Re: [v2 PATCH 1/4] timers: framework to identify pinned timers.

[Oleg Nesterov <oleg@redhat.com>]

On 03/04, Arun R Bharadwaj wrote:
>
> +static inline unsigned long tbase_get_flag_bits(struct timer_list *timer)
> +{
> +	return tbase_get_deferrable(timer->base) |
> +				tbase_get_pinned(timer->base);
> +}

I'd say this looks a bit strange. Hopefully compiler can optimize this code
to return (unsigned long)base & (TBASE_DEFERRABLE_FLAG | TBASE_PINNED_FLAG).

> @@ -736,6 +759,7 @@ void add_timer_on(struct timer_list *tim
>  	struct tvec_base *base = per_cpu(tvec_bases, cpu);
>  	unsigned long flags;
>
> +	timer_set_pinned(timer);

But we never clear TBASE_PINNED_FLAG?

If we use mod_timer() next time, the timer remains "pinned". I do not say
this is really wrong, but a bit strange imho.

Oleg.