RDMA/rxe: Fix errant WARN_ONCE in rxe_completer()

In rxe_comp.c in rxe_completer() the function free_pkt() did not clear skb
which triggered a warning at 'done:' and could possibly at 'exit:'. The
WARN_ONCE() calls are not actually needed.  The call to free_pkt() is
moved to the end to clearly show that all skbs are freed.

Fixes: 899aba8 ("RDMA/rxe: Fix FIXME in rxe_udp_encap_recv()")
Link: https://lore.kernel.org/r/20210304192048.2958-1-rpearson@hpe.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/sw/rxe/rxe_comp.c

@@ -547,14 +547,16 @@ int rxe_completer(void *arg)
 	struct sk_buff *skb = NULL;
 	struct rxe_pkt_info *pkt = NULL;
 	enum comp_state state;
+	int ret = 0;
 
 	rxe_add_ref(qp);
 
 	if (!qp->valid || qp->req.state == QP_STATE_ERROR ||
 	    qp->req.state == QP_STATE_RESET) {
 		rxe_drain_resp_pkts(qp, qp->valid &&
 				    qp->req.state == QP_STATE_ERROR);
-		goto exit;
+		ret = -EAGAIN;
+		goto done;
 	}
 
 	if (qp->comp.timeout) {
@@ -564,8 +566,10 @@ int rxe_completer(void *arg)
 		qp->comp.timeout_retry = 0;
 	}
 
-	if (qp->req.need_retry)
-		goto exit;
+	if (qp->req.need_retry) {
+		ret = -EAGAIN;
+		goto done;
+	}
 
 	state = COMPST_GET_ACK;
 
@@ -636,8 +640,6 @@ int rxe_completer(void *arg)
 			break;
 
 		case COMPST_DONE:
-			if (pkt)
-				free_pkt(pkt);
 			goto done;
 
 		case COMPST_EXIT:
@@ -660,7 +662,8 @@ int rxe_completer(void *arg)
 			    qp->qp_timeout_jiffies)
 				mod_timer(&qp->retrans_timer,
 					  jiffies + qp->qp_timeout_jiffies);
-			goto exit;
+			ret = -EAGAIN;
+			goto done;
 
 		case COMPST_ERROR_RETRY:
 			/* we come here if the retry timer fired and we did
@@ -672,18 +675,18 @@ int rxe_completer(void *arg)
 			 */
 
 			/* there is nothing to retry in this case */
-			if (!wqe || (wqe->state == wqe_state_posted))
-				goto exit;
+			if (!wqe || (wqe->state == wqe_state_posted)) {
+				pr_warn("Retry attempted without a valid wqe\n");
+				ret = -EAGAIN;
+				goto done;
+			}
 
 			/* if we've started a retry, don't start another
 			 * retry sequence, unless this is a timeout.
 			 */
 			if (qp->comp.started_retry &&
-			    !qp->comp.timeout_retry) {
-				if (pkt)
-					free_pkt(pkt);
+			    !qp->comp.timeout_retry)
 				goto done;
-			}
 
 			if (qp->comp.retry_cnt > 0) {
 				if (qp->comp.retry_cnt != 7)
@@ -704,8 +707,6 @@ int rxe_completer(void *arg)
 					qp->comp.started_retry = 1;
 					rxe_run_task(&qp->req.task, 0);
 				}
-				if (pkt)
-					free_pkt(pkt);
 				goto done;
 
 			} else {
@@ -726,8 +727,8 @@ int rxe_completer(void *arg)
 				mod_timer(&qp->rnr_nak_timer,
 					  jiffies + rnrnak_jiffies(aeth_syn(pkt)
 						& ~AETH_TYPE_MASK));
-				free_pkt(pkt);
-				goto exit;
+				ret = -EAGAIN;
+				goto done;
 			} else {
 				rxe_counter_inc(rxe,
 						RXE_CNT_RNR_RETRY_EXCEEDED);
@@ -740,25 +741,15 @@ int rxe_completer(void *arg)
 			WARN_ON_ONCE(wqe->status == IB_WC_SUCCESS);
 			do_complete(qp, wqe);
 			rxe_qp_error(qp);
-			if (pkt)
-				free_pkt(pkt);
-			goto exit;
+			ret = -EAGAIN;
+			goto done;
 		}
 	}
 
-exit:
-	/* we come here if we are done with processing and want the task to
-	 * exit from the loop calling us
-	 */
-	WARN_ON_ONCE(skb);
-	rxe_drop_ref(qp);
-	return -EAGAIN;
-
 done:
-	/* we come here if we have processed a packet we want the task to call
-	 * us again to see if there is anything else to do
-	 */
-	WARN_ON_ONCE(skb);
+	if (pkt)
+		free_pkt(pkt);
 	rxe_drop_ref(qp);
-	return 0;
+
+	return ret;
 }