* [PATCH net-next 1/6] net: mptcp: improve fallback to TCP
2020-06-29 20:26 [PATCH net-next 0/6] MPTCP: improve fallback to TCP Davide Caratti
@ 2020-06-29 20:26 ` Davide Caratti
2020-06-29 23:29 ` Mat Martineau
2020-06-29 20:26 ` [PATCH net-next 2/6] mptcp: fallback in case of simultaneous connect Davide Caratti
` (5 subsequent siblings)
6 siblings, 1 reply; 14+ messages in thread
From: Davide Caratti @ 2020-06-29 20:26 UTC (permalink / raw)
To: Mat Martineau, Matthieu Baerts, David S. Miller, Jakub Kicinski,
netdev, mptcp
Keep using MPTCP sockets and a use "dummy mapping" in case of fallback
to regular TCP. When fallback is triggered, skip addition of the MPTCP
option on send.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/11
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/22
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
net/mptcp/options.c | 9 +++-
net/mptcp/protocol.c | 98 ++++++++++++--------------------------------
net/mptcp/protocol.h | 33 +++++++++++++++
net/mptcp/subflow.c | 47 +++++++++++++--------
4 files changed, 98 insertions(+), 89 deletions(-)
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index df9a51425c6f..b96d3660562f 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -624,6 +624,9 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
opts->suboptions = 0;
+ if (unlikely(mptcp_check_fallback(sk)))
+ return false;
+
if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
ret = true;
else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
@@ -714,7 +717,8 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk,
*/
if (!mp_opt->mp_capable) {
subflow->mp_capable = 0;
- tcp_sk(sk)->is_mptcp = 0;
+ pr_fallback(msk);
+ __mptcp_do_fallback(msk);
return false;
}
@@ -814,6 +818,9 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
struct mptcp_options_received mp_opt;
struct mptcp_ext *mpext;
+ if (__mptcp_check_fallback(msk))
+ return;
+
mptcp_get_options(skb, &mp_opt);
if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
return;
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index be09fd525f8f..84ae96be9837 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -52,11 +52,6 @@ static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk)
return msk->subflow;
}
-static bool __mptcp_needs_tcp_fallback(const struct mptcp_sock *msk)
-{
- return msk->first && !sk_is_mptcp(msk->first);
-}
-
static struct socket *mptcp_is_tcpsk(struct sock *sk)
{
struct socket *sock = sk->sk_socket;
@@ -94,7 +89,7 @@ static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk)
if (unlikely(sock))
return sock;
- if (likely(!__mptcp_needs_tcp_fallback(msk)))
+ if (likely(!__mptcp_check_fallback(msk)))
return NULL;
return msk->subflow;
@@ -133,6 +128,11 @@ static struct socket *__mptcp_socket_create(struct mptcp_sock *msk, int state)
list_add(&subflow->node, &msk->conn_list);
subflow->request_mptcp = 1;
+ /* accept() will wait on first subflow sk_wq, and we always wakes up
+ * via msk->sk_socket
+ */
+ RCU_INIT_POINTER(msk->first->sk_wq, &sk->sk_socket->wq);
+
set_state:
if (state != MPTCP_SAME_STATE)
inet_sk_state_store(sk, state);
@@ -229,6 +229,15 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
if (!skb)
break;
+ if (__mptcp_check_fallback(msk)) {
+ /* if we are running under the workqueue, TCP could have
+ * collapsed skbs between dummy map creation and now
+ * be sure to adjust the size
+ */
+ map_remaining = skb->len;
+ subflow->map_data_len = skb->len;
+ }
+
offset = seq - TCP_SKB_CB(skb)->seq;
fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
if (fin) {
@@ -466,8 +475,15 @@ static void mptcp_clean_una(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
struct mptcp_data_frag *dtmp, *dfrag;
- u64 snd_una = atomic64_read(&msk->snd_una);
bool cleaned = false;
+ u64 snd_una;
+
+ /* on fallback we just need to ignore snd_una, as this is really
+ * plain TCP
+ */
+ if (__mptcp_check_fallback(msk))
+ atomic64_set(&msk->snd_una, msk->write_seq);
+ snd_una = atomic64_read(&msk->snd_una);
list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
if (after64(dfrag->data_seq + dfrag->data_len, snd_una))
@@ -740,7 +756,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
int mss_now = 0, size_goal = 0, ret = 0;
struct mptcp_sock *msk = mptcp_sk(sk);
struct page_frag *pfrag;
- struct socket *ssock;
size_t copied = 0;
struct sock *ssk;
bool tx_ok;
@@ -759,15 +774,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
goto out;
}
-fallback:
- ssock = __mptcp_tcp_fallback(msk);
- if (unlikely(ssock)) {
- release_sock(sk);
- pr_debug("fallback passthrough");
- ret = sock_sendmsg(ssock, msg);
- return ret >= 0 ? ret + copied : (copied ? copied : ret);
- }
-
pfrag = sk_page_frag(sk);
restart:
mptcp_clean_una(sk);
@@ -819,17 +825,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
}
break;
}
- if (ret == 0 && unlikely(__mptcp_needs_tcp_fallback(msk))) {
- /* Can happen for passive sockets:
- * 3WHS negotiated MPTCP, but first packet after is
- * plain TCP (e.g. due to middlebox filtering unknown
- * options).
- *
- * Fall back to TCP.
