From: Mike Steiner <mike65536@xxxxxxxxx> Replaced raw nice values with constants and added macro to wrap range check with a descriptive name. Signed-off-by: Mike Steiner <mike65536@xxxxxxxxx> --- FYI, this is my first kernel patch. I ran checkpatch.pl on it and fixed the errors, except for 2 concerning spaces around "<" and ">" because it would make the code less readable. diff -up linux-2.6.27.1/kernel/sched.c new/kernel/sched.c --- linux-2.6.27.1/kernel/sched.c 2008-10-15 16:02:53.000000000 -0700 +++ new/kernel/sched.c 2008-10-16 20:37:27.000000000 -0700 @@ -24,6 +24,7 @@ * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins, * Thomas Gleixner, Mike Kravetz + * 2008-10-16 A few readability changes for nice values by Mike Steiner */ #include <linux/mm.h> @@ -77,13 +78,21 @@ #include "sched_cpupri.h" +#define MIN_NICE (-20) +#define MAX_NICE (19) + +/* + * If n is outside of range [a...z], use closest value in range. + */ +#define CONSTRAIN_TO_RANGE(a, n, z) ((n)<(a) ? (a) : ((n)>(z) ? (z) : (n))) + /* * Convert user-nice values [ -20 ... 0 ... 19 ] * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ], * and back. */ -#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20) -#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20) +#define NICE_TO_PRIO(nice) ((nice) - MIN_NICE + MAX_RT_PRIO) +#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO + MIN_NICE) #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio) /* @@ -4877,7 +4886,7 @@ void set_user_nice(struct task_struct *p unsigned long flags; struct rq *rq; - if (TASK_NICE(p) == nice || nice < -20 || nice > 19) + if (TASK_NICE(p) == nice || nice < MIN_NICE || nice > MAX_NICE) return; /* * We have to be careful, if called from sys_setpriority(), @@ -4951,16 +4960,11 @@ asmlinkage long sys_nice(int increment) * We don't have to worry. Conceptually one call occurs first * and we have a single winner. */ - if (increment < -40) - increment = -40; - if (increment > 40) - increment = 40; + increment = CONSTRAIN_TO_RANGE(-40, increment, 40); nice = PRIO_TO_NICE(current->static_prio) + increment; - if (nice < -20) - nice = -20; - if (nice > 19) - nice = 19; + + nice = CONSTRAIN_TO_RANGE(MIN_NICE, nice, MAX_NICE); if (increment < 0 && !can_nice(current, nice)) return -EPERM; -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
