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Message-Id: <fca26fe2e7d130ff878c14cb0242b33267c2617e.1611153172.git.pabeni@redhat.com>
Date: Wed, 20 Jan 2021 15:39:11 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, mptcp@...ts.01.org
Subject: [PATCH v2 net-next 2/5] mptcp: re-enable sndbuf autotune
After commit 6e628cd3a8f7 ("mptcp: use mptcp release_cb for
delayed tasks"), MPTCP never sets the flag bit SOCK_NOSPACE
on its subflow. As a side effect, autotune never takes place,
as it happens inside tcp_new_space(), which in turn is called
only when the mentioned bit is set.
Let's sendmsg() set the subflows NOSPACE bit when looking for
more memory and use the subflow write_space callback to propagate
the snd buf update and wake-up the user-space.
Additionally, this allows dropping a bunch of duplicate code and
makes the SNDBUF_LIMITED chrono relevant again for MPTCP subflows.
Fixes: 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks")
Reviewed-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
net/mptcp/protocol.c | 52 +++++++++++++++++---------------------------
net/mptcp/protocol.h | 19 ++++++++++++++++
net/mptcp/subflow.c | 7 +++++-
3 files changed, 45 insertions(+), 33 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index c5c80f9253832..d07e60330df56 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -730,10 +730,14 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
void __mptcp_flush_join_list(struct mptcp_sock *msk)
{
+ struct mptcp_subflow_context *subflow;
+
if (likely(list_empty(&msk->join_list)))
return;
spin_lock_bh(&msk->join_list_lock);
+ list_for_each_entry(subflow, &msk->join_list, node)
+ mptcp_propagate_sndbuf((struct sock *)msk, mptcp_subflow_tcp_sock(subflow));
list_splice_tail_init(&msk->join_list, &msk->conn_list);
spin_unlock_bh(&msk->join_list_lock);
}
@@ -1033,13 +1037,6 @@ static void __mptcp_clean_una(struct sock *sk)
__mptcp_update_wmem(sk);
sk_mem_reclaim_partial(sk);
}
-
- if (sk_stream_is_writeable(sk)) {
- /* pairs with memory barrier in mptcp_poll */
- smp_mb();
- if (test_and_clear_bit(MPTCP_NOSPACE, &msk->flags))
- sk_stream_write_space(sk);
- }
}
if (snd_una == READ_ONCE(msk->snd_nxt)) {
@@ -1358,8 +1355,7 @@ struct subflow_send_info {
u64 ratio;
};
-static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk,
- u32 *sndbuf)
+static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
{
struct subflow_send_info send_info[2];
struct mptcp_subflow_context *subflow;
@@ -1370,24 +1366,17 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk,
sock_owned_by_me((struct sock *)msk);
- *sndbuf = 0;
if (__mptcp_check_fallback(msk)) {
if (!msk->first)
return NULL;
- *sndbuf = msk->first->sk_sndbuf;
return sk_stream_memory_free(msk->first) ? msk->first : NULL;
}
/* re-use last subflow, if the burst allow that */
if (msk->last_snd && msk->snd_burst > 0 &&
sk_stream_memory_free(msk->last_snd) &&
- mptcp_subflow_active(mptcp_subflow_ctx(msk->last_snd))) {
- mptcp_for_each_subflow(msk, subflow) {
- ssk = mptcp_subflow_tcp_sock(subflow);
- *sndbuf = max(tcp_sk(ssk)->snd_wnd, *sndbuf);
- }
+ mptcp_subflow_active(mptcp_subflow_ctx(msk->last_snd)))
return msk->last_snd;
- }
/* pick the subflow with the lower wmem/wspace ratio */
for (i = 0; i < 2; ++i) {
@@ -1400,7 +1389,6 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk,
continue;
nr_active += !subflow->backup;
- *sndbuf = max(tcp_sk(ssk)->snd_wnd, *sndbuf);
if (!sk_stream_memory_free(subflow->tcp_sock))
continue;
@@ -1430,6 +1418,7 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk,
sk_stream_wspace(msk->last_snd));
return msk->last_snd;
}
+
return NULL;
}
@@ -1450,7 +1439,6 @@ static void mptcp_push_pending(struct sock *sk, unsigned int flags)
};
struct mptcp_data_frag *dfrag;
int len, copied = 0;
- u32 sndbuf;
while ((dfrag = mptcp_send_head(sk))) {
info.sent = dfrag->already_sent;
@@ -1461,12 +1449,7 @@ static void mptcp_push_pending(struct sock *sk, unsigned int flags)
prev_ssk = ssk;
