Fix GPE livelock that occurs on HP/Compaq laptops, mostly in the thermal

zone code.  The GPE handler method (i.e. _L00) generates various Notify
events that need to be run to completion before the GPE is re-enabled.
In ACPI-CA, we queue an asynch callback at the same priority as a Notify
so that it will only run after all Notify handlers have completed.  The
callback re-enables the GPE afterwards.  We also changed the priority of
Notifies to be the same as GPEs, given the possibility that another GPE
could arrive before the Notifies have completed and we don't want it to
get queued ahead of the rest.

The ACPI-CA change was submitted by Alexey Starikovskiy (SUSE) and will
appear in a later release.  Special thanks to him for helping track this
bug down.

MFC after:	1 week
Tested by:	jhb, Yousif Hassan <yousif / alumni.jmu.edu>

1 files changed, 19 insertions, 3 deletions

diff --git a/sys/contrib/dev/acpica/evgpe.c b/sys/contrib/dev/acpica/evgpe.c
index e470eae..d18a1d7 100644
--- a/sys/contrib/dev/acpica/evgpe.c
+++ b/sys/contrib/dev/acpica/evgpe.c
@@ -123,6 +123,10 @@
 
 /* Local prototypes */
 
+static void
+AcpiEvAsynchEnableGpe (
+    void                    *Context);
+
 static void ACPI_SYSTEM_XFACE
 AcpiEvAsynchExecuteGpeMethod (
     void                    *Context);
@@ -684,14 +688,26 @@ AcpiEvAsynchExecuteGpeMethod (
         }
     }
 
-    if ((LocalGpeEventInfo.Flags & ACPI_GPE_XRUPT_TYPE_MASK) ==
+    /* Defer enabling of GPE until all notify handlers are done */
+    AcpiOsExecute(OSL_NOTIFY_HANDLER, AcpiEvAsynchEnableGpe, GpeEventInfo);
+    return_VOID;
+}
+
+static void
+AcpiEvAsynchEnableGpe (
+    void                    *Context)
+{
+    ACPI_GPE_EVENT_INFO     *GpeEventInfo = (void *) Context;
+    ACPI_STATUS             Status;
+
+    if ((GpeEventInfo->Flags & ACPI_GPE_XRUPT_TYPE_MASK) ==
             ACPI_GPE_LEVEL_TRIGGERED)
     {
         /*
          * GPE is level-triggered, we clear the GPE status bit after
          * handling the event.
          */
-        Status = AcpiHwClearGpe (&LocalGpeEventInfo);
+        Status = AcpiHwClearGpe (GpeEventInfo);
         if (ACPI_FAILURE (Status))
         {
             return_VOID;
@@ -700,7 +716,7 @@ AcpiEvAsynchExecuteGpeMethod (
 
     /* Enable this GPE */
 
-    (void) AcpiHwWriteGpeEnableReg (&LocalGpeEventInfo);
+    (void) AcpiHwWriteGpeEnableReg (GpeEventInfo);
     return_VOID;
 }