Re: [PATCH for-next v2] RDMA/rxe: Fix incomplete state save in rxe_requester

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Jul 21, 2023 at 03:07:49PM -0500, Bob Pearson wrote:
> If a send packet is dropped by the IP layer in rxe_requester()
> the call to rxe_xmit_packet() can fail with err == -EAGAIN.
> To recover, the state of the wqe is restored to the state before
> the packet was sent so it can be resent. However, the routines
> that save and restore the state miss a significnt part of the
> variable state in the wqe, the dma struct which is used to process
> through the sge table. And, the state is not saved before the packet
> is built which modifies the dma struct.
> 
> Under heavy stress testing with many QPs on a fast node sending
> large messages to a slow node dropped packets are observed and
> the resent packets are corrupted because the dma struct was not
> restored. This patch fixes this behavior and allows the test cases
> to succeed.
> 
> Fixes: 3050b9985024 ("IB/rxe: Fix race condition between requester and completer")
> Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
> ---
> v2:
>   Rebased to for-next
> 
>  drivers/infiniband/sw/rxe/rxe_req.c | 45 ++++++++++++++++-------------
>  1 file changed, 25 insertions(+), 20 deletions(-)

Applied to for-next, thanks

Jason