__mptcp_flush_join_list(msk);
- ssk = mptcp_subflow_get_send(msk, &sndbuf);
-
- /* do auto tuning */
- if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK) &&
- sndbuf > READ_ONCE(sk->sk_sndbuf))
- WRITE_ONCE(sk->sk_sndbuf, sndbuf);
+ ssk = mptcp_subflow_get_send(msk);
/* try to keep the subflow socket lock across
* consecutive xmit on the same socket
@@ -1533,11 +1516,6 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
while (len > 0) {
int ret = 0;
- /* do auto tuning */
- if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK) &&
- ssk->sk_sndbuf > READ_ONCE(sk->sk_sndbuf))
- WRITE_ONCE(sk->sk_sndbuf, ssk->sk_sndbuf);
-
if (unlikely(mptcp_must_reclaim_memory(sk, ssk))) {
__mptcp_update_wmem(sk);
sk_mem_reclaim_partial(sk);
@@ -1575,6 +1553,15 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
}
}
+static void mptcp_set_nospace(struct sock *sk)
+{
+ /* enable autotune */
+ set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+
+ /* will be cleared on avail space */
+ set_bit(MPTCP_NOSPACE, &mptcp_sk(sk)->flags);
+}
+
static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
struct mptcp_sock *msk = mptcp_sk(sk);
@@ -1676,7 +1663,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
continue;
wait_for_memory:
- set_bit(MPTCP_NOSPACE, &msk->flags);
+ mptcp_set_nospace(sk);
mptcp_push_pending(sk, msg->msg_flags);
ret = sk_stream_wait_memory(sk, &timeo);
if (ret)
@@ -3268,6 +3255,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
mptcp_copy_inaddrs(newsk, msk->first);
mptcp_rcv_space_init(msk, msk->first);
+ mptcp_propagate_sndbuf(newsk, msk->first);
/* set ssk->sk_socket of accept()ed flows to mptcp socket.
* This is needed so NOSPACE flag can be set from tcp stack.
@@ -3308,7 +3296,7 @@ static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
if (sk_stream_is_writeable(sk))
return EPOLLOUT | EPOLLWRNORM;
- set_bit(MPTCP_NOSPACE, &msk->flags);
+ mptcp_set_nospace(sk);
smp_mb__after_atomic(); /* msk->flags is changed by write_space cb */
if (sk_stream_is_writeable(sk))
return EPOLLOUT | EPOLLWRNORM;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 65d200a1072bf..871534df6140f 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -522,6 +522,25 @@ static inline bool mptcp_data_fin_enabled(const struct mptcp_sock *msk)
READ_ONCE(msk->write_seq) == READ_ONCE(msk->snd_nxt);
}
+static inline bool mptcp_propagate_sndbuf(struct sock *sk, struct sock *ssk)
+{
+ if ((sk->sk_userlocks & SOCK_SNDBUF_LOCK) || ssk->sk_sndbuf <= READ_ONCE(sk->sk_sndbuf))
+ return false;
+
+ WRITE_ONCE(sk->sk_sndbuf, ssk->sk_sndbuf);
+ return true;
+}
+
+static inline void mptcp_write_space(struct sock *sk)
+{
+ if (sk_stream_is_writeable(sk)) {
+ /* pairs with memory barrier in mptcp_poll */
+ smp_mb();
+ if (test_and_clear_bit(MPTCP_NOSPACE, &mptcp_sk(sk)->flags))
+ sk_stream_write_space(sk);
+ }
+}
+
void mptcp_destroy_common(struct mptcp_sock *msk);
void __init mptcp_token_init(void);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 22313710d7696..1ca0c82b0dbde 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -343,6 +343,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
if (subflow->conn_finished)
return;
+ mptcp_propagate_sndbuf(parent, sk);
subflow->rel_write_seq = 1;
subflow->conn_finished = 1;
subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
@@ -1040,7 +1041,10 @@ static void subflow_data_ready(struct sock *sk)
static void subflow_write_space(struct sock *ssk)
{
- /* we take action in __mptcp_clean_una() */
+ struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
+
+ mptcp_propagate_sndbuf(sk, ssk);
+ mptcp_write_space(sk);
}
static struct inet_connection_sock_af_ops *
@@ -1302,6 +1306,7 @@ static void subflow_state_change(struct sock *sk)
__subflow_state_change(sk);
if (subflow_simultaneous_connect(sk)) {
+ mptcp_propagate_sndbuf(parent, sk);
mptcp_do_fallback(sk);
mptcp_rcv_space_init(mptcp_sk(parent), sk);
pr_fallback(mptcp_sk(parent));
--
2.26.2
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