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mptcp: implement and use MPTCP-level retransmission

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On timeout event, schedule a work queue to do the retransmission.
Retransmission code closely resembles the sendmsg() implementation and
re-uses mptcp_sendmsg_frag, providing a dummy msghdr - for flags'
sake - and peeking the relevant dfrag from the rtx head.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2020-03-27 14:48:48 -07:00 committed by David S. Miller
parent 3f8e0aae17
commit 3b1d6210a9
2 changed files with 95 additions and 4 deletions
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98
net/mptcp/protocol.c
View File

@ -283,6 +283,10 @@ static void mptcp_reset_timer(struct sock *sk)
void mptcp_data_acked(struct sock *sk)
{
mptcp_reset_timer(sk);
if (!sk_stream_is_writeable(sk) &&
schedule_work(&mptcp_sk(sk)->work))
sock_hold(sk);
}
static void mptcp_stop_timer(struct sock *sk)
@ -900,10 +904,13 @@ static void mptcp_retransmit_handler(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
if (atomic64_read(&msk->snd_una) == msk->write_seq)
if (atomic64_read(&msk->snd_una) == msk->write_seq) {
mptcp_stop_timer(sk);
else
mptcp_reset_timer(sk);
} else {
set_bit(MPTCP_WORK_RTX, &msk->flags);
if (schedule_work(&msk->work))
sock_hold(sk);
}
}
static void mptcp_retransmit_timer(struct timer_list *t)
@ -925,6 +932,37 @@ static void mptcp_retransmit_timer(struct timer_list *t)
sock_put(sk);
}
/* Find an idle subflow. Return NULL if there is unacked data at tcp
* level.
*
* A backup subflow is returned only if that is the only kind available.
*/
static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
struct sock *backup = NULL;
sock_owned_by_me((const struct sock *)msk);
mptcp_for_each_subflow(msk, subflow) {
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
/* still data outstanding at TCP level? Don't retransmit. */
if (!tcp_write_queue_empty(ssk))
return NULL;
if (subflow->backup) {
if (!backup)
backup = ssk;
continue;
}
return ssk;
}
return backup;
}
/* subflow sockets can be either outgoing (connect) or incoming
* (accept).
*
@ -958,11 +996,62 @@ static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
static void mptcp_worker(struct work_struct *work)
{
struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
struct sock *sk = &msk->sk.icsk_inet.sk;
struct sock *ssk, *sk = &msk->sk.icsk_inet.sk;
int orig_len, orig_offset, ret, mss_now = 0, size_goal = 0;
struct mptcp_data_frag *dfrag;
u64 orig_write_seq;
size_t copied = 0;
struct msghdr msg;
long timeo = 0;
lock_sock(sk);
mptcp_clean_una(sk);
__mptcp_flush_join_list(msk);
__mptcp_move_skbs(msk);
if (!test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags))
goto unlock;
dfrag = mptcp_rtx_head(sk);
if (!dfrag)
goto unlock;
ssk = mptcp_subflow_get_retrans(msk);
if (!ssk)
goto reset_unlock;
lock_sock(ssk);
msg.msg_flags = MSG_DONTWAIT;
orig_len = dfrag->data_len;
orig_offset = dfrag->offset;
orig_write_seq = dfrag->data_seq;
while (dfrag->data_len > 0) {
ret = mptcp_sendmsg_frag(sk, ssk, &msg, dfrag, &timeo, &mss_now,
&size_goal);
if (ret < 0)
break;
copied += ret;
dfrag->data_len -= ret;
dfrag->offset += ret;
}
if (copied)
tcp_push(ssk, msg.msg_flags, mss_now, tcp_sk(ssk)->nonagle,
size_goal);
dfrag->data_seq = orig_write_seq;
dfrag->offset = orig_offset;
dfrag->data_len = orig_len;
mptcp_set_timeout(sk, ssk);
release_sock(ssk);
reset_unlock:
if (!mptcp_timer_pending(sk))
mptcp_reset_timer(sk);
unlock:
release_sock(sk);
sock_put(sk);
}
@ -1124,6 +1213,7 @@ static int mptcp_disconnect(struct sock *sk, int flags)
lock_sock(sk);
__mptcp_clear_xmit(sk);
release_sock(sk);
mptcp_cancel_work(sk);
return tcp_disconnect(sk, flags);
}

1
net/mptcp/protocol.h
View File

@ -88,6 +88,7 @@
/* MPTCP socket flags */
#define MPTCP_DATA_READY 0
#define MPTCP_SEND_SPACE 1
#define MPTCP_WORK_RTX 2
static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
{