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Subject[PATCH 2/2] kobject: send KOBJ_REMOVE uevent when the object is removed from sysfs
Date
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" <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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
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