[PATCH] irq: Guard handle_bad_irq log messages

[Guenter Roeck <linux@roeck-us.net>]

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.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=197953
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Dmitry Torokhov <dtor@chromium.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 kernel/irq/handle.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 79f987b942b8..ad4d7a995f18 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -28,9 +28,11 @@
  */
 void handle_bad_irq(struct irq_desc *desc)
 {
+	static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 5);
 	unsigned int irq = irq_desc_get_irq(desc);
 
-	print_irq_desc(irq, desc);
+	if (__ratelimit(&ratelimit))
+		print_irq_desc(irq, desc);
 	kstat_incr_irqs_this_cpu(desc);
 	ack_bad_irq(irq);
 }
-- 
2.7.4