[PATCH] RDMA: Add rdma_connect_locked()

[Guoqing Jiang]

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 <guoqing.jiang at cloud.ionos.com>
> Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state"
> Signed-off-by: Jason Gunthorpe <jgg at 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

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

Tested-by: Guoqing Jiang<guoqing.jiang at cloud.ionos.com>


Thanks,
Guoqing