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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Fri, 8 Nov 2019 23:18:39 +0100
Message-ID: <CAAeHK+zyvqJs_5X61NriLdHoityTdVJ0O=a-xrcq+-7Vb_F0FQ@mail.gmail.com>
Subject: Re: [PATCH 0/1] usb: gadget: add raw-gadget interface
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     USB list <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Felipe Balbi <balbi@kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>
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On Fri, Nov 8, 2019 at 10:45 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Fri, 8 Nov 2019, Andrey Konovalov wrote:
>
> > This patchset (currently a single patch) adds a new userspace interface
> > for the USB Gadget subsystem called USB Raw Gadget (I don't mind changing
> > the name to something else if there are better ideas). This is what
> > currently being used to enable coverage-buided USB fuzzing with syzkaller:
> >
> > https://github.com/google/syzkaller/blob/master/docs/linux/external_fuzzing_usb.md
> >
> > Initially I was using GadgetFS (together with the Dummy HCD/UDC module)
> > to perform emulation of USB devices for fuzzing, but later switched to a
> > custom written interface. The incentive to implement a different interface
> > was to provide a somewhat raw and direct access to the USB Gadget layer
> > for the userspace, where every USB request is passed to the userspace to
> > get a response. See documentation for the list of differences between
> > Raw Gadget and GadgetFS.
> >
> > This patchset has been pushed to the public Linux kernel Gerrit instance:
> >
> > https://linux-review.googlesource.com/c/linux/kernel/git/torvalds/linux/+/2144
> >
> > Andrey Konovalov (1):
> >   usb: gadget: add raw-gadget interface
> >
> >  Documentation/usb/index.rst         |    1 +
> >  Documentation/usb/raw-gadget.rst    |   60 ++
> >  drivers/usb/gadget/Kconfig          |    9 +
> >  drivers/usb/gadget/Makefile         |    2 +
> >  drivers/usb/gadget/raw.c            | 1150 +++++++++++++++++++++++++++
>
> As a general rule, gadget drivers don't go directly in
> drivers/usb/gadget.  raw.c counts as a legacy driver (because it's not
> written to use the composite gadget framework), so it belongs in
> drivers/usb/gadget/legacy.  That's where the gadgetfs driver lives, for
> example.

Hi Alan! Sure, I'll move it to legacy/ in v2. Thanks!