Re: [PATCH] RDMA: Add rdma_connect_locked()

On 10/26/20 15:25, Jason Gunthorpe wrote:

There are two flows for handling RDMA_CM_EVENT_ROUTE_RESOLVED, either the
handler triggers a completion and another thread does rdma_connect() or
the handler directly calls rdma_connect().

In all cases rdma_connect() needs to hold the handler_mutex, but when
handler's are invoked this is already held by the core code. This causes
ULPs using the 2nd method to deadlock.

Provide a rdma_connect_locked() and have all ULPs call it from their
handlers.

Reported-by: Guoqing Jiang <redacted>
Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state"
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
  drivers/infiniband/core/cma.c            | 39 +++++++++++++++++++++---
  drivers/infiniband/ulp/iser/iser_verbs.c |  2 +-
  drivers/infiniband/ulp/rtrs/rtrs-clt.c   |  4 +--
  drivers/nvme/host/rdma.c                 | 10 +++---
  include/rdma/rdma_cm.h                   | 13 +-------
  net/rds/ib_cm.c                          |  5 +--
  6 files changed, 47 insertions(+), 26 deletions(-)

Seems people are not testing these four ULPs against rdma-next.. Here is a
quick fix for the issue:

https://lore.kernel.org/r/3b1f7767-98e2-93e0-b718-16d1c5346140@cloud.ionos.com (local)

I can't see the previous calltrace with this patch.

Tested-by: Guoqing Jiang<redacted>


Thanks,
Guoqing