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Subject: Re: [PATCH] sched/rt: silence double clock update warning by using
 rq_lock wrappers
From:   Valentin Schneider <valentin.schneider@arm.com>
To:     Phil Auld <pauld@redhat.com>, linux-kernel@vger.kernel.org
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>
References: <20190815145354.27484-1-pauld@redhat.com>
 <f094734a-eeae-02db-dd0b-d7fe7e9d5db8@arm.com>
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Date:   Mon, 16 Sep 2019 09:56:46 +0100
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[Added Steven to Cc]

On 15/08/2019 18:24, Valentin Schneider wrote:
> On 15/08/2019 15:53, Phil Auld wrote:
>> With WARN_DOUBLE_CLOCK enabled a false positive warning can occur in rt
>>
>>         [] rq->clock_update_flags & RQCF_UPDATED
>>         [] WARNING: CPU: 6 PID: 21426 at kernel/sched/core.c:225 
>> 						update_rq_clock+0x90/0x130
>>           [] Call Trace:
>>           []  update_rq_clock+0x90/0x130
>>           []  sched_rt_period_timer+0x11f/0x340
>>           []  __hrtimer_run_queues+0x100/0x280
>>           []  hrtimer_interrupt+0x100/0x220
>>           []  smp_apic_timer_interrupt+0x6a/0x130
>>           []  apic_timer_interrupt+0xf/0x20
>>
>> sched_rt_period_timer does:
>>                 raw_spin_lock(&rq->lock);
>>                 update_rq_clock(rq);
>>
>> which triggers the warning because of not using the rq_lock wrappers.
>> So, use the wrappers.
>>
>> Signed-off-by: Phil Auld <pauld@redhat.com>
>> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Valentin Schneider <valentin.schneider@arm.com>
>> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> 
> Looks sane to me, and no missing _irqsave this time around ;)
> 
> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
> 

Stumbled on that one while reviewing my inbox, ping?