On Wed, Dec 9, 2020 at 5:45 PM Jack Wang <jinpu.wang@xxxxxxxxxxxxxxx> wrote:
>
> If there are many establishments/teardowns, we need to make sure
> we do not consume too much system memory. Thus let on going
> session closing to finish before accepting new connection.
>
> Inspired by commit 777dc82395de ("nvmet-rdma: occasionally flush ongoing controller teardown")
> Signed-off-by: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxx>
> Reviewed-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
Please ignore this one, it could lead to deadlock, due to the fact
cma_ib_req_handler is holding
mutex_lock(&listen_id->handler_mutex) when calling into
rtrs_rdma_connect, we call close_work which will call rdma_destroy_id,
which
could try to hold the same handler_mutex, so deadlock.
Sorry & thanks!
Jack
> ---
> drivers/infiniband/ulp/rtrs/rtrs-srv.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> index ed4628f032bb..0a2202c28b54 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> +++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> @@ -1791,6 +1791,10 @@ static int rtrs_rdma_connect(struct rdma_cm_id *cm_id,
> err = -ENOMEM;
> goto reject_w_err;
> }
> + if (!cid) {
> + /* Let inflight session teardown complete */
> + flush_workqueue(rtrs_wq);
> + }
> mutex_lock(&srv->paths_mutex);
> sess = __find_sess(srv, &msg->sess_uuid);
> if (sess) {
> --
> 2.25.1
>
