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Date:   Fri, 12 Jul 2019 17:58:59 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Joel Fernandes <joel@joelfernandes.org>
Cc:     linux-kernel@vger.kernel.org,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Bjorn Helgaas <bhelgaas@google.com>,
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        "David S. Miller" <davem@davemloft.net>, edumazet@google.com,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Josh Triplett <josh@joshtriplett.org>, keescook@chromium.org,
        kernel-hardening@lists.openwall.com,
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        Len Brown <lenb@kernel.org>, linux-acpi@vger.kernel.org,
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        Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
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        Tejun Heo <tj@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, will@kernel.org,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>
Subject: Re: [PATCH v1 1/6] rcu: Add support for consolidated-RCU reader
 checking
Message-ID: <20190712155859.GV3419@hirez.programming.kicks-ass.net>
References: <20190711234401.220336-1-joel@joelfernandes.org>
 <20190711234401.220336-2-joel@joelfernandes.org>
 <20190712111125.GT3402@hirez.programming.kicks-ass.net>
 <20190712151051.GB235410@google.com>
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On Fri, Jul 12, 2019 at 11:10:51AM -0400, Joel Fernandes wrote:
> Agreed, I will do it this way (without the debug_locks) like:
> 
> ---8<-----------------------
> 
> diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
> index ba861d1716d3..339aebc330db 100644
> --- a/kernel/rcu/update.c
> +++ b/kernel/rcu/update.c
> @@ -296,27 +296,15 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
>  
>  int rcu_read_lock_any_held(void)
>  {
>  	if (!debug_lockdep_rcu_enabled())
>  		return 1;
>  	if (!rcu_is_watching())
>  		return 0;
>  	if (!rcu_lockdep_current_cpu_online())
>  		return 0;
> +	if (lock_is_held(&rcu_lock_map) || lock_is_held(&rcu_sched_lock_map))
> +		return 1;
> +	return !preemptible();
>  }
>  EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);

OK, that looks sane. Thanks!