Re: [PATCH] irq: Guard handle_bad_irq log messages

[Joe Perches <joe@perches.com>]

On Sat, 2017-12-02 at 08:29 -0800, Guenter Roeck wrote:
> 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.

Thanks.

There is also dummychip.c

Perhaps this should be updated in the
static inline in kernel/irq/debug.h instead.

> diff --git 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);
>  }