+ /*
+ * Try to send a simple ACK to work around a Mellanox bug
+ * which doesn't accept a RDMA read response or atomic
+ * response as an ACK for earlier SENDs or RDMA writes.
+ */
+ if (qp->r_head_ack_queue == qp->s_tail_ack_queue &&
+ !(qp->s_flags & IPATH_S_ACK_PENDING) &&
+ qp->s_ack_state == OP(ACKNOWLEDGE)) {
+ spin_unlock_irqrestore(&qp->s_lock, flags);
+ qp->r_nak_state = 0;
+ qp->r_ack_psn = qp->s_ack_queue[i].psn - 1;
+ goto send_ack;
+ }