Release 4.11 net/ipv4/tcp_metrics.c

#include <linux/rcupdate.h>
#include <linux/spinlock.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/cache.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/tcp.h>
#include <linux/hash.h>
#include <linux/tcp_metrics.h>
#include <linux/vmalloc.h>

#include <net/inet_connection_sock.h>
#include <net/net_namespace.h>
#include <net/request_sock.h>
#include <net/inetpeer.h>
#include <net/sock.h>
#include <net/ipv6.h>
#include <net/dst.h>
#include <net/tcp.h>
#include <net/genetlink.h>


int sysctl_tcp_nometrics_save __read_mostly;

static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
						   const struct inetpeer_addr *daddr,
						   struct net *net, unsigned int hash);


struct tcp_fastopen_metrics {
	
u16	mss;
	
u16	syn_loss:10,		/* Recurring Fast Open SYN losses */
		
try_exp:2;		/* Request w/ exp. option (once) */
	
unsigned long	last_syn_loss;	/* Last Fast Open SYN loss */
	
struct	tcp_fastopen_cookie	cookie;
};

/* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
 * Kernel only stores RTT and RTTVAR in usec resolution
 */

#define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)


struct tcp_metrics_block {
	
struct tcp_metrics_block __rcu	*tcpm_next;
	
possible_net_t			tcpm_net;
	
struct inetpeer_addr		tcpm_saddr;
	
struct inetpeer_addr		tcpm_daddr;
	
unsigned long			tcpm_stamp;
	
u32				tcpm_ts;
	
u32				tcpm_ts_stamp;
	
u32				tcpm_lock;
	
u32				tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
	
struct tcp_fastopen_metrics	tcpm_fastopen;

	
struct rcu_head			rcu_head;
};



static inline struct net *tm_net(struct tcp_metrics_block *tm)
{
	return read_pnet(&tm->tcpm_net);
}

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static bool tcp_metric_locked(struct tcp_metrics_block *tm,
			      enum tcp_metric_index idx)
{
	return tm->tcpm_lock & (1 << idx);
}

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static u32 tcp_metric_get(struct tcp_metrics_block *tm,
			  enum tcp_metric_index idx)
{
	return tm->tcpm_vals[idx];
}

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static void tcp_metric_set(struct tcp_metrics_block *tm,
			   enum tcp_metric_index idx,
			   u32 val)
{
	tm->tcpm_vals[idx] = val;
}

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static bool addr_same(const struct inetpeer_addr *a,
		      const struct inetpeer_addr *b)
{
	return inetpeer_addr_cmp(a, b) == 0;
}

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2
7.14%
1
33.33%
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28
100.00%
3
100.00%


struct tcpm_hash_bucket {
	
struct tcp_metrics_block __rcu	*chain;
};


static struct tcpm_hash_bucket	*tcp_metrics_hash __read_mostly;

static unsigned int		tcp_metrics_hash_log __read_mostly;

static DEFINE_SPINLOCK(tcp_metrics_lock);



static void tcpm_suck_dst(struct tcp_metrics_block *tm,
			  const struct dst_entry *dst,
			  bool fastopen_clear)
{
	u32 msval;
	u32 val;

	tm->tcpm_stamp = jiffies;

	val = 0;
	if (dst_metric_locked(dst, RTAX_RTT))
		val |= 1 << TCP_METRIC_RTT;
	if (dst_metric_locked(dst, RTAX_RTTVAR))
		val |= 1 << TCP_METRIC_RTTVAR;
	if (dst_metric_locked(dst, RTAX_SSTHRESH))
		val |= 1 << TCP_METRIC_SSTHRESH;
	if (dst_metric_locked(dst, RTAX_CWND))
		val |= 1 << TCP_METRIC_CWND;
	if (dst_metric_locked(dst, RTAX_REORDERING))
		val |= 1 << TCP_METRIC_REORDERING;
	tm->tcpm_lock = val;

	msval = dst_metric_raw(dst, RTAX_RTT);
	tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;

	msval = dst_metric_raw(dst, RTAX_RTTVAR);
	tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
	tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
	tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
	tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
	tm->tcpm_ts = 0;
	tm->tcpm_ts_stamp = 0;
	if (fastopen_clear) {
		tm->tcpm_fastopen.mss = 0;
		tm->tcpm_fastopen.syn_loss = 0;
		tm->tcpm_fastopen.try_exp = 0;
		tm->tcpm_fastopen.cookie.exp = false;
		tm->tcpm_fastopen.cookie.len = 0;
	}
}

