smb: server: let smb_direct_cm_handler() call ib_drain_qp() after smb_direct_disconne...

smb: server: let smb_direct_cm_handler() call ib_drain_qp() after smb_direct_disconnect_rdma_work()

All handlers triggered by ib_drain_qp() should already see the
broken connection.

smb_direct_cm_handler() is called under a mutex of the rdma_cm,
we should make sure ib_drain_qp() and all rdma layer logic completes
and unlocks the mutex.

It means free_transport() will also already see the connection
as SMBDIRECT_SOCKET_DISCONNECTED, so we need to call
crdma_[un]lock_handler(sc->rdma.cm_id) around
ib_drain_qp(), rdma_destroy_qp(), ib_free_cq() and ib_dealloc_pd().

Otherwise we free resources while the ib_drain_qp() within
smb_direct_cm_handler() is still running.

We have to unlock before rdma_destroy_id() as it locks again.

Fixes: 141fa9824c0f ("ksmbd: call ib_drain_qp when disconnected")
Fixes: 4c564f03e23b ("smb: server: make use of common smbdirect_socket")
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>