>
> [...]
> > > static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
> > > struct mhi_result *mhi_res)
> > > {
> > > @@ -142,19 +175,42 @@ static void mhi_net_dl_callback(struct mhi_device
> > > *mhi_dev,
> > > free_desc_count = mhi_get_free_desc_count(mhi_dev,
> > > DMA_FROM_DEVICE);
> > >
> > > if (unlikely(mhi_res->transaction_status)) {
> > > - dev_kfree_skb_any(skb);
> > > -
> > > - /* MHI layer stopping/resetting the DL channel */
> > > - if (mhi_res->transaction_status == -ENOTCONN)
> > > + switch (mhi_res->transaction_status) {
> > > + case -EOVERFLOW:
> > > + /* Packet can not fit in one MHI buffer and has
> > > been
> > > + * split over multiple MHI transfers, do
> > > re-aggregation.
> > > + * That usually means the device side MTU is
> > > larger than
> > > + * the host side MTU/MRU. Since this is not
> > > optimal,
> > > + * print a warning (once).
> > > + */
> > > + netdev_warn_once(mhi_netdev->ndev,
> > > + "Fragmented packets received,
> > > fix MTU?\n");
> > > + skb_put(skb, mhi_res->bytes_xferd);
> > > + mhi_net_skb_agg(mhi_netdev, skb);
> > > + break;
> > > + case -ENOTCONN:
> > > + /* MHI layer stopping/resetting the DL channel */
> > > + dev_kfree_skb_any(skb);
> > > return;
> > > -
> > > - u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
> > > - u64_stats_inc(&mhi_netdev->stats.rx_errors);
> > > - u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
> > > + default:
> > > + /* Unknown error, simply drop */
> > > + dev_kfree_skb_any(skb);
> > > +
> > > u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
> > > + u64_stats_inc(&mhi_netdev->stats.rx_errors);
> > > + u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
> > > + }
> > > } else {
> > > + skb_put(skb, mhi_res->bytes_xferd);
> > > +
> > > + if (mhi_netdev->skbagg_head) {
> > > + /* Aggregate the final fragment */
> > > + skb = mhi_net_skb_agg(mhi_netdev, skb);
> > > + mhi_netdev->skbagg_head = NULL;
> > > + }
> > > +
> > > u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
> > > u64_stats_inc(&mhi_netdev->stats.rx_packets);
> > > - u64_stats_add(&mhi_netdev->stats.rx_bytes,
> > > mhi_res->bytes_xferd);
> > > + u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len);
> >
> > might this change stats? it will if skb->len != 0 before skb_put. Even
> > if so, perhaps it doesn't matter.
>
> Don't get that point, skb is the received MHI buffer, we simply set
> its size because MHI core don't (skb->len is always 0 before put).
> Then if it is part of a fragmented transfer we just do the extra
> 'skb = skb_agg+ skb', so skb->len should always be right here,
> whether it's a standalone/linear packet or a multi-frag packet.
Great. I did not know that skb->len is 0 before put for this codepath.
It isn't for other protocols, and then any protocol headers would have
been counted.
