Re: [PATCH] cdc_ncm: do not call usbnet_link_change from cdc_ncm_bind

On Mon, Mar 7, 2016 at 12:15 PM, Bjørn Mork [off-list ref] wrote:

usbnet_link_change will call schedule_work and should be
avoided if bind is failing. Otherwise we will end up with
scheduled work referring to a netdev which has gone away.

Instead of making the call conditional, we can just defer
it to usbnet_probe, using the driver_info flag made for
this purpose.

So looking at this, I wonder...

Why is that FLAG_LINK_INTR thing not just always used?

The _only_ thing that FLAG_LINK_INTR does is to cause

        usbnet_link_change(dev, 0, 0);

to be called after network device attach. That doesn't seem to be controversial.

Looking at some examples, we have ax88179_178a.c that doesn't set the
flag, but instead does that usbnet_link_change() call at the end of
ax88179_bind().

There are a few drivers that seem to never call that
usbnet_link_change() at all, and don't have that FLAG_LINK_INTR flag.
Would they break?

Stupid grep:

    git grep -lw FLAG_ETHER |
        xargs grep -L FLAG_LINK_INTR |
        xargs grep -L usbnet_link_change |
        sed 's:drivers/net/usb/::'

gives

    cdc_eem.c
    ch9200.c
    cx82310_eth.c
    int51x1.c
    rndis_host.c

so maybe that FLAG_LINK_INTR si required.

Why is it called "FLAG_LINK_INTR" anyway? There doesn't seem to be
anything "INTR" about it.

               Linus