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12.26%
2
22.22%
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26
9.96%
2
22.22%
Daniel Lee
18
6.90%
1
11.11%
Julian Anastasov
6
2.30%
1
11.11%
Total
261
100.00%
9
100.00%


#define TCP_METRICS_TIMEOUT		(60 * 60 * HZ)



static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
{
	if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
		tcpm_suck_dst(tm, dst, false);
}

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#define TCP_METRICS_RECLAIM_DEPTH	5

#define TCP_METRICS_RECLAIM_PTR		(struct tcp_metrics_block *) 0x1UL


#define deref_locked(p)	\
	rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))



static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
					  struct inetpeer_addr *saddr,
					  struct inetpeer_addr *daddr,
					  unsigned int hash)
{
	struct tcp_metrics_block *tm;
	struct net *net;
	bool reclaim = false;

	spin_lock_bh(&tcp_metrics_lock);
	net = dev_net(dst->dev);

	/* While waiting for the spin-lock the cache might have been populated
         * with this entry and so we have to check again.
         */
	tm = __tcp_get_metrics(saddr, daddr, net, hash);
	if (tm == TCP_METRICS_RECLAIM_PTR) {
		reclaim = true;
		tm = NULL;
	}
	if (tm) {
		tcpm_check_stamp(tm, dst);
		goto out_unlock;
	}

	if (unlikely(reclaim)) {
		struct tcp_metrics_block *oldest;

		oldest = deref_locked(tcp_metrics_hash[hash].chain);
		for (tm = deref_locked(oldest->tcpm_next); tm;
		     tm = deref_locked(tm->tcpm_next)) {
			if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
				oldest = tm;
		}
		tm = oldest;
	} else {
		tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
		if (!tm)
			goto out_unlock;
	}
	write_pnet(&tm->tcpm_net, net);
	tm->tcpm_saddr = *saddr;
	tm->tcpm_daddr = *daddr;

	tcpm_suck_dst(tm, dst, true);

	if (likely(!reclaim)) {
		tm->tcpm_next = tcp_metrics_hash[hash].chain;
		rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
	}

out_unlock:
	spin_unlock_bh(&tcp_metrics_lock);
	return tm;
}

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22.91%
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37.50%
Eric W. Biedermann
10
3.64%
1
12.50%
Eric Dumazet
5
1.82%
2
25.00%
Total
275
100.00%
8
100.00%



static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
{
	if (tm)
		return tm;
	if (depth > TCP_METRICS_RECLAIM_DEPTH)
		return TCP_METRICS_RECLAIM_PTR;
	return NULL;
}

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static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
						   const struct inetpeer_addr *daddr,
						   struct net *net, unsigned int hash)
{
	struct tcp_metrics_block *tm;
	int depth = 0;

	for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
	     tm = rcu_dereference(tm->tcpm_next)) {
		if (addr_same(&tm->tcpm_saddr, saddr) &&
		    addr_same(&tm->tcpm_daddr, daddr) &&
		    net_eq(tm_net(tm), net))
			break;
		depth++;
	}
	return tcp_get_encode(tm, depth);
}

