Re: [PATCH] usb: core: Emit KOBJ_CHANGE on unbound interface

[Fabien Sanglard]

My original patch focuses on fixing the silent failure for usbfs
drivers (like ADB). Since other drivers survive a reset without issues
from a user space perspective, I wanted to avoid being disruptive to
unaffected systems.

That said, unifying the behavior upon reset would be elegant. My main
concern is whether some existing udev rules or netlink listeners in
user space might break if we generalize this behavior and start
emitting unexpected CHANGE events for interfaces that successfully
rebound (which already emit UNBIND -> BIND).

But it might be worth "trying". I am unsure what the kernel team
philosophy is in this regard. If you all agree, we could trigger the
KOBJ_CHANGE event unconditionally inside rebind_marked_interfaces()
instead of conditionally inside usb_rebind_intf().

Fab

On Tue, Oct 13, 2026 at 2:35 AM Oliver Neukum <oneukum@xxxxxxxx> wrote:
>
> On 12.10.26 19:16, Fabien Sanglard wrote:
>
> > As a result, userspace clients like adb only see UNBIND and must poll
> > /dev/bus/usb to detect when the interface is ready again. Emit a
> > KOBJ_CHANGE uevent when device_attach() finds no matching driver so
> > userspace is notified that the interface can be reclaimed.
>
> Hi,
>
> why do you want to limit this to that specific case?
> Why not not always tell user space tat a device has
> been reset?
>
>         Regards
>                 Oliver
>