linux-kernel - Re: [PATCH] RCU: Adjust the comment of function rcu_is

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Date:   Mon, 8 Oct 2018 21:05:41 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     zhouzhouyi@...il.com
Cc:     josh@...htriplett.org, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RCU: Adjust the comment of function rcu_is_watching

On Mon, Oct 08, 2018 at 06:50:41AM +0000, zhouzhouyi@...il.com wrote:
> From: Zhouyi Zhou <zhouzhouyi@...il.com>
> 
> Because RCU avoids interrupting idle CPUs, rcu_is_watching is used to
> test whether or not it is currently legal to run RCU read-side 
> critical sections on this CPU. 
> 
> First sentence and last sentence of current comment for rcu_is_watching
> have opposite meaning of what is expected.  
> 
> Signed-off-by: Zhouyi Zhou <zhouzhouyi@...il.com>

Good eyes!  Applied and pushed, thank you!

							Thanx, Paul

> ---
>  kernel/rcu/tree.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 0b760c1..adb04ea 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1010,12 +1010,12 @@ void rcu_irq_enter_irqson(void)
>  }
> 
>  /**
> - * rcu_is_watching - see if RCU thinks that the current CPU is idle
> + * rcu_is_watching - see if RCU thinks that the current CPU is not idle
>   *
>   * Return true if RCU is watching the running CPU, which means that this
>   * CPU can safely enter RCU read-side critical sections.  In other words,
> - * if the current CPU is in its idle loop and is neither in an interrupt
> - * or NMI handler, return true.
> + * if the current CPU is not in its idle loop or is in an interrupt or
> + * NMI handler, return true.
>   */
>  bool notrace rcu_is_watching(void)
>  {
> -- 
> 2.1.4
>