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

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Date:	Thu, 21 Nov 2013 21:19:21 +0000
From:	Mark Einon <mark.einon@...il.com>
To:	ZHAO Gang <gamerh2o@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org
Subject: Re: [PATCH v3 2/5] staging: et131x: drop packet when error occurs in
 et131x_tx

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@...il.com>

Acked-by: Mark Einon <mark.einon@...il.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;
>  
> -	/* 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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