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

Ben Hutchings
2013-07-22T17:11:19Z

On Mon, 2013-07-22 at 10:07 -0700, Eric Dumazet wrote:
> 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

Look at the hw_features initialisation...

Ben.

--
Ben Hutchings, Staff Engineer, Solarflare
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