linux-kernel - [PATCH tip/core/rcu] Fix TINY_RCU rcu_is_cpu_rrupt_from

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Message-ID: <20121116192625.GA447@linux.vnet.ibm.com>
Date:	Fri, 16 Nov 2012 11:26:25 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, edumazet@...gle.com, darren@...art.com,
	fweisbec@...il.com, sbw@....edu, patches@...aro.org
Subject: [PATCH tip/core/rcu] Fix TINY_RCU rcu_is_cpu_rrupt_from_idle check

The rcu_is_cpu_rrupt_from_idle() needs to allow for one interrupt level
from the idle loop, but TINY_RCU checks for a call from the idle loop
itself.  This commit fixes this issue.

Reported-by: Josh Triplett <josh@...htriplett.org>
Signed-off-by: Paul E. McKenney <paul.mckenney@...aro.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

 b/kernel/rcutiny.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index e4c6a59..e7dce58 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -195,7 +195,7 @@ EXPORT_SYMBOL(rcu_is_cpu_idle);
  */
 int rcu_is_cpu_rrupt_from_idle(void)
 {
-	return rcu_dynticks_nesting <= 0;
+	return rcu_dynticks_nesting <= 1;
 }
 
 /*

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