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SubjectRe: [patch 34/39] tick: broadcast-hrtimer: Remove overly clever return value abuse
On 04/15/2015 02:39 AM, Thomas Gleixner wrote:
> The assignment of bc_moved in the conditional construct relies on the
> fact that in the case of hrtimer_start() invocation the return value
> is always 0. It took me a while to understand it.
>
> We want to get rid of the hrtimer_start() return value. Open code the
> logic which makes it readable as well.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
> ---
> kernel/time/tick-broadcast-hrtimer.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> Index: tip/kernel/time/tick-broadcast-hrtimer.c
> ===================================================================
> --- tip.orig/kernel/time/tick-broadcast-hrtimer.c
> +++ tip/kernel/time/tick-broadcast-hrtimer.c
> @@ -66,9 +66,11 @@ static int bc_set_next(ktime_t expires,
> * hrtimer_{start/cancel} functions call into tracing,
> * calls to these functions must be bound within RCU_NONIDLE.
> */
> - RCU_NONIDLE(bc_moved = (hrtimer_try_to_cancel(&bctimer) >= 0) ?
> - !hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED) :
> - 0);
> + RCU_NONIDLE({
> + bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0;
> + if (bc_moved)
> + hrtimer_start(&bctimer, expires,
> + HRTIMER_MODE_ABS_PINNED);});
> if (bc_moved) {
> /* Bind the "device" to the cpu */
> bc->bound_on = smp_processor_id();

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>



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