Re: [PATCH] gpiolib: fix device_create() result check

From: Greg KH
Date: Tue Nov 03 2009 - 19:02:18 EST

On Tue, Nov 03, 2009 at 02:44:01PM -0800, Andrew Morton wrote:
> On Tue, 20 Oct 2009 20:35:23 +0400
> Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx> wrote:
> > In case of failure, device_create() returns not NULL but the error code.
> > The current code checks for non-NULL though which causes kernel oops in
> > sysfs_create_group() when device_create() fails. Check for error using
> > IS_ERR() and propagate the error value using PTR_ERR() instead of fixed
> > -ENODEV code returned now...
> Does anyone notice any missing information here?
> /**
> * device_create - creates a device and registers it with sysfs
> * @class: pointer to the struct class that this device should be registered to
> * @parent: pointer to the parent struct device of this new device, if any
> * @devt: the dev_t for the char device to be added
> * @drvdata: the data to be added to the device for callbacks
> * @fmt: string for the device's name
> *
> * This function can be used by char device classes. A struct device
> * will be created in sysfs, registered to the specified class.
> *
> * A "dev" file will be created, showing the dev_t for the device, if
> * the dev_t is not 0,0.
> * If a pointer to a parent struct device is passed in, the newly created
> * struct device will be a child of that device in sysfs.
> * The pointer to the struct device will be returned from the call.
> * Any further sysfs files that might be required can be created using this
> * pointer.
> *
> * Note: the struct class passed to this function must have previously
> * been created with a call to class_create().
> */
> Why do we do this to ourselves?

Because we suck at writing documentation? :)

Patches to add the one line:
"If an error happens, a PTR_ERR is returned instead of a pointer
to the device"
would be appreciated.

And yes, I like Alan's idea, that would be much nicer overall for lots
of functions like this.


greg k-h
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