On Tue, May 03, 2011 at 05:46:05PM -0400, Robert P. J. Day wrote:
>
> still perusing various drivers to use as examples in class, and i
> ran across this snippet in the load routine of drivers/char/raw.c:
>
> ===== start excerpt =====
>
> cdev_init(&raw_cdev, &raw_fops);
> ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
> if (ret) {
> kobject_put(&raw_cdev.kobj);
> goto error_region;
> }
>
> ===== end =====
>
> of course it's wise to check the return code from cdev_add() to make
> sure it worked, but is it really necessary to call kobject_put()
> there?
No, that is wrong. No one should ever mess with the kobject in a cdev.
I want to call it something other than a kobject, as it's not really
used as you would think of a kobject (it's used in the hash lookup of
the object when userspace opens a chardev, it has nothing to do with
sysfs.)
> i don't recall other character drivers calling that if they
> note that cdev_add() failed. it's probably harmless, but it can't be
> necessary, can it? unless that driver is doing something unusual
> somewhere else in its code.
Hopefully not.
Nice auditing, you are going to start sending patches for this, right?
:)
thanks,
greg k-h
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