Re: [PATCH 1/1] TX throttling bug-fixing patch of AX88179_178A

Eric Dumazet
2013-07-22T17:07:59Z

On Sat, 2013-07-20 at 17:16 +0800, freddy@asix.com.tw wrote:
> From: Freddy Xin <freddy@asix.com.tw>
>
> Disable TSO and SG network features in reset() and bind() functions,
> and check the return value of skb_linearize() in tx_fixup() to prevent
> TX throttling.
>
> Signed-off-by: Freddy Xin <freddy@asix.com.tw>
> ---
> drivers/net/usb/ax88179_178a.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/usb/ax88179_178a.c b/drivers/net/usb/ax88179_178a.c
> index 1e3c302..eb71331 100644
> --- a/drivers/net/usb/ax88179_178a.c
> +++ b/drivers/net/usb/ax88179_178a.c
> @@ -1029,7 +1029,7 @@ static int ax88179_bind(struct usbnet *dev, struct usb_interface *intf)
> dev->mii.supports_gmii = 1;
>
> dev->net->features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
> - NETIF_F_RXCSUM | NETIF_F_SG | NETIF_F_TSO;
> + NETIF_F_RXCSUM;
>
> dev->net->hw_features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
> NETIF_F_RXCSUM | NETIF_F_SG | NETIF_F_TSO;
> @@ -1173,7 +1173,9 @@ ax88179_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
> if (((skb->len + 8) % frame_size) == 0)
> tx_hdr2 |= 0x80008000; /* Enable padding */
>
> - skb_linearize(skb);
> + if (skb_linearize(skb))
> + return NULL;
> +
>

I guess that if a driver does not advertise NETIF_F_SG, this
skb_linearize() call is not needed : All frames reaching your xmit
function should already be linear

Thanks