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Commit 91b5b21c authored by Lawrence Brakmo's avatar Lawrence Brakmo Committed by David S. Miller
Browse files

bpf: Add support for changing congestion control 



Added support for changing congestion control for SOCK_OPS bpf
programs through the setsockopt bpf helper function. It also adds
a new SOCK_OPS op, BPF_SOCK_OPS_NEEDS_ECN, that is needed for
congestion controls, like dctcp, that need to enable ECN in the
SYN packets.

Signed-off-by: default avatarLawrence Brakmo <brakmo@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d9925368

include/net/tcp.h

+8 −1
Original line number Diff line number Diff line
@@ -1004,7 +1004,9 @@ void tcp_get_default_congestion_control(char *name); 
void tcp_get_available_congestion_control(char *buf, size_t len);

void tcp_get_allowed_congestion_control(char *buf, size_t len);

int tcp_set_allowed_congestion_control(char *allowed);

int tcp_set_congestion_control(struct sock *sk, const char *name);

int tcp_set_congestion_control(struct sock *sk, const char *name, bool load);

void tcp_reinit_congestion_control(struct sock *sk,

				   const struct tcp_congestion_ops *ca);

u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);

void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
@@ -2078,4 +2080,9 @@ static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 
		rwnd = 0;

	return rwnd;

}



static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)

{

	return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1);

}

#endif	/* _TCP_H */

include/uapi/linux/bpf.h

+3 −0
Original line number Diff line number Diff line
@@ -778,6 +778,9 @@ enum { 
						 * passive connection is

						 * established

						 */

	BPF_SOCK_OPS_NEEDS_ECN,		/* If connection's congestion control

					 * needs ECN

					 */

};



#endif /* _UAPI__LINUX_BPF_H__ */

net/core/filter.c

+17 −1
Original line number Diff line number Diff line
@@ -2719,8 +2719,24 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock, 
		}

	} else if (level == SOL_TCP &&

		   sk->sk_prot->setsockopt == tcp_setsockopt) {

		/* Place holder */

#ifdef CONFIG_INET

		if (optname == TCP_CONGESTION) {

			char name[TCP_CA_NAME_MAX];



			strncpy(name, optval, min_t(long, optlen,

						    TCP_CA_NAME_MAX-1));

			name[TCP_CA_NAME_MAX-1] = 0;

			ret = tcp_set_congestion_control(sk, name, false);

			if (!ret && bpf_sock->op > BPF_SOCK_OPS_NEEDS_ECN)

				/* replacing an existing ca */

				tcp_reinit_congestion_control(sk,

					inet_csk(sk)->icsk_ca_ops);

		} else {

			ret = -EINVAL;

		}

#else

		ret = -EINVAL;

#endif

	} else {

		ret = -EINVAL;

	}

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -2481,7 +2481,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, 
		name[val] = 0;



		lock_sock(sk);

		err = tcp_set_congestion_control(sk, name);

		err = tcp_set_congestion_control(sk, name, true);

		release_sock(sk);

		return err;

	}

net/ipv4/tcp_cong.c

+22 −10
Original line number Diff line number Diff line
@@ -189,7 +189,7 @@ void tcp_init_congestion_control(struct sock *sk) 
		INET_ECN_dontxmit(sk);

}



static void tcp_reinit_congestion_control(struct sock *sk,

void tcp_reinit_congestion_control(struct sock *sk,

				   const struct tcp_congestion_ops *ca)

{

	struct inet_connection_sock *icsk = inet_csk(sk);
@@ -333,8 +333,12 @@ int tcp_set_allowed_congestion_control(char *val) 
	return ret;

}



/* Change congestion control for socket */

int tcp_set_congestion_control(struct sock *sk, const char *name)

/* Change congestion control for socket. If load is false, then it is the

 * responsibility of the caller to call tcp_init_congestion_control or

 * tcp_reinit_congestion_control (if the current congestion control was

 * already initialized.

 */

int tcp_set_congestion_control(struct sock *sk, const char *name, bool load)

{

	struct inet_connection_sock *icsk = inet_csk(sk);

	const struct tcp_congestion_ops *ca;
@@ -344,21 +348,29 @@ int tcp_set_congestion_control(struct sock *sk, const char *name) 
		return -EPERM;



	rcu_read_lock();

	if (!load)

		ca = tcp_ca_find(name);

	else

		ca = __tcp_ca_find_autoload(name);

	/* No change asking for existing value */

	if (ca == icsk->icsk_ca_ops) {

		icsk->icsk_ca_setsockopt = 1;

		goto out;

	}

	if (!ca)

	if (!ca) {

		err = -ENOENT;

	else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) ||

		   ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)))

	} else if (!load) {

		icsk->icsk_ca_ops = ca;

		if (!try_module_get(ca->owner))

			err = -EBUSY;

	} else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) ||

		     ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))) {

		err = -EPERM;

	else if (!try_module_get(ca->owner))

	} else if (!try_module_get(ca->owner)) {

		err = -EBUSY;

	else

	} else {

		tcp_reinit_congestion_control(sk, ca);

	}

 out:

	rcu_read_unlock();

	return err;