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kobject: send KOBJ_REMOVE uevent when the object is removed from sysfs

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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.

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20200524153041.2361-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2020-05-24 17:30:41 +02:00
parent f7d8f3f092
commit 0e5596c54a
1 changed files with 7 additions and 7 deletions
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14
lib/kobject.c
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@ -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",