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Subject: Re: [PATCH v3] sched/core: Fix uclamp ABI bug, clean up and robustify
 sched_read_attr() ABI logic and code
To:     Ingo Molnar <mingo@kernel.org>
Cc:     Thadeu Lima de Souza Cascardo <cascardo@canonical.com>,
        linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Patrick Bellasi <patrick.bellasi@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jiri Olsa <jolsa@redhat.com>
References: <20190903171645.28090-1-cascardo@canonical.com>
 <20190903171645.28090-2-cascardo@canonical.com>
 <20190904075532.GA26751@gmail.com> <20190904084934.GA117671@gmail.com>
 <20190904085519.GA127156@gmail.com>
 <db065b81-c373-f291-ad48-f556a209cc95@arm.com>
 <20190904103925.GA60962@gmail.com>
From:   Dietmar Eggemann <dietmar.eggemann@arm.com>
Message-ID: <43e9f6ae-7ebc-d3d8-eecf-860cdef7fdec@arm.com>
Date:   Wed, 4 Sep 2019 12:55:33 +0200
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On 04/09/2019 12:39, Ingo Molnar wrote:
> 
> * Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
> 
>>> -v3 attached. Build and minimally boot tested.
>>>
>>> Thanks,
>>>
>>> 	Ingo
>>>
>>
>> This patch fixes the issue (almost).
>>
>> LTP's sched_getattr01 passes again. But IMHO the prio 'chrt -p $$'
>> should be 0 instead of -65536.
> 
> Yeah, I forgot to zero-initialize the structure ...
> 
> Does the attached -v4 work any better for you?

Yeah, looks better now.

# chrt -p $$
[  258.245786] sched_attr_copy_to_user(): copied 48 bytes. (ksize: 56,
usize: 48)
pid 1635's current scheduling policy: SCHED_OTHER
pid 1635's current scheduling priority: 0

w/o the extra printk:

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>