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10
9.09%
1
25.00%
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110
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4
100.00%



static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
						       struct dst_entry *dst)
{
	struct tcp_metrics_block *tm;
	struct inetpeer_addr saddr, daddr;
	unsigned int hash;
	struct net *net;

	saddr.family = req->rsk_ops->family;
	daddr.family = req->rsk_ops->family;
	switch (daddr.family) {
	case AF_INET:
		inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
		inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
		hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
		break;
#if IS_ENABLED(CONFIG_IPV6)
	case AF_INET6:
		inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
		inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
		hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
		break;
#endif
	default:
		return NULL;
	}

	net = dev_net(dst->dev);
	hash ^= net_hash_mix(net);
	hash = hash_32(hash, tcp_metrics_hash_log);

	for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
	     tm = rcu_dereference(tm->tcpm_next)) {
		if (addr_same(&tm->tcpm_saddr, &saddr) &&
		    addr_same(&tm->tcpm_daddr, &daddr) &&
		    net_eq(tm_net(tm), net))
			break;
	}
	tcpm_check_stamp(tm, dst);
	return tm;
}

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31
11.83%
2
20.00%
Eric Dumazet
28
10.69%
3
30.00%
Eric W. Biedermann
17
6.49%
2
20.00%
Total
262
100.00%
10
100.00%



static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
{
	struct tcp_metrics_block *tm;
	struct inetpeer_addr saddr, daddr;
	unsigned int hash;
	struct net *net;

	if (tw->tw_family == AF_INET) {
		inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
		inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
		hash = ipv4_addr_hash(tw->tw_daddr);
	}
#if IS_ENABLED(CONFIG_IPV6)
	else if (tw->tw_family == AF_INET6) {
		if (ipv6_addr_v4mapped(&tw->tw_v6_daddr)) {
			inetpeer_set_addr_v4(&saddr, tw->tw_rcv_saddr);
			inetpeer_set_addr_v4(&daddr, tw->tw_daddr);
			hash = ipv4_addr_hash(tw->tw_daddr);
		} else {
			inetpeer_set_addr_v6(&saddr, &tw->tw_v6_rcv_saddr);
			inetpeer_set_addr_v6(&daddr, &tw->tw_v6_daddr);
			hash = ipv6_addr_hash(&tw->tw_v6_daddr);
		}
	}
#endif
	else
		return NULL;

	net = twsk_net(tw);
	hash ^= net_hash_mix(net);
	hash = hash_32(hash, tcp_metrics_hash_log);

	for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
	     tm = rcu_dereference(tm->tcpm_next)) {
		if (addr_same(&tm->tcpm_saddr, &saddr) &&
		    addr_same(&tm->tcpm_daddr, &daddr) &&
		    net_eq(tm_net(tm), net))
			break;
	}
	return tm;
}

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30.50%
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23.08%
David Ahern
44
16.99%
2
15.38%
Eric W. Biedermann
17
6.56%
2
15.38%
Eric Dumazet
17
6.56%
4
30.77%
Total
259
100.00%
13
100.00%



static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
						 struct dst_entry *dst,
						 bool create)
{
	struct tcp_metrics_block *tm;
	struct inetpeer_addr saddr, daddr;
	unsigned int hash;
	struct net *net;

	if (sk->sk_family == AF_INET) {
		inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
		inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
		hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
	}
#if IS_ENABLED(CONFIG_IPV6)
	else if (sk->sk_family == AF_INET6) {
		if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
			inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
			inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
			hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
		} else {
			inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
			inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
			hash = ipv6_addr_hash(&sk->sk_v6_daddr);
		}
	}
#endif
	else
		return NULL;

	net = dev_net(dst->dev);
	hash ^= net_hash_mix(net);
	hash = hash_32(hash, tcp_metrics_hash_log);

	tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
	if (tm == TCP_METRICS_RECLAIM_PTR)
		tm = NULL;
	if (!tm && create)
		tm = tcpm_new(dst, &saddr, &daddr, hash);
	else
		tcpm_check_stamp(tm, dst);

	return tm;
}

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David S. Miller
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Christoph Paasch
83
29.64%
3
23.08%
David Ahern
50
17.86%
2
15.38%
Eric Dumazet
17
6.07%
4
30.77%
Eric W. Biedermann
7
2.50%
1
7.69%
Total
280
100.00%
13
100.00%

