ethdev: fix link status query

When application works with LSC interrupts the ethdev layer skips
the PMD callback and update according to the link status exists on
device data. It is because it assumes the link status on the device data
is the correct one since any link change is processed by the application.

As multiple PMDs install the link status interrupt handler only on port
start and uninstall it on port stop, the link status may be incorrect in
case the query is called after port stop or before port start.

Fixing the query implementation to use the PMD callback for such cases.

Fixes: b77d21c ("ethdev: add link status get/set helper functions")
Cc: stable@dpdk.org

Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>

lib/librte_ether/rte_ethdev.c

@@ -1789,7 +1789,8 @@ rte_eth_link_get(uint16_t port_id, struct rte_eth_link *eth_link)
 	RTE_ETH_VALID_PORTID_OR_RET(port_id);
 	dev = &rte_eth_devices[port_id];
 
-	if (dev->data->dev_conf.intr_conf.lsc)
+	if (dev->data->dev_conf.intr_conf.lsc &&
+	    dev->data->dev_started)
 		rte_eth_linkstatus_get(dev, eth_link);
 	else {
 		RTE_FUNC_PTR_OR_RET(*dev->dev_ops->link_update);
@@ -1806,7 +1807,8 @@ rte_eth_link_get_nowait(uint16_t port_id, struct rte_eth_link *eth_link)
 	RTE_ETH_VALID_PORTID_OR_RET(port_id);
 	dev = &rte_eth_devices[port_id];
 
-	if (dev->data->dev_conf.intr_conf.lsc)
+	if (dev->data->dev_conf.intr_conf.lsc &&
+	    dev->data->dev_started)
 		rte_eth_linkstatus_get(dev, eth_link);
 	else {
 		RTE_FUNC_PTR_OR_RET(*dev->dev_ops->link_update);