- */
- release_sock(ssk);
- goto fallback;
- }
copied += ret;
@@ -972,7 +967,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
int nonblock, int flags, int *addr_len)
{
struct mptcp_sock *msk = mptcp_sk(sk);
- struct socket *ssock;
int copied = 0;
int target;
long timeo;
@@ -981,16 +975,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
return -EOPNOTSUPP;
lock_sock(sk);
- ssock = __mptcp_tcp_fallback(msk);
- if (unlikely(ssock)) {
-fallback:
- release_sock(sk);
- pr_debug("fallback-read subflow=%p",
- mptcp_subflow_ctx(ssock->sk));
- copied = sock_recvmsg(ssock, msg, flags);
- return copied;
- }
-
timeo = sock_rcvtimeo(sk, nonblock);
len = min_t(size_t, len, INT_MAX);
@@ -1056,9 +1040,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
pr_debug("block timeout %ld", timeo);
mptcp_wait_data(sk, &timeo);
- ssock = __mptcp_tcp_fallback(msk);
- if (unlikely(ssock))
- goto fallback;
}
if (skb_queue_empty(&sk->sk_receive_queue)) {
@@ -1335,8 +1316,6 @@ static void mptcp_subflow_shutdown(struct sock *ssk, int how,
break;
}
- /* Wake up anyone sleeping in poll. */
- ssk->sk_state_change(ssk);
release_sock(ssk);
}
@@ -1660,12 +1639,6 @@ void mptcp_finish_connect(struct sock *ssk)
sk = subflow->conn;
msk = mptcp_sk(sk);
- if (!subflow->mp_capable) {
- MPTCP_INC_STATS(sock_net(sk),
- MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
- return;
- }
-
pr_debug("msk=%p, token=%u", sk, subflow->token);
mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq);
@@ -1971,23 +1944,10 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
{
struct sock *sk = sock->sk;
struct mptcp_sock *msk;
- struct socket *ssock;
__poll_t mask = 0;
msk = mptcp_sk(sk);
- lock_sock(sk);
- ssock = __mptcp_tcp_fallback(msk);
- if (!ssock)
- 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;
@@ -1997,8 +1957,6 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
if (sk->sk_shutdown & RCV_SHUTDOWN)
mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
- release_sock(sk);
-
return mask;
}
@@ -2006,18 +1964,11 @@ static int mptcp_shutdown(struct socket *sock, int how)
{
struct mptcp_sock *msk = mptcp_sk(sock->sk);
struct mptcp_subflow_context *subflow;
- struct socket *ssock;
int ret = 0;
pr_debug("sk=%p, how=%d", msk, how);
lock_sock(sock->sk);
- ssock = __mptcp_tcp_fallback(msk);
- if (ssock) {
- release_sock(sock->sk);
- return inet_shutdown(ssock, how);
- }
-
if (how == SHUT_WR || how == SHUT_RDWR)
inet_sk_state_store(sock->sk, TCP_FIN_WAIT1);
@@ -2043,6 +1994,9 @@ static int mptcp_shutdown(struct socket *sock, int how)
mptcp_subflow_shutdown(tcp_sk, how, 1, msk->write_seq);
}
+ /* Wake up anyone sleeping in poll. */
+ sock->sk->sk_state_change(sock->sk);
+
out_unlock:
release_sock(sock->sk);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index c05552e5fa23..a709df659ae0 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -89,6 +89,7 @@
#define MPTCP_SEND_SPACE 1
#define MPTCP_WORK_RTX 2
#define MPTCP_WORK_EOF 3
+#define MPTCP_FALLBACK_DONE 4
struct mptcp_options_received {
u64 sndr_key;
@@ -457,4 +458,36 @@ static inline bool before64(__u64 seq1, __u64 seq2)
void mptcp_diag_subflow_init(struct tcp_ulp_ops *ops);
+static inline bool __mptcp_check_fallback(struct mptcp_sock *msk)
+{
+ return test_bit(MPTCP_FALLBACK_DONE, &msk->flags);
+}
+
+static inline bool mptcp_check_fallback(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+
+ return __mptcp_check_fallback(msk);
+}
+
+static inline void __mptcp_do_fallback(struct mptcp_sock *msk)
+{
+ if (test_bit(MPTCP_FALLBACK_DONE, &msk->flags)) {
+ pr_debug("TCP fallback already done (msk=%p)", msk);
+ return;
+ }
+ set_bit(MPTCP_FALLBACK_DONE, &msk->flags);
+}
+
+static inline void mptcp_do_fallback(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+
+ __mptcp_do_fallback(msk);
+}
+
+#define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=%p)", __func__, a)
+
#endif /* __MPTCP_PROTOCOL_H */
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 102db8c88e97..cb8a42ff4646 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -216,7 +216,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_options_received mp_opt;
struct sock *parent = subflow->conn;
- struct tcp_sock *tp = tcp_sk(sk);
subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
@@ -230,6 +229,8 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
return;
subflow->conn_finished = 1;
+ subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
+ pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
mptcp_get_options(skb, &mp_opt);
if (subflow->request_mptcp && mp_opt.mp_capable) {
@@ -245,21 +246,20 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
subflow->thmac, subflow->remote_nonce);
} else {
- tp->is_mptcp = 0;
+ if (subflow->request_mptcp)
+ MPTCP_INC_STATS(sock_net(sk),
+ MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
+ mptcp_do_fallback(sk);
+ pr_fallback(mptcp_sk(subflow->conn));
}
- if (!tp->is_mptcp)
+ if (mptcp_check_fallback(sk))
return;
if (subflow->mp_capable) {
pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk),
subflow->remote_key);
mptcp_finish_connect(sk);
-
- if (skb) {
- pr_debug("synack seq=%u", TCP_SKB_CB(skb)->seq);
- subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
- }
} else if (subflow->mp_join) {
u8 hmac[SHA256_DIGEST_SIZE];
@@ -279,9 +279,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
- if (skb)
- subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
-
if (!mptcp_finish_join(sk))
goto do_reset;
@@ -557,7 +554,8 @@ enum mapping_status {
MAPPING_OK,
MAPPING_INVALID,
MAPPING_EMPTY,
- MAPPING_DATA_FIN
+ MAPPING_DATA_FIN,
+ MAPPING_DUMMY
};
static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq)
@@ -621,6 +619,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk)
if (!skb)
return MAPPING_EMPTY;
+ if (mptcp_check_fallback(ssk))
+ return MAPPING_DUMMY;
+
mpext = mptcp_get_ext(skb);
if (!mpext || !mpext->use_map) {
if (!subflow->map_valid && !skb->len) {
@@ -762,6 +763,16 @@ static bool subflow_check_data_avail(struct sock *ssk)
ssk->sk_err = EBADMSG;
goto fatal;
}
+ if (status == MAPPING_DUMMY) {
+ __mptcp_do_fallback(msk);
+ skb = skb_peek(&ssk->sk_receive_queue);
+ subflow->map_valid = 1;
+ subflow->map_seq = READ_ONCE(msk->ack_seq);
+ subflow->map_data_len = skb->len;
+ subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq -
+ subflow->ssn_offset;
+ return true;
+ }
if (status != MAPPING_OK)
return false;
@@ -885,14 +896,18 @@ static void subflow_data_ready(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct sock *parent = subflow->conn;
+ struct mptcp_sock *msk;
- if (!subflow->mp_capable && !subflow->mp_join) {
- subflow->tcp_data_ready(sk);
-
+ msk = mptcp_sk(parent);
+ if (inet_sk_state_load(sk) == TCP_LISTEN) {
+ set_bit(MPTCP_DATA_READY, &msk->flags);
parent->sk_data_ready(parent);
return;
}
+ WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
+ !subflow->mp_join);
+
if (mptcp_subflow_data_available(sk))
mptcp_data_ready(parent, sk);
}
@@ -1117,7 +1132,7 @@ static void subflow_state_change(struct sock *sk)
* a fin packet carrying a DSS can be unnoticed if we don't trigger
* the data available machinery here.
