[PATCH for-next 2/2] RDMA/erdma: Add drain_sq and drain_rq support

[Cheng Xu <chengyou@xxxxxxxxxxxxxxxxx>]

For erdma, hardware won't process any WRs after modifying QP state to
error, so the default __ib_drain_sq and __ib_drain_rq can not work for
erdma device. Here, we introduce custom implementation of drain_sq and
drain_rq interface to fit erdma hardware.

Signed-off-by: Cheng Xu <chengyou@xxxxxxxxxxxxxxxxx>
---
 drivers/infiniband/hw/erdma/erdma_qp.c    | 71 +++++++++++++++++++++++
 drivers/infiniband/hw/erdma/erdma_verbs.h | 10 ++++
 2 files changed, 81 insertions(+)

diff --git a/drivers/infiniband/hw/erdma/erdma_qp.c b/drivers/infiniband/hw/erdma/erdma_qp.c
index abf8b134d076..57fdb946fbfd 100644
--- a/drivers/infiniband/hw/erdma/erdma_qp.c
+++ b/drivers/infiniband/hw/erdma/erdma_qp.c
@@ -599,3 +599,74 @@ int erdma_post_recv_nodrain(struct ib_qp *ibqp,
 {
 	return erdma_post_recv(ibqp, recv_wr, bad_recv_wr, false);
 }
+
+static void erdma_drain_qp_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct erdma_drain_cqe *cqe =
+		container_of(wc->wr_cqe, struct erdma_drain_cqe, cqe);
+
+	complete(&cqe->done);
+}
+
+static void erdma_drain_qp_common(struct ib_qp *ibqp, struct completion *comp,
+				  struct ib_cq *ibcq)
+{
+	struct ib_qp_attr attr = { .qp_state = IB_QPS_ERR };
+	struct erdma_qp *qp = to_eqp(ibqp);
+	const struct ib_send_wr *bad_swr;
+	const struct ib_recv_wr *bad_rwr;
+	struct ib_rdma_wr swr = {
+		.wr = {
+			.next = NULL,
+			{ .wr_cqe   = &qp->kern_qp.sdrain.cqe, },
+			.opcode = IB_WR_RDMA_WRITE,
+			.send_flags = IB_SEND_SIGNALED,
+		},
+	};
+	struct ib_recv_wr rwr = {
+		.next = NULL,
+		.wr_cqe = &qp->kern_qp.rdrain.cqe,
+		.num_sge = 0,
+	};
+
+	if (qp->flags & ERDMA_QP_FLAGS_DRAIN_ISSUED)
+		goto wait_for_completion;
+
+	qp->flags |= ERDMA_QP_FLAGS_DRAIN_ISSUED;
+
+	qp->kern_qp.rdrain.cqe.done = erdma_drain_qp_done;
+	init_completion(&qp->kern_qp.rdrain.done);
+
+	qp->kern_qp.sdrain.cqe.done = erdma_drain_qp_done;
+	init_completion(&qp->kern_qp.sdrain.done);
+
+	if (erdma_post_recv(ibqp, &rwr, &bad_rwr, true))
+		return;
+
+	if (erdma_post_send(ibqp, &swr.wr, &bad_swr, true))
+		return;
+
+	if (ib_modify_qp(ibqp, &attr, IB_QP_STATE))
+		return;
+
+wait_for_completion:
+	if (ibcq->poll_ctx == IB_POLL_DIRECT)
+		while (wait_for_completion_timeout(comp, HZ / 10) <= 0)
+			ib_process_cq_direct(ibcq, -1);
+	else
+		wait_for_completion(comp);
+}
+
+void erdma_drain_sq(struct ib_qp *ibqp)
+{
+	struct erdma_qp *qp = to_eqp(ibqp);
+
+	erdma_drain_qp_common(ibqp, &qp->kern_qp.sdrain.done, ibqp->send_cq);
+}
+
+void erdma_drain_rq(struct ib_qp *ibqp)
+{
+	struct erdma_qp *qp = to_eqp(ibqp);
+
+	erdma_drain_qp_common(ibqp, &qp->kern_qp.rdrain.done, ibqp->recv_cq);
+}
diff --git a/drivers/infiniband/hw/erdma/erdma_verbs.h b/drivers/infiniband/hw/erdma/erdma_verbs.h
index f4148fbac878..4cec92c8a737 100644
--- a/drivers/infiniband/hw/erdma/erdma_verbs.h
+++ b/drivers/infiniband/hw/erdma/erdma_verbs.h
@@ -133,6 +133,11 @@ struct erdma_uqp {
 	u32 rq_offset;
 };
 
+struct erdma_drain_cqe {
+	struct ib_cqe cqe;
+	struct completion done;
+};
+
 struct erdma_kqp {
 	u16 sq_pi;
 	u16 sq_ci;
@@ -155,6 +160,9 @@ struct erdma_kqp {
 	void *sq_db_info;
 	void *rq_db_info;
 
+	struct erdma_drain_cqe sdrain;
+	struct erdma_drain_cqe rdrain;
+
 	u8 sig_all;
 };
 
@@ -341,6 +349,8 @@ int erdma_post_send_nodrain(struct ib_qp *ibqp,
 int erdma_post_recv_nodrain(struct ib_qp *ibqp,
 			    const struct ib_recv_wr *recv_wr,
 			    const struct ib_recv_wr **bad_recv_wr);
+void erdma_drain_sq(struct ib_qp *ibqp);
+void erdma_drain_rq(struct ib_qp *ibqp);
 int erdma_poll_cq(struct ib_cq *ibcq, int num_entries, struct ib_wc *wc);
 struct ib_mr *erdma_ib_alloc_mr(struct ib_pd *ibpd, enum ib_mr_type mr_type,
 				u32 max_num_sg);
-- 
2.27.0