From dd753d87436ce7ef2a958d684b38d5acc99c9f5c Mon Sep 17 00:00:00 2001 From: Andrew Boyer Date: Wed, 23 Nov 2016 12:39:18 -0500 Subject: [PATCH] IB/rxe: Advance the consumer pointer before posting the CQE A simple userspace application might poll the CQ, find a completion, and then attempt to post a new WQE to the SQ. A spurious error can occur if the userspace application detects a full SQ in the instant before the kernel is able to advance the SQ consumer pointer. This is noticeable when using single-entry SQs with ibv_rc_pingpong if lots of kernel and userspace library debugging is enabled. Signed-off-by: Andrew Boyer Reviewed-by: Yonatan Cohen Signed-off-by: Doug Ledford --- drivers/infiniband/sw/rxe/rxe_comp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c index 6c5e29d..d46c49b 100644 --- a/drivers/infiniband/sw/rxe/rxe_comp.c +++ b/drivers/infiniband/sw/rxe/rxe_comp.c @@ -420,11 +420,12 @@ static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe) (wqe->wr.send_flags & IB_SEND_SIGNALED) || (qp->req.state == QP_STATE_ERROR)) { make_send_cqe(qp, wqe, &cqe); + advance_consumer(qp->sq.queue); rxe_cq_post(qp->scq, &cqe, 0); + } else { + advance_consumer(qp->sq.queue); } - advance_consumer(qp->sq.queue); - /* * we completed something so let req run again * if it is trying to fence -- 2.7.4