IB/hfi1: Handle port down properly in pio

The call to sc_buffer_alloc currently returns NULL (no buffer) or
a buffer descriptor.

There is a third case when the port is down.  Currently that
returns NULL and this prevents the caller from properly handling the
sc_buffer_alloc() failure.  A verbs code link test after the call is
racy so the indication needs to come from the state check inside the allocation
routine to be valid.

Fix by encoding the ECOMM failure like SDMA.   IS_ERR_OR_NULL() tests
are added at all call sites.  For verbs send, this needs to treat any
error by returning a completion without any MMIO copy.

Fixes: 7724105 ("IB/hfi1: add driver files")
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/pio.c

@@ -1443,7 +1443,8 @@ void sc_stop(struct send_context *sc, int flag)
  * @cb: optional callback to call when the buffer is finished sending
  * @arg: argument for cb
  *
- * Return a pointer to a PIO buffer if successful, NULL if not enough room.
+ * Return a pointer to a PIO buffer, NULL if not enough room, -ECOMM
+ * when link is down.
  */
 struct pio_buf *sc_buffer_alloc(struct send_context *sc, u32 dw_len,
 				pio_release_cb cb, void *arg)
@@ -1459,7 +1460,7 @@ struct pio_buf *sc_buffer_alloc(struct send_context *sc, u32 dw_len,
 	spin_lock_irqsave(&sc->alloc_lock, flags);
 	if (!(sc->flags & SCF_ENABLED)) {
 		spin_unlock_irqrestore(&sc->alloc_lock, flags);
-		goto done;
+		return ERR_PTR(-ECOMM);
 	}
 
 retry:

drivers/infiniband/hw/hfi1/rc.c

@@ -1432,7 +1432,7 @@ void hfi1_send_rc_ack(struct hfi1_packet *packet, bool is_fecn)
 	pbc = create_pbc(ppd, pbc_flags, qp->srate_mbps,
 			 sc_to_vlt(ppd->dd, sc5), plen);
 	pbuf = sc_buffer_alloc(rcd->sc, plen, NULL, NULL);
-	if (!pbuf) {
+	if (IS_ERR_OR_NULL(pbuf)) {
 		/*
 		 * We have no room to send at the moment.  Pass
 		 * responsibility for sending the ACK to the send engine

drivers/infiniband/hw/hfi1/ud.c

@@ -683,7 +683,7 @@ void return_cnp_16B(struct hfi1_ibport *ibp, struct rvt_qp *qp,
 	pbc = create_pbc(ppd, pbc_flags, qp->srate_mbps, vl, plen);
 	if (ctxt) {
 		pbuf = sc_buffer_alloc(ctxt, plen, NULL, NULL);
-		if (pbuf) {
+		if (!IS_ERR_OR_NULL(pbuf)) {
 			trace_pio_output_ibhdr(ppd->dd, &hdr, sc5);
 			ppd->dd->pio_inline_send(ppd->dd, pbuf, pbc,
 						 &hdr, hwords);
@@ -738,7 +738,7 @@ void return_cnp(struct hfi1_ibport *ibp, struct rvt_qp *qp, u32 remote_qpn,
 	pbc = create_pbc(ppd, pbc_flags, qp->srate_mbps, vl, plen);
 	if (ctxt) {
 		pbuf = sc_buffer_alloc(ctxt, plen, NULL, NULL);
-		if (pbuf) {
+		if (!IS_ERR_OR_NULL(pbuf)) {
 			trace_pio_output_ibhdr(ppd->dd, &hdr, sc5);
 			ppd->dd->pio_inline_send(ppd->dd, pbuf, pbc,
 						 &hdr, hwords);

drivers/infiniband/hw/hfi1/verbs.c

@@ -1039,10 +1039,10 @@ int hfi1_verbs_send_pio(struct rvt_qp *qp, struct hfi1_pkt_state *ps,
 	if (cb)
 		iowait_pio_inc(&priv->s_iowait);
 	pbuf = sc_buffer_alloc(sc, plen, cb, qp);
-	if (unlikely(!pbuf)) {
+	if (unlikely(IS_ERR_OR_NULL(pbuf))) {
 		if (cb)
 			verbs_pio_complete(qp, 0);
-		if (ppd->host_link_state != HLS_UP_ACTIVE) {
+		if (IS_ERR(pbuf)) {
 			/*
 			 * If we have filled the PIO buffers to capacity and are
 			 * not in an active state this request is not going to