From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Mon, 16 May 2011 21:27:31 +0000 (-0700)
Subject: rcu: Make rcu_enter_nohz() pay attention to nesting
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4305ce7894dd38b0633bfc8978437320119223bd;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git

rcu: Make rcu_enter_nohz() pay attention to nesting

The old version of rcu_enter_nohz() forced RCU into nohz mode even if
the nesting count was non-zero.  This change causes rcu_enter_nohz()
to hold off for non-zero nesting counts.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 195b3a3313e3..99c6038ad04d 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -324,8 +324,8 @@ void rcu_enter_nohz(void)
 	smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
 	local_irq_save(flags);
 	rdtp = &__get_cpu_var(rcu_dynticks);
-	rdtp->dynticks++;
-	rdtp->dynticks_nesting--;
+	if (--rdtp->dynticks_nesting == 0)
+		rdtp->dynticks++;
 	WARN_ON_ONCE(rdtp->dynticks & 0x1);
 	local_irq_restore(flags);
 }