[PATCH net-next v2 1/2] net: mana: introduce helper to get a master netdev

[Konstantin Taranov <kotaranov@linux.microsoft.com>]

From: Konstantin Taranov <kotaranov@microsoft.com>

Add helper to get a master netdevice for a given port.
When mana is used with netvsc, the VF netdev is controlled
by an upper netvsc device. In a baremetal case, the VF
netdev is the master device.

Signed-off-by: Konstantin Taranov <kotaranov@microsoft.com>
---
 drivers/net/ethernet/microsoft/mana/mana_en.c | 18 ++++++++++++++++++
 include/net/mana/mana.h                       |  2 ++
 2 files changed, 20 insertions(+)

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index d087cf9..b893339 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -2948,3 +2948,21 @@ out:
 	gd->gdma_context = NULL;
 	kfree(ac);
 }
+
+/* the caller should hold rcu_read_lock */
+struct net_device *mana_get_master_netdev_rcu(struct mana_context *ac, u32 port_index)
+{
+	struct net_device *ndev;
+
+	if (port_index >= ac->num_ports)
+		return NULL;
+
+	/* When mana is used in netvsc, the upper netdevice should be returned. */
+	if (ac->ports[port_index]->flags & IFF_SLAVE)
+		ndev = netdev_master_upper_dev_get_rcu(ac->ports[port_index]);
+	else
+		ndev = ac->ports[port_index];
+
+	return ndev;
+}
+EXPORT_SYMBOL_NS(mana_get_master_netdev_rcu, NET_MANA);
diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
index 46f741e..2d3625c 100644
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -797,4 +797,6 @@ void mana_destroy_wq_obj(struct mana_port_context *apc, u32 wq_type,
 int mana_cfg_vport(struct mana_port_context *apc, u32 protection_dom_id,
 		   u32 doorbell_pg_id);
 void mana_uncfg_vport(struct mana_port_context *apc);
+
+struct net_device *mana_get_master_netdev_rcu(struct mana_context *ac, u32 port_index);
 #endif /* _MANA_H */
-- 
2.43.0