*/
- if (subflow->mp_capable && mptcp_subflow_data_available(sk))
+ if (mptcp_subflow_data_available(sk))
mptcp_data_ready(parent, sk);
if (!(parent->sk_shutdown & RCV_SHUTDOWN) &&
--
2.26.2
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH net-next 1/6] net: mptcp: improve fallback to TCP
2020-06-29 20:26 ` [PATCH net-next 1/6] net: mptcp: " Davide Caratti
@ 2020-06-29 23:29 ` Mat Martineau
0 siblings, 0 replies; 14+ messages in thread
From: Mat Martineau @ 2020-06-29 23:29 UTC (permalink / raw)
To: Davide Caratti
Cc: Matthieu Baerts, David S. Miller, Jakub Kicinski, netdev, mptcp
On Mon, 29 Jun 2020, Davide Caratti wrote:
> Keep using MPTCP sockets and a use "dummy mapping" in case of fallback
> to regular TCP. When fallback is triggered, skip addition of the MPTCP
> option on send.
>
> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/11
> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/22
> Co-developed-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Davide Caratti <dcaratti@redhat.com>
> ---
> net/mptcp/options.c | 9 +++-
> net/mptcp/protocol.c | 98 ++++++++++++--------------------------------
> net/mptcp/protocol.h | 33 +++++++++++++++
> net/mptcp/subflow.c | 47 +++++++++++++--------
> 4 files changed, 98 insertions(+), 89 deletions(-)
>
Thanks Davide and Paolo! Appreciate the simplification of the fallback
code.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH net-next 2/6] mptcp: fallback in case of simultaneous connect
2020-06-29 20:26 [PATCH net-next 0/6] MPTCP: improve fallback to TCP Davide Caratti
2020-06-29 20:26 ` [PATCH net-next 1/6] net: mptcp: " Davide Caratti
@ 2020-06-29 20:26 ` Davide Caratti
2020-06-29 23:29 ` Mat Martineau
2020-06-29 20:26 ` [PATCH net-next 3/6] mptcp: check for plain TCP sock at accept time Davide Caratti
` (4 subsequent siblings)
6 siblings, 1 reply; 14+ messages in thread
From: Davide Caratti @ 2020-06-29 20:26 UTC (permalink / raw)
To: Mat Martineau, Matthieu Baerts, David S. Miller, Jakub Kicinski,
netdev, mptcp
when a MPTCP client tries to connect to itself, tcp_finish_connect() is
never reached. Because of this, depending on the socket current state,
multiple faulty behaviours can be observed:
1) a WARN_ON() in subflow_data_ready() is hit
WARNING: CPU: 2 PID: 882 at net/mptcp/subflow.c:911 subflow_data_ready+0x18b/0x230
[...]
CPU: 2 PID: 882 Comm: gh35 Not tainted 5.7.0+ #187
[...]
RIP: 0010:subflow_data_ready+0x18b/0x230
[...]
Call Trace:
tcp_data_queue+0xd2f/0x4250
tcp_rcv_state_process+0xb1c/0x49d3
tcp_v4_do_rcv+0x2bc/0x790
__release_sock+0x153/0x2d0
release_sock+0x4f/0x170
mptcp_shutdown+0x167/0x4e0
__sys_shutdown+0xe6/0x180
__x64_sys_shutdown+0x50/0x70
do_syscall_64+0x9a/0x370
entry_SYSCALL_64_after_hwframe+0x44/0xa9
2) client is stuck forever in mptcp_sendmsg() because the socket is not
TCP_ESTABLISHED
crash> bt 4847
PID: 4847 TASK: ffff88814b2fb100 CPU: 1 COMMAND: "gh35"
#0 [ffff8881376ff680] __schedule at ffffffff97248da4
#1 [ffff8881376ff778] schedule at ffffffff9724a34f
#2 [ffff8881376ff7a0] schedule_timeout at ffffffff97252ba0
#3 [ffff8881376ff8a8] wait_woken at ffffffff958ab4ba
#4 [ffff8881376ff940] sk_stream_wait_connect at ffffffff96c2d859
#5 [ffff8881376ffa28] mptcp_sendmsg at ffffffff97207fca
#6 [ffff8881376ffbc0] sock_sendmsg at ffffffff96be1b5b
#7 [ffff8881376ffbe8] sock_write_iter at ffffffff96be1daa
#8 [ffff8881376ffce8] new_sync_write at ffffffff95e5cb52
#9 [ffff8881376ffe50] vfs_write at ffffffff95e6547f
#10 [ffff8881376ffe90] ksys_write at ffffffff95e65d26
#11 [ffff8881376fff28] do_syscall_64 at ffffffff956088ba
#12 [ffff8881376fff50] entry_SYSCALL_64_after_hwframe at ffffffff9740008c
RIP: 00007f126f6956ed RSP: 00007ffc2a320278 RFLAGS: 00000217
RAX: ffffffffffffffda RBX: 0000000020000044 RCX: 00007f126f6956ed
RDX: 0000000000000004 RSI: 00000000004007b8 RDI: 0000000000000003
RBP: 00007ffc2a3202a0 R8: 0000000000400720 R9: 0000000000400720
R10: 0000000000400720 R11: 0000000000000217 R12: 00000000004004b0
R13: 00007ffc2a320380 R14: 0000000000000000 R15: 0000000000000000
ORIG_RAX: 0000000000000001 CS: 0033 SS: 002b
3) tcpdump captures show that DSS is exchanged even when MP_CAPABLE handshake
didn't complete.
