| Message ID | 20110411075829.7b9bf1e5@nehalam |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, Apr 11, 2011 at 07:58:29AM -0700, Stephen Hemminger wrote: > On Mon, 11 Apr 2011 02:51:00 +0200 > Michał Mirosław <mirq-linux@rere.qmqm.pl> wrote: > > > On Sun, Apr 10, 2011 at 11:53:02AM -0700, Stephen Hemminger wrote: > > > On Sun, 10 Apr 2011 15:13:21 +0200 (CEST) > > > Michał Mirosław <mirq-linux@rere.qmqm.pl> wrote: > > > > Caveats: > > > > - driver modifies vlan_features on HW VLAN TX changes > > > > - broken RX checksum will be reenabled on features change > > > To be more precise. This is acceptable if and only if all cases > > > where features are disabled in response to MTU and chip versions > > > are exactly the same. We don't want to let some user stumble upon > > > cases where hardware features don't work in their configuration. > > I was referring to the unlikely case detected by sky2_rx_checksum(). > > Before this conversion, user could reenable the feature using ethtool. > > The change is that now, in this case, it's reenabled also when other > > features are changed (i.e. whenever netdev_update_features() gets called). > > Ok. > > It does expose a pre-existing issue. If this logic trips (and I have > gotten reports of it happening), then the GRO will not get disabled. > Probably need to mask of GRO as well, since GRO depends on RXCSUM. This is not a problem, since the code checks skb->ip_summed for protocols that implement GRO. See tcp4_gro_receive() for example. This might be a slight hit in performance, though. Best Regards, Michał Mirosław -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 11 Apr 2011 19:58:23 +0200 Michał Mirosław <mirq-linux@rere.qmqm.pl> wrote: > On Mon, Apr 11, 2011 at 07:58:29AM -0700, Stephen Hemminger wrote: > > On Mon, 11 Apr 2011 02:51:00 +0200 > > Michał Mirosław <mirq-linux@rere.qmqm.pl> wrote: > > > > > On Sun, Apr 10, 2011 at 11:53:02AM -0700, Stephen Hemminger wrote: > > > > On Sun, 10 Apr 2011 15:13:21 +0200 (CEST) > > > > Michał Mirosław <mirq-linux@rere.qmqm.pl> wrote: > > > > > Caveats: > > > > > - driver modifies vlan_features on HW VLAN TX changes > > > > > - broken RX checksum will be reenabled on features change > > > > To be more precise. This is acceptable if and only if all cases > > > > where features are disabled in response to MTU and chip versions > > > > are exactly the same. We don't want to let some user stumble upon > > > > cases where hardware features don't work in their configuration. > > > I was referring to the unlikely case detected by sky2_rx_checksum(). > > > Before this conversion, user could reenable the feature using ethtool. > > > The change is that now, in this case, it's reenabled also when other > > > features are changed (i.e. whenever netdev_update_features() gets called). > > > > Ok. > > > > It does expose a pre-existing issue. If this logic trips (and I have > > gotten reports of it happening), then the GRO will not get disabled. > > Probably need to mask of GRO as well, since GRO depends on RXCSUM. > > This is not a problem, since the code checks skb->ip_summed for protocols > that implement GRO. See tcp4_gro_receive() for example. This might be > a slight hit in performance, though. The performance hit is expected, just thought that GRO depended on rx checksum. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/drivers/net/sky2.c 2011-04-11 07:56:50.569361209 -0700 +++ b/drivers/net/sky2.c 2011-04-11 07:57:34.502312648 -0700 @@ -2538,7 +2538,7 @@ static void sky2_rx_checksum(struct sky2 * It will be reenabled on next ndo_set_features, but if it's * really broken, will get disabled again */ - sky2->netdev->features &= ~NETIF_F_RXCSUM; + sky2->netdev->features &= ~(NETIF_F_RXCSUM | NETIF_F_GRO); sky2_write32(sky2->hw, Q_ADDR(rxqaddr[sky2->port], Q_CSR), BMU_DIS_RX_CHKSUM); }