On Tue, Dec 03, 2013 at 03:41:43PM -0700, Bjorn Helgaas wrote: > [+cc Matt, Tejun] > > On Tue, Dec 03, 2013 at 10:04:25AM -0800, Greg Kroah-Hartman wrote: > > On Tue, Oct 08, 2013 at 02:20:16PM -0600, Bjorn Helgaas wrote: > > > There's no explicit "unlink from sysfs" interface for ksets, so I think > > > callers of kset_unregister() expect the kset to be removed from sysfs > > > immediately, without waiting for the last reference to be released. > > > > > > This patch makes the sysfs removal happen immediately, so the caller may > > > create a new kset with the same name as soon as kset_unregister() returns. > > > > > > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > > With the PCI MSI attribute change, this patch is no longer needed, > > right? > > Well, yes and no. The attached patch extends Russell's delayed kobject > release to make the delay somewhat random. I *think* that should be > valid, but correct me if I'm wrong. Heh, I like it, mind if I queue it up? > With the random delay patch, it's easy to trigger the "sysfs: cannot > create duplicate filename" error, e.g., by unloading and reloading the > edd module, because the module unload only waits for the /sys/module/edd > object to be released. Other objects, such as the /sys/firmware/edd > kset, may be released later. > > Modules like edd could be changed to explicitly call kobject_del() on > the kset kobject. Maybe that's a better approach, so we consistently > use kobject_del() to remove things from sysfs. But I don't know whether > it's really useful to allow the kset to hang around in sysfs after > kset_unregister(), and it's sort of subtle to track down problems like > this. > > Several other kset_unregister() callers have this situation, so if we > don't change it to call kobject_del() internally, maybe we should add a > note to Documentation/kobject.txt about calling kobject_del() first. > The existing hint only talks about using it when you need a two-stage > delete, which isn't really the case here. > > If we *do* decide to change kset_unregister(), I have an updated > documentation patch that makes it more clear that the release may > happen after kset_unregister() returns. Ok, I'll take this patch, it makes sense on the module unload path for example. Thanks for the explanation. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
