Optimize filter_cfg_parts

First, we don't need to scan the complete volume list once we found one
on the boot medium. Second, we can now rely on the fact that volumes on
the boot medium come first and drop any sorting logic.

Signed-off-by: Jan Kiszka <[email protected]>

env/syspart.c

@@ -51,14 +51,6 @@ EFI_STATUS enumerate_cfg_parts(UINTN *config_volumes, UINTN *numHandles)
 	return EFI_SUCCESS;
 }
 
-static VOID swap_uintn(UINTN *a, UINTN *b)
-{
-	UINTN tmp;
-	tmp = *a;
-	*a = *b;
-	*b = tmp;
-}
-
 UINTN filter_cfg_parts(UINTN *config_volumes, UINTN numHandles)
 {
 	BOOLEAN use_envs_on_bootmedium_only = FALSE;
@@ -69,6 +61,7 @@ UINTN filter_cfg_parts(UINTN *config_volumes, UINTN numHandles)
 
 		if (v->onbootmedium) {
 			use_envs_on_bootmedium_only = TRUE;
+			break;
 		};
 	}
 
@@ -78,18 +71,18 @@ UINTN filter_cfg_parts(UINTN *config_volumes, UINTN numHandles)
 	}
 
 	INFO(L"Booting with environments from boot medium only.\n");
-	UINTN num_sorted = 0;
+	UINTN num_filtered = 0;
 	for (UINTN j = 0; j < numHandles; j++) {
 		UINTN cvi = config_volumes[j];
 		VOLUME_DESC *v = &volumes[cvi];
 
 		if (v->onbootmedium) {
-			swap_uintn(&config_volumes[j],
-				   &config_volumes[num_sorted++]);
+			/* boot volumes are guaranteed to be first in the list */
+			num_filtered++;
 		} else {
 			WARNING(L"Ignoring config on volume #%d\n", cvi);
 		}
 	}
 
-	return num_sorted;
+	return num_filtered;
 }