Hi Bjørn, Il giorno ven 4 gen 2019 alle ore 14:24 Bjørn Mork <bj...@mork.no> ha scritto: > > Daniele Palmas <dnl...@gmail.com> writes: > > > This patch adds MTU default value to qmap network interface in > > order to avoid "RTNETLINK answers: No buffer space available" > > error when setting an ipv6 address. > > > > Signed-off-by: Daniele Palmas <dnl...@gmail.com> > > --- > > drivers/net/usb/qmi_wwan.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c > > index 774e1ff..735ad83 100644 > > --- a/drivers/net/usb/qmi_wwan.c > > +++ b/drivers/net/usb/qmi_wwan.c > > @@ -123,6 +123,7 @@ static void qmimux_setup(struct net_device *dev) > > dev->addr_len = 0; > > dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST; > > dev->netdev_ops = &qmimux_netdev_ops; > > + dev->mtu = 1500; > > dev->needs_free_netdev = true; > > } > > Setting some value makes sense, but hard coding 1500 feels wrong. > Should this relate to the real device mtu somehow? Do we need a > ndo_change_mtu to enforce this relationship? Should qmimux_rx_fixup() > respect the qmap device mtu? >
yes, all your questions seem relevant to me: in the the first draft of my patch qmap mtu was related to the real dev mtu, considering also the qmap header, but then I took a look at how the rmnet driver is managing mtu. If I'm not wrong, it seems that mtu is hardcoded also for rmnet (RMNET_DFLT_PACKET_SIZE = 1500 defined in drivers/net/ethernet/qualcomm/rmnet/rmnet_private.h and applied in rmnet_vnd_setup function at rmnet_vnd.c). I do not see any part of code in which the rmnet mtu is related to the mtu of the underlying device (but maybe it's me that is missing something obvious) so I used the same approach, hard coding the value. Maybe should usbnet_change_mtu be called with the qmap network interface mtu (+ qmap header size ?) when creating a qmap device, like in qmi_wwan_netdev_setup? Sorry in advance if I'm writing silly things... Thanks, Daniele > I'm fine with this patch as a first step and immediate fix, so > > Acked-by: Bjørn Mork <bj...@mork.no>
