On Sat, May 7, 2011 at 11:02 AM, Joe Perches <joe@xxxxxxxxxxx> wrote:
> On Sat, 2011-05-07 at 14:31 -0300, Rafael Aquini wrote:
>> To exemplify my point, I'll taking that very __ad_timer_to_ticks() as an example:
>> static u16 __ad_timer_to_ticks(u16 timer_type, u16 par)
>> {
>> u16 retval = 0;
>>
>> switch (timer_type) {
>> case AD_CURRENT_WHILE_TIMER: /* for rx machine usage */
>> if (par)
>> retval = (AD_SHORT_TIMEOUT_TIME*ad_ticks_per_sec);
>> else
>> retval = (AD_LONG_TIMEOUT_TIME*ad_ticks_per_sec);
>> break;
>> case AD_ACTOR_CHURN_TIMER: /* for local churn machine */
>> retval = (AD_CHURN_DETECTION_TIME*ad_ticks_per_sec);
>> break;
>> case AD_PERIODIC_TIMER: /* for periodic machine */
>> retval = (par*ad_ticks_per_sec);
>> break;
>> case AD_PARTNER_CHURN_TIMER: /* for remote churn machine */
>> retval = (AD_CHURN_DETECTION_TIME*ad_ticks_per_sec);
>> break;
>> case AD_WAIT_WHILE_TIMER: /* for selection machine */
>> retval = (AD_AGGREGATE_WAIT_TIME*ad_ticks_per_sec);
>> break;
>> }
>> return retval;
>> }
>>
>> If, for some unknown reason timer_type receives an 'alien' value, and
>> we were
>> using retval uninitialized, this function, as it is, would return an
>> unpredictable value to its caller. Unless we have the switch block
>> re-factored, we cannot leave retval uninitialized. So, it's not just a
>> matter of leaving the variable uninitialized, or initialize it just to
>> get rid of a compiler warning. That's why those comments are not
>> helpful anyway.
>
> I'd write this not using a retval variable at all as:
But isn't the preferred style to have a single exit point?
> switch (timer_type) {
> case AD_CURRENT_WHILE_TIMER: /* for rx machine usage */
> if (par)
> return AD_SHORT_TIMEOUT_TIME * ad_ticks_per_sec;
> return AD_LONG_TIMEOUT_TIME * ad_ticks_per_sec;
> case AD_ACTOR_CHURN_TIMER: /* for local churn machine */
> return AD_CHURN_DETECTION_TIME * ad_ticks_per_sec;
> ...
> }
> WARN(1, "Invalid timer type: %u\n", timer_type)
> return 0;
> }
>
>
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