From: Bob Pearson rpearsonhpe@gmail.com
[ Upstream commit 7cb33d1bc1ac8e51fd88928f96674d392f8e07c4 ]
When a local operation (invalidate mr, reg mr, bind mw) is finished there will be no ack packet coming from a responder to cause the wqe to be completed. This may happen anyway if a subsequent wqe performs IO. Currently if the wqe is signalled the completer tasklet is scheduled immediately but not otherwise.
This leads to a deadlock if the next wqe has the fence bit set in send flags and the operation is not signalled. This patch removes the condition that the wqe must be signalled in order to schedule the completer tasklet which is the simplest fix for this deadlock and is fairly low cost. This is the analog for local operations of always setting the ackreq bit in all last or only request packets even if the operation is not signalled.
Link: https://lore.kernel.org/r/20220523223251.15350-1-rpearsonhpe@gmail.com Reported-by: Jenny Hack jhack@hpe.com Fixes: c1a411268a4b ("RDMA/rxe: Move local ops to subroutine") Signed-off-by: Bob Pearson rpearsonhpe@gmail.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/sw/rxe/rxe_req.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c index 7812e3d6a6c2..4ea9319f0d52 100644 --- a/drivers/infiniband/sw/rxe/rxe_req.c +++ b/drivers/infiniband/sw/rxe/rxe_req.c @@ -612,9 +612,11 @@ static int rxe_do_local_ops(struct rxe_qp *qp, struct rxe_send_wqe *wqe) wqe->status = IB_WC_SUCCESS; qp->req.wqe_index = next_index(qp->sq.queue, qp->req.wqe_index);
- if ((wqe->wr.send_flags & IB_SEND_SIGNALED) || - qp->sq_sig_type == IB_SIGNAL_ALL_WR) - rxe_run_task(&qp->comp.task, 1); + /* There is no ack coming for local work requests + * which can lead to a deadlock. So go ahead and complete + * it now. + */ + rxe_run_task(&qp->comp.task, 1);
return 0; }