$ tcpdump -tnnr bad.pcap
IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [S], seq 3208913911, win 65483, options [mss 65495,sackOK,TS val 3291706876 ecr 3291694721,nop,wscale 7,mptcp capable v1], length 0
IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [S.], seq 3208913911, ack 3208913912, win 65483, options [mss 65495,sackOK,TS val 3291706876 ecr 3291706876,nop,wscale 7,mptcp capable v1], length 0
IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [.], ack 1, win 512, options [nop,nop,TS val 3291706876 ecr 3291706876], length 0
IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [F.], seq 1, ack 1, win 512, options [nop,nop,TS val 3291707876 ecr 3291706876,mptcp dss fin seq 0 subseq 0 len 1,nop,nop], length 0
IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [.], ack 2, win 512, options [nop,nop,TS val 3291707876 ecr 3291707876], length 0
force a fallback to TCP in these cases, and adjust the main socket
state to avoid hanging in mptcp_sendmsg().
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/35
Reported-by: Christoph Paasch <cpaasch@apple.com>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
net/mptcp/protocol.h | 10 ++++++++++
net/mptcp/subflow.c | 10 ++++++++++
2 files changed, 20 insertions(+)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index a709df659ae0..1d05d9841b5c 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -490,4 +490,14 @@ static inline void mptcp_do_fallback(struct sock *sk)
#define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=%p)", __func__, a)
+static inline bool subflow_simultaneous_connect(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct sock *parent = subflow->conn;
+
+ return sk->sk_state == TCP_ESTABLISHED &&
+ !mptcp_sk(parent)->pm.server_side &&
+ !subflow->conn_finished;
+}
+
#endif /* __MPTCP_PROTOCOL_H */
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index cb8a42ff4646..548f9e347ff5 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1128,6 +1128,16 @@ static void subflow_state_change(struct sock *sk)
__subflow_state_change(sk);
+ if (subflow_simultaneous_connect(sk)) {
+ mptcp_do_fallback(sk);
+ pr_fallback(mptcp_sk(parent));
+ subflow->conn_finished = 1;
+ if (inet_sk_state_load(parent) == TCP_SYN_SENT) {
+ inet_sk_state_store(parent, TCP_ESTABLISHED);
+ parent->sk_state_change(parent);
+ }
+ }
+
/* as recvmsg() does not acquire the subflow socket for ssk selection
* a fin packet carrying a DSS can be unnoticed if we don't trigger
* the data available machinery here.
--
2.26.2
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH net-next 2/6] mptcp: fallback in case of simultaneous connect
2020-06-29 20:26 ` [PATCH net-next 2/6] mptcp: fallback in case of simultaneous connect Davide Caratti
@ 2020-06-29 23:29 ` Mat Martineau
0 siblings, 0 replies; 14+ messages in thread
From: Mat Martineau @ 2020-06-29 23:29 UTC (permalink / raw)
To: Davide Caratti
Cc: Matthieu Baerts, David S. Miller, Jakub Kicinski, netdev, mptcp
On Mon, 29 Jun 2020, Davide Caratti wrote:
> when a MPTCP client tries to connect to itself, tcp_finish_connect() is
> never reached. Because of this, depending on the socket current state,
> multiple faulty behaviours can be observed:
>
> 1) a WARN_ON() in subflow_data_ready() is hit
> WARNING: CPU: 2 PID: 882 at net/mptcp/subflow.c:911 subflow_data_ready+0x18b/0x230
> [...]
> CPU: 2 PID: 882 Comm: gh35 Not tainted 5.7.0+ #187
> [...]
> RIP: 0010:subflow_data_ready+0x18b/0x230
> [...]
> Call Trace:
> tcp_data_queue+0xd2f/0x4250
> tcp_rcv_state_process+0xb1c/0x49d3
> tcp_v4_do_rcv+0x2bc/0x790
> __release_sock+0x153/0x2d0
> release_sock+0x4f/0x170
> mptcp_shutdown+0x167/0x4e0
> __sys_shutdown+0xe6/0x180
> __x64_sys_shutdown+0x50/0x70
> do_syscall_64+0x9a/0x370
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> 2) client is stuck forever in mptcp_sendmsg() because the socket is not
> TCP_ESTABLISHED
>
> crash> bt 4847
> PID: 4847 TASK: ffff88814b2fb100 CPU: 1 COMMAND: "gh35"
> #0 [ffff8881376ff680] __schedule at ffffffff97248da4
> #1 [ffff8881376ff778] schedule at ffffffff9724a34f
> #2 [ffff8881376ff7a0] schedule_timeout at ffffffff97252ba0
> #3 [ffff8881376ff8a8] wait_woken at ffffffff958ab4ba
> #4 [ffff8881376ff940] sk_stream_wait_connect at ffffffff96c2d859
> #5 [ffff8881376ffa28] mptcp_sendmsg at ffffffff97207fca
> #6 [ffff8881376ffbc0] sock_sendmsg at ffffffff96be1b5b
> #7 [ffff8881376ffbe8] sock_write_iter at ffffffff96be1daa
> #8 [ffff8881376ffce8] new_sync_write at ffffffff95e5cb52
> #9 [ffff8881376ffe50] vfs_write at ffffffff95e6547f
> #10 [ffff8881376ffe90] ksys_write at ffffffff95e65d26
> #11 [ffff8881376fff28] do_syscall_64 at ffffffff956088ba
> #12 [ffff8881376fff50] entry_SYSCALL_64_after_hwframe at ffffffff9740008c
> RIP: 00007f126f6956ed RSP: 00007ffc2a320278 RFLAGS: 00000217
> RAX: ffffffffffffffda RBX: 0000000020000044 RCX: 00007f126f6956ed
> RDX: 0000000000000004 RSI: 00000000004007b8 RDI: 0000000000000003
> RBP: 00007ffc2a3202a0 R8: 0000000000400720 R9: 0000000000400720
> R10: 0000000000400720 R11: 0000000000000217 R12: 00000000004004b0
> R13: 00007ffc2a320380 R14: 0000000000000000 R15: 0000000000000000
> ORIG_RAX: 0000000000000001 CS: 0033 SS: 002b
>
> 3) tcpdump captures show that DSS is exchanged even when MP_CAPABLE handshake
> didn't complete.
