MdePkg/UefiLib: introduce EfiEventGroupSignal

This is a small convenience function that eases signaling an event group
(identified by GUID). An example where it can be used is Platform BDS
signaling the End-of-DXE event group.

The naming follows EfiNamedEventSignal().

The patch modifies the library class header, and updates the most commonly
used library instance at once. Other library instances in the edk2 tree
will be adapted in the following patches.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Suggested-by: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

MdePkg/Include/Library/UefiLib.h

@@ -223,6 +223,24 @@ EfiNamedEventSignal (
   IN CONST EFI_GUID  *Name
   );
 
+/**
+  Signals an event group by placing a new event in the group temporarily and
+  signaling it.
+
+  @param[in] EventGroup          Supplies the unique identifier of the event
+                                 group to signal.
+
+  @retval EFI_SUCCESS            The event group was signaled successfully.
+  @retval EFI_INVALID_PARAMETER  EventGroup is NULL.
+  @return                        Error codes that report problems about event
+                                 creation or signaling.
+**/
+EFI_STATUS
+EFIAPI
+EfiEventGroupSignal (
+  IN CONST EFI_GUID *EventGroup
+  );
+
 /** 
   Returns the current TPL.
 

MdePkg/Library/UefiLib/UefiLib.c

@@ -304,6 +304,49 @@ EfiNamedEventSignal (
   return Status;
 }
 
+/**
+  Signals an event group by placing a new event in the group temporarily and
+  signaling it.
+
+  @param[in] EventGroup          Supplies the unique identifier of the event
+                                 group to signal.
+
+  @retval EFI_SUCCESS            The event group was signaled successfully.
+  @retval EFI_INVALID_PARAMETER  EventGroup is NULL.
+  @return                        Error codes that report problems about event
+                                 creation or signaling.
+**/
+EFI_STATUS
+EFIAPI
+EfiEventGroupSignal (
+  IN CONST EFI_GUID *EventGroup
+  )
+{
+  EFI_STATUS Status;
+  EFI_EVENT  Event;
+
+  if (EventGroup == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  Status = gBS->CreateEventEx (
+                  EVT_NOTIFY_SIGNAL,
+                  TPL_CALLBACK,
+                  InternalEmptyFunction,
+                  NULL,
+                  EventGroup,
+                  &Event
+                  );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  Status = gBS->SignalEvent (Event);
+  gBS->CloseEvent (Event);
+
+  return Status;
+}
+
 /** 
   Returns the current TPL.