On Sat, Oct 22, 2016 at 09:27:59PM +0200, Stefan Richter wrote:
> Adding Cc: linux1394-devel, dropping several Ccs, no additional comment.
>
> On Oct 22 Stefan Richter wrote:
> > On Oct 20 Jarod Wilson wrote:
> > > firewire-net:
> > > - set min/max_mtu
> > > - remove fwnet_change_mtu
> > [...]
> > > --- a/drivers/firewire/net.c
> > > +++ b/drivers/firewire/net.c
> > > @@ -1349,15 +1349,6 @@ static netdev_tx_t fwnet_tx(struct sk_buff
> > > *skb, struct net_device *net) return NETDEV_TX_OK;
> > > }
> > >
> > > -static int fwnet_change_mtu(struct net_device *net, int new_mtu)
> > > -{
> > > - if (new_mtu < 68)
> > > - return -EINVAL;
> > > -
> > > - net->mtu = new_mtu;
> > > - return 0;
> > > -}
> > > -
> > > static const struct ethtool_ops fwnet_ethtool_ops = {
> > > .get_link = ethtool_op_get_link,
> > > };
> > > @@ -1366,7 +1357,6 @@ static const struct net_device_ops
> > > fwnet_netdev_ops = { .ndo_open = fwnet_open,
> > > .ndo_stop = fwnet_stop,
> > > .ndo_start_xmit = fwnet_tx,
> > > - .ndo_change_mtu = fwnet_change_mtu,
> > > };
> > >
> > > static void fwnet_init_dev(struct net_device *net)
> > > @@ -1435,7 +1425,6 @@ static int fwnet_probe(struct fw_unit *unit,
> > > struct net_device *net;
> > > bool allocated_netdev = false;
> > > struct fwnet_device *dev;
> > > - unsigned max_mtu;
> > > int ret;
> > > union fwnet_hwaddr *ha;
> > >
> > > @@ -1478,9 +1467,10 @@ static int fwnet_probe(struct fw_unit *unit,
> > > * Use the RFC 2734 default 1500 octets or the maximum payload
> > > * as initial MTU
> > > */
> > > - max_mtu = (1 << (card->max_receive + 1))
> > > - - sizeof(struct rfc2734_header) - IEEE1394_GASP_HDR_SIZE;
> > > - net->mtu = min(1500U, max_mtu);
> > > + net->max_mtu = (1 << (card->max_receive + 1))
> > > + - sizeof(struct rfc2734_header) - IEEE1394_GASP_HDR_SIZE;
> > > + net->mtu = min(1500U, net->max_mtu);
> > > + net->min_mtu = ETH_MIN_MTU;
> > >
> > > /* Set our hardware address while we're at it */
> > > ha = (union fwnet_hwaddr *)net->dev_addr;
> >
> > Please preserve the current behavior, i.e. do not enforce any particular
> > upper bound. (Especially none based on the local link layer controller's
> > max_receive parameter.)
> >
> > BTW, after having read RFC 2734, RFC 3146, and the code, I am convinced
> > that net->mtu should be initialized to 1500, not less. But such a change
> > should be done in a separate patch.
Okay, since it's already merged in net-next, I can do a follow-up patch
here to set max_mtu to ETH_MAX_MTU (65535), which is the largest possible
size the kernel can handle, so far as I can tell. But as long as I'm going
to be in here, if we just want to use an initial mtu of 1500, I could
clean that up at the same time, and entirely remove the max_mtu
calculation stuff, if that's what you think is more correct here.
--
Jarod Wilson
ja...@redhat.com
