Re: How to avoid getting ndo_open() immediately after probe

On Thu, Dec 02, 2021 at 09:29:21PM +0100, Lino Sanfilippo wrote:

Hi,

On 02.12.21 at 19:11, Arijit De wrote:

quoted

Hi,

I have handled the probe() and registered the netdev structure using register_netdev().
I have observed in other opensource driver(i.e. Intel e1000e driver) that ndo_open() gets called only when we try to bring up the interface (i.e. ifconfig <ip> ifconfig eth0 <ip-addr> netmask <net-mask> up).
But in my network driver I am getting ndo_open() call immediately after I handle the probe(). It's a wrong behavior, also my network interface is getting to UP/RUNNING state(as shown below) even without any valid ip address.

There is nothing wrong here. As soon as you register the netdevice with the kernel it is available
for userspace and userspace is free to bring it up. This may happen immediately after registration,
so your driver has to be prepared for this.
Its absolutely fine to bring up a network device without any ip address assigned.

And if you are using NFS root, the kernel can actually call ndo_open()
before register_netdev() even completes.

This is a common bug i look for in new drivers, register_netdev()
pretty much has to be the last thing done inside the probe function.

       Andrew