[PATCH RT 3/5] powerpc/64bit,PREEMPT_RT: Check preempt_count before preempting

[Steven Rostedt <rostedt@goodmis.org>]

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From: Priyanka Jain <Priyanka.Jain@freescale.com>

In ret_from_except_lite() with CONFIG_PREEMPT enabled,
add the missing check to compare value of preempt_count
with zero before continuing with preemption process of
the current task.
If preempt_count is non-zero, restore reg and return,
else continue the preemption process.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/powerpc/kernel/entry_64.S |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index a9b98cc..7af1ea7 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -596,6 +596,8 @@ resume_kernel:
 #ifdef CONFIG_PREEMPT
 	/* Check if we need to preempt */
 	lwz	r8,TI_PREEMPT(r9)
+	cmpwi	0,r8,0		/* if non-zero, just restore regs and return */
+	bne	restore
 	andi.	r0,r4,_TIF_NEED_RESCHED
 	bne+	1f
 
-- 
1.7.10.4