[PATCH 2/2] efi_loader: remove non vital devices first

[Heinrich Schuchardt]

Am 13. November 2024 17:03:03 MEZ schrieb Simon Glass <sjg at chromium.org>:
>Hi Heinrich,
>
>On Wed, 13 Nov 2024 at 08:17, Heinrich Schuchardt <xypron.glpk at gmx.de>
>wrote:
>>
>> Am 13. November 2024 15:39:22 MEZ schrieb Simon Glass <sjg at chromium.org>:
>> >Hi,
>> >
>> >On Wed, 13 Nov 2024 at 05:52, Heinrich Schuchardt <xypron.glpk at gmx.de>
>wrote:
>> >>
>> >> On 11/1/24 21:29, Mark Kettenis wrote:
>> >> >> From: Janne Grunau <j at jannau.net>
>> >> >> Date: Thu, 31 Oct 2024 23:48:02 +0100
>> >> >>
>> >> >> DM_FLAG_VITAL marks devices which are essential for the operation of
>> >> >> other devices. Removing these devices before their users can result
>in
>> >> >> hangs or crashes.
>> >> >> This potentially fixes EFI boot of Renesas rcar3 devices. Their
>clock
>> >> >> devices (and with this series the dart iommu) are the only devices
>> >> >> markes as vital.
>> >> >> The arm boot code already handles devioce removal in this way.
>> >> >
>> >> > There is a typo in that last sentence of the commit message
>(devioce).
>> >> > Otherwise:
>> >> >
>> >> >> Signed-off-by: Janne Grunau <j at jannau.net>
>> >> >
>> >> > Reviewed-by: Mark Kettenis <kettenis at openbsd.org>
>> >> >
>> >> >> ---
>> >> >>   lib/efi_loader/efi_boottime.c | 1 +
>> >> >>   1 file changed, 1 insertion(+)
>> >> >>
>> >> >> diff --git a/lib/efi_loader/efi_boottime.c
>b/lib/efi_loader/efi_boottime.c
>> >> >> index
>4f52284b4c653c252b0ed6c0c87da8901448d4b4..7db3c95782970f8c06a970a8ee86b1804cd848b6
>100644
>> >> >> --- a/lib/efi_loader/efi_boottime.c
>> >> >> +++ b/lib/efi_loader/efi_boottime.c
>> >> >> @@ -2234,6 +2234,7 @@ static efi_status_t EFIAPI
>efi_exit_boot_services(efi_handle_t image_handle,
>> >> >>              if (IS_ENABLED(CONFIG_USB_DEVICE))
>> >> >>                      udc_disconnect();
>> >> >>              board_quiesce_devices();
>> >> >> +            dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL |
>DM_REMOVE_NON_VITAL);
>> >> >>              dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL);
>> >>
>> >> Simon's patch 6224dc9ba428 ("arm: Remove vital devices last") addressed
>> >> the same issue for bootm on arm. But what about about other
>architectures?
>> >>
>> >> This logic should be moved to drivers/core/root.c instead of
>replicating
>> >> code.
>> >
>> >We could have a common helper, but it should not be in driver/core as
>> >this ordering is more of a policy decision. Unless we can add a
>> >parameter telling dm exactly what to do...
>> >
>> >BTW, Heinrich, this behaviour is exactly what my bootflow_efi() test
>> >was supposed to check. But since it doesn't have the
>> >exit-boot-services piece at your request...
>> >
>> >Regards,
>> >Simon
>>
>>
>> Why can't we generally remove non-vital devices first if all are to be
>removed?
>>
>> I cannot see anything device specific here.
>
>No objection to that...but it needs to be in a new function, not become the
>default behaviour of dm_remove_devices_flags(), which is supposed to do
>what it is told and in one pass.

dm_remove_device_flags() makes no specific promises concerning the deletion sequence and its internal working. But obviously it will fail if non-vital redources are not deleted first.

Leaving this broken function exported and writing a new one has no user benefit.

We could copy the old function to a new static function that we call as needed from the old function name.

Best regards

Heinruch

>
>Regards,
>Simon