[tip:core/rcu] rcu: Cleanup: balance rcu_irq_enter()/rcu_irq_exit() calls

tip-bot for Lai Jiangshan
2009-11-02T16:19:21Z

Commit-ID: c5e0cb3ddc5f14cedcfc50c0fb3b5fc6b56576da
Gitweb: http://git.kernel.org/tip/c5e0cb3ddc5f14cedcfc50c0fb3b5fc6b56576da
Author: Lai Jiangshan <laijs@cn.fujitsu.com>
AuthorDate: Wed, 28 Oct 2009 08:14:48 -0700
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 2 Nov 2009 16:06:37 +0100

rcu: Cleanup: balance rcu_irq_enter()/rcu_irq_exit() calls

Currently, rcu_irq_exit() is invoked only for CONFIG_NO_HZ,
while rcu_irq_enter() is invoked unconditionally. This patch
moves rcu_irq_exit() out from under CONFIG_NO_HZ so that the
calls are balanced.

This patch has no effect on the behavior of the kernel because
both rcu_irq_enter() and rcu_irq_exit() are empty for
!CONFIG_NO_HZ, but the code is easier to understand if the calls
are obviously balanced in all cases.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12567428891605-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/softirq.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index f8749e5..21939d9 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -302,9 +302,9 @@ void irq_exit(void)
if (!in_interrupt() && local_softirq_pending())
invoke_softirq();

+ rcu_irq_exit();
#ifdef CONFIG_NO_HZ
/* Make sure that timer wheel updates are propagated */
- rcu_irq_exit();
if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched())
tick_nohz_stop_sched_tick(0);
#endif