net/smc: Ensure the active closing peer first closes clcsock

BugLink: https://bugs.launchpad.net/bugs/1953370
[ Upstream commit 606a63c9783a32a45bd2ef0eee393711d75b3284 ]

The side that actively closed socket, it's clcsock doesn't enter
TIME_WAIT state, but the passive side does it. It should show the same
behavior as TCP sockets.

Consider this, when client actively closes the socket, the clcsock in
server enters TIME_WAIT state, which means the address is occupied and
won't be reused before TIME_WAIT dismissing. If we restarted server, the
service would be unavailable for a long time.

To solve this issue, shutdown the clcsock in [A], perform the TCP active
close progress first, before the passive closed side closing it. So that
the actively closed side enters TIME_WAIT, not the passive one.

Client                                            |  Server
close() // client actively close                  |
  smc_release()                                   |
      smc_close_active() // PEERCLOSEWAIT1        |
          smc_close_final() // abort or closed = 1|
              smc_cdc_get_slot_and_msg_send()     |
          [A]                                     |
                                                  |smc_cdc_msg_recv_action() // ACTIVE
                                                  |  queue_work(smc_close_wq, &conn->close_work)
                                                  |    smc_close_passive_work() // PROCESSABORT or APPCLOSEWAIT1
                                                  |      smc_close_passive_abort_received() // only in abort
                                                  |
                                                  |close() // server recv zero, close
                                                  |  smc_release() // PROCESSABORT or APPCLOSEWAIT1
                                                  |    smc_close_active()
                                                  |      smc_close_abort() or smc_close_final() // CLOSED
                                                  |        smc_cdc_get_slot_and_msg_send() // abort or closed = 1
smc_cdc_msg_recv_action()                         |    smc_clcsock_release()
  queue_work(smc_close_wq, &conn->close_work)     |      sock_release(tcp) // actively close clc, enter TIME_WAIT
    smc_close_passive_work() // PEERCLOSEWAIT1    |    smc_conn_free()
      smc_close_passive_abort_received() // CLOSED|
      smc_conn_free()                             |
      smc_clcsock_release()                       |
        sock_release(tcp) // passive close clc    |

Link: https://www.spinics.net/lists/netdev/msg780407.html
Fixes: b38d732477e4 ("smc: socket closing and linkgroup cleanup")
Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
Reviewed-by: Wen Gu <guwen@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index 0f9ffba07d26858cfd07c53567e14700884553d4..04620b53b74a79f0303ec9dfffa34ff0b6b11829 100644 (file)
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -228,6 +228,12 @@ again:
                        /* send close request */
                        rc = smc_close_final(conn);
                        sk->sk_state = SMC_PEERCLOSEWAIT1;
+
+                       /* actively shutdown clcsock before peer close it,
+                        * prevent peer from entering TIME_WAIT state.
+                        */
+                       if (smc->clcsock && smc->clcsock->sk)
+                               rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
                } else {
                        /* peer event has changed the state */
                        goto again;