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mptcp: tag sequence_seq with socket state

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Paolo Abeni suggested to avoid re-syncing new subflows because
they inherit options from listener. In case options were set on
listener but are not set on mptcp-socket there is no need to
do any synchronisation for new subflows.

This change sets sockopt_seq of new mptcp sockets to the seq of
the mptcp listener sock.

Subflow sequence is set to the embedded tcp listener sk.
Add a comment explaing why sk_state is involved in sockopt_seq
generation.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
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:
Florian Westphal 2021-04-15 16:44:54 -07:00 committed by David S. Miller
parent 7896248983
commit df00b087da
4 changed files with 62 additions and 5 deletions
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12
net/mptcp/protocol.c
View File

@ -733,18 +733,23 @@ wake:
static bool mptcp_do_flush_join_list(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
bool ret = false;
if (likely(list_empty(&msk->join_list)))
return false;
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_for_each_entry(subflow, &msk->join_list, node) {
u32 sseq = READ_ONCE(subflow->setsockopt_seq);
mptcp_propagate_sndbuf((struct sock *)msk, mptcp_subflow_tcp_sock(subflow));
if (READ_ONCE(msk->setsockopt_seq) != sseq)
ret = true;
}
list_splice_tail_init(&msk->join_list, &msk->conn_list);
spin_unlock_bh(&msk->join_list_lock);
return true;
return ret;
}
void __mptcp_flush_join_list(struct mptcp_sock *msk)
@ -2718,6 +2723,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
msk->snd_nxt = msk->write_seq;
msk->snd_una = msk->write_seq;
msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;
msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
if (mp_opt->mp_capable) {
msk->can_ack = true;

4
net/mptcp/protocol.h
View File

@ -256,6 +256,8 @@ struct mptcp_sock {
u64 time; /* start time of measurement window */
u64 rtt_us; /* last maximum rtt of subflows */
} rcvq_space;
u32 setsockopt_seq;
};
#define mptcp_lock_sock(___sk, cb) do { \
@ -414,6 +416,8 @@ struct mptcp_subflow_context {
long delegated_status;
struct list_head delegated_node; /* link into delegated_action, protected by local BH */
u32 setsockopt_seq;
struct sock *tcp_sock; /* tcp sk backpointer */
struct sock *conn; /* parent mptcp_sock */
const struct inet_connection_sock_af_ops *icsk_af_ops;

47
net/mptcp/sockopt.c
View File

@ -24,6 +24,27 @@ static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)
return msk->first;
}
static u32 sockopt_seq_reset(const struct sock *sk)
{
sock_owned_by_me(sk);
/* Highbits contain state. Allows to distinguish sockopt_seq
* of listener and established:
* s0 = new_listener()
* sockopt(s0) - seq is 1
* s1 = accept(s0) - s1 inherits seq 1 if listener sk (s0)
* sockopt(s0) - seq increments to 2 on s0
* sockopt(s1) // seq increments to 2 on s1 (different option)
* new ssk completes join, inherits options from s0 // seq 2
* Needs sync from mptcp join logic, but ssk->seq == msk->seq
*
* Set High order bits to sk_state so ssk->seq == msk->seq test
* will fail.
*/
return (u32)sk->sk_state << 24u;
}
static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
sockptr_t optval, unsigned int optlen)
{
@ -350,22 +371,44 @@ int mptcp_getsockopt(struct sock *sk, int level, int optname,
return -EOPNOTSUPP;
}
static void __mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)
{
}
void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
msk_owned_by_me(msk);
if (READ_ONCE(subflow->setsockopt_seq) != msk->setsockopt_seq) {
__mptcp_sockopt_sync(msk, ssk);
subflow->setsockopt_seq = msk->setsockopt_seq;
}
}
void mptcp_sockopt_sync_all(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
struct sock *sk = (struct sock *)msk;
u32 seq;
msk_owned_by_me(msk);
seq = sockopt_seq_reset(sk);
mptcp_for_each_subflow(msk, subflow) {
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
u32 sseq = READ_ONCE(subflow->setsockopt_seq);
mptcp_sockopt_sync(msk, ssk);
if (sseq != msk->setsockopt_seq) {
__mptcp_sockopt_sync(msk, ssk);
WRITE_ONCE(subflow->setsockopt_seq, seq);
} else if (sseq != seq) {
WRITE_ONCE(subflow->setsockopt_seq, seq);
}
cond_resched();
}
msk->setsockopt_seq = seq;
}

4
net/mptcp/subflow.c
View File

@ -679,6 +679,9 @@ create_child:
goto out;
}
/* ssk inherits options of listener sk */
ctx->setsockopt_seq = listener->setsockopt_seq;
if (ctx->mp_capable) {
/* this can't race with mptcp_close(), as the msk is
* not yet exposted to user-space
@ -694,6 +697,7 @@ create_child:
* created mptcp socket
*/
new_msk->sk_destruct = mptcp_sock_destruct;
mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
ctx->conn = new_msk;