IB/{rdmavt, hfi1, qib}: Add a counter for credit waits

This patch adds a counter for credit waits to assist field debugging.

Link: https://lore.kernel.org/r/20190911113047.126040.10857.stgit@awfm-01.aw.intel.com
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

include/rdma/rdmavt_qp.h

@@ -973,6 +973,41 @@ static inline void rvt_free_rq(struct rvt_rq *rq)
 	rq->wq = NULL;
 }
 
+/**
+ * rvt_to_iport - Get the ibport pointer
+ * @qp: the qp pointer
+ *
+ * This function returns the ibport pointer from the qp pointer.
+ */
+static inline struct rvt_ibport *rvt_to_iport(struct rvt_qp *qp)
+{
+	struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
+
+	return rdi->ports[qp->port_num - 1];
+}
+
+/**
+ * rvt_rc_credit_avail - Check if there are enough RC credits for the request
+ * @qp: the qp
+ * @wqe: the request
+ *
+ * This function returns false when there are not enough credits for the given
+ * request and true otherwise.
+ */
+static inline bool rvt_rc_credit_avail(struct rvt_qp *qp, struct rvt_swqe *wqe)
+{
+	lockdep_assert_held(&qp->s_lock);
+	if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT) &&
+	    rvt_cmp_msn(wqe->ssn, qp->s_lsn + 1) > 0) {
+		struct rvt_ibport *rvp = rvt_to_iport(qp);
+
+		qp->s_flags |= RVT_S_WAIT_SSN_CREDIT;
+		rvp->n_rc_crwaits++;
+		return false;
+	}
+	return true;
+}
+
 struct rvt_qp_iter *rvt_qp_iter_init(struct rvt_dev_info *rdi,
 				     u64 v,
 				     void (*cb)(struct rvt_qp *qp, u64 v));