On Tuesday, 14 October 2025 at 12:15:12 Matias Ezequiel Vara Larsen <[email protected]> wrote: > On Thu, Sep 11, 2025 at 10:59:40PM +0200, Francesco Valla wrote: > > Hello Mikhail, Harald, > > > > hoping there will be a v6 of this patch soon, a few comments: > > > > On Monday, 8 January 2024 at 14:10:35 Mikhail Golubev-Ciuchea > > <[email protected]> wrote: > > > > [...] > > > + > > > +/* Compare with m_can.c/m_can_echo_tx_event() */ > > > +static int virtio_can_read_tx_queue(struct virtqueue *vq) > > > +{ > > > + struct virtio_can_priv *can_priv = vq->vdev->priv; > > > + struct net_device *dev = can_priv->dev; > > > + struct virtio_can_tx *can_tx_msg; > > > + struct net_device_stats *stats; > > > + unsigned long flags; > > > + unsigned int len; > > > + u8 result; > > > + > > > + stats = &dev->stats; > > > + > > > + /* Protect list and virtio queue operations */ > > > + spin_lock_irqsave(&can_priv->tx_lock, flags); > > > + > > > + can_tx_msg = virtqueue_get_buf(vq, &len); > > > + if (!can_tx_msg) { > > > + spin_unlock_irqrestore(&can_priv->tx_lock, flags); > > > + return 0; /* No more data */ > > > + } > > > + > > > + if (unlikely(len < sizeof(struct virtio_can_tx_in))) { > > > + netdev_err(dev, "TX ACK: Device sent no result code\n"); > > > + result = VIRTIO_CAN_RESULT_NOT_OK; /* Keep things going */ > > > + } else { > > > + result = can_tx_msg->tx_in.result; > > > + } > > > + > > > + if (can_priv->can.state < CAN_STATE_BUS_OFF) { > > > + /* Here also frames with result != VIRTIO_CAN_RESULT_OK are > > > + * echoed. Intentional to bring a waiting process in an upper > > > + * layer to an end. > > > + * TODO: Any better means to indicate a problem here? > > > + */ > > > + if (result != VIRTIO_CAN_RESULT_OK) > > > + netdev_warn(dev, "TX ACK: Result = %u\n", result); > > > > Maybe an error frame reporting CAN_ERR_CRTL_UNSPEC would be better? > > > I am not sure. In xilinx_can.c, CAN_ERR_CRTL_UNSPEC is indicated during > a problem in the rx path and this is the tx path. I think the comment > refers to improving the way the driver informs this error to the user > but I may be wrong. >
Since we have no detail of what went wrong here, I suggested CAN_ERR_CRTL_UNSPEC as it is "unspecified error", to be coupled with a controller error with id CAN_ERR_CRTL; however, a different error might be more appropriate. For sure, at least in my experience, having a warn printed to kmsg is *not* enough, as the application sending the message(s) would not be able to detect the error. > > For sure, counting the known errors as valid tx_packets and tx_bytes > > is misleading. > > > > I'll remove the counters below. > We don't really know what's wrong here - the packet might have been sent and and then not ACK'ed, as well as any other error condition (as it happens in the reference implementation from the original authors [1]). Echoing the packet only "to bring a waiting process in an upper layer to an end" and incrementing counters feels wrong, but maybe someone more expert than me can advise better here. [1] https://github.com/OpenSynergy/qemu/commit/115540168f92ba5351a20b9c62552782ea1e3e04 Regards, Francesco
