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Date: Wed, 8 Jun 2016 09:56:12 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
        linux-kernel@vger.kernel.org, Mel Gorman <mgorman@techsingularity.net>,
        Matt Fleming <matt@codeblueprint.co.uk>,
        Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/2] sched/debug: fix deadlock when enabling sched events
Message-ID: <20160608075612.GA9369@gmail.com>
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 <50a0f7f2a5f8d69e0440c3430f06be7ccbe59903.1465322027.git.jpoimboe@redhat.com>
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* Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -789,6 +789,13 @@ static void update_curr_fair(struct rq *rq)
>  	update_curr(cfs_rq_of(&rq->curr->se));
>  }
>  
> +void trace_sched_stat_register(void)
> +{
> +#ifdef CONFIG_SCHEDSTATS
> +	force_schedstat_enabled();
> +#endif
> +}

I think it would be cleaner to provide an empty force_schedstat_enabled() 
definition in sched.h, on !CONFIG_SCHEDSTATS.

But it might make sense to further decouple schedstats from tracing?

Thanks,

	Ingo