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Date: Thu, 13 Jan 2011 14:02:19 +0800
Message-ID: <AANLkTinsdFAkSouApSYDehtMEA41POWYF3dKvrMTO1Q9@mail.gmail.com>
Subject: Re: [patch] Re: autogroup: sched_setscheduler() fails
From: Yong Zhang <yong.zhang0@gmail.com>
To: Mike Galbraith <efault@gmx.de>
Cc: bharata@linux.vnet.ibm.com, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
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On Thu, Jan 13, 2011 at 1:59 PM, Yong Zhang <yong.zhang0@gmail.com> wrote:
> On Thu, Jan 13, 2011 at 11:54 AM, Mike Galbraith <efault@gmx.de> wrote:
>> sched, autogroup: fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure.
>>
>> If CONFIG_RT_GROUP_SCHED is set, __sched_setscheduler() fails due to autogroup
>> not allocating rt_runtime.  Free unused/unusable rt_se and rt_rq, redirect RT
>> tasks to the root task group, and tell __sched_setscheduler() that it's ok.
>>
>> Signed-off-by: Mike Galbraith <efault@gmx.de>
>> Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
>
> This looks more clear ;)
>
> And a little comment below
>
>>
>> ---
>>  kernel/sched.c           |    3 ++-
>>  kernel/sched_autogroup.c |   27 +++++++++++++++++++++++++++
>>  kernel/sched_autogroup.h |    4 ++++
>>  3 files changed, 33 insertions(+), 1 deletion(-)
>> @@ -106,6 +128,11 @@ task_wants_autogroup(struct task_struct
>>        return true;
>>  }
>>
>> +static inline bool task_group_is_autogroup(struct task_group *tg)
>> +{
>> +       return tg != &root_task_group && tg->autogroup;
>
> Isn't just checking tg->autogroup sufficient?

But if task_group_is_autogroup() will be called in other place in the future,
checking (tg != &root_task_group) is needed.

>
> if tg == &root_task_group
>
>> --- linux-2.6.orig/kernel/sched.c
>> +++ linux-2.6/kernel/sched.c
>> @@ -4874,7 +4874,8 @@ recheck:
>>                 * assigned.
>>                 */
>>                if (rt_bandwidth_enabled() && rt_policy(policy) &&
>> -                               task_group(p)->rt_bandwidth.rt_runtime == 0) {
>> +                               task_group(p)->rt_bandwidth.rt_runtime == 0 &&
>
> this check will fail.
>
> Thanks,
> Yong
>
> --
> Only stand for myself
>



-- 
Only stand for myself