Commit 35a5fe69 authored Dec 05, 2013 by Bjorn Helgaas Committed by Greg Kroah-Hartman Dec 07, 2013

kobject: remove kset from sysfs immediately in kset_unregister()

There's no "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.
Without this, every caller has to call "kobject_del(&kset->kobj)" first
unless it knows it will never create a new kset with the same name.

This sometimes shows up on module unload and reload, where the reload fails
because it tries to create a kobject with the same name as one from the
original load that still exists. CONFIG_DEBUG_KOBJECT_RELEASE=y makes this
problem easier to hit.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 89c86a64

Documentation/kobject.txt

+4 −1

Original line number	Diff line number	Diff line
		@@ -342,7 +342,10 @@ kset use:

		When you are finished with the kset, call:
		void kset_unregister(struct kset *kset);
		to destroy it.
		to destroy it. This removes the kset from sysfs and decrements its reference
		count. When the reference count goes to zero, the kset will be released.
		Because other references to the kset may still exist, the release may happen
		after kset_unregister() returns.

		An example of using a kset can be seen in the
		samples/kobject/kset-example.c file in the kernel tree.

lib/kobject.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -855,6 +855,7 @@ void kset_unregister(struct kset *k)
		{
		if (!k)
		return;
		kobject_del(&k->kobj);
		kobject_put(&k->kobj);
		}

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