linux-kernel - Re: [PATCH] platform_driver_register: warn if probe is in .init.text

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Message-ID: <20100126084741.GC20792@pengutronix.de>
Date:	Tue, 26 Jan 2010 09:47:41 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Greg KH <gregkh@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform_driver_register: warn if probe is in
	.init.text

Hello,

On Mon, Jan 25, 2010 at 06:09:01AM +0900, OGAWA Hirofumi wrote:
> Uwe Kleine-König <u.kleine-koenig@...gutronix.de> writes:
> 
> > +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.
> > +	 */
> > +	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);
> > +#endif
> > +	return ret;
> > +}
> 
> Um..., can't we extend modpost or such one for this? I think the static
> analysis is better (assume the changing ->probe dynamically is really
> rare).
I like the idea and will look later into modpost if this can be done
there.

Best regards
Uwe

-- 
Pengutronix e.K.                              | Uwe Kleine-König            |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |
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