Re: [PATCH 2.6.28-rc6] ACPICA: don't cond_resched() when irqs_disabled()

[Len Brown <lenb@kernel.org>]

On Fri, 19 Dec 2008, Wu Fengguang wrote:

> Hi Len,
> 
> FYI: this patch from Lin Ming will generate the following messages:
> 
> on closing lid =>                                                                                                                
>                                                                                                                                  
> [ 8993.764829] irq status before SMI: enable                                                                                     
> [ 8993.768028] irq status after SMI: disable, value: 0xF3                                                                        
>                                                                                                                                      
> on opening lid =>                                                                                                                    
>                                                                                                                                      
> [ 8987.590636] irq status before SMI: enable                                                                                         
> [ 8987.669829] irq status after SMI: enable, value: 0xF3                                                                             
> 
> ---
>  drivers/acpi/executer/exregion.c |   12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> --- linux-2.6.orig/drivers/acpi/executer/exregion.c
> +++ linux-2.6/drivers/acpi/executer/exregion.c
> @@ -300,8 +300,20 @@ acpi_ex_system_io_space_handler(u32 func
>  
>  	case ACPI_WRITE:
>  
> +		if (address == 0xB2) {
> +			printk("irq status before SMI: %s\n",
> +				irqs_disabled() ? "disable" : "enable");
> +		}
> +
>  		status = acpi_os_write_port((acpi_io_address) address,
>  					    (u32) * value, bit_width);
> +
> +		if (address == 0xB2) {
> +			printk("irq status after SMI: %s, value: 0x%X\n",
> +				irqs_disabled() ? "disable" : "enable",
> +				(u32) *value);
> +		}
> +
>  		break;
>  
>  	default:
> 
> We are now exploring how the Windows execution path manages to avoid this bug.

sigh.

It might be prudent for us to WARN_ON() the IRQ state
being different before and after any IO write -- in case
others are running into this too.

-- Len Brown, Intel Open Source Technology Center