Commit 1891c4a0 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

mptcp: add subflow write space signalling and mptcp_poll 



Add new SEND_SPACE flag to indicate that a subflow has enough space to
accept more data for transmission.

It gets cleared at the end of mptcp_sendmsg() in case ssk has run
below the free watermark.

It is (re-set) from the wspace callback.

This allows us to use msk->flags to determine the poll mask.

Co-developed-by: default avatarPeter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: default avatarPeter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarChristoph Paasch <cpaasch@apple.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 648ef4b8

net/mptcp/protocol.c

+53 −0
Original line number Diff line number Diff line
@@ -176,6 +176,23 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, 
	return ret;

}



static void ssk_check_wmem(struct mptcp_sock *msk, struct sock *ssk)

{

	struct socket *sock;



	if (likely(sk_stream_is_writeable(ssk)))

		return;



	sock = READ_ONCE(ssk->sk_socket);



	if (sock) {

		clear_bit(MPTCP_SEND_SPACE, &msk->flags);

		smp_mb__after_atomic();

		/* set NOSPACE only after clearing SEND_SPACE flag */

		set_bit(SOCK_NOSPACE, &sock->flags);

	}

}



static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)

{

	struct mptcp_sock *msk = mptcp_sk(sk);
@@ -219,6 +236,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 
	if (copied > 0)

		ret = copied;



	ssk_check_wmem(msk, ssk);

	release_sock(ssk);

	release_sock(sk);

	return ret;
@@ -315,6 +333,7 @@ static int mptcp_init_sock(struct sock *sk) 
	struct mptcp_sock *msk = mptcp_sk(sk);



	INIT_LIST_HEAD(&msk->conn_list);

	__set_bit(MPTCP_SEND_SPACE, &msk->flags);



	return 0;

}
@@ -576,6 +595,13 @@ static void mptcp_sock_graft(struct sock *sk, struct socket *parent) 
	write_unlock_bh(&sk->sk_callback_lock);

}



static bool mptcp_memory_free(const struct sock *sk, int wake)

{

	struct mptcp_sock *msk = mptcp_sk(sk);



	return wake ? test_bit(MPTCP_SEND_SPACE, &msk->flags) : true;

}



static struct proto mptcp_prot = {

	.name		= "MPTCP",

	.owner		= THIS_MODULE,
@@ -591,6 +617,7 @@ static struct proto mptcp_prot = { 
	.hash		= inet_hash,

	.unhash		= inet_unhash,

	.get_port	= mptcp_get_port,

	.stream_memory_free	= mptcp_memory_free,

	.obj_size	= sizeof(struct mptcp_sock),

	.no_autobind	= true,

};
@@ -767,8 +794,34 @@ unlock_fail: 
static __poll_t mptcp_poll(struct file *file, struct socket *sock,

			   struct poll_table_struct *wait)

{

	const struct mptcp_sock *msk;

	struct sock *sk = sock->sk;

	struct socket *ssock;

	__poll_t mask = 0;



	msk = mptcp_sk(sk);

	lock_sock(sk);

	ssock = __mptcp_nmpc_socket(msk);

	if (ssock) {

		mask = ssock->ops->poll(file, ssock, wait);

		release_sock(sk);

		return mask;

	}



	release_sock(sk);

	sock_poll_wait(file, sock, wait);

	lock_sock(sk);



	if (test_bit(MPTCP_DATA_READY, &msk->flags))

		mask = EPOLLIN | EPOLLRDNORM;

	if (sk_stream_is_writeable(sk) &&

	    test_bit(MPTCP_SEND_SPACE, &msk->flags))

		mask |= EPOLLOUT | EPOLLWRNORM;

	if (sk->sk_shutdown & RCV_SHUTDOWN)

		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;



	release_sock(sk);



	return mask;

}

net/mptcp/protocol.h

+1 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ 


/* MPTCP socket flags */

#define MPTCP_DATA_READY	BIT(0)

#define MPTCP_SEND_SPACE	BIT(1)



/* MPTCP connection sock */

struct mptcp_sock {

net/mptcp/subflow.c

+3 −0
Original line number Diff line number Diff line
@@ -529,6 +529,9 @@ static void subflow_write_space(struct sock *sk) 


	sk_stream_write_space(sk);

	if (parent && sk_stream_is_writeable(sk)) {

		set_bit(MPTCP_SEND_SPACE, &mptcp_sk(parent)->flags);

		smp_mb__after_atomic();

		/* set SEND_SPACE before sk_stream_write_space clears NOSPACE */

		sk_stream_write_space(parent);

	}

}

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