mptcp: fix subflow accounting on close

[ Upstream commit 95d686517884a403412b000361cee2b08b2ed1e6 ]

If the PM closes a fully established MPJ subflow or the subflow
creation errors out in it's early stage the subflows counter is
not bumped accordingly.

This change adds the missing accounting, additionally taking care
of updating accordingly the 'accept_subflow' flag.

Fixes: a88c9e496937 ("mptcp: do not block subflows creation on errors")
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 7bea318ac5f285f9ba9b5ece531a0c5eb1387e05..1eb83cbe8aae0fe5e7ad38d81710edb7ef761a33 100644 (file)
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -178,14 +178,13 @@ void mptcp_pm_subflow_check_next(struct mptcp_sock *msk, const struct sock *ssk,
        struct mptcp_pm_data *pm = &msk->pm;
        bool update_subflows;
 
-       update_subflows = (ssk->sk_state == TCP_CLOSE) &&
-                         (subflow->request_join || subflow->mp_join);
+       update_subflows = subflow->request_join || subflow->mp_join;
        if (!READ_ONCE(pm->work_pending) && !update_subflows)
                return;
 
        spin_lock_bh(&pm->lock);
        if (update_subflows)
-               pm->subflows--;
+               __mptcp_pm_close_subflow(msk);
 
        /* Even if this subflow is not really established, tell the PM to try
         * to pick the next ones, if possible.

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 85317ce38e3fa2d8e53fde8790c52a6ba8638d2f..a1c845eb47bdec6611a53f77b6dea36c92702445 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -835,6 +835,20 @@ unsigned int mptcp_pm_get_add_addr_accept_max(struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_subflows_max(struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_local_addr_max(struct mptcp_sock *msk);
 
+/* called under PM lock */
+static inline void __mptcp_pm_close_subflow(struct mptcp_sock *msk)
+{
+       if (--msk->pm.subflows < mptcp_pm_get_subflows_max(msk))
+               WRITE_ONCE(msk->pm.accept_subflow, true);
+}
+
+static inline void mptcp_pm_close_subflow(struct mptcp_sock *msk)
+{
+       spin_lock_bh(&msk->pm.lock);
+       __mptcp_pm_close_subflow(msk);
+       spin_unlock_bh(&msk->pm.lock);
+}
+
 void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk);
 void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk);
 

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index bea47a1180dc2c082b85e8fbd5229eef5440a2c6..1d4d84efe8f5b40c1e26c40cc98709fc85abd7e8 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1380,20 +1380,20 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
        struct sockaddr_storage addr;
        int remote_id = remote->id;
        int local_id = loc->id;
+       int err = -ENOTCONN;
        struct socket *sf;
        struct sock *ssk;
        u32 remote_token;
        int addrlen;
        int ifindex;
        u8 flags;
-       int err;
 
        if (!mptcp_is_fully_established(sk))
-               return -ENOTCONN;
+               goto err_out;
 
        err = mptcp_subflow_create_socket(sk, &sf);
        if (err)
-               return err;
+               goto err_out;
 
        ssk = sf->sk;
        subflow = mptcp_subflow_ctx(ssk);
@@ -1456,6 +1456,12 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
 failed:
        subflow->disposable = 1;
        sock_release(sf);
+
+err_out:
+       /* we account subflows before the creation, and this failures will not
+        * be caught by sk_state_change()
+        */
+       mptcp_pm_close_subflow(msk);
        return err;
 }