netdev - Re: [PATCH 3/9] rcu/sync: Remove custom check for reader-section (v2)

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Date:   Tue, 16 Jul 2019 11:39:02 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Borislav Petkov <bp@...en8.de>, c0d1n61at3@...il.com,
        "David S. Miller" <davem@...emloft.net>, edumazet@...gle.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Josh Triplett <josh@...htriplett.org>, keescook@...omium.org,
        kernel-hardening@...ts.openwall.com, kernel-team@...roid.com,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-pm@...r.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        neilb@...e.com, netdev@...r.kernel.org,
        Pavel Machek <pavel@....cz>, peterz@...radead.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        rcu@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Tejun Heo <tj@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, will@...nel.org,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>
Subject: Re: [PATCH 3/9] rcu/sync: Remove custom check for reader-section (v2)

On Mon, Jul 15, 2019 at 10:36:59AM -0400, Joel Fernandes (Google) wrote:
> The rcu/sync code was doing its own check whether we are in a reader
> section. With RCU consolidating flavors and the generic helper added in
> this series, this is no longer need. We can just use the generic helper
> and it results in a nice cleanup.
> 
> Cc: Oleg Nesterov <oleg@...hat.com>
> Acked-by: Oleg Nesterov <oleg@...hat.com>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>

This one looks good!

							Thanx, Paul

> ---
>  include/linux/rcu_sync.h | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
> index 9b83865d24f9..0027d4c8087c 100644
> --- a/include/linux/rcu_sync.h
> +++ b/include/linux/rcu_sync.h
> @@ -31,9 +31,7 @@ struct rcu_sync {
>   */
>  static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
>  {
> -	RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
> -			 !rcu_read_lock_bh_held() &&
> -			 !rcu_read_lock_sched_held(),
> +	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
>  			 "suspicious rcu_sync_is_idle() usage");
>  	return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
>  }
> -- 
> 2.22.0.510.g264f2c817a-goog
>