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mptcp: keep track of advertised windows right edge

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Before sending 'x' new bytes also check that the new snd_una would
be within the permitted receive window.

For every ACK that also contains a DSS ack, check whether its tcp-level
receive window would advance the current mptcp window right edge and
update it if so.

Signed-off-by: Florian Westphal <fw@strlen.de>
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Florian Westphal 2020-11-16 10:48:13 +01:00 committed by Jakub Kicinski
parent 8edf08649e
commit 6f8a612a33
3 changed files with 69 additions and 5 deletions
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24
net/mptcp/options.c
View File

@ -809,11 +809,14 @@ static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
return cur_ack;
}
static void update_una(struct mptcp_sock *msk,
struct mptcp_options_received *mp_opt)
static void ack_update_msk(struct mptcp_sock *msk,
const struct sock *ssk,
struct mptcp_options_received *mp_opt)
{
u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
u64 new_wnd_end, wnd_end, old_wnd_end = atomic64_read(&msk->wnd_end);
u64 snd_nxt = READ_ONCE(msk->snd_nxt);
struct sock *sk = (struct sock *)msk;
/* avoid ack expansion on update conflict, to reduce the risk of
* wrongly expanding to a future ack sequence number, which is way
@ -825,12 +828,25 @@ static void update_una(struct mptcp_sock *msk,
if (after64(new_snd_una, snd_nxt))
new_snd_una = old_snd_una;
new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
while (after64(new_wnd_end, old_wnd_end)) {
wnd_end = old_wnd_end;
old_wnd_end = atomic64_cmpxchg(&msk->wnd_end, wnd_end,
new_wnd_end);
if (old_wnd_end == wnd_end) {
if (mptcp_send_head(sk))
mptcp_schedule_work(sk);
break;
}
}
while (after64(new_snd_una, old_snd_una)) {
snd_una = old_snd_una;
old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
new_snd_una);
if (old_snd_una == snd_una) {
mptcp_data_acked((struct sock *)msk);
mptcp_data_acked(sk);
break;
}
}
@ -930,7 +946,7 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
* monodirectional flows will stuck
*/
if (mp_opt.use_ack)
update_una(msk, &mp_opt);
ack_update_msk(msk, sk, &mp_opt);
/* Zero-data-length packets are dropped by the caller and not
* propagated to the MPTCP layer, so the skb extension does not

49
net/mptcp/protocol.c
View File

@ -57,6 +57,12 @@ static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk)
return msk->subflow;
}
/* Returns end sequence number of the receiver's advertised window */
static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
{
return atomic64_read(&msk->wnd_end);
}
static bool mptcp_is_tcpsk(struct sock *sk)
{
struct socket *sock = sk->sk_socket;
@ -174,6 +180,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)
if (after64(seq, max_seq)) {
/* out of window */
mptcp_drop(sk, skb);
pr_debug("oow by %ld", (unsigned long)seq - (unsigned long)max_seq);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW);
return;
}
@ -847,6 +854,7 @@ static void mptcp_clean_una(struct sock *sk)
*/
if (__mptcp_check_fallback(msk))
atomic64_set(&msk->snd_una, msk->snd_nxt);
snd_una = atomic64_read(&msk->snd_una);
list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
@ -944,12 +952,30 @@ struct mptcp_sendmsg_info {
unsigned int flags;
};
static int mptcp_check_allowed_size(struct mptcp_sock *msk, u64 data_seq,
int avail_size)
{
u64 window_end = mptcp_wnd_end(msk);
if (__mptcp_check_fallback(msk))
return avail_size;
if (!before64(data_seq + avail_size, window_end)) {
u64 allowed_size = window_end - data_seq;
return min_t(unsigned int, allowed_size, avail_size);
}
return avail_size;
}
static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
struct mptcp_data_frag *dfrag,
struct mptcp_sendmsg_info *info)
{
u64 data_seq = dfrag->data_seq + info->sent;
struct mptcp_sock *msk = mptcp_sk(sk);
bool zero_window_probe = false;
struct mptcp_ext *mpext = NULL;
struct sk_buff *skb, *tail;
bool can_collapse = false;
@ -979,6 +1005,16 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
avail_size = info->size_goal - skb->len;
}
/* Zero window and all data acked? Probe. */
avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size);
if (avail_size == 0) {
if (skb || atomic64_read(&msk->snd_una) != msk->snd_nxt)
return 0;
zero_window_probe = true;
data_seq = atomic64_read(&msk->snd_una) - 1;
avail_size = 1;
}
if (WARN_ON_ONCE(info->sent > info->limit ||
info->limit > dfrag->data_len))
return 0;
@ -996,6 +1032,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
if (skb == tail) {
WARN_ON_ONCE(!can_collapse);
mpext->data_len += ret;
WARN_ON_ONCE(zero_window_probe);
goto out;
}
@ -1013,6 +1050,12 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
mpext->data_seq, mpext->subflow_seq, mpext->data_len,
mpext->dsn64);
if (zero_window_probe) {
mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
mpext->frozen = 1;
ret = 0;
tcp_push_pending_frames(ssk);
}
out:
mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
return ret;
@ -1866,7 +1909,7 @@ static void mptcp_worker(struct work_struct *work)
info.limit = dfrag->already_sent;
while (info.sent < dfrag->already_sent) {
ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
if (ret < 0)
if (ret <= 0)
break;
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS);
@ -2226,6 +2269,8 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
msk->write_seq = subflow_req->idsn + 1;
msk->snd_nxt = msk->write_seq;
atomic64_set(&msk->snd_una, msk->write_seq);
atomic64_set(&msk->wnd_end, msk->snd_nxt + req->rsk_rcv_wnd);
if (mp_opt->mp_capable) {
msk->can_ack = true;
msk->remote_key = mp_opt->sndr_key;
@ -2258,6 +2303,8 @@ void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
TCP_INIT_CWND * tp->advmss);
if (msk->rcvq_space.space == 0)
msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;
atomic64_set(&msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
}
static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,

1
net/mptcp/protocol.h
View File

@ -215,6 +215,7 @@ struct mptcp_sock {
struct sock *last_snd;
int snd_burst;
atomic64_t snd_una;
atomic64_t wnd_end;
unsigned long timer_ival;
u32 token;
unsigned long flags;