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Date: Sun, 26 Jul 2015 09:10:10 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: Scott Feldman <sfeldma@...il.com>
Cc: Netdev <netdev@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>, idosch@...lanox.com,
eladr@...lanox.com,
"ogerlitz@...lanox.com" <ogerlitz@...lanox.com>,
Roopa Prabhu <roopa@...ulusnetworks.com>,
Florian Fainelli <f.fainelli@...il.com>,
Thomas Graf <tgraf@...g.ch>,
Alexei Starovoitov <ast@...mgrid.com>,
Jamal Hadi Salim <jhs@...atatu.com>,
Daniel Borkmann <daniel@...earbox.net>,
john fastabend <john.fastabend@...il.com>,
"simon.horman@...ronome.com" <simon.horman@...ronome.com>,
John Linville <linville@...driver.com>,
Andy Gospodarek <andy@...yhouse.net>,
Shrijeet Mukherjee <shm@...ulusnetworks.com>,
"nhorman@...driver.com" <nhorman@...driver.com>,
Jiri Pirko <jiri@...lanox.com>
Subject: Re: [patch net-next 4/4] mlxsw: Introduce Mellanox SwitchX-2 ASIC
support
Sun, Jul 26, 2015 at 04:45:07AM CEST, sfeldma@...il.com wrote:
>On Thu, Jul 23, 2015 at 8:43 AM, Jiri Pirko <jiri@...nulli.us> wrote:
>> From: Jiri Pirko <jiri@...lanox.com>
>>
>> Benefit from the previously introduced Mellanox Switch infrastructure and
>> add driver for SwitchX-2 ASIC. Note that this driver is very simple now.
>> It implements bare minimum for getting device to work on slow-path.
>> Fast-path offload functionality is going to be added soon.
>>
>> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
>> Signed-off-by: Ido Schimmel <idosch@...lanox.com>
>> Signed-off-by: Elad Raz <eladr@...lanox.com>
>
>[cut]
>
>> +static netdev_tx_t mlxsw_sx_port_xmit(struct sk_buff *skb,
>> + struct net_device *dev)
>> +{
>> + struct mlxsw_sx_port *mlxsw_sx_port = netdev_priv(dev);
>> + struct mlxsw_sx *mlxsw_sx = mlxsw_sx_port->mlxsw_sx;
>> + struct mlxsw_sx_port_pcpu_stats *pcpu_stats;
>> + const struct mlxsw_tx_info tx_info = {
>> + .local_port = mlxsw_sx_port->local_port,
>> + .is_emad = false,
>> + };
>> + int err;
>> +
>> + if (unlikely(skb_headroom(skb) < MLXSW_TXHDR_LEN)) {
>
>Does this happen at all since dev->hard_header_len was set in probe to
>add MLXSW_TXHDR_LEN?
This needs to be done for example for bridge forwarding case and other
forwarding cases.
>
>> + struct sk_buff *skb_new;
>> +
>> + skb_new = skb_realloc_headroom(skb, MLXSW_TXHDR_LEN);
>> + dev_kfree_skb_any(skb);
>> + if (!skb_new) {
>> + this_cpu_inc(mlxsw_sx_port->pcpu_stats->tx_dropped);
>> + return NETDEV_TX_OK;
>> + }
>> + skb = skb_new;
>> + }
>> + mlxsw_sx_txhdr_construct(skb, &tx_info);
>> + err = mlxsw_core_skb_transmit(mlxsw_sx, skb, &tx_info);
>> + if (err == -EAGAIN)
>> + return NETDEV_TX_BUSY;
>
>I think there is a problem here when returning NETDEV_TX_BUSY when
>original skb might have been freed above in the headroom check. (ref
>Documentation/networking/driver.txt).
I have to check this out a bit more. Thanks for pointing that out.
>
>[cut]
>
>> +static int mlxsw_sx_port_dev_addr_get(struct mlxsw_sx_port *mlxsw_sx_port)
>> +{
>> + struct mlxsw_sx *mlxsw_sx = mlxsw_sx_port->mlxsw_sx;
>> + struct net_device *dev = mlxsw_sx_port->dev;
>> + char ppad_pl[MLXSW_REG_PPAD_LEN];
>> + int err;
>> +
>> + mlxsw_reg_ppad_pack(ppad_pl, false, 0);
>> + err = mlxsw_reg_query(mlxsw_sx->core, MLXSW_REG(ppad), ppad_pl);
>> + if (err)
>> + return err;
>> + mlxsw_reg_ppad_mac_memcpy_from(ppad_pl, dev->dev_addr);
>> + /* The last byte in base mac address is always 0 */
>> + dev->dev_addr[ETH_ALEN - 1] += mlxsw_sx_port->local_port;
>
>If MLXSW_PORT_MAX_PORTS > 256, you'll wrap this. Is dev_addr[ETH_ALEN
>- 2] available to carry into?
That will never happen. MLXSW_PORT_MAX_PORTS is 0x40 and address got
from ppad register always ends with 0
>
>> + return 0;
>> +}
>> +
>
>[cut]
>
>> +static int mlxsw_sx_port_create(struct mlxsw_sx *mlxsw_sx, u8 local_port)
>> +{
>> + struct mlxsw_sx_port *mlxsw_sx_port;
>> + struct net_device *dev;
>> + bool usable;
>> + int err;
>> +
>> + dev = alloc_etherdev(sizeof(struct mlxsw_sx_port));
>> + if (!dev)
>> + return -ENOMEM;
>> + mlxsw_sx_port = netdev_priv(dev);
>> + mlxsw_sx_port->dev = dev;
>> + mlxsw_sx_port->mlxsw_sx = mlxsw_sx;
>> + mlxsw_sx_port->local_port = local_port;
>> +
>> + mlxsw_sx_port->pcpu_stats =
>> + netdev_alloc_pcpu_stats(struct mlxsw_sx_port_pcpu_stats);
>> + if (!mlxsw_sx_port->pcpu_stats) {
>> + err = -ENOMEM;
>> + goto err_alloc_stats;
>> + }
>> +
>> + dev->netdev_ops = &mlxsw_sx_port_netdev_ops;
>> + dev->ethtool_ops = &mlxsw_sx_port_ethtool_ops;
>> + dev->switchdev_ops = &mlxsw_sx_port_switchdev_ops;
>> +
>> + err = mlxsw_sx_port_dev_addr_get(mlxsw_sx_port);
>> + if (err) {
>> + dev_err(mlxsw_sx->bus_info->dev, "Port %d: Unable to get port mac address\n",
>> + mlxsw_sx_port->local_port);
>> + goto err_dev_addr_get;
>> + }
>> +
>> + netif_carrier_off(dev);
>> +
>> + dev->features |= NETIF_F_NETNS_LOCAL | NETIF_F_LLTX |
>
>Not supposed to use LLTX in new drivers, according to
>include/linux/netdev_features.h.
In our case, wee need to use this. Since multiple port netdevs may use
the same send dataqueue, we need to do locking ourselves.
Thanks for review!
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