Re: [PATCH v6 0/5] tools/usbip: Patch set summary

[Shuah Khan <skhan@linuxfoundation.org>]

On 11/30/21 3:22 PM, Lars Gunnarsson wrote:
> To forward a remote usb device over usbip the following steps is required:
> 
> 1. Execute "usbip bind" on remote end.
> 2. Execute "usbip attach" on local end.
> 
> These steps must be perfomed in above order and after usb device is plugged in.
> If the usb device is unplugged on the remote end the steps above needs to be
> performed again to establish the connection. This patch set implements a feature
> to persistently forward devices on a given bus. When using flag "-p|--persistent"
> on remot end, the USB device becomes exported when plugged in. When using flag
> "-p|--persistent" on local end, the USB device becomes imported when available
> on remote end. Thus it is only required to run the usbip command once on each
> end, in any order, to persistently forward usb devices on a given bus.
> 
> This is sent in five separate patches:
>    tools/usbip: update protocol documentation
>    tools/usbip: update manual pages
>    tools/usbip: add usb event monitor into libusbip
>    tools/usbip: export USB devices on a given bus persistently
>    tools/usbip: import USB devices on a given bus persistently
> 

When -p is used, the command stays in foreground. This is a very
different use model compared to current model. In addition, once
persistent flag is set on a bus, all devices even the ones that
are inserted in the future get exported. What happens if one of
the devices shouldn't be exported?

There are several conditions to be thought through:

- What happens if if the command that is running on the foreground
   is killed on either end?
- What happens when one or more devices are detached?
- What happens when one or more devices are unbound from
   the server?

Let's walk through these scenarios.

thanks,
-- Shuah