Re: [PATCH v2 3/7] [PATCH 3/8] can: CAN Network device driver and Netlink interface

Wolfgang Grandegger
2009-05-14T07:56:13Z

Jonathan Corbet wrote:
> [Quick review ...]
>
>> +/*
>> + * CAN device restart for bus-off recovery
>> + */
>> +int can_restart_now(struct net_device *dev)
>> +{
>> + struct can_priv *priv = netdev_priv(dev);
>> + struct net_device_stats *stats = &dev->stats;
>> + struct sk_buff *skb;
>> + struct can_frame *cf;
>> + int err;
>> +
>> + /* Synchronize with dev->hard_start_xmit() */
>> + netif_tx_lock(dev);
>> +
>> + /* Ensure that no more messages can go out */
>> + if (netif_carrier_ok(dev))
>> + netif_carrier_off(dev);
>> +
>> + /* Ensure that no more messages can come in */
>> + err = priv->do_set_mode(dev, CAN_MODE_STOP);
>> + if (err)
>> + return err;
>
> This leaves _xmit_lock held and carrier off. Is that really what you want
> to do?
>
>> +
>> + /* Now it's save to clean up */
>> + del_timer_sync(&priv->restart_timer);
>> + can_flush_echo_skb(dev);
>> +
>> + dev_dbg(dev->dev.parent, "restarted\n");
>> + priv->can_stats.restarts++;
>> +
>> + /* send restart message upstream */
>> + skb = dev_alloc_skb(sizeof(struct can_frame));
>> + if (skb == NULL)
>> + return -ENOMEM;
>
> ...here too...
>
>> + skb->dev = dev;
>> + skb->protocol = htons(ETH_P_CAN);
>> + cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
>> + memset(cf, 0, sizeof(struct can_frame));
>> + cf->can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED;
>> + cf->can_dlc = CAN_ERR_DLC;
>> +
>> + netif_rx(skb);
>> +
>> + dev->last_rx = jiffies;
>> + stats->rx_packets++;
>> + stats->rx_bytes += cf->can_dlc;
>> +
>> + /* Now restart the device */
>> + err = priv->do_set_mode(dev, CAN_MODE_START);
>> + if (err)
>> + return err;
>
> ...and here too. Do you maybe want to get rid of the middle-of-function
> returns and switch to the "goto out" convention?

Right, needs to be fixed.

>> + netif_carrier_on(dev);
>> +
>> + netif_tx_unlock(dev);
>> +
>> + return 0;
>> +}
>> +
>> +static void can_restart_after(unsigned long data)
>> +{
>> + struct net_device *dev = (struct net_device *)data;
>> +
>> + can_restart_now(dev);
>> +}
>
> can_restart_after what? I find myself confused by this function and
> wondering why it exists.

It's just a wrapper to make the compile happy. It's the timer callback
function used here:

priv->restart_timer.function = can_restart_after;

in contrast to can_restart_now(), which can be called via netlink
interface as well. Would the name "can_restart_callback" be more
appropriate?

Wolfgang.