On Thu 2019-05-02 18:31:27, Tobin C. Harding wrote:
> On Thu, May 02, 2019 at 09:30:44AM +0200, Petr Mladek wrote:
> > On Thu 2019-05-02 09:12:32, Greg Kroah-Hartman wrote:
> > > On Thu, May 02, 2019 at 12:31:42PM +1000, Tobin C. Harding wrote:
> > > > Currently we use custom logic to track kobject initialization. Recently
> > > > a predicate function was added to the kobject API so we now no longer
> > > > need to do this.
> > > >
> > > > Use kobject API to check for initialized state of kobjects instead of
> > > > using custom logic to track state.
> > > >
> > > > Signed-off-by: Tobin C. Harding <tobin@xxxxxxxxxx>
> > > > ---
> > > > include/linux/livepatch.h | 6 ------
> > > > kernel/livepatch/core.c | 18 +++++-------------
> > > > 2 files changed, 5 insertions(+), 19 deletions(-)
> > > >
> > > > @@ -626,7 +626,7 @@ static void __klp_free_objects(struct klp_patch *patch, bool nops_only)
> > > > list_del(&obj->node);
> > > >
> > > > /* Might be called from klp_init_patch() error path. */
> > > > - if (obj->kobj_added) {
> > > > + if (kobject_is_initialized(&obj->kobj)) {
> > > > kobject_put(&obj->kobj);
> > > > } else if (obj->dynamic) {
> > > > klp_free_object_dynamic(obj);
> > >
> > > Same here, let's not be lazy.
> > >
> > > The code should "know" if the kobject has been initialized or not
> > > because it is the entity that asked for it to be initialized. Don't add
> > > extra logic to the kobject core (like the patch before this did) just
> > > because this one subsystem wanted to only write 1 "cleanup" function.
> >
> > We use kobject for a mix of statically and dynamically defined
> > structures[*]. And we misunderstood the behavior of kobject_init().
> >
> > Anyway, the right solution is to call kobject_init()
> > already in klp_init_patch_early() for the statically
> > defined structures and in klp_alloc*() for the dynamically
> > allocated ones. Then we could simply call kobject_put()
> > every time.
> >
> > Tobin, this goes deeper into the livepatching code that
> > you probably expected. Do you want to do the above
> > suggested change or should I prepare the patch?
>
> I'd love for you to handle this one Petr, I'd say its a net gain
> time wise that way since if I do it you'll have to review it too
> carefully anyways.
>
> So that will mean patch #1 and #5 of this series are dropped and handed
> off to you (thanks). Patch #2 and #3 Greg said he will take. Patch #4
> is not needed. That's a win in my books :)
Sound like a great plan. I am going to work on the patch for
the livepatching code.
Anyway, thanks a lot for your patches. It is a big relief to realize
that we could remove some hacks and do it clearly, modulo the static
structures ;-)
Best Regards,
Petr
