On Thu, Dec 5, 2013 at 5:01 PM, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > 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? Sure, that'd be fine. I'll resend these two patches with my sign-off and updated changelogs. >> 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. -- 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
