On Wed, 2016-08-31 at 13:51 +0200, Samuel Thibault wrote: > Svante Signell, on Wed 31 Aug 2016 13:42:58 +0200, wrote: > > > > > > Which is the original bug then? > You didn't say what application you are actually trying to fix, but the > issue you have shown is that task_priority returns permission denied > when change_threads is true (and I guessed you want that to work as > normal user). I just said that the test was expected to have issues > since the nice value is negative.
The application is openntpd, which I'm working on porting and ntpd where this call is made requires you to be root. > Now, it's not normal that a root process can't use a negative number. So > investigation is needed there. You are right: Working values are [0, 24], <0 returns EACCESS, >24 returns ESRCH (irrespective if being root or not). I would expect values [-20,19] to be OK converted to [5,44] with #define NICE_TO_MACH_PRIORITY(nice) ((nice) + 25) from hurd/hurd/resource.h and #define invalid_pri(pri) (((pri) < 0) || ((pri) >= NRQS)), where NRQS = 50 from kern/sched.h. to work. In fact, according to invalid_pri(pri) the range could be [-26,25]. but that would not make sense, right?
