Re: [PATCH] cred: Use RCU primitives to access RCU pointers

Oleg Nesterov
2020-01-28T12:38:48Z

On 01/28, Jann Horn wrote:
>
> On Tue, Jan 28, 2020 at 12:48 PM Oleg Nesterov <oleg@redhat.com> wrote:
> > On 01/28, Jann Horn wrote:
> > > On Tue, Jan 28, 2020 at 8:28 AM Amol Grover <frextrite@gmail.com> wrote:
> > > > task_struct.cred and task_struct.real_cred are annotated by __rcu,
> > >
> > > task_struct.cred doesn't actually have RCU semantics though, see
> > > commit d7852fbd0f0423937fa287a598bfde188bb68c22. For task_struct.cred,
> > > it would probably be more correct to remove the __rcu annotation?
> >
> > Yes, but get_task_cred() assumes it has RCU semantics...
>
> Oh, huh. AFAICS get_task_cred() makes no sense semantically, and I
> think it ought to be deleted.

Ah, sorry for noise Jann. Somehow I managed to missread this function
as if it uses task->cred. No, it reads ->real_cred so it is fine.

Oleg.