Re: [PATCH net-next v2] net: mana: Handle SKB if TX SGEs exceed hardware limit

[Eric Dumazet <edumazet@google.com>]

On Thu, Nov 6, 2025 at 5:01 AM Aditya Garg
<gargaditya@linux.microsoft.com> wrote:
>
> On 06-11-2025 05:47, Jakub Kicinski wrote:
> > On Wed, 5 Nov 2025 22:10:23 +0530 Aditya Garg wrote:
> >>>>            if (err) {
> >>>>                    (void)skb_dequeue_tail(&txq->pending_skbs);
> >>>> +          mana_unmap_skb(skb, apc);
> >>>>                    netdev_warn(ndev, "Failed to post TX OOB: %d\n", err);
> >>>
> >>> You have a print right here and in the callee. This condition must
> >>> (almost) never happen in practice. It's likely fine to just drop
> >>> the packet.
> >>
> >> The logs placed in callee doesn't covers all the failure scenarios,
> >> hence I feel to have this log here with proper status. Maybe I can
> >> remove the log in the callee?
> >
> > I think my point was that since there are logs (per packet!) when the
> > condition is hit -- if it did in fact hit with any noticeable frequency
> > your users would have complained. So handling the condition gracefully
> > and returning BUSY is likely just unnecessary complexity in practice.
> >
>
> In this, we are returning tx_busy when the error reason is -ENOSPC, for
> all other errors, skb is dropped.
> Is it okay requeue only for -ENOSPC cases or should we drop the skb?

I would avoid NETDEV_TX_BUSY like the plague.
Most drivers get it wrong (including mana)
Documentation/networking/driver.rst

Please drop the packet.

>
> > The logs themselves I don't care all that much about. Sure, having two
> > lines for one error is a bit unclean.
> >
> >>> Either way -- this should be a separate patch.
> >>>
> >> Are you suggesting a separate patch altogether or two patch in the same
> >> series?
> >
> > The changes feel related enough to make them a series, but either way
> > is fine.
>
> Regards,
> Aditya
>