Re: [Xen-devel] [PATCH v2 2/3] xen: RCU: make the period of the idle timer configurable.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.09.17 at 12:16, <dario.faggioli@xxxxxxxxxx> wrote:
> @@ -569,6 +579,16 @@ void __init rcu_init(void)
>  {
>      void *cpu = (void *)(long)smp_processor_id();
>  
> +    /* We don't allow 0, or anything higher than IDLE_TIMER_PERIOD_MAX */
> +    if ( idle_timer_period_ms < 1 ||

The literal 1 here looks suspicious. How about simply refusing 0
(as well as too high values)? The also simply document the value
must be non-zero in the command line doc.

> +         idle_timer_period_ms > IDLE_TIMER_PERIOD_MAX / MILLISECS(1) )
> +    {
> +        printk("WARNING: rcu-idle-timer-period-ms outside of [%d,%ld]ms!\n",
> +               1, IDLE_TIMER_PERIOD_MAX / MILLISECS(1));

Clearly the %d can be literal 1 if the above literal 1 was to stay.
If you follow my suggestion, use "(0," instead. As to the %ld -
wouldn't that rather need to be PRI_stime (due to MILLISECS()
returning s_time_t)?

And then, as a cosmetic thing, idle_timer_period_ms now isn't
really needed outside of this function. I'd prefer if you moved it
and the integer_param() into this function, to limit their scopes
as much as possible.

Jan


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