>
> $ tcpdump -tnnr bad.pcap
> IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [S], seq 3208913911, win 65483, options [mss 65495,sackOK,TS val 3291706876 ecr 3291694721,nop,wscale 7,mptcp capable v1], length 0
> IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [S.], seq 3208913911, ack 3208913912, win 65483, options [mss 65495,sackOK,TS val 3291706876 ecr 3291706876,nop,wscale 7,mptcp capable v1], length 0
> IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [.], ack 1, win 512, options [nop,nop,TS val 3291706876 ecr 3291706876], length 0
> IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [F.], seq 1, ack 1, win 512, options [nop,nop,TS val 3291707876 ecr 3291706876,mptcp dss fin seq 0 subseq 0 len 1,nop,nop], length 0
> IP 127.0.0.1.20000 > 127.0.0.1.20000: Flags [.], ack 2, win 512, options [nop,nop,TS val 3291707876 ecr 3291707876], length 0
>
> force a fallback to TCP in these cases, and adjust the main socket
> state to avoid hanging in mptcp_sendmsg().
>
> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/35
> Reported-by: Christoph Paasch <cpaasch@apple.com>
> Suggested-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Davide Caratti <dcaratti@redhat.com>
> ---
> net/mptcp/protocol.h | 10 ++++++++++
> net/mptcp/subflow.c | 10 ++++++++++
> 2 files changed, 20 insertions(+)
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH net-next 3/6] mptcp: check for plain TCP sock at accept time
2020-06-29 20:26 [PATCH net-next 0/6] MPTCP: improve fallback to TCP Davide Caratti
2020-06-29 20:26 ` [PATCH net-next 1/6] net: mptcp: " Davide Caratti
2020-06-29 20:26 ` [PATCH net-next 2/6] mptcp: fallback in case of simultaneous connect Davide Caratti
@ 2020-06-29 20:26 ` Davide Caratti
2020-06-29 23:30 ` Mat Martineau
2020-06-29 20:26 ` [PATCH net-next 4/6] mptcp: create first subflow at msk creation time Davide Caratti
` (3 subsequent siblings)
6 siblings, 1 reply; 14+ messages in thread
From: Davide Caratti @ 2020-06-29 20:26 UTC (permalink / raw)
To: Mat Martineau, Matthieu Baerts, David S. Miller, Jakub Kicinski,
netdev, mptcp
From: Paolo Abeni <pabeni@redhat.com>
This cleanup the code a bit and avoid corrupted states
on weird syscall sequence (accept(), connect()).
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
net/mptcp/protocol.c | 69 +++++---------------------------------------
1 file changed, 7 insertions(+), 62 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 84ae96be9837..dbeb6fe374f5 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -52,13 +52,10 @@ static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk)
return msk->subflow;
}
-static struct socket *mptcp_is_tcpsk(struct sock *sk)
+static bool mptcp_is_tcpsk(struct sock *sk)
{
struct socket *sock = sk->sk_socket;
- if (sock->sk != sk)
- return NULL;
-
if (unlikely(sk->sk_prot == &tcp_prot)) {
/* we are being invoked after mptcp_accept() has
* accepted a non-mp-capable flow: sk is a tcp_sk,
@@ -68,27 +65,21 @@ static struct socket *mptcp_is_tcpsk(struct sock *sk)
* bypass mptcp.
*/
sock->ops = &inet_stream_ops;
- return sock;
+ return true;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
} else if (unlikely(sk->sk_prot == &tcpv6_prot)) {
sock->ops = &inet6_stream_ops;
- return sock;
+ return true;
#endif
}
- return NULL;
+ return false;
}
static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk)
{
- struct socket *sock;
-
sock_owned_by_me((const struct sock *)msk);
- sock = mptcp_is_tcpsk((struct sock *)msk);
- if (unlikely(sock))
- return sock;
-
if (likely(!__mptcp_check_fallback(msk)))
return NULL;
@@ -1466,7 +1457,6 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
return NULL;
pr_debug("msk=%p, subflow is mptcp=%d", msk, sk_is_mptcp(newsk));
-
if (sk_is_mptcp(newsk)) {
struct mptcp_subflow_context *subflow;
struct sock *new_mptcp_sock;
@@ -1821,42 +1811,6 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
return err;
}
-static int mptcp_v4_getname(struct socket *sock, struct sockaddr *uaddr,
- int peer)
-{
- if (sock->sk->sk_prot == &tcp_prot) {
- /* we are being invoked from __sys_accept4, after
- * mptcp_accept() has just accepted a non-mp-capable
- * flow: sk is a tcp_sk, not an mptcp one.
- *
- * Hand the socket over to tcp so all further socket ops
- * bypass mptcp.
- */
- sock->ops = &inet_stream_ops;
- }
-
- return inet_getname(sock, uaddr, peer);
-}
-
-#if IS_ENABLED(CONFIG_MPTCP_IPV6)
-static int mptcp_v6_getname(struct socket *sock, struct sockaddr *uaddr,
- int peer)
-{
- if (sock->sk->sk_prot == &tcpv6_prot) {
- /* we are being invoked from __sys_accept4 after
- * mptcp_accept() has accepted a non-mp-capable
- * subflow: sk is a tcp_sk, not mptcp.
- *
- * Hand the socket over to tcp so all further
- * socket ops bypass mptcp.
