RDMA/bnxt_re: Fix RQE posting logic

This patch adds code to ring RQ Doorbell aggressively
so that the adapter can DMA RQ buffers sooner, instead
of DMA all WQEs in the post_recv WR list together at the
end of the post_recv verb.
Also use spinlock to serialize RQ posting

Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/bnxt_re/bnxt_re.h

@@ -58,6 +58,8 @@
 
 #define BNXT_RE_UD_QP_HW_STALL		0x400000
 
+#define BNXT_RE_RQ_WQE_THRESHOLD	32
+
 struct bnxt_re_work {
 	struct work_struct	work;
 	unsigned long		event;

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -1249,6 +1249,7 @@ struct ib_qp *bnxt_re_create_qp(struct ib_pd *ib_pd,
 
 	qp->ib_qp.qp_num = qp->qplib_qp.id;
 	spin_lock_init(&qp->sq_lock);
+	spin_lock_init(&qp->rq_lock);
 
 	if (udata) {
 		struct bnxt_re_qp_resp resp;
@@ -2281,7 +2282,10 @@ int bnxt_re_post_recv(struct ib_qp *ib_qp, struct ib_recv_wr *wr,
 	struct bnxt_re_qp *qp = container_of(ib_qp, struct bnxt_re_qp, ib_qp);
 	struct bnxt_qplib_swqe wqe;
 	int rc = 0, payload_sz = 0;
+	unsigned long flags;
+	u32 count = 0;
 
+	spin_lock_irqsave(&qp->rq_lock, flags);
 	while (wr) {
 		/* House keeping */
 		memset(&wqe, 0, sizeof(wqe));
@@ -2310,9 +2314,21 @@ int bnxt_re_post_recv(struct ib_qp *ib_qp, struct ib_recv_wr *wr,
 			*bad_wr = wr;
 			break;
 		}
+
+		/* Ring DB if the RQEs posted reaches a threshold value */
+		if (++count >= BNXT_RE_RQ_WQE_THRESHOLD) {
+			bnxt_qplib_post_recv_db(&qp->qplib_qp);
+			count = 0;
+		}
+
 		wr = wr->next;
 	}
-	bnxt_qplib_post_recv_db(&qp->qplib_qp);
+
+	if (count)
+		bnxt_qplib_post_recv_db(&qp->qplib_qp);
+
+	spin_unlock_irqrestore(&qp->rq_lock, flags);
+
 	return rc;
 }
 

drivers/infiniband/hw/bnxt_re/ib_verbs.h

@@ -74,6 +74,7 @@ struct bnxt_re_qp {
 	struct bnxt_re_dev	*rdev;
 	struct ib_qp		ib_qp;
 	spinlock_t		sq_lock;	/* protect sq */
+	spinlock_t		rq_lock;	/* protect rq */
 	struct bnxt_qplib_qp	qplib_qp;
 	struct ib_umem		*sumem;
 	struct ib_umem		*rumem;