[RFC 2/4] ethdev: omit promiscuous config restore if not required

[Dariusz Sosnowski <dsosnowski@nvidia.com>]

This patch adds a new device flag - RTE_ETH_DEV_PROMISC_FORCE_RESTORE.
If device driver sets this flag, then it requires that ethdev library
forcefully reapplies promiscuous mode configuration,
after the port is started.
As a result, unnecessary work can be removed from rte_eth_dev_start()
for drivers which apply all available configuration in dev_start()
(such drivers do not set the flag).

If RFC is approved, then the next version of this patch
should set the new flag for all drivers to maintain the same behavior,
until drivers adjust and it can be safely cleared.

Signed-off-by: Dariusz Sosnowski <dsosnowski@nvidia.com>
---
 lib/ethdev/rte_ethdev.c | 8 +++++---
 lib/ethdev/rte_ethdev.h | 6 ++++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
index 362a1883f0..ff08abd566 100644
--- a/lib/ethdev/rte_ethdev.c
+++ b/lib/ethdev/rte_ethdev.c
@@ -1726,9 +1726,11 @@ eth_dev_config_restore(struct rte_eth_dev *dev,
 	if (!(*dev_info->dev_flags & RTE_ETH_DEV_NOLIVE_MAC_ADDR))
 		eth_dev_mac_restore(dev, dev_info);
 
-	ret = eth_dev_promiscuous_restore(dev, port_id);
-	if (ret != 0)
-		return ret;
+	if (*dev_info->dev_flags & RTE_ETH_DEV_PROMISC_FORCE_RESTORE) {
+		ret = eth_dev_promiscuous_restore(dev, port_id);
+		if (ret != 0)
+			return ret;
+	}
 
 	ret = eth_dev_allmulticast_restore(dev, port_id);
 	if (ret != 0)
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index 548fada1c7..0fc23fb924 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -2120,6 +2120,12 @@ struct rte_eth_dev_owner {
  * PMDs filling the queue xstats themselves should not set this flag
  */
 #define RTE_ETH_DEV_AUTOFILL_QUEUE_XSTATS RTE_BIT32(6)
+/**
+ * If this flag is set, then device driver requires that
+ * ethdev library forcefully reapplies promiscuous mode configuration,
+ * after driver's dev_start() callback is called.
+ */
+#define RTE_ETH_DEV_PROMISC_FORCE_RESTORE RTE_BIT32(7)
 /**@}*/
 
 /**
-- 
2.39.5