Messages in this thread | | | Date | Tue, 5 May 2015 18:50:17 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] sched: Handle priority boosted tasks proper in setscheduler() |
| |
On Tue, 5 May 2015, Steven Rostedt wrote: > On Tue, 5 May 2015 18:31:20 +0200 (CEST) > Thomas Gleixner <tglx@linutronix.de> wrote: > > > On Tue, 5 May 2015, Steven Rostedt wrote: > > > I got pulled onto other things so I never finished it, but one thing > > > that worried me about this fix is this: > > > > > > T1 - FIFO policy (prio = 10) > > > lock(rtmutex); > > > > > > T2 (prio = 20) > > > lock(rtmutex) > > > boost T1 (prio = 20) > > > > > > TI (prio = 20) > > > sys_sched_setscheduler(prio = 30) > > > TI (prio = 30) > > > > > > T1 (prio = 30) > > > sys_sched_setscheduler(SCHED_OTHER) > > > new_effective_prio = 20, oldprio = 30 > > > > > > Before the code stopped at the rt_mutex_check_prio(), but now it > > > continues. Will having the policy change cause problems here? > > > > No, because it stays effective in the FIFO domain. > > > > Ah, the policy passed in isn't used, so we are safe. But, but I also > found that we still call __setscheduler(), which does: > > p->prio = normal_prio(); > > Isn't that going to null out the boosting?
Crap. Yes, I missed that. So __setscheduler() assumes that there is no boosting going on. So we need:
p->prio = effective_prio(p);
there instead.
Thanks,
tglx
| |