- */
- sock->ops = &inet6_stream_ops;
- }
-
- return inet6_getname(sock, uaddr, peer);
-}
-#endif
-
static int mptcp_listen(struct socket *sock, int backlog)
{
struct mptcp_sock *msk = mptcp_sk(sock->sk);
@@ -1885,15 +1839,6 @@ static int mptcp_listen(struct socket *sock, int backlog)
return err;
}
-static bool is_tcp_proto(const struct proto *p)
-{
-#if IS_ENABLED(CONFIG_MPTCP_IPV6)
- return p == &tcp_prot || p == &tcpv6_prot;
-#else
- return p == &tcp_prot;
-#endif
-}
-
static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
int flags, bool kern)
{
@@ -1915,7 +1860,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
release_sock(sock->sk);
err = ssock->ops->accept(sock, newsock, flags, kern);
- if (err == 0 && !is_tcp_proto(newsock->sk->sk_prot)) {
+ if (err == 0 && !mptcp_is_tcpsk(newsock->sk)) {
struct mptcp_sock *msk = mptcp_sk(newsock->sk);
struct mptcp_subflow_context *subflow;
@@ -2011,7 +1956,7 @@ static const struct proto_ops mptcp_stream_ops = {
.connect = mptcp_stream_connect,
.socketpair = sock_no_socketpair,
.accept = mptcp_stream_accept,
- .getname = mptcp_v4_getname,
+ .getname = inet_getname,
.poll = mptcp_poll,
.ioctl = inet_ioctl,
.gettstamp = sock_gettstamp,
@@ -2065,7 +2010,7 @@ static const struct proto_ops mptcp_v6_stream_ops = {
.connect = mptcp_stream_connect,
.socketpair = sock_no_socketpair,
.accept = mptcp_stream_accept,
- .getname = mptcp_v6_getname,
+ .getname = inet6_getname,
.poll = mptcp_poll,
.ioctl = inet6_ioctl,
.gettstamp = sock_gettstamp,
--
2.26.2
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH net-next 3/6] mptcp: check for plain TCP sock at accept time
2020-06-29 20:26 ` [PATCH net-next 3/6] mptcp: check for plain TCP sock at accept time Davide Caratti
@ 2020-06-29 23:30 ` Mat Martineau
0 siblings, 0 replies; 14+ messages in thread
From: Mat Martineau @ 2020-06-29 23:30 UTC (permalink / raw)
To: Davide Caratti
Cc: Matthieu Baerts, David S. Miller, Jakub Kicinski, netdev, mptcp
On Mon, 29 Jun 2020, Davide Caratti wrote:
> From: Paolo Abeni <pabeni@redhat.com>
>
> This cleanup the code a bit and avoid corrupted states
> on weird syscall sequence (accept(), connect()).
>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Davide Caratti <dcaratti@redhat.com>
> ---
> net/mptcp/protocol.c | 69 +++++---------------------------------------
> 1 file changed, 7 insertions(+), 62 deletions(-)
>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH net-next 4/6] mptcp: create first subflow at msk creation time
2020-06-29 20:26 [PATCH net-next 0/6] MPTCP: improve fallback to TCP Davide Caratti
` (2 preceding siblings ...)
2020-06-29 20:26 ` [PATCH net-next 3/6] mptcp: check for plain TCP sock at accept time Davide Caratti
@ 2020-06-29 20:26 ` Davide Caratti
2020-06-29 23:30 ` Mat Martineau
2020-06-29 20:26 ` [PATCH net-next 5/6] mptcp: __mptcp_tcp_fallback() returns a struct sock Davide Caratti
` (2 subsequent siblings)
6 siblings, 1 reply; 14+ messages in thread
From: Davide Caratti @ 2020-06-29 20:26 UTC (permalink / raw)
To: Mat Martineau, Matthieu Baerts, David S. Miller, Jakub Kicinski,
netdev, mptcp
From: Paolo Abeni <pabeni@redhat.com>
This cleans the code a bit and makes the behavior more consistent.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
net/mptcp/protocol.c | 53 +++++++++++++++++---------------------------
1 file changed, 20 insertions(+), 33 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index dbeb6fe374f5..ad619bda71cc 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -86,32 +86,16 @@ static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk)
return msk->subflow;
}
-static bool __mptcp_can_create_subflow(const struct mptcp_sock *msk)
-{
- return !msk->first;
-}
-
-static struct socket *__mptcp_socket_create(struct mptcp_sock *msk, int state)
+static int __mptcp_socket_create(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
struct sock *sk = (struct sock *)msk;
struct socket *ssock;
int err;
- ssock = __mptcp_tcp_fallback(msk);
- if (unlikely(ssock))
- return ssock;
-
- ssock = __mptcp_nmpc_socket(msk);
- if (ssock)
- goto set_state;
-
- if (!__mptcp_can_create_subflow(msk))
- return ERR_PTR(-EINVAL);
-
err = mptcp_subflow_create_socket(sk, &ssock);
if (err)
- return ERR_PTR(err);
+ return err;
msk->first = ssock->sk;
msk->subflow = ssock;
@@ -124,10 +108,7 @@ static struct socket *__mptcp_socket_create(struct mptcp_sock *msk, int state)
*/
RCU_INIT_POINTER(msk->first->sk_wq, &sk->sk_socket->wq);
-set_state:
- if (state != MPTCP_SAME_STATE)
- inet_sk_state_store(sk, state);
- return ssock;
+ return 0;
}
static void __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
@@ -1255,6 +1236,10 @@ static int mptcp_init_sock(struct sock *sk)
if (ret)
return ret;
+ ret = __mptcp_socket_create(mptcp_sk(sk));
+ if (ret)
+ return ret;
+
sk_sockets_allocated_inc(sk);
sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[2];
@@ -1744,9 +1729,9 @@ static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
int err;
lock_sock(sock->sk);
- ssock = __mptcp_socket_create(msk, MPTCP_SAME_STATE);
- if (IS_ERR(ssock)) {
- err = PTR_ERR(ssock);
+ ssock = __mptcp_nmpc_socket(msk);
+ if (!ssock) {
+ err = -EINVAL;
goto unlock;
}
@@ -1776,13 +1761,14 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
goto do_connect;
}
- mptcp_token_destroy(msk);
- ssock = __mptcp_socket_create(msk, TCP_SYN_SENT);
- if (IS_ERR(ssock)) {
