[2/9] driver core fixes: device_register() retval check in platform.c

[2/9] driver core fixes: device_register() retval check in platform.c

[Cornelia Huck]

From: Cornelia Huck <cornelia.huck@de.ibm.com>

Check the return value of device_register() in platform_bus_init().

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/base/platform.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- linux-2.6-CH.orig/drivers/base/platform.c
+++ linux-2.6-CH/drivers/base/platform.c
@@ -563,8 +563,15 @@ EXPORT_SYMBOL_GPL(platform_bus_type);
 
 int __init platform_bus_init(void)
 {
-	device_register(&platform_bus);
-	return bus_register(&platform_bus_type);
+	int error;
+
+	error = device_register(&platform_bus);
+	if (error)
+		return error;
+	error =  bus_register(&platform_bus_type);
+	if (error)
+		device_unregister(&platform_bus);
+	return error;
 }
 
 #ifndef ARCH_HAS_DMA_GET_REQUIRED_MASK

Re: [2/9] driver core fixes: device_register() retval check in platform.c

[Russell King]

On Fri, Sep 22, 2006 at 11:36:55AM +0200, Cornelia Huck wrote:
> From: Cornelia Huck <cornelia.huck@de.ibm.com>
> 
> Check the return value of device_register() in platform_bus_init().
> 
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> 
> ---
>  drivers/base/platform.c |   11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> --- linux-2.6-CH.orig/drivers/base/platform.c
> +++ linux-2.6-CH/drivers/base/platform.c
> @@ -563,8 +563,15 @@ EXPORT_SYMBOL_GPL(platform_bus_type);
>  
>  int __init platform_bus_init(void)
>  {
> -	device_register(&platform_bus);
> -	return bus_register(&platform_bus_type);
> +	int error;
> +
> +	error = device_register(&platform_bus);
> +	if (error)
> +		return error;
> +	error =  bus_register(&platform_bus_type);
> +	if (error)
> +		device_unregister(&platform_bus);
> +	return error;

I don't think there's much value in patches such as this - if the
platform bus type didn't register, what happens when we then try
to register a platform device driver or a platform device?  ISTR
doing that before the bus type is registered leads to an OOPS.

So, presumably to do this properly, if the platform_bus_type failed
to register, you need to force all platform device/platform device
driver registrations to also fail.

At that point, is the added complexity really worth it?

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core

Re: [2/9] driver core fixes: device_register() retval check in platform.c

[Cornelia Huck]

On Sat, 23 Sep 2006 22:10:32 +0100,
Russell King <rmk+lkml@arm.linux.org.uk> wrote:

> I don't think there's much value in patches such as this - if the
> platform bus type didn't register, what happens when we then try
> to register a platform device driver or a platform device?  ISTR
> doing that before the bus type is registered leads to an OOPS.

Yes, since the klists have not yet been initialized.

> So, presumably to do this properly, if the platform_bus_type failed
> to register, you need to force all platform device/platform device
> driver registrations to also fail.

We should fail registration (gracefully) of all devices/drivers which
specify a bus that is !NULL but has not been registered. Unfortunately,
I don't see an easy way to do this.

However, we can fail the registration of devices that specify a parent
that is !NULL but not yet added to the tree. This catches platform
devices registering before platform_bus_type (since platform_bus is not
registered then), similar for other bus types like iucv.
(Unfortunately, not drivers...)


From: Cornelia Huck <cornelia.huck@de.ibm.com>

Force parent devices to be registered before their children. Otherwise we'll
oops when creating the child's sysfs directory.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/base/bus.c  |    6 ++++--
 drivers/base/core.c |    5 ++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

--- linux-2.6.18-mm1.orig/drivers/base/core.c
+++ linux-2.6.18-mm1/drivers/base/core.c
@@ -474,7 +474,10 @@ int device_add(struct device *dev)
 	}
 
 	parent = get_device(dev->parent);
-
+	if (parent && !device_is_registered(parent)) {
+		error = -EINVAL;
+		goto Error;
+	}
 	pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
 
 	/* first, register with generic layer. */
--- linux-2.6.18-mm1.orig/drivers/base/bus.c
+++ linux-2.6.18-mm1/drivers/base/bus.c
@@ -418,7 +418,8 @@ int bus_attach_device(struct device * de
 			ret = 0;
 		} else
 			dev->is_registered = 0;
-	}
+	} else
+		dev->is_registered = 1;
 	return ret;
 }
 
@@ -443,7 +444,8 @@ void bus_remove_device(struct device * d
 		pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
 		device_release_driver(dev);
 		put_bus(dev->bus);
-	}
+	} else
+		dev->is_registered = 0;
 }
 
 static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)