ibmvnic: Fix reset scheduler error handling

In some cases, if the driver is waiting for a reset following
a device parameter change, failure to schedule a reset can result
in a hang since a completion signal is never sent.

If the device configuration is being altered by a tool such
as ethtool or ifconfig, it could cause the console to hang
if the reset request does not get scheduled. Add some additional
error handling code to exit the wait_for_completion if there is
one in progress.

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -1875,23 +1875,25 @@ static void __ibmvnic_reset(struct work_struct *work)
 	mutex_unlock(&adapter->reset_lock);
 }
 
-static void ibmvnic_reset(struct ibmvnic_adapter *adapter,
-			  enum ibmvnic_reset_reason reason)
+static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
+			 enum ibmvnic_reset_reason reason)
 {
 	struct ibmvnic_rwi *rwi, *tmp;
 	struct net_device *netdev = adapter->netdev;
 	struct list_head *entry;
+	int ret;
 
 	if (adapter->state == VNIC_REMOVING ||
 	    adapter->state == VNIC_REMOVED) {
+		ret = EBUSY;
 		netdev_dbg(netdev, "Adapter removing, skipping reset\n");
-		return;
+		goto err;
 	}
 
 	if (adapter->state == VNIC_PROBING) {
 		netdev_warn(netdev, "Adapter reset during probe\n");
-		adapter->init_done_rc = EAGAIN;
-		return;
+		ret = adapter->init_done_rc = EAGAIN;
+		goto err;
 	}
 
 	mutex_lock(&adapter->rwi_lock);
@@ -1901,15 +1903,17 @@ static void ibmvnic_reset(struct ibmvnic_adapter *adapter,
 		if (tmp->reset_reason == reason) {
 			netdev_dbg(netdev, "Skipping matching reset\n");
 			mutex_unlock(&adapter->rwi_lock);
-			return;
+			ret = EBUSY;
+			goto err;
 		}
 	}
 
 	rwi = kzalloc(sizeof(*rwi), GFP_KERNEL);
 	if (!rwi) {
 		mutex_unlock(&adapter->rwi_lock);
 		ibmvnic_close(netdev);
-		return;
+		ret = ENOMEM;
+		goto err;
 	}
 
 	rwi->reset_reason = reason;
@@ -1918,6 +1922,12 @@ static void ibmvnic_reset(struct ibmvnic_adapter *adapter,
 
 	netdev_dbg(adapter->netdev, "Scheduling reset (reason %d)\n", reason);
 	schedule_work(&adapter->ibmvnic_reset);
+
+	return 0;
+err:
+	if (adapter->wait_for_reset)
+		adapter->wait_for_reset = false;
+	return -ret;
 }
 
 static void ibmvnic_tx_timeout(struct net_device *dev)
@@ -2052,31 +2062,40 @@ static void ibmvnic_netpoll_controller(struct net_device *dev)
 
 static int wait_for_reset(struct ibmvnic_adapter *adapter)
 {
+	int rc, ret;
+
 	adapter->fallback.mtu = adapter->req_mtu;
 	adapter->fallback.rx_queues = adapter->req_rx_queues;
 	adapter->fallback.tx_queues = adapter->req_tx_queues;
 	adapter->fallback.rx_entries = adapter->req_rx_add_entries_per_subcrq;
 	adapter->fallback.tx_entries = adapter->req_tx_entries_per_subcrq;
 
 	init_completion(&adapter->reset_done);
-	ibmvnic_reset(adapter, VNIC_RESET_CHANGE_PARAM);
 	adapter->wait_for_reset = true;
+	rc = ibmvnic_reset(adapter, VNIC_RESET_CHANGE_PARAM);
+	if (rc)
+		return rc;
 	wait_for_completion(&adapter->reset_done);
 
+	ret = 0;
 	if (adapter->reset_done_rc) {
+		ret = -EIO;
 		adapter->desired.mtu = adapter->fallback.mtu;
 		adapter->desired.rx_queues = adapter->fallback.rx_queues;
 		adapter->desired.tx_queues = adapter->fallback.tx_queues;
 		adapter->desired.rx_entries = adapter->fallback.rx_entries;
 		adapter->desired.tx_entries = adapter->fallback.tx_entries;
 
 		init_completion(&adapter->reset_done);
-		ibmvnic_reset(adapter, VNIC_RESET_CHANGE_PARAM);
+		adapter->wait_for_reset = true;
+		rc = ibmvnic_reset(adapter, VNIC_RESET_CHANGE_PARAM);
+		if (rc)
+			return ret;
 		wait_for_completion(&adapter->reset_done);
 	}
 	adapter->wait_for_reset = false;
 
-	return adapter->reset_done_rc;
+	return ret;
 }
 
 static int ibmvnic_change_mtu(struct net_device *netdev, int new_mtu)