mptcp: avoid duplicated SUB_CLOSED events

The initial subflow might have already been closed, but still in the
connection list. When the worker is instructed to close the subflows
that have been marked as closed, it might then try to close the initial
subflow again.

 A consequence of that is that the SUB_CLOSED event can be seen twice:

  # ip mptcp endpoint
  1.1.1.1 id 1 subflow dev eth0
  2.2.2.2 id 2 subflow dev eth1

  # ip mptcp monitor &
  [         CREATED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9
  [     ESTABLISHED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9
  [  SF_ESTABLISHED] remid=0 locid=2 saddr4=2.2.2.2 daddr4=9.9.9.9

  # ip mptcp endpoint delete id 1
  [       SF_CLOSED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9
  [       SF_CLOSED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9

The first one is coming from mptcp_pm_nl_rm_subflow_received(), and the
second one from __mptcp_close_subflow().

To avoid doing the post-closed processing twice, the subflow is now
marked as closed the first time.

Note that it is not enough to check if we are dealing with the first
subflow and check its sk_state: the subflow might have been reset or
closed before calling mptcp_close_ssk().

Fixes: b911c97c7dc7 ("mptcp: add netlink event support")
Cc: stable@vger.kernel.org
Tested-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b571fba88a2f966c808a070f69c391707ee3cb71..37ebcb7640ebb37d513db11906c5fb2fbc003b22 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2508,6 +2508,12 @@ out:
 void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
                     struct mptcp_subflow_context *subflow)
 {
+       /* The first subflow can already be closed and still in the list */
+       if (subflow->close_event_done)
+               return;
+
+       subflow->close_event_done = true;
+
        if (sk->sk_state == TCP_ESTABLISHED)
                mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
 

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 240d7c2ea55130755db7484f9d7f7671c2618bf1..26eb898a202b34d2bba7b5b3054936a4a1979202 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -524,7 +524,8 @@ struct mptcp_subflow_context {
                stale : 1,          /* unable to snd/rcv data, do not use for xmit */
                valid_csum_seen : 1,        /* at least one csum validated */
                is_mptfo : 1,       /* subflow is doing TFO */
-               __unused : 10;
+               close_event_done : 1,       /* has done the post-closed part */
+               __unused : 9;
        bool    data_avail;
        bool    scheduled;
        u32     remote_nonce;