Messages in this thread | | | Date | Mon, 25 Jan 2010 09:14:39 -0800 | From | Dmitry Torokhov <> | Subject | Re: [PATCH] platform_driver_register: warn if probe is in .init.text |
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On Sat, Jan 23, 2010 at 10:49:16AM +0100, Uwe Kleine-König wrote: > 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.
You are right, without hotplug we don't try to bind to devices that come in later so we are safe to discard probe.
> 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? >
Yes.
> 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). >
The presence of CONFIG_HOTPLUG depends on particular .config, so, for example, you may not have it set while I have. So you will boot, get the suggestion, submit a patch, then I will boot and will get a warning that the probe function is in wrong section.
So in general I wonder if it is possible to request that all probe functions are marked as __devinit or not marked at all, regardless of CONFIG_HOTPLUG and CONFIG_MODULE settings.
-- Dmitry -- 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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