Re: [PATCH] Revert "net: linkwatch: add check for netdevice being present to linkwatch_do_dev"

[Jakub Kicinski]

On Wed, 23 Sep 2020 22:49:37 -0700 Saeed Mahameed wrote:
> 2) Another problematic scenario which i see is repeated in many
> drivers:
> 
> shutdown/suspend()
>     rtnl_lock()
>     netif_device_detach()//Mark !present;
>     stop()->carrier_off()->linkwatch_event()
>     // at this point device is still IFF_UP and !present
>     // due to the early detach above..  
>     rtnl_unlock();

Maybe we can solve this by providing drivers with a better helper for
the suspend use case?

AFAIU netif_device_detach() is used by both IO errors and drivers
willingly detaching the device during normal operation (e.g. for
suspend).

Since the suspend path can sleep if we have a separate helper perhaps
we could fire off the appropriate events synchronously, and quiescence
the stack properly?