Re: [PATCH v7 2/3] sched/task: Add the put_task_struct_atomic_safe() function

[Wander Lairson Costa]

On Thu, May 04, 2023 at 05:24:24PM +0200, Peter Zijlstra wrote:
> On Thu, May 04, 2023 at 11:55:15AM -0300, Wander Lairson Costa wrote:
> 
> > > Then I'm thinking something trivial like so:
> > >
> > > static inline void put_task_struct(struct task_struct *t)
> > > {
> > >         if (!refcount_dec_and_test(&t->usage))
> > >                 return;
> > >
> > >         if (IS_ENABLED(CONFIG_PREEMPT_RT) && !preemptible())
> > >                 call_rcu(&t->rcu, __put_task_struct_rcu);
> > >
> > >         __put_task_struct(t);
> > > }
> > >
> > 
> > That's what v5 [1] does. What would be the path in this case? Should I
> > resend it as v8?
> 
> It's almost what v5 does. v5 also has a !in_task() thing. v5 also
> violates codingstyle :-)

IIRC, the in_task() is there because preemptible() doesn't check if it
is running in interrupt context.

> 
> But yeah.. something like that.
>