Re: [PATCH, RFC] USBIP protocol documentation

David Chang
2011-08-09T09:23:18Z

Hi Greg,

2011/6/28 Németh Márton <nm127@freemail.hu>:
> From: Márton Németh <nm127@freemail.hu>
>
> USBIP v1.0.0 protocol documentation.
>
> Signed-off-by: Márton Németh <nm127@freemail.hu>
> ---
>
> Hi,
>
> I tried to document the USBIP protocol as implemented in the Linux kernel 3.0-rc2.
>
> The description is a preliminary draft only, it may contain mistakes. I tried
> to document what I have understand from the source code and from the actual
> captured network traffic when the USBIP is in action. Please review it, correct it,
> point out the missing parts.
>
> During I have documented the protocol a question came into my mind: why do we
> have two different type of package when the URB completition handler is called,
> namely USB_RET_SUBMIT and USBIP_RET_UNLINK? As far as I can see this causes race
> condition because for one URB the completition handler is only called once. If
> the one URB is sent in with USB_CMD_SUBMIT and then unlinked with USB_CMD_UNLINK
> the completition handler is called only once. In the protocol, however, we have
> two different type of packets: USB_RET_SUBMIT and USBIP_RET_UNLINK. The status
> field of these messages may contain anything in this case depending on the timing.
>
> Regards,
>
>        Márton Németh

Sorry, just one question about the usbip protocol document.
I would like to know why didn't you apply this patch.
Thanks in advance!

Best Regards,
David

>
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