[3.13.y.z extended stable] Patch "sparc64: Do not disable interrupts in nmi_cpu_busy()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    sparc64: Do not disable interrupts in nmi_cpu_busy()

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 3554b332fcee8513ae5528ed1fd01666f133c193 Mon Sep 17 00:00:00 2001
From: "David S. Miller" <davem at davemloft.net>
Date: Mon, 11 Aug 2014 20:45:01 -0700
Subject: sparc64: Do not disable interrupts in nmi_cpu_busy()

[ Upstream commit 58556104e9cd0107a7a8d2692cf04ef31669f6e4 ]

nmi_cpu_busy() is a SMP function call that just makes sure that all of the
cpus are spinning using cpu cycles while the NMI test runs.

It does not need to disable IRQs because we just care about NMIs executing
which will even with 'normal' IRQs disabled.

It is not legal to enable hard IRQs in a SMP cross call, in fact this bug
triggers the BUG check in irq_work_run_list():

	BUG_ON(!irqs_disabled());

Because now irq_work_run() is invoked from the tail of
generic_smp_call_function_single_interrupt().

Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/sparc/kernel/nmi.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
index 6479256..fce8ab1 100644
--- a/arch/sparc/kernel/nmi.c
+++ b/arch/sparc/kernel/nmi.c
@@ -141,7 +141,6 @@ static inline unsigned int get_nmi_count(int cpu)

 static __init void nmi_cpu_busy(void *data)
 {
-	local_irq_enable_in_hardirq();
 	while (endflag == 0)
 		mb();
 }
--
1.9.1