Re: [PATCH] sched: Handle priority boosted tasks proper in setscheduler()

[Thomas Gleixner <tglx@linutronix.de>]

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.

Thanks,

	tglx