Re: [patch V2 3/3] signal: Allow tasks to cache one sigqueue struct

[Oleg Nesterov]

On 03/11, Thomas Gleixner wrote:
>
> @@ -456,7 +460,12 @@ static void __sigqueue_free(struct sigqu
>  		return;
>  	if (atomic_dec_and_test(&q->user->sigpending))
>  		free_uid(q->user);
> -	kmem_cache_free(sigqueue_cachep, q);
> +
> +	/* Cache one sigqueue per task */
> +	if (!current->sigqueue_cache)
> +		current->sigqueue_cache = q;
> +	else
> +		kmem_cache_free(sigqueue_cachep, q);
>  }

This doesn't look right, note that __exit_signal() does
flush_sigqueue(&sig->shared_pending) at the end, after exit_task_sighand()
was already called.

I'd suggest to not add the new exit_task_sighand() helper and simply free
current->sigqueue_cache at the end of __exit_signal().

Oleg.