Re: [PATCH v2 6/8] binder: allow freeze notification for dead nodes

[Carlos Llamas]

On Mon, Sep 30, 2024 at 03:30:01PM +0200, Alice Ryhl wrote:
> On Fri, Sep 27, 2024 at 6:32 PM Carlos Llamas <cmllamas@xxxxxxxxxx> wrote:
> >
> > There are different ways to proceed with this dead node scenario:
> >
> > 1. return ESRCH
> > 2. silently fail and don't allocate a ref->freeze
> > 3. allocate a ref->freeze but don't notify the current state
> > 4. allocate and send a "fake" state notification.
> >
> > I like 1 just because it is technically the correct thing to do from the
> > driver's perspective. However, it does complicate things in userspace as
> > we've discussed. Option 2, could work but it would also fail with EINVAL
> > if a "clear notification" is sent later anyway. Option 3 changes the
> > behavior of guaranteeing a notification upon success. Option 4 can cause
> > trouble on how a "not-frozen" notification is handled in userspace e.g
> > start sending transactions.
> >
> > As you can see there is no clear winner here, we have to compromise
> > something and option #3 is the best we can do IMO.
> 
> I am happy with both #3 and #4. I think #1 and #2 are problematic
> because they will lead to userspace getting errors on correct use of
> Binder.

After talking with userspace folks it seems that #3 would be their
preferred approach. So this v2 patch it the way to go then!

Thanks,
Carlos Llamas