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mptcp: refactor token container

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Replace the radix tree with a hash table allocated
at boot time. The radix tree has some shortcoming:
a single lock is contented by all the mptcp operation,
the lookup currently use such lock, and traversing
all the items would require a lock, too.

With hash table instead we trade a little memory to
address all the above - a per bucket lock is used.

To hash the MPTCP sockets, we re-use the msk' sk_node
entry: the MPTCP sockets are never hashed by the stack.
Replace the existing hash proto callbacks with a dummy
implementation, annotating the above constraint.

Additionally refactor the token creation to code to:

- limit the number of consecutive attempts to a fixed
maximum. Hitting a hash bucket with a long chain is
considered a failed attempt

- accept() no longer can fail to token management.

- if token creation fails at connect() time, we do
fallback to TCP (before the connection was closed)

v1 -> v2:
 - fix "no newline at end of file" - Jakub

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni
2020-06-26 19:30:00 +02:00
committed by David S. Miller
parent d39dceca38
commit 2c5ebd001d
4 changed files with 233 additions and 110 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
net/mptcp/subflow.c
View File

@@ -32,12 +32,9 @@ static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
static int subflow_rebuild_header(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
int local_id, err = 0;
int local_id;
if (subflow->request_mptcp && !subflow->token) {
pr_debug("subflow=%p", sk);
err = mptcp_token_new_connect(sk);
} else if (subflow->request_join && !subflow->local_nonce) {
if (subflow->request_join && !subflow->local_nonce) {
struct mptcp_sock *msk = (struct mptcp_sock *)subflow->conn;
pr_debug("subflow=%p", sk);
@@ -57,9 +54,6 @@ static int subflow_rebuild_header(struct sock *sk)
}
out:
if (err)
return err;
return subflow->icsk_af_ops->rebuild_header(sk);
}
@@ -72,8 +66,7 @@ static void subflow_req_destructor(struct request_sock *req)
if (subflow_req->msk)
sock_put((struct sock *)subflow_req->msk);
if (subflow_req->mp_capable)
mptcp_token_destroy_request(subflow_req->token);
mptcp_token_destroy_request(req);
tcp_request_sock_ops.destructor(req);
}
@@ -135,6 +128,7 @@ static void subflow_init_req(struct request_sock *req,
subflow_req->mp_capable = 0;
subflow_req->mp_join = 0;
subflow_req->msk = NULL;
mptcp_token_init_request(req);
#ifdef CONFIG_TCP_MD5SIG
/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
@@ -250,7 +244,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
subflow->remote_nonce = mp_opt.nonce;
pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
subflow->thmac, subflow->remote_nonce);
} else if (subflow->request_mptcp) {
} else {
tp->is_mptcp = 0;
}
@@ -386,7 +380,7 @@ static void mptcp_sock_destruct(struct sock *sk)
sock_orphan(sk);
}
mptcp_token_destroy(mptcp_sk(sk)->token);
mptcp_token_destroy(mptcp_sk(sk));
inet_sock_destruct(sk);
}
@@ -505,6 +499,7 @@ create_child:
*/
new_msk->sk_destruct = mptcp_sock_destruct;
mptcp_pm_new_connection(mptcp_sk(new_msk), 1);
mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
ctx->conn = new_msk;
new_msk = NULL;