On Sun, May 24, 2020 at 5:31 PM Greg Kroah-Hartman
<gre...@linuxfoundation.org> wrote:
>
> It is possible for a KOBJ_REMOVE uevent to be sent to userspace way
> after the files are actually gone from sysfs, due to how reference
> counting for kobjects work. This should not be a problem, but it would
> be good to properly send the information when things are going away, not
> at some later point in time in the future.
>
> Before this move, if a kobject's parent was torn down before the child,
> when the call to kobject_uevent() happened, the parent walk to try to
> reconstruct the full path of the kobject could be a total mess and cause
> crashes. It's not good to try to tear down a kobject tree from top
> down, but let's at least try to not to crash if a user does so.
>
> Cc: "Rafael J. Wysocki" <raf...@kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
LGTM
Reviewed-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> ---
> lib/kobject.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/lib/kobject.c b/lib/kobject.c
> index 83198cb37d8d..2509e22ad74a 100644
> --- a/lib/kobject.c
> +++ b/lib/kobject.c
> @@ -620,6 +620,13 @@ void kobject_del(struct kobject *kobj)
> if (ktype)
> sysfs_remove_groups(kobj, ktype->default_groups);
>
> + /* send "remove" if the caller did not do it but sent "add" */
> + if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
> + pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
> + kobject_name(kobj), kobj);
> + kobject_uevent(kobj, KOBJ_REMOVE);
> + }
> +
> sysfs_remove_dir(kobj);
> sysfs_put(sd);
>
> @@ -673,13 +680,6 @@ static void kobject_cleanup(struct kobject *kobj)
> pr_debug("kobject: '%s' (%p): does not have a release()
> function, it is broken and must be fixed. See Documentation/kobject.txt.\n",
> kobject_name(kobj), kobj);
>
> - /* send "remove" if the caller did not do it but sent "add" */
> - if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
> - pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event\n",
> - kobject_name(kobj), kobj);
> - kobject_uevent(kobj, KOBJ_REMOVE);
> - }
> -
> /* remove from sysfs if the caller did not do it */
> if (kobj->state_in_sysfs) {
> pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
> --
> 2.26.2
>
