linux-kernel - [PATCH tip/core/rcu 07/14] rcu: Adjust the comment of function rcu_is

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Date:   Sun, 11 Nov 2018 11:28:57 -0800
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        Zhouyi Zhou <zhouzhouyi@...il.com>,
        "Paul E . McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 07/14] rcu: Adjust the comment of function rcu_is_watching

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.  However, the first sentence and last sentences
of current comment for rcu_is_watching have opposite meaning of what
is expected.  This commit therefore fixes this header comment.

Signed-off-by: Zhouyi Zhou <zhouzhouyi@...il.com>
Signed-off-by: Paul E. McKenney <paulmck@...ux.ibm.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 e7c9848d1e1b..429a46fb087a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -904,12 +904,12 @@ 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)
 {
-- 
2.17.1