+ } else {
+ /*
+ * We are out of PIO buffers at the moment.
+ * Pass responsibility for sending the ACK to the
+ * send tasklet so that when a PIO buffer becomes
+ * available, the ACK is sent ahead of other outgoing
+ * packets.
+ */
+ dev->n_rc_qacks++;
+ spin_lock_irq(&qp->s_lock);
+ /* Don't coalesce if a RDMA read or atomic is pending. */
+ if (qp->s_ack_state == OP(ACKNOWLEDGE) ||
+ qp->s_ack_state < OP(RDMA_READ_REQUEST)) {
+ qp->s_ack_state = qp->r_ack_state;
+ qp->s_nak_state = qp->r_nak_state;
+ qp->s_ack_psn = qp->r_ack_psn;
+ qp->r_ack_state = OP(ACKNOWLEDGE);
+ }
+ spin_unlock_irq(&qp->s_lock);
+
+ /* Call ipath_do_rc_send() in another thread. */
+ tasklet_hi_schedule(&qp->s_task);