Re: [patch, 2.6.11-rc2] sched: RLIMIT_RT_CPU_RATIO feature

[Ingo Molnar]

* Peter Williams <pwil3058@xxxxxxxxxxxxxx> wrote:

> As I understand this (and I may be wrong), the intention is that if a
> task has its RT_CPU_RATIO rlimit set to a value greater than zero then
> setting its scheduling policy to SCHED_RR or SCHED_FIFO is allowed. 

correct.

> This causes me to ask the following questions:
> 
> 1. Why is current->signal->rlim[RLIMIT_RT_CPU_RATIO].rlim_cur being used 
> in setscheduler() instead of p->signal->rlim[RLIMIT_RT_CPU_RATIO].rlim_cur?
>
> 2. What stops a task that had a non zero RT_CPU_RATIO rlimit and
> changed its policy to SCHED_RR or SCHED_FIFO from then setting
> RT_CPU_RATIO rlimit back to zero and escaping the controls?  As far as
> I can see (and, once again, I may be wrong) the mechanism for setting
> rlimits only requires CAP_SYS_RESOURCE privileges in order to increase
> the value.

you are right, both are bugs.

i've uploaded the -D6 patch that should have both fixed:

  http://redhat.com/~mingo/rt-limit-patches/

thanks,

	Ingo
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