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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: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2020-01-21 16:56:25 -08:00 committed by David S. Miller
parent 648ef4b886
commit 1891c4a076
3 changed files with 57 additions and 0 deletions
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53
net/mptcp/protocol.c
View File

@ -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 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
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;
}

1
net/mptcp/protocol.h
View File

@ -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 {

3
net/mptcp/subflow.c
View File

@ -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);
}
}