| Message ID | 20201019153232.1.I797f9874972a07fc381fe586b6748ce71c7b1fda@changeid (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | kobject: Don't emit change events if not in sysfs | expand |
On Mon, Oct 19, 2020 at 03:32:57PM -0700, Abhishek Pandit-Subedi wrote: > Add a check to make sure the kobj is created and in sysfs before sending > a change event notification. Otherwise, udev rules that depend on the > change notification may find that the path that changed doesn't actually > exist. Why is the user of the kobject trying to emit a uevent before it is registered? Shouldn't we fix the root problem here instead? Otherwise the event is still "gone", the caller will not know what to do about it. Please fix the root problem here. thanks, greg k-h
Hi Greg, I was debugging without a live repro and I was told this patch improved behavior but it's only by chance (someone bisected a Dell D6000 dock's displayport issue to this commit and this change seemed to help; udev logs later shows that's not the case). I took another look at device_init_wakeup and I can see that device_set_wakeup_capable does indeed check for device_is_registered before adding the wakeup attributes so the ordering of events I suspected cannot occur. Thanks for pushing back Greg. It made me take a deeper look at an assumption I hadn't challenged. Please consider this patch abandoned. Abhishek On Mon, Oct 19, 2020 at 10:56 PM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Mon, Oct 19, 2020 at 03:32:57PM -0700, Abhishek Pandit-Subedi wrote: > > Add a check to make sure the kobj is created and in sysfs before sending > > a change event notification. Otherwise, udev rules that depend on the > > change notification may find that the path that changed doesn't actually > > exist. > > Why is the user of the kobject trying to emit a uevent before it is > registered? Shouldn't we fix the root problem here instead? Otherwise > the event is still "gone", the caller will not know what to do about it. > > Please fix the root problem here. > > thanks, > > greg k-h
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index 7998affa45d49a..f08197e907d5ce 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -473,6 +473,11 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, if (action == KOBJ_REMOVE) kobj->state_remove_uevent_sent = 1; + if (action == KOBJ_CHANGE && !kobj->state_in_sysfs) { + pr_debug("kobject: can't emit KOBJ_CHANGE until in sysfs\n"); + return -EINVAL; + } + pr_debug("kobject: '%s' (%p): %s\n", kobject_name(kobj), kobj, __func__);
Add a check to make sure the kobj is created and in sysfs before sending a change event notification. Otherwise, udev rules that depend on the change notification may find that the path that changed doesn't actually exist. Fixes: a45aca510b73b7 (PM: sleep: core: Emit changed uevent on wakeup_sysfs_add/remove) Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org> --- lib/kobject_uevent.c | 5 +++++ 1 file changed, 5 insertions(+)