Re: [patch net-next 0/4] net: allow to change carrier from userspace

On Wed, 12 Dec 2012 19:25:56 +0100
Jiri Pirko [off-list ref] wrote:

Wed, Dec 12, 2012 at 07:12:08PM CET, shemminger@vyatta.com wrote:

quoted

On Wed, 12 Dec 2012 19:10:17 +0100
Jiri Pirko [off-list ref] wrote:

quoted

quoted

# ip li show dev dummy0
12: dummy0: <NO-CARRIER,BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state DORMANT mode DORMANT   

if you mean this "NO-CARRIER"
it has no direct relation with netif_carrier_ok().

It is the same value (IFF_RUNNING) that is visible from user space.

static inline bool netif_carrier_ok(const struct net_device *dev)
{
	        return !test_bit(__LINK_STATE_NOCARRIER, &dev->state);
}

So netif_carrier[ok/on/off] are working with on __LINK_STATE_NOCARRIER
bit. Not with IFF_RUNNING flag.

What is the code path that you are worried about netif_carrier_ok being set or clear?
The interaction here is complex, and right now LINK_STATE_NOCARRIER is purely
controlled by the driver, your patch changes that, but before acking I want
to make sure why it is required.