On 5/11/22 00:08, Theodore Dubois wrote:
The translation is needed to avoid returning a negative number from a
successful syscall, and this requirement doesn't apply to setpriority.
See the implementation of getpriority in kernel/sys.c.
Confirmed. See:
$ grepc -tf getpriority kernel/
./kernel/sys.c:274:
SYSCALL_DEFINE2(getpriority, int, which, int, who)
{
...
niceval = nice_to_rlimit(task_nice(p));
if (niceval > retval)
retval = niceval;
...
return retval;
}
$ grepc -tf setpriority kernel/
./kernel/sys.c:204:
SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
{
...
if (niceval < MIN_NICE)
niceval = MIN_NICE;
if (niceval > MAX_NICE)
niceval = MAX_NICE;
...
}
$ grepc -tm M.._NICE
./include/linux/sched/prio.h:5:
#define MAX_NICE 19
./include/linux/sched/prio.h:6:
#define MIN_NICE -20
$ grepc -tf nice_to_rlimit
./include/linux/sched/prio.h:32:
static inline long nice_to_rlimit(long nice)
{
return (MAX_NICE - nice + 1);
}
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
