The 09/23/2020 20:45, Vladimir Oltean wrote:
>
> On Wed, Sep 23, 2020 at 10:35:30PM +0200, Horatiu Vultur wrote:
> > The 09/23/2020 20:22, Vladimir Oltean wrote:
> > > On Wed, Sep 23, 2020 at 10:08:00PM +0200, Horatiu Vultur wrote:
> > > > The 09/23/2020 14:24, Vladimir Oltean wrote:
> > > > > + if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) {
> > > > > + struct sk_buff *clone;
> > > > > +
> > > > > + clone = skb_clone_sk(skb);
> > > > > + if (!clone) {
> > > > > + kfree_skb(skb);
> > > > > + return NETDEV_TX_OK;
> > > >
> > > > Why do you return NETDEV_TX_OK?
> > > > Because the frame is not sent yet.
> > >
> > > I suppose I _could_ increment the tx_dropped counters, if that's what
> > > you mean.
> >
> > Yeah, something like that I was thinking.
> >
> > Also I am just thinking, not sure if it is correct but, can you return
> > NETDEV_TX_BUSY and not free the skb?
> >
>
> Do you have a use case for NETDEV_TX_BUSY instead of plain dropping the
> skb, some situation where it would be better?
Not really.
>
> I admit I haven't tested this particular code path, but my intuition
> tells me that under OOM, the last thing you need is some networking
> driver just trying and trying again to send a packet.
Yes, I totally understand your point and I aggree with you.
>
> Documentation/networking/driver.rst:
I looked also initially in this document, that is the reason why I was
not sure if it is correct to return NETDEV_TX_BUSY.
>
> 1) The ndo_start_xmit method must not return NETDEV_TX_BUSY under
> any normal circumstances. It is considered a hard error unless
> there is no way your device can tell ahead of time when it's
> transmit function will become busy.
>
> Looking up the uses of NETDEV_TX_BUSY, I see pretty much only congestion
> type of events.
>
> Thanks,
> -Vladimir
--
/Horatiu
