linux-kernel - Re: [PATCH] usb: udc: add gadget state kobject uevent

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+k=oDxnHJN6NgMM_Ziz92_0d8+anfMEqz7WvBCrg5RAn9MzCg@mail.gmail.com>
Date:	Thu, 18 Jul 2013 16:25:17 +0800
From:	Rong Wang <wr011235813@...il.com>
To:	Peter Chen <peter.chen@...escale.com>
Cc:	Greg KH <gregkh@...uxfoundation.org>, balbi@...com,
	Arnd Bergmann <arnd@...db.de>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Rong.Wang@....com
Subject: Re: [PATCH] usb: udc: add gadget state kobject uevent

Hi Peter,


On Wed, Jul 17, 2013 at 10:36 AM, Peter Chen <peter.chen@...escale.com> wrote:
> On Mon, Jul 15, 2013 at 11:31:17PM -0700, Greg KH wrote:
>> On Tue, Jul 16, 2013 at 11:49:07AM +0800, Rong Wang wrote:
>> > Hi Greg,
>> >
>> > The USB on our platform can change roles between HOST and GADGET, but
>> > it is not capable of OTG.
>>
>> That kind of sounds like the definition of OTG :)
>>
>> > When the USB changes between roles the udev will run some scripts
>> > automatically according to the udev rules.
>>
>> What exactly does udev/userspace see when the roles change?
>>
>> And what can trigger the change in roles?
>>
>> > The default role is GADGET, and we bind the g_mass_storage to the USB
>> > GADGET role.
>> >
>> > We should secure the back end file storage between the device and the
>> > host PC connecting to our device.
>> > We need to know when the GADGET is really connect to a host PC, then
>> > we can umount the file on the device
>> > and export it to the g_mass_storage.
>>
>> I thought you already get an event for this, otherwise no one would be
>> able to properly deal with this.
>>
>> > The question is since we default GADGET, so the g_mass_storage.ko is
>> > installed early but connecting to a host PC
>> > is randomly, But the udev has no idea when a host PC connects our device.
>> >
>> > So we consider it's reasonable to let the udev know the GADGET device state.
>> > Is there any alternative to our question?
>>
>> I thought we already export events for gadget device states, have you
>> looked for them?  I can't dig through the code at the moment, but this
>> seems like a pretty common issue...
>>
>
> If I understand correctly,  what Rong wants is udev can be notified the
> udc state changes, like connect/disconnect event. Currently, we only
> export it to /sys.

OK. Thanks for your share.

And you develop a new utility rather than udev to monitor that file?
And you probably create a work queue in your udc driver to do this work?

>
> --
>
> Best Regards,
> Peter Chen
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-usb" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/