[efi] Process veto objects in reverse order of enumeration

While not guaranteed by the UEFI specification, the enumeration of
handles, protocols, and openers will generally return results in order
of creation.  Processing these objects in reverse order (as is already
done when calling DisconnectController() on the list of all handles)
will generally therefore perform the forcible uninstallation
operations in reverse order of object creation, which minimises the
number of implicit operations performed (e.g. when disconnecting a
controller that itself still has existent child controllers).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 11 insertions, 7 deletions

diff --git a/src/interface/efi/efi_veto.c b/src/interface/efi/efi_veto.c
index bc19a00..a3b60d6 100644
--- a/src/interface/efi/efi_veto.c
+++ b/src/interface/efi/efi_veto.c
@@ -227,7 +227,7 @@ static int efi_veto_close_protocol ( struct efi_veto *veto, EFI_HANDLE handle,
 
 	/* Close anything opened by this driver */
 	for ( i = 0 ; i < count ; i++ ) {
-		opener = &openers[i];
+		opener = &openers[ count - i - 1 ];
 		if ( ( opener->AgentHandle != driver ) &&
 		     ( opener->AgentHandle != image ) ) {
 			continue;
@@ -265,6 +265,7 @@ static int efi_veto_close_handle ( struct efi_veto *veto, EFI_HANDLE handle ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	EFI_HANDLE driver = veto->driver;
 	EFI_GUID **protocols;
+	EFI_GUID *protocol;
 	UINTN count;
 	unsigned int i;
 	EFI_STATUS efirc;
@@ -283,8 +284,9 @@ static int efi_veto_close_handle ( struct efi_veto *veto, EFI_HANDLE handle ) {
 
 	/* Close each protocol */
 	for ( i = 0 ; i < count ; i++ ) {
+		protocol = protocols[ count - i - 1];
 		if ( ( rc = efi_veto_close_protocol ( veto, handle,
-						      protocols[i] ) ) != 0 )
+						      protocol ) ) != 0 )
 			goto err_close;
 	}
 
@@ -307,6 +309,7 @@ static int efi_veto_close ( struct efi_veto *veto ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	EFI_HANDLE driver = veto->driver;
 	EFI_HANDLE *handles;
+	EFI_HANDLE handle;
 	UINTN count;
 	unsigned int i;
 	EFI_STATUS efirc;
@@ -323,7 +326,8 @@ static int efi_veto_close ( struct efi_veto *veto ) {
 
 	/* Close each handle */
 	for ( i = 0 ; i < count ; i++ ) {
-		if ( ( rc = efi_veto_close_handle ( veto, handles[i] ) ) != 0 )
+		handle = handles[ count - i - 1 ];
+		if ( ( rc = efi_veto_close_handle ( veto, handle ) ) != 0 )
 			goto err_close;
 	}
 
@@ -628,7 +632,7 @@ void efi_veto ( void ) {
 	struct efi_veto veto;
 	EFI_HANDLE *drivers;
 	EFI_HANDLE driver;
-	UINTN num_drivers;
+	UINTN count;
 	unsigned int i;
 	char *manufacturer;
 	EFI_STATUS efirc;
@@ -637,7 +641,7 @@ void efi_veto ( void ) {
 	/* Locate all driver binding protocol handles */
 	if ( ( efirc = bs->LocateHandleBuffer (
 			ByProtocol, &efi_driver_binding_protocol_guid,
-			NULL, &num_drivers, &drivers ) ) != 0 ) {
+			NULL, &count, &drivers ) ) != 0 ) {
 		rc = -EEFI ( efirc );
 		DBGC ( &efi_vetoes, "EFIVETO could not list all drivers: "
 		       "%s\n", strerror ( rc ) );
@@ -650,8 +654,8 @@ void efi_veto ( void ) {
 	DBGC ( &efi_vetoes, "EFIVETO manufacturer is \"%s\"\n", manufacturer );
 
 	/* Unload any vetoed drivers */
-	for ( i = 0 ; i < num_drivers ; i++ ) {
-		driver = drivers[i];
+	for ( i = 0 ; i < count ; i++ ) {
+		driver = drivers[ count - i - 1 ];
 		if ( ( rc = efi_veto_find ( driver, manufacturer,
 					    &veto ) ) != 0 ) {
 			DBGC ( driver, "EFIVETO %s could not determine "