ibmvnic: avoid calling napi_disable() twice

__ibmvnic_open calls napi_disable without checking whether NAPI polling
has already been disabled or not. This could cause napi_disable
being called twice, which could generate deadlock. For example,
the first napi_disable will spin until NAPI_STATE_SCHED is cleared
by napi_complete_done, then set it again.
When napi_disable is called the second time, it will loop infinitely
because no dev->poll will be running to clear NAPI_STATE_SCHED.

To prevent above scenario from happening, call ibmvnic_napi_disable()
which checks if napi is disabled or not before calling napi_disable.

Fixes: bfc32f29 ("ibmvnic: Move resource initialization to its own routine")
Suggested-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: Lijun Pan <lijunp213@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -1149,8 +1149,7 @@ static int __ibmvnic_open(struct net_device *netdev)
 
 	rc = set_link_state(adapter, IBMVNIC_LOGICAL_LNK_UP);
 	if (rc) {
-		for (i = 0; i < adapter->req_rx_queues; i++)
-			napi_disable(&adapter->napi[i]);
+		ibmvnic_napi_disable(adapter);
 		release_resources(adapter);
 		return rc;
 	}