Messages in this thread |  | | | Date | Sat, 23 Jan 2010 10:49:16 +0100 | | From | Uwe Kleine-König <> | | Subject | Re: [PATCH] platform_driver_register: warn if probe is in .init.text |
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Helle Dmitry,
On Fri, Jan 22, 2010 at 03:49:37PM -0800, Dmitry Torokhov wrote: > On Fri, Jan 22, 2010 at 08:49:18PM +0100, Uwe Kleine-König wrote: > > +int platform_driver_register(struct platform_driver *drv) > > +{ > > + int ret = __platform_driver_register(drv); > > + > > +#if defined(CONFIG_HOTPLUG) > > + /* > > + * drivers that are registered by platform_driver_register > > + * should not have their probe function in .init.text. The > > + * reason is that a probe can happen after .init.text is > > + * discarded which then results in an oops. The alternatives > > + * are using .devinit.text for the probe function or "register" > > + * with platform_driver_probe. > > + */ > > > What about CONFIG_MODULE case (without hotplug)? The driver may be > compiled in (and thus probe will be discarded) but device might be > created by a loadable module which is loaded later. I don't see the problem here. If the driver is registered using platform_driver_register and the probe function lives in .init.text it doesn't matter where the device comes from. If there is one you can unbind and bind at a later time when .init is already discarded. No?
More general, using platform_driver_register the pointer to the probe function have to stay valid as it is saved for later use, so it must not be an .init pointer.
> > + if (drv->probe && kernel_init_text_address((unsigned long)drv->probe)) > > + pr_warning("oops-warning: probe function of platform driver %s" > > + " lives in .init.text\n", drv->driver.name); > > +#else > > + /* > > + * without HOTPLUG probe functions can be discarded after the driver is > > + * loaded. > > + * There is a little chance for false positives, namely if the driver is > > + * registered after the .init sections are discarded. > > + */ > > + if (drv->probe && !kernel_init_text_address((unsigned long)drv->probe)) > > + pr_info("probably the probe function of platform driver %s can" > > + " be moved to .init.text\n", drv->driver.name); > > It really depends on the user's (or rather builder's) local > configuration so how can we make this suggestion? Can you point out a situation that makes the suggestion wrong? AFAIK there only the possibility that the driver is loaded after .init is discarded (as written in the comment).
Thanks Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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