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Date: Thu, 12 Nov 2020 11:48:10 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: netdev@...r.kernel.org
Cc: Eric Dumazet <edumazet@...gle.com>, mptcp@...ts.01.org,
Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 12/13] mptcp: keep track of advertised windows right edge
From: Florian Westphal <fw@...len.de>
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@...len.de>
Co-developed-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
net/mptcp/options.c | 24 ++++++++++++++++++----
net/mptcp/protocol.c | 49 +++++++++++++++++++++++++++++++++++++++++++-
net/mptcp/protocol.h | 1 +
3 files changed, 69 insertions(+), 5 deletions(-)
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 1be272d2bd95..f2d1e27a2bc1 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -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
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 05b8112050b9..05daed57ae4a 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -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;
}
@@ -842,6 +849,7 @@ 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) {
@@ -939,12 +947,30 @@ 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;
@@ -974,6 +1000,16 @@ 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;
@@ -991,6 +1027,7 @@ 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;
}
@@ -1008,6 +1045,12 @@ 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;
@@ -1861,7 +1904,7 @@ 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);
@@ -2219,6 +2262,8 @@ 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;
@@ -2251,6 +2296,8 @@ 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,
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 8345011fc0ba..b4c8dbe9236b 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -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;
--
2.26.2
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