RE: ACPI: disable stray GPE, prevent ACPI interrupt storm

[Zhang Rui <rui.zhang@intel.com>]

On Wed, 2007-11-21 at 07:11 +0800, Moore, Robert wrote:
> BTW, this kind of change begs for a comment
> 
Sounds good. :)

Thanks,
Rui
>     default:
>         /*
>          * Even if we don't know the GPE type, make sure that we always
>          * disable it. This can prevent a certain type of GPE flood,
> where
>          * the GPE has no _Lxx/_Exx method, and it cannot be determined

>          * whether the GPE is wake, run, or wake/run.
>          */
>         Status = AcpiHwWriteGpeEnableReg (GpeEventInfo);
>         break;
> 
> 
> >-----Original Message-----
> >From: Len Brown [mailto:lenb@kernel.org]
> >Sent: Tuesday, November 20, 2007 10:43 AM
> >To: Moore, Robert
> >Cc: linux-acpi@vger.kernel.org; Zhang, Rui; Alexey Starikovskiy
> >Subject: ACPI: disable stray GPE, prevent ACPI interrupt storm
> >
> >Bob,
> >Rui's Linux patch below modifies an ACPICA file.
> >
> >thanks,
> >-Len
> >
> >commit a7f9b1f24974da287771e2d70b30d9ca7bd66684
> >Author: Zhang Rui <rui.zhang@intel.com>
> >Date:   Tue Nov 20 13:38:59 2007 -0500
> >
> >    ACPI: disable stray GPE, prevent ACPI interrupt storm
> >
> >    GPEs are disabled depending on their type --
> >    WAKE, WAKE_RUN, and RUNTIME.  An error is returned
> >    if we are asked to disable a GPE that has no type.
> >
> >    But at least one system exists that enables a GPE from AML
> >    that is not the EC GPE, and has no _Lxx/_Exx AML handler,
> >    and is thus never initialized.
> >
> >    In this case, when an external CRT is plugged in,
> >    the GPE fires, we attempt to disable the GPE,
> >    but instead just return an error.
> >    So the GPE stays asserted and an ACPI interrupt storm follows.
> >
> >    The fix is to disable a firing GPE,
> >    even if it comes from outer space.
> >
> >    http://bugzilla.kernel.org/show_bug.cgi?id=6217
> >
> >    Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> >    Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
> >    Signed-off-by: Len Brown <len.brown@intel.com>
> >
> >diff --git a/drivers/acpi/events/evgpe.c b/drivers/acpi/events/evgpe.c
> >index e22f4a9..056b788 100644
> >--- a/drivers/acpi/events/evgpe.c
> >+++ b/drivers/acpi/events/evgpe.c
> >@@ -270,18 +270,18 @@ acpi_status acpi_ev_disable_gpe(struct
> >acpi_gpe_event_info *gpe_event_info)
> > 	case ACPI_GPE_TYPE_WAKE_RUN:
> > 		ACPI_CLEAR_BIT(gpe_event_info->flags,
> ACPI_GPE_WAKE_ENABLED);
> >
> >-		/*lint -fallthrough */
> >+		/* fallthrough */
> >
> > 	case ACPI_GPE_TYPE_RUNTIME:
> >
> > 		/* Disable the requested runtime GPE */
> >
> > 		ACPI_CLEAR_BIT(gpe_event_info->flags,
> ACPI_GPE_RUN_ENABLED);
> >-		status = acpi_hw_write_gpe_enable_reg(gpe_event_info);
> >-		break;
> >+
> >+		/* fallthrough */
> >
> > 	default:
> >-		return_ACPI_STATUS(AE_BAD_PARAMETER);
> >+		acpi_hw_write_gpe_enable_reg(gpe_event_info);
> > 	}
> >
> > 	return_ACPI_STATUS(AE_OK);