SCI handlers: Optimize installation by only locking SCI list once.

The code was locking the list twice. Allocate the new SCI handler object
up front to eliminate the second lock, and free the object on any
error.

1 files changed, 29 insertions, 23 deletions

diff --git a/source/components/events/evxface.c b/source/components/events/evxface.c
index d43fe8d60..c95667bf3 100644
--- a/source/components/events/evxface.c
+++ b/source/components/events/evxface.c
@@ -523,6 +523,7 @@ AcpiInstallSciHandler (
     ACPI_SCI_HANDLER        Address,
     void                    *Context)
 {
+    ACPI_SCI_HANDLER_INFO   *NewSciHandler;
     ACPI_SCI_HANDLER_INFO   *SciHandler;
     ACPI_CPU_FLAGS          Flags;
     ACPI_STATUS             Status;
@@ -536,52 +537,57 @@ AcpiInstallSciHandler (
         return_ACPI_STATUS (AE_BAD_PARAMETER);
     }
 
+    /* Allocate and init a handler object */
+
+    NewSciHandler = ACPI_ALLOCATE (sizeof (ACPI_SCI_HANDLER_INFO));
+    if (!NewSciHandler)
+    {
+        return_ACPI_STATUS (AE_NO_MEMORY);
+    }
+
+    NewSciHandler->Address = Address;
+    NewSciHandler->Context = Context;
+
     Status = AcpiUtAcquireMutex (ACPI_MTX_EVENTS);
     if (ACPI_FAILURE (Status))
     {
-        return_ACPI_STATUS (Status);
+        goto Exit;
     }
 
-    /* Ensure handler does not already exist */
+    /* Lock list during installation */
 
     Flags = AcpiOsAcquireLock (AcpiGbl_GpeLock);
     SciHandler = AcpiGbl_SciHandlerList;
+
+    /* Ensure handler does not already exist */
+
     while (SciHandler)
     {
         if (Address == SciHandler->Address)
         {
             Status = AE_ALREADY_EXISTS;
-            goto UnlockAndExit2;
+            goto UnlockAndExit;
         }
-        SciHandler = SciHandler->Next;
-    }
-    AcpiOsReleaseLock (AcpiGbl_GpeLock, Flags);
 
-    /* Allocate and init handler object */
-
-    SciHandler = ACPI_ALLOCATE_ZEROED (sizeof (ACPI_SCI_HANDLER_INFO));
-    if (!SciHandler)
-    {
-        Status = AE_NO_MEMORY;
-        goto UnlockAndExit;
+        SciHandler = SciHandler->Next;
     }
 
-    SciHandler->Address = Address;
-    SciHandler->Context = Context;
-
-    /* Install the new handler into the global list with lock */
+    /* Install the new handler into the global list (at head) */
 
-    Flags = AcpiOsAcquireLock (AcpiGbl_GpeLock);
+    NewSciHandler->Next = AcpiGbl_SciHandlerList;
+    AcpiGbl_SciHandlerList = NewSciHandler;
 
-    SciHandler->Next = AcpiGbl_SciHandlerList;
-    AcpiGbl_SciHandlerList = SciHandler;
 
-UnlockAndExit2:
+UnlockAndExit:
 
     AcpiOsReleaseLock (AcpiGbl_GpeLock, Flags);
-
-UnlockAndExit:
     (void) AcpiUtReleaseMutex (ACPI_MTX_EVENTS);
+
+Exit:
+    if (ACPI_FAILURE (Status))
+    {
+        ACPI_FREE (NewSciHandler);
+    }
     return_ACPI_STATUS (Status);
 }