- err = PTR_ERR(ssock);
+ ssock = __mptcp_nmpc_socket(msk);
+ if (!ssock) {
+ err = -EINVAL;
goto unlock;
}
+ mptcp_token_destroy(msk);
+ inet_sk_state_store(sock->sk, TCP_SYN_SENT);
subflow = mptcp_subflow_ctx(ssock->sk);
#ifdef CONFIG_TCP_MD5SIG
/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
@@ -1820,13 +1806,14 @@ static int mptcp_listen(struct socket *sock, int backlog)
pr_debug("msk=%p", msk);
lock_sock(sock->sk);
- mptcp_token_destroy(msk);
- ssock = __mptcp_socket_create(msk, TCP_LISTEN);
- if (IS_ERR(ssock)) {
- err = PTR_ERR(ssock);
+ ssock = __mptcp_nmpc_socket(msk);
+ if (!ssock) {
+ err = -EINVAL;
goto unlock;
}
+ mptcp_token_destroy(msk);
+ inet_sk_state_store(sock->sk, TCP_LISTEN);
sock_set_flag(sock->sk, SOCK_RCU_FREE);
err = ssock->ops->listen(ssock, backlog);
--
2.26.2
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH net-next 4/6] mptcp: create first subflow at msk creation time
2020-06-29 20:26 ` [PATCH net-next 4/6] mptcp: create first subflow at msk creation time Davide Caratti
@ 2020-06-29 23:30 ` Mat Martineau
0 siblings, 0 replies; 14+ messages in thread
From: Mat Martineau @ 2020-06-29 23:30 UTC (permalink / raw)
To: Davide Caratti
Cc: Matthieu Baerts, David S. Miller, Jakub Kicinski, netdev, mptcp
On Mon, 29 Jun 2020, Davide Caratti wrote:
> From: Paolo Abeni <pabeni@redhat.com>
>
> This cleans the code a bit and makes the behavior more consistent.
>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Davide Caratti <dcaratti@redhat.com>
> ---
> net/mptcp/protocol.c | 53 +++++++++++++++++---------------------------
> 1 file changed, 20 insertions(+), 33 deletions(-)
>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH net-next 5/6] mptcp: __mptcp_tcp_fallback() returns a struct sock
2020-06-29 20:26 [PATCH net-next 0/6] MPTCP: improve fallback to TCP Davide Caratti
` (3 preceding siblings ...)
2020-06-29 20:26 ` [PATCH net-next 4/6] mptcp: create first subflow at msk creation time Davide Caratti
@ 2020-06-29 20:26 ` Davide Caratti
2020-06-29 23:30 ` Mat Martineau
2020-06-29 20:26 ` [PATCH net-next 6/6] mptcp: close poll() races Davide Caratti
2020-06-30 0:29 ` [PATCH net-next 0/6] MPTCP: improve fallback to TCP David Miller
6 siblings, 1 reply; 14+ messages in thread
From: Davide Caratti @ 2020-06-29 20:26 UTC (permalink / raw)
To: Mat Martineau, Matthieu Baerts, David S. Miller, Jakub Kicinski,
netdev, mptcp
From: Paolo Abeni <pabeni@redhat.com>
Currently __mptcp_tcp_fallback() always return NULL
on incoming connections, because MPTCP does not create
the additional socket for the first subflow.
Since the previous commit no __mptcp_tcp_fallback()
caller needs a struct socket, so let __mptcp_tcp_fallback()
return the first subflow sock and cope correctly even with
incoming connections.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
net/mptcp/protocol.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index ad619bda71cc..f2b2bd37e371 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -76,14 +76,14 @@ static bool mptcp_is_tcpsk(struct sock *sk)
return false;
}
-static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk)
+static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)
{
sock_owned_by_me((const struct sock *)msk);
if (likely(!__mptcp_check_fallback(msk)))
return NULL;
- return msk->subflow;
+ return msk->first;
}
static int __mptcp_socket_create(struct mptcp_sock *msk)
@@ -1498,7 +1498,7 @@ static int mptcp_setsockopt(struct sock *sk, int level, int optname,
char __user *optval, unsigned int optlen)
{
struct mptcp_sock *msk = mptcp_sk(sk);
- struct socket *ssock;
+ struct sock *ssk;
pr_debug("msk=%p", msk);
@@ -1509,11 +1509,10 @@ static int mptcp_setsockopt(struct sock *sk, int level, int optname,
* to the one remaining subflow.
*/
lock_sock(sk);
- ssock = __mptcp_tcp_fallback(msk);
+ ssk = __mptcp_tcp_fallback(msk);
release_sock(sk);
- if (ssock)
- return tcp_setsockopt(ssock->sk, level, optname, optval,
- optlen);
+ if (ssk)
+ return tcp_setsockopt(ssk, level, optname, optval, optlen);
return -EOPNOTSUPP;
}
@@ -1522,7 +1521,7 @@ static int mptcp_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *option)
{
struct mptcp_sock *msk = mptcp_sk(sk);
- struct socket *ssock;
+ struct sock *ssk;
pr_debug("msk=%p", msk);
@@ -1533,11 +1532,10 @@ static int mptcp_getsockopt(struct sock *sk, int level, int optname,
* to the one remaining subflow.
*/
lock_sock(sk);
- ssock = __mptcp_tcp_fallback(msk);
+ ssk = __mptcp_tcp_fallback(msk);
release_sock(sk);
- if (ssock)
- return tcp_getsockopt(ssock->sk, level, optname, optval,
- option);
+ if (ssk)
+ return tcp_getsockopt(ssk, level, optname, optval, option);
return -EOPNOTSUPP;
}
--
2.26.2
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH net-next 5/6] mptcp: __mptcp_tcp_fallback() returns a struct sock
2020-06-29 20:26 ` [PATCH net-next 5/6] mptcp: __mptcp_tcp_fallback() returns a struct sock Davide Caratti
@ 2020-06-29 23:30 ` Mat Martineau
0 siblings, 0 replies; 14+ messages in thread
From: Mat Martineau @ 2020-06-29 23:30 UTC (permalink / raw)
To: Davide Caratti
Cc: Matthieu Baerts, David S. Miller, Jakub Kicinski, netdev, mptcp
On Mon, 29 Jun 2020, Davide Caratti wrote:
> From: Paolo Abeni <pabeni@redhat.com>
>
> Currently __mptcp_tcp_fallback() always return NULL
> on incoming connections, because MPTCP does not create
> the additional socket for the first subflow.
