4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guenter Roeck <li...@roeck-us.net>


[ Upstream commit 11bca0a83f83f6093d816295668e74ef24595944 ]

An interrupt storm on a bad interrupt will cause the kernel
log to be clogged.

[   60.089234] ->handle_irq():  ffffffffbe2f803f,
[   60.090455] 0xffffffffbf2af380
[   60.090510] handle_bad_irq+0x0/0x2e5
[   60.090522] ->irq_data.chip(): ffffffffbf2af380,
[   60.090553]    IRQ_NOPROBE set
[   60.090584] ->handle_irq():  ffffffffbe2f803f,
[   60.090590] handle_bad_irq+0x0/0x2e5
[   60.090596] ->irq_data.chip(): ffffffffbf2af380,
[   60.090602] 0xffffffffbf2af380
[   60.090608] ->action():           (null)
[   60.090779] handle_bad_irq+0x0/0x2e5

This was seen when running an upstream kernel on Acer Chromebook R11.  The
system was unstable as result.

Guard the log message with __printk_ratelimit to reduce the impact.  This
won't prevent the interrupt storm from happening, but at least the system
remains stable.

Signed-off-by: Guenter Roeck <li...@roeck-us.net>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: Dmitry Torokhov <d...@chromium.org>
Cc: Joe Perches <j...@perches.com>
Cc: Andy Shevchenko <andriy.shevche...@linux.intel.com>
Cc: Mika Westerberg <mika.westerb...@linux.intel.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=197953
Link: 
https://lkml.kernel.org/r/1512234784-21038-1-git-send-email-li...@roeck-us.net
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 kernel/irq/debug.h |    5 +++++
 1 file changed, 5 insertions(+)

--- a/kernel/irq/debug.h
+++ b/kernel/irq/debug.h
@@ -11,6 +11,11 @@
 
 static inline void print_irq_desc(unsigned int irq, struct irq_desc *desc)
 {
+       static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 5);
+
+       if (!__ratelimit(&ratelimit))
+               return;
+
        printk("irq %d, desc: %p, depth: %d, count: %d, unhandled: %d\n",
                irq, desc, desc->depth, desc->irq_count, desc->irqs_unhandled);
        printk("->handle_irq():  %p, ", desc->handle_irq);


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