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Date: Sun, 18 Oct 2009 00:51:27 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Greg KH <gregkh@...e.de>
Cc: Éric Piel <eric.piel@...mplin-utc.net>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-input@...r.kernel.org
Subject: Re: [REGRESSION] "bind" a device to a driver doesn't not work
anymore
On Mon, Oct 12, 2009 at 08:17:41PM -0700, Dmitry Torokhov wrote:
> On Mon, Oct 12, 2009 at 11:54:17AM -0700, Greg KH wrote:
> > On Mon, Oct 12, 2009 at 11:33:13AM -0700, Dmitry Torokhov wrote:
> > > On Mon, Oct 12, 2009 at 10:35:51AM -0700, Greg KH wrote:
> > > > On Mon, Oct 12, 2009 at 08:48:46AM -0700, Dmitry Torokhov wrote:
> > > > > > So at least, unbind should fail as well as bind.
> > > > > >
> > > > >
> > > > > That would be Greg's domain s it is driver core decision whether to
> > > > > allow unbinding platform devices registered with
> > > > > platform_driver_probe().
> > > >
> > > > No, I do not see why that should not be allowed.
> > > >
> > >
> > > Because once you did unbind the device you are stuck (unless the driver
> > > is compiled as a module, but then you could just unload the module
> > > instead of unbinding). Disallowing unbind would allow discarding not
> > > only __devinit but __devexit sections when driver is built in which
> > > would make ebedded people happy[^Hier].
> >
> > Yeah, good point.
> >
> > Does anyone do bind/unbind with platform devices today?
> >
> > If not, a patch changing this would be welcome.
> >
>
> How about this one?
>
*ping* We need to resolve this, otherwise everyone who likes to rebind
i8042 in couse of STR/STD will be in trouble.
> --
> Dmitry
>
>
> Driver core: allow certain drivers prohibit bind/unbind via sysfs
>
> From: Dmitry Torokhov <dmitry.torokhov@...il.com>
>
> Platform drivers registered via platform_driver_probe() can be bound
> to devices only once, upon registration, because discard their probe()
> routines to save memory. Unbinding the driver through sysfs 'unbind'
> leaves the device stranded and confuses users so let's not create
> bind and unbind attributes for such drivers.
>
> Signed-off-by: Dmitry Torokhov <dtor@...l.ru>
> ---
>
> drivers/base/bus.c | 17 +++++++++++------
> drivers/base/platform.c | 6 +++++-
> include/linux/device.h | 4 +++-
> 3 files changed, 19 insertions(+), 8 deletions(-)
>
>
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index 973bf2a..63c143e 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -689,15 +689,19 @@ int bus_add_driver(struct device_driver *drv)
> printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
> __func__, drv->name);
> }
> - error = add_bind_files(drv);
> - if (error) {
> - /* Ditto */
> - printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
> - __func__, drv->name);
> +
> + if (!drv->suppress_bind_attrs) {
> + error = add_bind_files(drv);
> + if (error) {
> + /* Ditto */
> + printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
> + __func__, drv->name);
> + }
> }
>
> kobject_uevent(&priv->kobj, KOBJ_ADD);
> return 0;
> +
> out_unregister:
> kfree(drv->p);
> drv->p = NULL;
> @@ -720,7 +724,8 @@ void bus_remove_driver(struct device_driver *drv)
> if (!drv->bus)
> return;
>
> - remove_bind_files(drv);
> + if (!drv->suppress_bind_attrs)
> + remove_bind_files(drv);
> driver_remove_attrs(drv->bus, drv);
> driver_remove_file(drv, &driver_attr_uevent);
> klist_remove(&drv->p->knode_bus);
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index ed156a1..4fa954b 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -521,11 +521,15 @@ int __init_or_module platform_driver_probe(struct platform_driver *drv,
> {
> int retval, code;
>
> + /* make sure driver won't have bind/unbind attributes */
> + drv->driver.suppress_bind_attrs = true;
> +
> /* temporary section violation during probe() */
> drv->probe = probe;
> retval = code = platform_driver_register(drv);
>
> - /* Fixup that section violation, being paranoid about code scanning
> + /*
> + * Fixup that section violation, being paranoid about code scanning
> * the list of drivers in order to probe new devices. Check to see
> * if the probe was successful, and make sure any forced probes of
> * new devices fail.
> diff --git a/include/linux/device.h b/include/linux/device.h
> index aca31bf..2ea3e49 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -124,7 +124,9 @@ struct device_driver {
> struct bus_type *bus;
>
> struct module *owner;
> - const char *mod_name; /* used for built-in modules */
> + const char *mod_name; /* used for built-in modules */
> +
> + bool suppress_bind_attrs; /* disables bind/unbind via sysfs */
>
> int (*probe) (struct device *dev);
> int (*remove) (struct device *dev);
--
Dmitry
--
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