netdevsim: fix backwards compatibility in nsim_get_iflink()

The default ndo_get_iflink() implementation returns the current ifindex
of the netdev. But the overridden nsim_get_iflink() returns 0 if the
current nsim is not linked, breaking backwards compatibility for
userspace that depend on this behaviour.

Fix the problem by returning the current ifindex if not linked to a
peer.

Fixes: 8debcf5832c3 ("netdevsim: add ndo_get_iflink() implementation")
Reported-by: Yu Watanabe <watanabe.yu@gmail.com>
Suggested-by: Yu Watanabe <watanabe.yu@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index c22897bf5509cad18a208cc41e25aa53d22ba2be..017a6102be0a220175523c6130de840f3a5997fb 100644 (file)
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -324,7 +324,8 @@ static int nsim_get_iflink(const struct net_device *dev)
 
        rcu_read_lock();
        peer = rcu_dereference(nsim->peer);
-       iflink = peer ? READ_ONCE(peer->netdev->ifindex) : 0;
+       iflink = peer ? READ_ONCE(peer->netdev->ifindex) :
+                       READ_ONCE(dev->ifindex);
        rcu_read_unlock();
 
        return iflink;