 kfree_rcu(tm, rcu_head);
1052                         } else {
1053                                 pp = &tm->tcpm_next;
1054                         }
1055                 }
1056                 spin_unlock_bh(&tcp_metrics_lock);
1057         }
1058 }
1059 
1060 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
1061 {
1062         struct tcpm_hash_bucket *hb;
1063         struct tcp_metrics_block *tm;
1064         struct tcp_metrics_block __rcu **pp;
1065         struct inetpeer_addr saddr, daddr;
1066         unsigned int hash;
1067         struct net *net = genl_info_net(info);
1068         int ret;
1069         bool src = true, found = false;
1070 
1071         ret = parse_nl_addr(info, &daddr, &hash, 1);
1072         if (ret < 0)
1073                 return ret;
1074         if (ret > 0) {
1075                 tcp_metrics_flush_all(net);
1076                 return 0;
1077         }
1078         ret = parse_nl_saddr(info, &saddr);
1079         if (ret < 0)
1080                 src = false;
1081 
1082         hash ^= net_hash_mix(net);
1083         hash = hash_32(hash, tcp_metrics_hash_log);
1084         hb = tcp_metrics_hash + hash;
1085         pp = &hb->chain;
1086         spin_lock_bh(&tcp_metrics_lock);
1087         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
1088                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
1089                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
1090                     net_eq(tm_net(tm), net)) {
1091                         *pp = tm->tcpm_next;
1092                         kfree_rcu(tm, rcu_head);
1093                         found = true;
1094                 } else {
1095                         pp = &tm->tcpm_next;
1096                 }
1097         }
1098         spin_unlock_bh(&tcp_metrics_lock);
1099         if (!found)
1100                 return -ESRCH;
1101         return 0;
1102 }
1103 
1104 static const struct genl_ops tcp_metrics_nl_ops[] = {
1105         {
1106                 .cmd = TCP_METRICS_CMD_GET,
1107                 .doit = tcp_metrics_nl_cmd_get,
1108                 .dumpit = tcp_metrics_nl_dump,
1109                 .policy = tcp_metrics_nl_policy,
1110         },
1111         {
1112                 .cmd = TCP_METRICS_CMD_DEL,
1113                 .doit = tcp_metrics_nl_cmd_del,
1114                 .policy = tcp_metrics_nl_policy,
1115                 .flags = GENL_ADMIN_PERM,
1116         },
1117 };
1118 
1119 static unsigned int tcpmhash_entries;
1120 static int __init set_tcpmhash_entries(char *str)
1121 {
1122         ssize_t ret;
1123 
1124         if (!str)
1125                 return 0;
1126 
1127         ret = kstrtouint(str, 0, &tcpmhash_entries);
1128         if (ret)
1129                 return 0;
1130 
1131         return 1;
1132 }
1133 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1134 
1135 static int __net_init tcp_net_metrics_init(struct net *net)
1136 {
1137         size_t size;
1138         unsigned int slots;
1139 
1140         if (!net_eq(net, &init_net))
1141                 return 0;
1142 
1143         slots = tcpmhash_entries;
1144         if (!slots) {
1145                 if (totalram_pages >= 128 * 1024)
1146                         slots = 16 * 1024;
1147                 else
1148                         slots = 8 * 1024;
1149         }
1150 
1151         tcp_metrics_hash_log = order_base_2(slots);
1152         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1153 
1154         tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1155         if (!tcp_metrics_hash)
1156                 tcp_metrics_hash = vzalloc(size);
1157 
1158         if (!tcp_metrics_hash)
1159                 return -ENOMEM;
1160 
1161         return 0;
1162 }
1163 
1164 static void __net_exit tcp_net_metrics_exit(struct net *net)
1165 {
1166         tcp_metrics_flush_all(net);
1167 }
1168 
1169 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1170         .init   =       tcp_net_metrics_init,
1171         .exit   =       tcp_net_metrics_exit,
1172 };
1173 
1174 void __init tcp_metrics_init(void)
1175 {
1176         int ret;
1177 
1178         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1179         if (ret < 0)
1180                 panic("Could not allocate the tcp_metrics hash table\n");
1181 
1182         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1183                                             tcp_metrics_nl_ops);
1184         if (ret < 0)
1185                 panic("Could not register tcp_metrics generic netlink\n");
1186 }
1187 

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