Re: [PATCH v2 2/3] locking/percpu-rwsem: Rework writer block/wake to not use wait-queues

[Oleg Nesterov]

On 12/05, Oleg Nesterov wrote:
>
> Yes, but on a second thought task_rcu_dereference() won't really help,

I forgot to explain why, see below.

> 	#define xxx_wait_event(xxx, event) {
> 		// comment to explain why
> 		WARN_ON(current->exit_state);

Otherwise this process/thread can be already (auto)reaped and wakeup
can't rely on rcu.

And task_rcu_dereference() can't help because it can return NULL in
this case.

Oleg.