[PATCH] RCU: Adjust the comment of function rcu_is_watching

[PATCH] RCU: Adjust the comment of function rcu_is_watching

[zhouzhouyi]

From: Zhouyi Zhou <zhouzhouyi@gmail.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@gmail.com>
---
 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

Re: [PATCH] RCU: Adjust the comment of function rcu_is_watching

[Paul E. McKenney]

On Mon, Oct 08, 2018 at 06:50:41AM +0000, zhouzhouyi@gmail.com wrote:
> From: Zhouyi Zhou <zhouzhouyi@gmail.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@gmail.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
>