On Wed, 2018-01-17 at 15:52 +0200, Max Gurtovoy wrote:
> +/*
> + * __ib_drain_srq() - Block until all Last WQE Reached event arrives, or
> + * timeout expires (best effort).
> + * @qp: queue pair associated with SRQ to drain
> + *
> + * In order to avoid WQE and data segment leakage, one should destroy
> + * QP associated after performing the following:
> + * - moving QP to err state
> + * - wait for the Affiliated Asynchronous Last WQE Reached Event
> + * - drain the CQ
> + */
> +static void __ib_drain_srq(struct ib_qp *qp)
> +{
> + struct ib_qp_attr attr = { .qp_state = IB_QPS_ERR };
> + struct ib_cq *cq;
> + int ret;
> +
> + if (!qp->srq) {
> + WARN_ONCE(1, "QP 0x%p is not associated with SRQ\n", qp);
> + return;
> + }
> +
> + ret = ib_modify_qp(qp, &attr, IB_QP_STATE);
> + if (ret) {
> + WARN_ONCE(ret, "failed to drain shared recv queue: %d\n", ret);
> + return;
> + }
> +
> + if (ib_srq_has_cq(qp->srq->srq_type)) {
> + cq = qp->srq->ext.cq;
> + } else if (qp->recv_cq) {
> + cq = qp->recv_cq;
> + } else {
> + WARN_ONCE(1, "QP 0x%p has no CQ associated with SRQ\n", qp);
> + return;
> + }
> +
> + /*
> + * ULP should invoke ib_notify_qp on IB_EVENT_QP_LAST_WQE_REACHED
> + * arrival, otherwise timeout will expire and leakage may occur.
> + * Use long timeout, for the buggy ULPs/HCAs that don't notify the
> + * QP nor raising IB_EVENT_QP_LAST_WQE_REACHED event.
> + */
> + if (wait_for_completion_timeout(&qp->srq_completion, 10 * HZ) > 0)
> + ib_process_cq_direct(cq, -1);
> +}
Hello Max,
It seems weird to me that __ib_drain_srq() does not follow the same approach as
__ib_drain_rq(). Have you considered to post an additional receive work entry
on the SRQ and to wait until the completion for that work entry is signaled?
That would avoid that a completion has to be added in the ib_qp data structure
and would also avoid that all ULPs that use SRQs have to be modified.
Thanks,
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