Re: [PATCH 2/3] Conditionally restart the RX ring from packet return

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

On 11/07/2026 13:52, Tu Dinh wrote:
> Currently, the RX ring is restarted on packet return regardless of
> whether there are sufficient resources to afford it. In cases where the
> packet cache has been exhausted, restarting the RX ring will be
> counterproductive.
> 
> Make ReceiverRingFill return STATUS_SUCCESS only if the RX ring has
> been filled without errors. Base the decision of restarting the RX ring
> from __ReceiverRingReturnPacket on this return status.
> 
> Move __ReceiverRingReturnPacket below ReceiverRingFill as the former now
> makes use of the latter.
> 
> Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>

I'll split the moving of __ReceiverRingReturnPacket into a separate 
patch in the next version.

> ---
>   src/xenvif/receiver.c | 95 +++++++++++++++++++++++--------------------
>   1 file changed, 51 insertions(+), 44 deletions(-)
> 
> diff --git a/src/xenvif/receiver.c b/src/xenvif/receiver.c
> index 359935c..29bd325 100644
> --- a/src/xenvif/receiver.c
> +++ b/src/xenvif/receiver.c
> @@ -1709,49 +1709,6 @@ __ReceiverRingSend(
>           __ReceiverRingReleaseLock(Ring);
>   }
>   
> -_IRQL_requires_(DISPATCH_LEVEL)
> -static FORCEINLINE VOID
> -__ReceiverRingReturnPacket(
> -    IN  PXENVIF_RECEIVER_RING   Ring,
> -    IN  PXENVIF_RECEIVER_PACKET Packet,
> -    IN  BOOLEAN                 Locked
> -    )
> -{
> -    PMDL                        Mdl;
> -
> -    Mdl = &Packet->Mdl;
> -
> -    while (Mdl != NULL) {
> -        PMDL    Next;
> -
> -        Next = Mdl->Next;
> -        Mdl->Next = NULL;
> -
> -        __ReceiverRingPutMdl(Ring, Mdl, Locked);
> -
> -        Mdl = Next;
> -    }
> -
> -    if (__ReceiverRingIsStopped(Ring)) {
> -        KIRQL   Irql;
> -
> -        KeRaiseIrql(DISPATCH_LEVEL, &Irql);
> -
> -        if (!Locked)
> -            __ReceiverRingAcquireLock(Ring);
> -
> -        if (__ReceiverRingIsStopped(Ring)) {
> -            __ReceiverRingStart(Ring);
> -            __ReceiverRingTrigger(Ring, TRUE);
> -        }
> -
> -        if (!Locked)
> -            __ReceiverRingReleaseLock(Ring);
> -
> -        KeLowerIrql(Irql);
> -    }
> -}
> -
>   static FORCEINLINE PXENVIF_RECEIVER_FRAGMENT
>   __ReceiverRingPreparePacket(
>       IN  PXENVIF_RECEIVER_RING   Ring,
> @@ -1828,7 +1785,7 @@ __ReceiverRingPushRequests(
>       Ring->RequestsPushed = Ring->RequestsPosted;
>   }
>   
> -static VOID
> +static NTSTATUS
>   ReceiverRingFill(
>       IN  PXENVIF_RECEIVER_RING   Ring
>       )
> @@ -1837,6 +1794,7 @@ ReceiverRingFill(
>       PXENVIF_FRONTEND            Frontend;
>       RING_IDX                    req_prod;
>       RING_IDX                    rsp_cons;
> +    NTSTATUS                    status;
>   
>       Receiver = Ring->Receiver;
>       Frontend = Receiver->Frontend;
> @@ -1848,6 +1806,7 @@ ReceiverRingFill(
>   
>       KeMemoryBarrier();
>   
> +    status = STATUS_SUCCESS;
>       while (req_prod - rsp_cons < RING_SIZE(&Ring->Front)) {
>           PXENVIF_RECEIVER_PACKET     Packet;
>           PXENVIF_RECEIVER_FRAGMENT   Fragment;
> @@ -1857,6 +1816,7 @@ ReceiverRingFill(
>           Packet = __ReceiverRingGetPacket(Ring, TRUE);
>   
>           if (Packet == NULL) {
> +            status = STATUS_INSUFFICIENT_RESOURCES;
>               __ReceiverRingStop(Ring);
>               break;
>           }
> @@ -1864,6 +1824,7 @@ ReceiverRingFill(
>           Fragment = __ReceiverRingPreparePacket(Ring, Packet);
>           
>           if (Fragment == NULL) {
> +            status = STATUS_INSUFFICIENT_RESOURCES;
>               __ReceiverRingPutPacket(Ring, Packet, TRUE);
>               break;
>           }
> @@ -1889,6 +1850,52 @@ ReceiverRingFill(
>       Ring->Front.req_prod_pvt = req_prod;
>   
>       __ReceiverRingPushRequests(Ring);
> +
> +    return status;
> +}
> +
> +_IRQL_requires_(DISPATCH_LEVEL)
> +static FORCEINLINE VOID
> +__ReceiverRingReturnPacket(
> +    IN  PXENVIF_RECEIVER_RING   Ring,
> +    IN  PXENVIF_RECEIVER_PACKET Packet,
> +    IN  BOOLEAN                 Locked
> +    )
> +{
> +    PMDL                        Mdl;
> +
> +    Mdl = &Packet->Mdl;
> +
> +    while (Mdl != NULL) {
> +        PMDL    Next;
> +
> +        Next = Mdl->Next;
> +        Mdl->Next = NULL;
> +
> +        __ReceiverRingPutMdl(Ring, Mdl, Locked);
> +
> +        Mdl = Next;
> +    }
> +
> +    if (__ReceiverRingIsStopped(Ring)) {
> +        KIRQL   Irql;
> +
> +        KeRaiseIrql(DISPATCH_LEVEL, &Irql);
> +
> +        if (!Locked)
> +            __ReceiverRingAcquireLock(Ring);
> +
> +        if (__ReceiverRingIsStopped(Ring) &&
> +            NT_SUCCESS(ReceiverRingFill(Ring))) {
> +            __ReceiverRingStart(Ring);
> +            __ReceiverRingTrigger(Ring, TRUE);
> +        }
> +
> +        if (!Locked)
> +            __ReceiverRingReleaseLock(Ring);
> +
> +        KeLowerIrql(Irql);
> +    }
>   }
>   
>   static FORCEINLINE VOID



--
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