[PATCH] efi_loader: Make DisconnectController follow the EFI spec

[Ilias Apalodimas]

commit 239d59a65e20 ("efi_loader: reconnect drivers on failure")
tried to fix the UninstallProtocol interface which must reconnect
any controllers it disconnected by calling ConnectController()
in case of failure. However, the reconnect functionality was wired in
efi_disconnect_all_drivers() instead of efi_uninstall_protocol().

As a result some SCT tests started failing.
Specifically, BBTestOpenProtocolInterfaceTest333CheckPoint3() test
 - Calls ConnectController for DriverImageHandle1
 - Calls DisconnectController for DriverImageHandle1 which will
   disconnect everything apart from TestProtocol4. That will remain
   open on purpose.
 - Calls ConnectController for DriverImageHandle2. TestProtocol4
   which was explicitly preserved was installed wth BY_DRIVER attributes.
   The new protocol will call DisconnectController since its attributes
   are BY_DRIVER|EXCLUSIVE, but TestProtocol4 will not be removed. The
   test expects EFI_ACCESS_DENIED which works fine.

   The problem is that DisconnectController, will eventually call
   EFI_DRIVER_BINDING_PROTOCOL.Stop(). But on the aforementioned test
   this will call CloseProtocol -- the binding protocol is defined in
   'DBindingDriver3.c' and the .Stop function uses CloseProtocol.
   If that close protocol call fails with EFI_NOT_FOUND, the current code
   will try to mistakenly reconnect all drivers and the subsequent tests
   that rely on the device being disconnected will fail.

Move the reconnection in efi_uninstall_protocol() were it belongs.

Fixes: commit 239d59a65e20 ("efi_loader: reconnect drivers on failure")
Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
Heinrich this is critical. Although it doesn't break anything on our normal
use cases it does break the ACS testing for SystemReady-IR and I prefer
landing it in -master before the 2024.01 release

 lib/efi_loader/efi_boottime.c | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 0b7579cb5af1..370eaee8ce1a 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -1339,7 +1339,7 @@ static efi_status_t efi_disconnect_all_drivers
 				 const efi_guid_t *protocol,
 				 efi_handle_t child_handle)
 {
-	efi_uintn_t number_of_drivers, tmp;
+	efi_uintn_t number_of_drivers;
 	efi_handle_t *driver_handle_buffer;
 	efi_status_t r, ret;

@@ -1350,31 +1350,17 @@ static efi_status_t efi_disconnect_all_drivers
 	if (!number_of_drivers)
 		return EFI_SUCCESS;

-	tmp = number_of_drivers;
 	while (number_of_drivers) {
-		ret = EFI_CALL(efi_disconnect_controller(
+		r = EFI_CALL(efi_disconnect_controller(
 				handle,
 				driver_handle_buffer[--number_of_drivers],
 				child_handle));
-		if (ret != EFI_SUCCESS)
-			goto reconnect;
-	}
-
-	free(driver_handle_buffer);
-	return ret;
-
-reconnect:
-	/* Reconnect all disconnected drivers */
-	for (; number_of_drivers < tmp; number_of_drivers++) {
-		r = EFI_CALL(efi_connect_controller(handle,
-						    &driver_handle_buffer[number_of_drivers],
-						    NULL, true));
 		if (r != EFI_SUCCESS)
-			EFI_PRINT("Failed to reconnect controller\n");
+			ret = r;
 	}

 	free(driver_handle_buffer);
-	return ret;
+	return (ret != EFI_SUCCESS ? ret : EFI_SUCCESS);
 }

 /**
@@ -1409,6 +1395,7 @@ static efi_status_t efi_uninstall_protocol
 	r = efi_disconnect_all_drivers(handle, protocol, NULL);
 	if (r != EFI_SUCCESS) {
 		r = EFI_ACCESS_DENIED;
+		EFI_CALL(efi_connect_controller(handle, NULL, NULL, true));
 		goto out;
 	}
 	/* Close protocol */
--
2.37.2