/* Save metrics learned by this TCP session.  This function is called
 * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 * or goes from LAST-ACK to CLOSE.
 */


void tcp_update_metrics(struct sock *sk)
{
	const struct inet_connection_sock *icsk = inet_csk(sk);
	struct dst_entry *dst = __sk_dst_get(sk);
	struct tcp_sock *tp = tcp_sk(sk);
	struct net *net = sock_net(sk);
	struct tcp_metrics_block *tm;
	unsigned long rtt;
	u32 val;
	int m;

	sk_dst_confirm(sk);
	if (sysctl_tcp_nometrics_save || !dst)
		return;

	rcu_read_lock();
	if (icsk->icsk_backoff || !tp->srtt_us) {
		/* This session failed to estimate rtt. Why?
                 * Probably, no packets returned in time.  Reset our
                 * results.
                 */
		tm = tcp_get_metrics(sk, dst, false);
		if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
			tcp_metric_set(tm, TCP_METRIC_RTT, 0);
		goto out_unlock;
	} else
		tm = tcp_get_metrics(sk, dst, true);

	if (!tm)
		goto out_unlock;

	rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
	m = rtt - tp->srtt_us;

	/* If newly calculated rtt larger than stored one, store new
         * one. Otherwise, use EWMA. Remember, rtt overestimation is
         * always better than underestimation.
         */
	if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
		if (m <= 0)
			rtt = tp->srtt_us;
		else
			rtt -= (m >> 3);
		tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
	}

	if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
		unsigned long var;

		if (m < 0)
			m = -m;

		/* Scale deviation to rttvar fixed point */
		m >>= 1;
		if (m < tp->mdev_us)
			m = tp->mdev_us;

		var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
		if (m >= var)
			var = m;
		else
			var -= (var - m) >> 2;

		tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
	}

	if (tcp_in_initial_slowstart(tp)) {
		/* Slow start still did not finish. */
		if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
			val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
			if (val && (tp->snd_cwnd >> 1) > val)
				tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
					       tp->snd_cwnd >> 1);
		}
		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
			val = tcp_metric_get(tm, TCP_METRIC_CWND);
			if (tp->snd_cwnd > val)
				tcp_metric_set(tm, TCP_METRIC_CWND,
					       tp->snd_cwnd);
		}
	} else if (!tcp_in_slow_start(tp) &&
		   icsk->icsk_ca_state == TCP_CA_Open) {
		/* Cong. avoidance phase, cwnd is reliable. */
		if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
			tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
				       max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
			val = tcp_metric_get(tm, TCP_METRIC_CWND);
			tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
		}
	} else {
		/* Else slow start did not finish, cwnd is non-sense,
                 * ssthresh may be also invalid.
                 */
		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
			val = tcp_metric_get(tm, TCP_METRIC_CWND);
			tcp_metric_set(tm, TCP_METRIC_CWND,
				       (val + tp->snd_ssthresh) >> 1);
		}
		if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
			val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
			if (val && tp->snd_ssthresh > val)
				tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
					       tp->snd_ssthresh);
		}
		if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
			val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
			if (val < tp->reordering &&
			    tp->reordering != net->ipv4.sysctl_tcp_reordering)
				tcp_metric_set(tm, TCP_METRIC_REORDERING,
					       tp->reordering);
		}
	}
	tm->tcpm_stamp = jiffies;
out_unlock:
	rcu_read_unlock();
}

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David S. Miller
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2.24%
1
12.50%
Eric Dumazet
9
1.44%
1
12.50%
Julian Anastasov
5
0.80%
1
12.50%
Yuchung Cheng
4
0.64%
1
12.50%
Alexander Duyck
1
0.16%
1
12.50%
Total
625
100.00%
8
100.00%

