On Fri, Nov 30, 2007 at 05:10:33PM -0500, Alan Stern wrote: > On Fri, 30 Nov 2007, Greg KH wrote: > > > Ok, how about this: > > void kobject_init(struct kobject *kobj, struct ktype *ktype); > > > > and then: > > int kobject_add(struct kobject *kobj, struct kobject *parent, const > > char *fmt, ...); > > > > After we call kobject_init() we HAVE to call kobject_put() to clean up > > properly. So, if kobject_add() fails, we still need to clean up with > > kobject_put(); > > You could put that a little less strongly. After kobject_init() you > SHOULD call kobject_put() to clean up properly, and after kobject_add() > you MUST call kobject_del() and kobject_put(). > > However if kobject_add() is never called, or if it is called and it > fails, then it's okay to use kfree(). It's not clear whether this > distinction will matter in practice. It's probably best to document > this using your stronger description.
No, if kobject_add() fails, kobject_put() still must be called in order to free up the name pointer, unless you are somehow guessing that the "kobject_set_name()" portion of kobject_add() somehow failed. And you can't know that, so you have to call kobject_put() in order to be safe and clean up everything. Now why did we not do the final kobject_put() in kobject_del() as well? Doing two calls, always in order, seems a bit strange, anyone know why it's this way? > The same sort of rule should apply to other kernel objects, like struct > device. After intialization you have to do a final _put, before that > you just do a kfree(). (And initialization cannot fail.) Yes. > > That means we _can_ create a: > > int kobject_init_and_add(struct kobject *kobj, struct ktype *ktype, > > struct kobject *parent, const char *fmt, ...); > > > > and if that fails, then again, you have to call kobject_put() to clean > > things up, right? > > Right. Because you know that the failure must have occurred in the > _add portion. Ok, good, I might get this right yet :) thanks, greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