> Since the previous commit no __mptcp_tcp_fallback()
> caller needs a struct socket, so let __mptcp_tcp_fallback()
> return the first subflow sock and cope correctly even with
> incoming connections.
>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Davide Caratti <dcaratti@redhat.com>
> ---
> net/mptcp/protocol.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH net-next 6/6] mptcp: close poll() races
2020-06-29 20:26 [PATCH net-next 0/6] MPTCP: improve fallback to TCP Davide Caratti
` (4 preceding siblings ...)
2020-06-29 20:26 ` [PATCH net-next 5/6] mptcp: __mptcp_tcp_fallback() returns a struct sock Davide Caratti
@ 2020-06-29 20:26 ` Davide Caratti
2020-06-29 23:31 ` Mat Martineau
2020-06-30 0:29 ` [PATCH net-next 0/6] MPTCP: improve fallback to TCP David Miller
6 siblings, 1 reply; 14+ messages in thread
From: Davide Caratti @ 2020-06-29 20:26 UTC (permalink / raw)
To: Mat Martineau, Matthieu Baerts, David S. Miller, Jakub Kicinski,
netdev, mptcp
From: Paolo Abeni <pabeni@redhat.com>
mptcp_poll always return POLLOUT for unblocking
connect(), ensure that the socket is a suitable
state.
The MPTCP_DATA_READY bit is never cleared on accept:
ensure we don't leave mptcp_accept() with an empty
accept queue and such bit set.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
net/mptcp/protocol.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f2b2bd37e371..28ec26d97f96 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1841,6 +1841,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
if (!ssock)
goto unlock_fail;
+ clear_bit(MPTCP_DATA_READY, &msk->flags);
sock_hold(ssock->sk);
release_sock(sock->sk);
@@ -1861,6 +1862,8 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
}
}
+ if (inet_csk_listen_poll(ssock->sk))
+ set_bit(MPTCP_DATA_READY, &msk->flags);
sock_put(ssock->sk);
return err;
@@ -1869,21 +1872,33 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
return -EINVAL;
}
+static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
+{
+ return test_bit(MPTCP_DATA_READY, &msk->flags) ? EPOLLIN | EPOLLRDNORM :
+ 0;
+}
+
static __poll_t mptcp_poll(struct file *file, struct socket *sock,
struct poll_table_struct *wait)
{
struct sock *sk = sock->sk;
struct mptcp_sock *msk;
__poll_t mask = 0;
+ int state;
msk = mptcp_sk(sk);
sock_poll_wait(file, sock, wait);
- 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;
+ state = inet_sk_state_load(sk);
+ if (state == TCP_LISTEN)
+ return mptcp_check_readable(msk);
+
+ if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
+ mask |= mptcp_check_readable(msk);
+ 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;
--
2.26.2
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH net-next 6/6] mptcp: close poll() races
2020-06-29 20:26 ` [PATCH net-next 6/6] mptcp: close poll() races Davide Caratti
@ 2020-06-29 23:31 ` Mat Martineau
0 siblings, 0 replies; 14+ messages in thread
From: Mat Martineau @ 2020-06-29 23:31 UTC (permalink / raw)
To: Davide Caratti
Cc: Matthieu Baerts, David S. Miller, Jakub Kicinski, netdev, mptcp
On Mon, 29 Jun 2020, Davide Caratti wrote:
> From: Paolo Abeni <pabeni@redhat.com>
>
> mptcp_poll always return POLLOUT for unblocking
> connect(), ensure that the socket is a suitable
> state.
> The MPTCP_DATA_READY bit is never cleared on accept:
> ensure we don't leave mptcp_accept() with an empty
> accept queue and such bit set.
>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Davide Caratti <dcaratti@redhat.com>
> ---
> net/mptcp/protocol.c | 25 ++++++++++++++++++++-----
> 1 file changed, 20 insertions(+), 5 deletions(-)
>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net-next 0/6] MPTCP: improve fallback to TCP
2020-06-29 20:26 [PATCH net-next 0/6] MPTCP: improve fallback to TCP Davide Caratti
` (5 preceding siblings ...)
2020-06-29 20:26 ` [PATCH net-next 6/6] mptcp: close poll() races Davide Caratti
@ 2020-06-30 0:29 ` David Miller
6 siblings, 0 replies; 14+ messages in thread
From: David Miller @ 2020-06-30 0:29 UTC (permalink / raw)
To: dcaratti; +Cc: mathew.j.martineau, matthieu.baerts, kuba, netdev, mptcp
From: Davide Caratti <dcaratti@redhat.com>
Date: Mon, 29 Jun 2020 22:26:19 +0200
> there are situations where MPTCP sockets should fall-back to regular TCP:
> this series reworks the fallback code to pursue the following goals:
>
> 1) cleanup the non fallback code, removing most of 'if (<fallback>)' in
> the data path
> 2) improve performance for non-fallback sockets, avoiding locks in poll()
>
> further work will also leverage on this changes to achieve:
>
> a) more consistent behavior of gestockopt()/setsockopt() on passive sockets
> after fallback
> b) support for "infinite maps" as per RFC8684, section 3.7
>
> the series is made of the following items:
>
> - patch 1 lets sendmsg() / recvmsg() / poll() use the main socket also
> after fallback
> - patch 2 fixes 'simultaneous connect' scenario after fallback. The
> problem was present also before the rework, but the fix is much easier
> to implement after patch 1
> - patch 3, 4, 5 are clean-ups for code that is no more needed after the
> fallback rework
> - patch 6 fixes a race condition between close() and poll(). The problem
> was theoretically present before the rework, but it became almost
> systematic after patch 1
Series applied to net-next, thank you.
^ permalink raw reply [flat|nested] 14+ messages in thread