MIME-Version: 1.0
From: Andrey Konovalov <andreyknvl@google.com>
Date: Tue, 13 Jun 2017 14:21:08 +0200
Message-ID: <CAAeHK+ytJCrnJhN8ck0iwbOi=mNzrx150vYxp3GhCmk0Wvi0dA@mail.gmail.com>
Subject: gadgetfs: how to wait for USB device initialization?
To: Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Alan Stern <stern@rowland.harvard.edu>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@google.com>,
        Elena Reshetova <elena.reshetova@intel.com>,
        USB list <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Cc: syzkaller <syzkaller@googlegroups.com>,
        Dmitry Vyukov <dvyukov@google.com>, Kostya Serebryany <kcc@google.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi!

I'm trying to use gadgetfs to fuzz USB device drivers by simply
connecting random devices for now.

What I want to achieve right now is the following:

1. mount gadgetfs
2. emulate connection of a new USB device
3. wait for the device to finish initializing
4. unmount gadgetfs
5. goto 1

The question is how do I wait for the device to finish initializing
(the corresponding USB driver to finish probing?) before unmounting
gadgetfs? As I understand, when I write device description to
"/dev/gadget/dummy_udc" the initialization happens asynchronously
after writing is done.

To mount and unmount gadgetfs right now I do:
mount("none", "/dev/gadget", "gadgetfs", 0, NULL)
umount2("/dev/gadget", MNT_FORCE | MNT_DETACH)

Thanks!