[PATCH rdma v2] RDMA: Add rdma_connect_locked()

[Max Gurtovoy]

On 10/27/2020 2:20 PM, 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.
>
> Link: https://lore.kernel.org/r/0-v1-75e124dbad74+b05-rdma_connect_locking_jgg@nvidia.com
> Reported-and-tested-by: Guoqing Jiang <guoqing.jiang at cloud.ionos.com>
> Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state")
> Acked-by: Santosh Shilimkar <santosh.shilimkar at oracle.com>
> Acked-by: Jack Wang <jinpu.wang at cloud.ionos.com>
> Reviewed-by: Christoph Hellwig <hch at lst.de>
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> ---
>   drivers/infiniband/core/cma.c            | 40 +++++++++++++++++++++---
>   drivers/infiniband/ulp/iser/iser_verbs.c |  2 +-
>   drivers/infiniband/ulp/rtrs/rtrs-clt.c   |  4 +--
>   drivers/nvme/host/rdma.c                 |  4 +--
>   include/rdma/rdma_cm.h                   | 14 ++-------
>   net/rds/ib_cm.c                          |  5 +--
>   6 files changed, 46 insertions(+), 23 deletions(-)
>
> v2:
>   - Remove extra code from nvme (Chao)
>   - Fix long lines (CH)
>
> I've applied this version to rdma-rc - expecting to get these ULPs unbroken for rc2
> release
>
> Thanks,
> Jason
>
iser and nvme/rdma looks good to me,

Reviewed-by: Max Gurtovoy <mgurtovoy at nvidia.com>