[PATCH v3 3/7] usb: chipidea: usbmisc: fix a potential race condition

[Alexander Shishkin]

Sascha Hauer <s.hauer at pengutronix.de> writes:

> On Fri, Nov 23, 2012 at 01:36:36PM +0800, Peter Chen wrote:
>> On Wed, Nov 21, 2012 at 03:06:29PM +0100, Michael Grzeschik wrote:
>> > From: Marc Kleine-Budde <mkl at pengutronix.de>
>> > 
>> > This fixes a potential race condition where the ci13xxx_imx glue code
>> > could be fast enough to call one of the usbmisc_ops before he got a
>> > valid value on the static usbmisc pointer. To fix that we first set
>> > usbmisc, then call usbmisc_set_ops().
>> 
>> usbmisc is subsys_initcall, and cil13xxx_imx is module_init. Any
>> potential situation that the ci13xxx_imx's probe is ran before the
>> usbmisc's probe is completed?
>
> Not having looked at the code you are referring to at all I just want
> to say that: drivers can be modules (don't know if that's true for
> chipidea) and sooner or later we'll probably get devicetree overlays,

ChipIdea can be not even one, but two modules (ci_hdrc, the actual
controller driver, always a platform_driver) and platform bindings like
ci13xxx_imx, ci13xxx_pci, ci13xxx_msm, which can be platform or pci or
whatever else drivers.

> so the devicetree nodes might just appear during runtime. Depending on
> initcall order is generally not a good idea.

That's very true.

Regards,
--
Alex