netdev - [RFC v4 2/5] l3mdev: add function to retreive upper master

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Message-Id: <20181122010713.3995-3-abauvin@scaleway.com>
Date:   Thu, 22 Nov 2018 02:07:10 +0100
From:   Alexis Bauvin <abauvin@...leway.com>
To:     dsa@...ulusnetworks.com, roopa@...ulusnetworks.com
Cc:     netdev@...r.kernel.org, abauvin@...leway.com,
        akherbouche@...leway.com
Subject: [RFC v4 2/5] l3mdev: add function to retreive upper master

Existing functions to retreive the l3mdev of a device did not walk the
master chain to find the upper master. This patch adds a function to
find the l3mdev, even indirect through e.g. a bridge:

+----------+
|          |
| vrf-blue |
|          |
+----+-----+
     |
     |
+----+-----+
|          |
| br-blue  |
|          |
+----+-----+
     |
     |
+----+-----+
|          |
|   eth0   |
|          |
+----------+

This will properly resolve the l3mdev of eth0 to vrf-blue.

Signed-off-by: Alexis Bauvin <abauvin@...leway.com>
Reviewed-by: Amine Kherbouche <akherbouche@...leway.com>
Tested-by: Amine Kherbouche <akherbouche@...leway.com>
---
 include/net/l3mdev.h | 22 ++++++++++++++++++++++
 net/l3mdev/l3mdev.c  | 18 ++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
index 3832099289c5..78fa0ac4613c 100644
--- a/include/net/l3mdev.h
+++ b/include/net/l3mdev.h
@@ -101,6 +101,17 @@ struct net_device *l3mdev_master_dev_rcu(const struct net_device *_dev)
 	return master;
 }
 
+int l3mdev_master_upper_ifindex_by_index_rcu(struct net *net, int ifindex);
+static inline
+int l3mdev_master_upper_ifindex_by_index(struct net *net, int ifindex)
+{
+	rcu_read_lock();
+	ifindex = l3mdev_master_upper_ifindex_by_index_rcu(net, ifindex);
+	rcu_read_unlock();
+
+	return ifindex;
+}
+
 u32 l3mdev_fib_table_rcu(const struct net_device *dev);
 u32 l3mdev_fib_table_by_index(struct net *net, int ifindex);
 static inline u32 l3mdev_fib_table(const struct net_device *dev)
@@ -207,6 +218,17 @@ static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
 	return 0;
 }
 
+static inline
+int l3mdev_master_upper_ifindex_by_index_rcu(struct net *net, int ifindex)
+{
+	return 0;
+}
+static inline
+int l3mdev_master_upper_ifindex_by_index(struct net *net, int ifindex)
+{
+	return 0;
+}
+
 static inline
 struct net_device *l3mdev_master_dev_rcu(const struct net_device *dev)
 {
diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c
index 8da86ceca33d..309dee76724e 100644
--- a/net/l3mdev/l3mdev.c
+++ b/net/l3mdev/l3mdev.c
@@ -46,6 +46,24 @@ int l3mdev_master_ifindex_rcu(const struct net_device *dev)
 }
 EXPORT_SYMBOL_GPL(l3mdev_master_ifindex_rcu);
 
+/**
+ *	l3mdev_master_upper_ifindex_by_index - get index of upper l3 master
+ *					       device
+ *	@net: network namespace for device index lookup
+ *	@ifindex: targeted interface
+ */
+int l3mdev_master_upper_ifindex_by_index_rcu(struct net *net, int ifindex)
+{
+	struct net_device *dev;
+
+	dev = dev_get_by_index_rcu(net, ifindex);
+	while (dev && !netif_is_l3_master(dev))
+		dev = netdev_master_upper_dev_get(dev);
+
+	return dev ? dev->ifindex : 0;
+}
+EXPORT_SYMBOL_GPL(l3mdev_master_upper_ifindex_by_index_rcu);
+
 /**
  *	l3mdev_fib_table - get FIB table id associated with an L3
  *                             master interface
--