/* Initialize metrics on socket. */



void tcp_init_metrics(struct sock *sk)
{
	struct dst_entry *dst = __sk_dst_get(sk);
	struct tcp_sock *tp = tcp_sk(sk);
	struct tcp_metrics_block *tm;
	u32 val, crtt = 0; /* cached RTT scaled by 8 */

	sk_dst_confirm(sk);
	if (!dst)
		goto reset;

	rcu_read_lock();
	tm = tcp_get_metrics(sk, dst, true);
	if (!tm) {
		rcu_read_unlock();
		goto reset;
	}

	if (tcp_metric_locked(tm, TCP_METRIC_CWND))
		tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);

	val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
	if (val) {
		tp->snd_ssthresh = val;
		if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
			tp->snd_ssthresh = tp->snd_cwnd_clamp;
	} else {
		/* ssthresh may have been reduced unnecessarily during.
                 * 3WHS. Restore it back to its initial default.
                 */
		tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
	}
	val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
	if (val && tp->reordering != val) {
		tcp_disable_fack(tp);
		tp->reordering = val;
	}

	crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
	rcu_read_unlock();
reset:
	/* The initial RTT measurement from the SYN/SYN-ACK is not ideal
         * to seed the RTO for later data packets because SYN packets are
         * small. Use the per-dst cached values to seed the RTO but keep
         * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
         * Later the RTO will be updated immediately upon obtaining the first
         * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
         * influences the first RTO but not later RTT estimation.
         *
         * But if RTT is not available from the SYN (due to retransmits or
         * syn cookies) or the cache, force a conservative 3secs timeout.
         *
         * A bit of theory. RTT is time passed after "normal" sized packet
         * is sent until it is ACKed. In normal circumstances sending small
         * packets force peer to delay ACKs and calculation is correct too.
         * The algorithm is adaptive and, provided we follow specs, it
         * NEVER underestimate RTT. BUT! If peer tries to make some clever
         * tricks sort of "quick acks" for time long enough to decrease RTT
         * to low value, and then abruptly stops to do it and starts to delay
         * ACKs, wait for troubles.
         */
	if (crtt > tp->srtt_us) {
		/* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
		crtt /= 8 * USEC_PER_SEC / HZ;
		inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
	} else if (tp->srtt_us == 0) {
		/* RFC6298: 5.7 We've failed to get a valid RTT sample from
                 * 3WHS. This is most likely due to retransmission,
                 * including spurious one. Reset the RTO back to 3secs
                 * from the more aggressive 1sec to avoid more spurious
                 * retransmission.
                 */
		tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
		tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;

		inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
	}
	/* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
         * retransmitted. In light of RFC6298 more aggressive 1sec
         * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
         * retransmission has occurred.
         */
	if (tp->total_retrans > 1)
		tp->snd_cwnd = 1;
	else
		tp->snd_cwnd = tcp_init_cwnd(tp, dst);
	tp->snd_cwnd_stamp = tcp_time_stamp;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
David S. Miller
267
85.03%
3
30.00%
Eric Dumazet
17
5.41%
1
10.00%
Yuchung Cheng
16
5.10%
2
20.00%
Julian Anastasov
5
1.59%
1
10.00%
Neal Cardwell
5
1.59%
1
10.00%
Konstantin Khlebnikov
3
0.96%
1
10.00%
Ian Morris
1
0.32%
1
10.00%
Total
314
100.00%
10
100.00%



bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
			bool paws_check, bool timestamps)
{
	struct tcp_metrics_block *tm;
	bool ret;

	if (!dst)
		return false;

	rcu_read_lock();
	tm = __tcp_get_metrics_req(req, dst);
	if (paws_check) {
		if (tm &&
		    (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
		    ((s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW ||
		     !timestamps))
			ret = false;
		else
			ret = true;
	} else {
		if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
			ret = true;
		else
			ret = false;
	}
	rcu_read_unlock();

	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
David S. Miller
125
93.98%
3
75.00%
Hannes Frederic Sowa
8
6.02%
1
25.00%
Total
133
100.00%
4
100.00%



void tcp_fetch_timewait_stamp(