tcp_metrics.c

// SPDX-License-Identifier: GPL-2.0
#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>

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_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);
}

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

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