[0/7] rdma/siw: implement non-blocking connect

Message

Stefan Metzmacher June 15, 2022, 8:40 a.m. UTC

Hi Bernard,

as written a few month ago, I have a patchset with a lot
of fixes for siw.ko.

As requested I'm only send isolated chunks for easier review.

This is the first chunk adressing deadlocks in siw_connect()

The RDMA application layer expects rdma_connect() to be non-blocking
as the completion is handled via RDMA_CM_EVENT_ESTABLISHED and
other async events. It's not unlikely to hold a lock during
the rdma_connect() call.

Without out this a connection attempt to a non-existing/reachable
server block until the very long tcp timeout hits.
The application layer had no chance to have its own timeout handler
as that would just deadlock with the already blocking rdma_connect().

First rdma_connect() holds id_priv->handler_mutex and deadlocks
rdma_destroy_id().

And iw_cm_connect() called from within rdma_connect() sets
IWCM_F_CONNECT_WAIT during the call to cm_id->device->ops.iw_connect(),
siw_connect() in this case. It means that iw_cm_disconnect()
and iw_destroy_cm_id() will both deadlock waiting for
IWCM_F_CONNECT_WAIT being cleared.

Patches 1-6 are preparation patches to siw_connect()
in order to do the real non-blocking split in Patch 7.

Please have a look.

Thanks!
metze

Stefan Metzmacher (7):
  rdma/siw: make use of kernel_{bind,connect,listen}()
  rdma/siw: let siw_connect() set AWAIT_MPAREP before
    siw_send_mpareqrep()
  rdma/siw: create a temporary copy of private data
  rdma/siw: use error and out logic at the end of siw_connect()
  rdma/siw: start mpa timer before calling siw_send_mpareqrep()
  rdma/siw: call the blocking kernel_bindconnect() just before
    siw_send_mpareqrep()
  rdma/siw: implement non-blocking connect.

 drivers/infiniband/sw/siw/siw_cm.c | 165 ++++++++++++++++++++++-------
 drivers/infiniband/sw/siw/siw_cm.h |   1 +
 2 files changed, 127 insertions(+), 39 deletions(-)