Hi Jakub, On Mon, 2 Nov 2020 at 23:40, Jakub Kicinski <kuba@xxxxxxxxxx> wrote: > > On Fri, 30 Oct 2020 11:48:15 +0100 Loic Poulain wrote: > > This patch adds a new network driver implementing MHI transport for > > network packets. Packets can be in any format, though QMAP (rmnet) > > is the usual protocol (flow control + PDN mux). > > > > It support two MHI devices, IP_HW0 which is, the path to the IPA > > (IP accelerator) on qcom modem, And IP_SW0 which is the software > > driven IP path (to modem CPU). > > > > Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxx> > > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > > > +static int mhi_ndo_stop(struct net_device *ndev) > > +{ > > + struct mhi_net_dev *mhi_netdev = netdev_priv(ndev); > > + > > + netif_stop_queue(ndev); > > + netif_carrier_off(ndev); > > + cancel_delayed_work_sync(&mhi_netdev->rx_refill); > > Where do you free the allocated skbs? Does > mhi_unprepare_from_transfer() do that? When a buffer is queued, it is owned by the device until the transfer callback (ul_cb/dl_cb) is called. mhi_unprepare_from_transfer() causes the MHI channels to be reset which in turn leads to releasing the buffers, for each buffer the MHI core will call the mhi-net transfer callback with -ENOTCONN status, and we free it from here. > > The skbs should be freed somehow in .ndo_stop(). The skbs are released in remove() (mhi_unprepare_from_transfer), I do not do prepare/unprepare in ndo_open/ndo_stop because we need to have channels started during the whole life of the interface. That's because it set up kind of internal routing of on the device/modem side. Indeed, if channels are not started, configuration of the modem (via out-of-band qmi, at commands, etc) is not possible. > > > + return 0; > > +} > > + > > +static int mhi_ndo_xmit(struct sk_buff *skb, struct net_device *ndev) > > +{ > > + struct mhi_net_dev *mhi_netdev = netdev_priv(ndev); > > + struct mhi_device *mdev = mhi_netdev->mdev; > > + int err; > > + > > + err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); > > + if (unlikely(err)) { > > + net_err_ratelimited("%s: Failed to queue TX buf (%d)\n", > > + ndev->name, err); > > + > > + u64_stats_update_begin(&mhi_netdev->stats.tx_syncp); > > + u64_stats_inc(&mhi_netdev->stats.tx_dropped); > > + u64_stats_update_end(&mhi_netdev->stats.tx_syncp); > > + > > + /* drop the packet */ > > + kfree_skb(skb); > > dev_kfree_skb_any() > > > + } > > + > > + if (mhi_queue_is_full(mdev, DMA_TO_DEVICE)) > > + netif_stop_queue(ndev); > > + > > + return NETDEV_TX_OK; > > +} > > > +static void mhi_net_dl_callback(struct mhi_device *mhi_dev, > > + struct mhi_result *mhi_res) > > +{ > > + struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev); > > + struct sk_buff *skb = mhi_res->buf_addr; > > + int remaining; > > + > > + remaining = atomic_dec_return(&mhi_netdev->stats.rx_queued); > > + > > + if (unlikely(mhi_res->transaction_status)) { > > + 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); > > + > > + kfree_skb(skb); > > Are you sure this never runs with irqs disabled or from irq context? > > Otherwise dev_kfree_skb_any(). Yes will fix that. > > > + > > + /* MHI layer resetting the DL channel */ > > + if (mhi_res->transaction_status == -ENOTCONN) > > + return; > > + } else { > > + 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_update_end(&mhi_netdev->stats.rx_syncp); > > + > > + skb->protocol = htons(ETH_P_MAP); > > + skb_put(skb, mhi_res->bytes_xferd); > > + netif_rx(skb); > > + } > > + > > + /* Refill if RX buffers queue becomes low */ > > + if (remaining <= mhi_netdev->rx_queue_sz / 2) > > + schedule_delayed_work(&mhi_netdev->rx_refill, 0); > > +} > > + > > +static void mhi_net_ul_callback(struct mhi_device *mhi_dev, > > + struct mhi_result *mhi_res) > > +{ > > + struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev); > > + struct net_device *ndev = mhi_netdev->ndev; > > + struct sk_buff *skb = mhi_res->buf_addr; > > + > > + /* Hardware has consumed the buffer, so free the skb (which is not > > + * freed by the MHI stack) and perform accounting. > > + */ > > + consume_skb(skb); > > ditto > > > + u64_stats_update_begin(&mhi_netdev->stats.tx_syncp); > > + if (unlikely(mhi_res->transaction_status)) { > > + u64_stats_inc(&mhi_netdev->stats.tx_errors); > > + > > + /* MHI layer resetting the UL channel */ > > + if (mhi_res->transaction_status == -ENOTCONN) > > + return; > > u64_stats_update_end() > > > + } else { > > + u64_stats_inc(&mhi_netdev->stats.tx_packets); > > + u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd); > > + } > > + u64_stats_update_end(&mhi_netdev->stats.tx_syncp); > > + > > + if (netif_queue_stopped(ndev)) > > + netif_wake_queue(ndev); > > +} > > + > > +static void mhi_net_rx_refill_work(struct work_struct *work) > > +{ > > + struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev, > > + rx_refill.work); > > + struct net_device *ndev = mhi_netdev->ndev; > > + struct mhi_device *mdev = mhi_netdev->mdev; > > + int size = READ_ONCE(ndev->mtu); > > + struct sk_buff *skb; > > + int err; > > + > > + do { > > should this be a while(), not a do {} while() loop now? > > > + skb = netdev_alloc_skb(ndev, size); > > + if (unlikely(!skb)) > > + break; > > + > > + err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT); > > + if (unlikely(err)) { > > + net_err_ratelimited("%s: Failed to queue RX buf (%d)\n", > > + ndev->name, err); > > + kfree_skb(skb); > > + break; > > + } > > + > > + /* Do not hog the CPU if rx buffers are consumed faster than > > + * queued (unlikely). > > + */ > > + cond_resched(); > > + } while (atomic_inc_return(&mhi_netdev->stats.rx_queued) < mhi_netdev->rx_queue_sz); > > + > > + /* If we're still starved of rx buffers, reschedule later */ > > + if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued))) > > + schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2); > > +}