IB/rdmavt: Add new completion inline

There is opencoded send completion logic all over all the drivers. We need to convert to this routine to enforce ordering issues for completions. This routine fixes an ordering issue where the read of the SWQE fields necessary for creating the completion can race with a post send if the post send catches a send queue at the edge of being full. Is is possible in that situation to read SWQE fields that are being written. This new routine insures that SWQE fields are read prior to advancing the index that post send uses to determine queue fullness. Reviewed-by: Michael J. Ruhl <[email protected]> Signed-off-by: Mike Marciniszyn <[email protected]> Signed-off-by: Dennis Dalessandro <[email protected]> Signed-off-by: Doug Ledford <[email protected]>
jbg · Jun 21, 2019 · f56044d · f56044d
1 parent dd82e66
commit f56044d
Showing 1 changed file with 72 additions and 0 deletions.
diff --git a/include/rdma/rdmavt_qp.h b/include/rdma/rdmavt_qp.h
@@ -737,6 +737,78 @@ static inline void rvt_put_qp_swqe(struct rvt_qp *qp, struct rvt_swqe *wqe)
 		atomic_dec(&ibah_to_rvtah(wqe->ud_wr.ah)->refcount);
 }
 
+/**
+ * rvt_qp_sqwe_incr - increment ring index
+ * @qp: the qp
+ * @val: the starting value
+ *
+ * Return: the new value wrapping as appropriate
+ */
+static inline u32
+rvt_qp_swqe_incr(struct rvt_qp *qp, u32 val)
+{
+	if (++val >= qp->s_size)
+		val = 0;
+	return val;
+}
+
+/**
+ * rvt_qp_complete_swqe - insert send completion
+ * @qp - the qp
+ * @wqe - the send wqe
+ * @opcode - wc operation (driver dependent)
+ * @status - completion status
+ *
+ * Update the s_last information, and then insert a send
+ * completion into the completion
+ * queue if the qp indicates it should be done.
+ *
+ * See IBTA 10.7.3.1 for info on completion
+ * control.
+ *
+ * Return: new last
+ */
+static inline u32
+rvt_qp_complete_swqe(struct rvt_qp *qp,
+		     struct rvt_swqe *wqe,
+		     enum ib_wc_opcode opcode,
+		     enum ib_wc_status status)
+{
+	bool need_completion;
+	u64 wr_id;
+	u32 byte_len, last;
+	int flags = wqe->wr.send_flags;
+
+	rvt_put_qp_swqe(qp, wqe);
+
+	need_completion =
+		!(flags & RVT_SEND_RESERVE_USED) &&
+		(!(qp->s_flags & RVT_S_SIGNAL_REQ_WR) ||
+		(flags & IB_SEND_SIGNALED) ||
+		status != IB_WC_SUCCESS);
+	if (need_completion) {
+		wr_id = wqe->wr.wr_id;
+		byte_len = wqe->length;
+		/* above fields required before writing s_last */
+	}
+	last = rvt_qp_swqe_incr(qp, qp->s_last);
+	/* see rvt_qp_is_avail() */
+	smp_store_release(&qp->s_last, last);
+	if (need_completion) {
+		struct ib_wc w = {
+			.wr_id = wr_id,
+			.status = status,
+			.opcode = opcode,
+			.qp = &qp->ibqp,
+			.byte_len = byte_len,
+		};
+
+		rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.send_cq), &w,
+			     status != IB_WC_SUCCESS);
+	}
+	return last;
+}
+
 extern const int  ib_rvt_state_ops[];
 
 struct rvt_dev_info;