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mptcp: keep unaccepted MPC subflow into join list

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This will simplify all operation dealing with subflows
before accept time (e.g. data fin processing, add_addr).

The join list is already flushed by mptcp_stream_accept()
before returning the newly created msk to the user space.

This also fixes an potential bug present into the old code:
conn_list was manipulated without helding the msk lock
in mptcp_stream_accept().

Tested-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Paolo Abeni 2020-11-19 11:45:58 -08:00 committed by Jakub Kicinski
parent 8b819a84d4
commit 0397c6d85f
3 changed files with 22 additions and 21 deletions
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24
net/mptcp/protocol.c
View File

@ -2343,7 +2343,6 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
if (sk_is_mptcp(newsk)) {
struct mptcp_subflow_context *subflow;
struct sock *new_mptcp_sock;
struct sock *ssk = newsk;
subflow = mptcp_subflow_ctx(newsk);
new_mptcp_sock = subflow->conn;
@ -2358,22 +2357,8 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
/* acquire the 2nd reference for the owning socket */
sock_hold(new_mptcp_sock);
local_bh_disable();
bh_lock_sock(new_mptcp_sock);
msk = mptcp_sk(new_mptcp_sock);
msk->first = newsk;
newsk = new_mptcp_sock;
mptcp_copy_inaddrs(newsk, ssk);
list_add(&subflow->node, &msk->conn_list);
sock_hold(ssk);
mptcp_rcv_space_init(msk, ssk);
bh_unlock_sock(new_mptcp_sock);
__MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
local_bh_enable();
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
} else {
MPTCP_INC_STATS(sock_net(sk),
MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
@ -2824,6 +2809,12 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
if (err == 0 && !mptcp_is_tcpsk(newsock->sk)) {
struct mptcp_sock *msk = mptcp_sk(newsock->sk);
struct mptcp_subflow_context *subflow;
struct sock *newsk = newsock->sk;
bool slowpath;
slowpath = lock_sock_fast(newsk);
mptcp_copy_inaddrs(newsk, msk->first);
mptcp_rcv_space_init(msk, 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.
@ -2835,6 +2826,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
if (!ssk->sk_socket)
mptcp_sock_graft(ssk, newsock);
}
unlock_sock_fast(newsk, slowpath);
}
if (inet_csk_listen_poll(ssock->sk))

9
net/mptcp/protocol.h
View File

@ -403,6 +403,15 @@ mptcp_subflow_get_mapped_dsn(const struct mptcp_subflow_context *subflow)
return subflow->map_seq + mptcp_subflow_get_map_offset(subflow);
}
static inline void mptcp_add_pending_subflow(struct mptcp_sock *msk,
struct mptcp_subflow_context *subflow)
{
sock_hold(mptcp_subflow_tcp_sock(subflow));
spin_lock_bh(&msk->join_list_lock);
list_add_tail(&subflow->node, &msk->join_list);
spin_unlock_bh(&msk->join_list_lock);
}
int mptcp_is_enabled(struct net *net);
unsigned int mptcp_get_add_addr_timeout(struct net *net);
void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,

10
net/mptcp/subflow.c
View File

@ -578,6 +578,10 @@ create_child:
*/
inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
/* link the newly created socket to the msk */
mptcp_add_pending_subflow(mptcp_sk(new_msk), ctx);
WRITE_ONCE(mptcp_sk(new_msk)->first, child);
/* new mpc subflow takes ownership of the newly
* created mptcp socket
*/
@ -1124,11 +1128,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
if (err && err != -EINPROGRESS)
goto failed;
sock_hold(ssk);
spin_lock_bh(&msk->join_list_lock);
list_add_tail(&subflow->node, &msk->join_list);
spin_unlock_bh(&msk->join_list_lock);
mptcp_add_pending_subflow(msk, subflow);
return err;
failed: