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

[Peter Zijlstra]

On Thu, May 04, 2023 at 05:30:57PM +0200, Peter Zijlstra wrote:
> On Thu, May 04, 2023 at 05:23:07PM +0200, Oleg Nesterov wrote:

> > Yes, but as Sebastian explained CONFIG_PROVE_RAW_LOCK_NESTING won't like it.
> 
> This can help:
> 
>   https://lkml.kernel.org/r/168303194177.404.8610123576035502891.tip-bot2@tip-bot2

Explicitly:

static inline void put_task_struct(struct task_struct *t)
{
	if (!refcount_dec_and_test(&t->usage))
		return;

	if (!IS_ENABLED(CONFIG_PREEMPT_RT) || premptible()) {
		/*
		 * ... same comment as the other patch ...
		 */
		static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
		lock_map_acquire_try(&put_task_map);
		__put_task_struct(t);
		lock_map_release(&put_task_map);
		return;
	}

	call_rcu(&t->rcu, __put_task_struct_rcu);
}

Should not complain since we tell it to STFU :-)