On 11/18/2016 4:36 PM, Andrew Boyer wrote:
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 <andrew.boyer@xxxxxxxx>
---
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
Reviewed-by: Yonatan Cohen <yonatanc@xxxxxxxxxxxx>
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