`On Thu, Nov 08, 2018 at 12:15:05AM +0800, Muchun Song wrote:> We use a value to represent the priority of the RT task. But a smaller> value corresponds to a higher priority. If there are two RT task A and B,> their priorities are prio_a and prio_b, respectively. If prio_a is larger> than prio_b, which means that the priority of RT task A is lower than RT> task B. It may seem a bit strange.> > In rt.c, there are many if condition of priority comparison. We need to> think carefully about which priority is higher because of this opposite> logic when read those code. So we introduce prio_{higher,lower}() helper> for comparing RT task prority, which can make code more readable.> > Signed-off-by: Muchun Song <smuchun@gmail.com>> --->  kernel/sched/rt.c | 68 ++++++++++++++++++++++++++++++++--------------->  1 file changed, 46 insertions(+), 22 deletions(-)> > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c> index 9aa3287ce301..adf0f653c963 100644> --- a/kernel/sched/rt.c> +++ b/kernel/sched/rt.c> @@ -101,6 +101,28 @@ void init_rt_rq(struct rt_rq *rt_rq)>  	raw_spin_lock_init(&rt_rq->rt_runtime_lock);>  }> > +/**> + * prio_higher(a, b) returns true if the priority a> + * is higher than the priority b.> + */> +static inline bool prio_higher(int a, int b)> +{> +	return a < b;> +}> +> +#define prio_lower(a, b)	prio_higher(b, a)> +> +/**> + * prio_higher_eq(a, b) returns true if the priority a> + * is higher than or equal to the priority b.> + */> +static inline bool prio_higher_eq(int a, int b)> +{> +	return a <= b;> +}> +> +#define prio_lower_eq(a, b)	prio_higher_eq(b, a)I think you only need the less thing, because:static inline bool prio_lower(int a, int b){	return a > b;}prio_higher(a,b) := prio_lower(b,a)prio_higher_eq(a,b) := !prio_lower(a,b)prio_lower_eq(a,b) := !prio_lower(b,a)Now, I'm not sure if that actually improves readability if you go aroundand directly substitute those identities instead of doing those defines.The other option is of course to flip the in-kernel priority range theright way up, but that's a much more difficult patch and will terminallyconfuse people for a while.`