[3.16.y-ckt stable] Patch "MIPS: IRQ: Fix disable_irq on CPU IRQs" has been added to staging queue

[Luis Henriques]

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

    MIPS: IRQ: Fix disable_irq on CPU IRQs

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt7.

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

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 9d1d715ca78eae52dfa34994e749c7bdc5dd0139 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd at openwrt.org>
Date: Thu, 15 Jan 2015 19:05:28 +0100
Subject: MIPS: IRQ: Fix disable_irq on CPU IRQs

commit a3e6c1eff54878506b2dddcc202df9cc8180facb upstream.

If the irq_chip does not define .irq_disable, any call to disable_irq
will defer disabling the IRQ until it fires while marked as disabled.
This assumes that the handler function checks for this condition, which
handle_percpu_irq does not. In this case, calling disable_irq leads to
an IRQ storm, if the interrupt fires while disabled.

This optimization is only useful when disabling the IRQ is slow, which
is not true for the MIPS CPU IRQ.

Disable this optimization by implementing .irq_disable and .irq_enable

Signed-off-by: Felix Fietkau <nbd at openwrt.org>
Cc: linux-mips at linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8949/
Signed-off-by: Ralf Baechle <ralf at linux-mips.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/mips/kernel/irq_cpu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/mips/kernel/irq_cpu.c b/arch/mips/kernel/irq_cpu.c
index e498f2b3646a..f5598e25e906 100644
--- a/arch/mips/kernel/irq_cpu.c
+++ b/arch/mips/kernel/irq_cpu.c
@@ -56,6 +56,8 @@ static struct irq_chip mips_cpu_irq_controller = {
 	.irq_mask_ack	= mask_mips_irq,
 	.irq_unmask	= unmask_mips_irq,
 	.irq_eoi	= unmask_mips_irq,
+	.irq_disable	= mask_mips_irq,
+	.irq_enable	= unmask_mips_irq,
 };

 /*
@@ -92,6 +94,8 @@ static struct irq_chip mips_mt_cpu_irq_controller = {
 	.irq_mask_ack	= mips_mt_cpu_irq_ack,
 	.irq_unmask	= unmask_mips_irq,
 	.irq_eoi	= unmask_mips_irq,
+	.irq_disable	= mask_mips_irq,
+	.irq_enable	= unmask_mips_irq,
 };

 void __init mips_cpu_irq_init(void)
--
2.1.4