Re: [XENVIF PATCH] Skip hash update if frontend is not enabled

["Tu Dinh" <ngoc-tu.dinh@xxxxxxxxxx>]

On 02/09/2025 11:54, Owen Smith wrote:
> I don't think that any updated hash details will be resent if they are
> changed when Frontend->State != FRONTEND_ENABLED. FrontendEnable will
> call __FrontendUpdateHash before it sets Frontend->State
> to FRONTEND_ENABLED.
>
> Controller->Connected is used to guard writing hash data to the backend,
> but returns STATUS_NOT_SUPPORTED in this case, and this means Frontend-
>  >Hash is not updated and the status is reported back to NDIS.
>
> Owen
>

It doesn't trigger 100% of the time, but I found it easier to repro
under debugger.

At the moment of hang, Controller->Connected is still true but
Frontend->State has entered FRONTEND_CONNECTED (see attached log)

> On Thu, Aug 28, 2025 at 11:01 PM Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx> wrote:
>
>     NDIS may set OID_GEN_RECEIVE_SCALE_PARAMETERS during an
>     IRP_MN_REMOVE_DEVICE, after the frontend has been torn down. This will
>     cause the ensuing control request to hang.
>
>     Skip __FrontendUpdateHash if the frontend is not enabled. The skip is
>     done here since we still need to update Frontend->Hash in case the
>     frontend is enabled again later.
>
>     Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
>     ---
>       src/xenvif/frontend.c | 3 +++
>       1 file changed, 3 insertions(+)
>
>     diff --git a/src/xenvif/frontend.c b/src/xenvif/frontend.c
>     index 90ec2b1..c497f24 100644
>     --- a/src/xenvif/frontend.c
>     +++ b/src/xenvif/frontend.c
>     @@ -1889,6 +1889,9 @@ __FrontendUpdateHash(
>           ULONG                   Flags;
>           NTSTATUS                status;
>
>     +    if (Frontend->State != FRONTEND_ENABLED)
>     +        goto done;
>     +
>           Controller = __FrontendGetController(Frontend);
>
>           switch (Hash->Algorithm) {
>     --
>     2.51.0.windows.1
>
>
>
>     Ngoc Tu Dinh | Vates XCP-ng Developer
>
>     XCP-ng & Xen Orchestra - Vates solutions
>
>     web: https://vates.tech <https://vates.tech>
>


--
Ngoc Tu Dinh | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

Attachment: kd.log
Description: Text document