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    SubjectRe: [PATCH] platform_driver_register: warn if probe is in .init.text
    Hi Greg,

    On Fri, Jun 19, 2009 at 07:11:28AM -0700, Greg KH wrote:
    > On Fri, Jun 19, 2009 at 03:42:19PM +0200, Uwe Kleine-König wrote:
    > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
    > > ---
    > > drivers/base/platform.c | 42 ++++++++++++++++++++++++++++++++++++------
    > > include/linux/kernel.h | 2 ++
    > > include/linux/module.h | 12 ++++++++++++
    > > kernel/extable.c | 12 ++++++++++++
    > > kernel/module.c | 36 ++++++++++++++++++++++++++++++++++++
    > > 5 files changed, 98 insertions(+), 6 deletions(-)
    > >
    > > diff --git a/drivers/base/platform.c b/drivers/base/platform.c
    > > index 81cb01b..851ba84 100644
    > > --- a/drivers/base/platform.c
    > > +++ b/drivers/base/platform.c
    > > @@ -470,11 +470,7 @@ static void platform_drv_shutdown(struct device *_dev)
    > > drv->shutdown(dev);
    > > }
    > >
    > > -/**
    > > - * platform_driver_register
    > > - * @drv: platform driver structure
    > > - */
    > > -int platform_driver_register(struct platform_driver *drv)
    > > +static int __platform_driver_register(struct platform_driver *drv)
    > > {
    > > drv->driver.bus = &platform_bus_type;
    > > if (drv->probe)
    > > @@ -489,6 +485,40 @@ int platform_driver_register(struct platform_driver *drv)
    > >
    > > return driver_register(&drv->driver);
    > > }
    > > +
    > > +/**
    > > + * platform_driver_register
    > > + * @drv: platform driver structure
    > > + */
    > > +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.
    > > + */
    >
    > That's not true, remember, drivers built into the system, like platform
    > ones, can have their probe function in .init.text, as it will be called
    > before we discard .init.text, and will never be called again as the
    > device will never be "hot added" at any future time.
    >
    > So this could trigger a lot of false positives :(
    IMHO this is not a false positive. You can still do

    for f in unbind bind do echo $deviceid > /sys/bus/platform/drivers/$drivername/$f; done

    This type of driver should use platform_driver_probe.

    Best regards
    Uwe

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