Re: [PATCH v3 2/5] staging: et131x: drop packet when error occurs in et131x_tx

ZHAO Gang
2013-11-22T11:47:14Z

On Fri, Nov 22, 2013 at 5:17 PM, Denis Kirjanov <kirjanov@gmail.com> wrote:
> On 11/22/13, Mark Einon <mark.einon@gmail.com> wrote:
>> On Wed, Nov 20, 2013 at 03:55:27PM +0800, ZHAO Gang wrote:
>>> As TODO file suggested, drop packet instead of return NETDEV_TX_BUSY
>>> when tx failed.
>>>
>>> et131x_tx calls function et131x_send_packets, I put the work of
>>> et131x_send_packets directly into et131x_tx, and made some changes to
>>> let the code more readable.
>>>
>>> Signed-off-by: ZHAO Gang <gamerh2o@gmail.com>
>>
>> Acked-by: Mark Einon <mark.einon@gmail.com>
>>
>>> ---
>>> drivers/staging/et131x/et131x.c | 84
>>> +++++++++++------------------------------
>>> 1 file changed, 22 insertions(+), 62 deletions(-)
>>>
>>> diff --git a/drivers/staging/et131x/et131x.c
>>> b/drivers/staging/et131x/et131x.c
>>> index 836a4db..cda037a 100644
>>> --- a/drivers/staging/et131x/et131x.c
>>> +++ b/drivers/staging/et131x/et131x.c
>>> @@ -3123,55 +3123,6 @@ static int send_packet(struct sk_buff *skb, struct
>>> et131x_adapter *adapter)
>>> return 0;
>>> }
>>>
>>> -/* et131x_send_packets - This function is called by the OS to send
>>> packets
>>> - * @skb: the packet(s) to send
>>> - * @netdev:device on which to TX the above packet(s)
>>> - *
>>> - * Return 0 in almost all cases; non-zero value in extreme hard failure
>>> only
>>> - */
>>> -static int et131x_send_packets(struct sk_buff *skb, struct net_device
>>> *netdev)
>>> -{
>>> - int status = 0;
>>> - struct et131x_adapter *adapter = netdev_priv(netdev);
>>> -
>>> - /* Send these packets
>>> - *
>>> - * NOTE: The Linux Tx entry point is only given one packet at a time
>>> - * to Tx, so the PacketCount and it's array used makes no sense here
>>> - */
>>> -
>>> - /* TCB is not available */
>>> - if (adapter->tx_ring.used >= NUM_TCB) {
>>> - /* NOTE: If there's an error on send, no need to queue the
>>> - * packet under Linux; if we just send an error up to the
>>> - * netif layer, it will resend the skb to us.
>>> - */
>>> - status = -ENOMEM;
>>> - } else {
>>> - /* We need to see if the link is up; if it's not, make the
>>> - * netif layer think we're good and drop the packet
>>> - */
>>> - if ((adapter->flags & FMP_ADAPTER_FAIL_SEND_MASK) ||
>>> - !netif_carrier_ok(netdev)) {
>>> - dev_kfree_skb_any(skb);
>>> - skb = NULL;
>>> -
>>> - adapter->net_stats.tx_dropped++;
>>> - } else {
>>> - status = send_packet(skb, adapter);
>>> - if (status != 0 && status != -ENOMEM) {
>>> - /* On any other error, make netif think we're
>>> - * OK and drop the packet
>>> - */
>>> - dev_kfree_skb_any(skb);
>>> - skb = NULL;
>>> - adapter->net_stats.tx_dropped++;
>>> - }
>>> - }
>>> - }
>>> - return status;
>>> -}
>>> -
>>> /* free_send_packet - Recycle a struct tcb
>>> * @adapter: pointer to our adapter
>>> * @tcb: pointer to struct tcb
>>> @@ -4537,12 +4488,9 @@ static void et131x_multicast(struct net_device
>>> *netdev)
>>> /* et131x_tx - The handler to tx a packet on the device
>>> * @skb: data to be Tx'd
>>> * @netdev: device on which data is to be Tx'd
>>> - *
>>> - * Returns 0 on success, errno on failure (as defined in errno.h)
>>> */
>>> -static int et131x_tx(struct sk_buff *skb, struct net_device *netdev)
>>> +static netdev_tx_t et131x_tx(struct sk_buff *skb, struct net_device
>>> *netdev)
>>> {
>>> - int status = 0;
>>> struct et131x_adapter *adapter = netdev_priv(netdev);
>>>
>>> /* stop the queue if it's getting full */
>>> @@ -4553,17 +4501,29 @@ static int et131x_tx(struct sk_buff *skb, struct
>>> net_device *netdev)
>>> /* Save the timestamp for the TX timeout watchdog */
>>> netdev->trans_start = jiffies;
>>>
>>> - /* Call the device-specific data Tx routine */
>>> - status = et131x_send_packets(skb, netdev);
>>> + /* TCB is not available */
>>> + if (adapter->tx_ring.used >= NUM_TCB)
>>> + goto drop;
>
> That's wrong. You have to properly manage tx queue and not just drop packets

Could you kindly tell me what should be done to tx queue?

>
>>> - /* Check status and manage the netif queue if necessary */
>>> - if (status != 0) {
>>> - if (status == -ENOMEM)
>>> - status = NETDEV_TX_BUSY;
>>> - else
>>> - status = NETDEV_TX_OK;
>>> + /* We need to see if the link is up; if it's not, make the
>>> + * netif layer think we're good and drop the packet
>>> + */
>>> + if ((adapter->flags & FMP_ADAPTER_FAIL_SEND_MASK) ||
>>> + !netif_carrier_ok(netdev)) {
>>> + goto drop;
>>> + } else {
>>> + if (!send_packet(skb, adapter))
>>> + goto out;
>>> + /* On error (send_packet returns != 0), make netif
>>> + * think we're OK and drop the packet
>>> + */
>>> }
>>> - return status;
>>> +
>>> +drop:
>>> + dev_kfree_skb_any(skb);
>>> + adapter->net_stats.tx_dropped++;
>>> +out:
>>> + return NETDEV_TX_OK;
>>> }
>>>
>>> /* et131x_tx_timeout - Timeout handler
>>> --
>>> 1.8.3.1
>>>
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>
>
> --
> Regards,
> Denis