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

Sascha Hauer [off-list ref] writes:

On Fri, Nov 23, 2012 at 01:36:36PM +0800, Peter Chen wrote:

quoted

On Wed, Nov 21, 2012 at 03:06:29PM +0100, Michael Grzeschik wrote:

quoted

From: Marc Kleine-Budde <mkl@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