>>> On 06.02.11 at 14:42, Olaf Hering <olaf@xxxxxxxxx> wrote:
> Allow arbitrary mtu size until the frontend is connected. Once the
> connection is established, adjust mtu by checking if the backend
> supports the 'feature-sg'. If the backend does support it, keep the
> current mtu. Otherwise set it to the default value, which is 1500.
>
> This helps the vif-bridge hotplug script to set the mtu size to 9000
> while bringing up the guest.
Isn't this functionally the same as
http://xenbits.xen.org/XCP/linux-2.6.32.pq.hg?file/043b76e4943c/xen-netback-Allow-setting-of-large-MTU-before-rings.patch
or its pv-ops parent
https://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=commitdiff;h=bee2eec2355c4bf4e149a426d5e30527162de566
(in which case it would seem preferable to pull in that change)?
Ian, looking at that patch of yours again, the adjustment to
netbk_set_sg() seems a little odd: Why is it necessary to
reduce dev->mtu unconditionally (i.e. independent of the
value of "data") here?
Jan
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
>
> ---
> drivers/xen/netback/common.h | 8 ++++++++
> drivers/xen/netback/interface.c | 8 +++++++-
> drivers/xen/netback/xenbus.c | 9 +++++++++
> 3 files changed, 24 insertions(+), 1 deletion(-)
>
> --- linux-2.6.18-xen.hg.orig/drivers/xen/netback/common.h
> +++ linux-2.6.18-xen.hg/drivers/xen/netback/common.h
> @@ -82,6 +82,8 @@ typedef struct netif_st {
> u8 can_queue:1; /* can queue packets for receiver? */
> u8 copying_receiver:1; /* copy packets to receiver? */
>
> + u8 frontend_connected:1; /* is frontend already connected? */
> +
> /* Allow netif_be_start_xmit() to peek ahead in the rx request ring. */
> RING_IDX rx_req_cons_peek;
>
> @@ -217,4 +219,10 @@ static inline int netbk_can_sg(struct ne
> return netif->features & NETIF_F_SG;
> }
>
> +static inline int netbk_frontend_connected(struct net_device *dev)
> +{
> + netif_t *netif = netdev_priv(dev);
> + return !!netif->frontend_connected;
> +}
> +
> #endif /* __NETIF__BACKEND__COMMON_H__ */
> --- linux-2.6.18-xen.hg.orig/drivers/xen/netback/interface.c
> +++ linux-2.6.18-xen.hg/drivers/xen/netback/interface.c
> @@ -83,9 +83,13 @@ static int net_close(struct net_device *
> return 0;
> }
>
> +/* accept the max value if frontend is not yet connected */
> static int netbk_change_mtu(struct net_device *dev, int mtu)
> {
> - int max = netbk_can_sg(dev) ? 65535 - ETH_HLEN : ETH_DATA_LEN;
> + int max = 65535 - ETH_HLEN;
> +
> + if (netbk_frontend_connected(dev))
> + max = netbk_can_sg(dev) ? max : ETH_DATA_LEN;
>
> if (mtu > max)
> return -EINVAL;
> @@ -359,6 +363,8 @@ err_rx:
>
> void netif_disconnect(netif_t *netif)
> {
> + netif->frontend_connected = 0;
> +
> if (netback_carrier_ok(netif)) {
> rtnl_lock();
> netback_carrier_off(netif);
> --- linux-2.6.18-xen.hg.orig/drivers/xen/netback/xenbus.c
> +++ linux-2.6.18-xen.hg/drivers/xen/netback/xenbus.c
> @@ -329,6 +329,13 @@ static int xen_net_read_mac(struct xenbu
> return 0;
> }
>
> +static void xen_net_adjust_mtu(netif_t *netif)
> +{
> + if (!netif->dev->change_mtu)
> + return;
> + netif->dev->change_mtu(netif->dev, netif->dev->mtu);
> +}
> +
> static void connect(struct backend_info *be)
> {
> int err;
> @@ -338,6 +345,8 @@ static void connect(struct backend_info
> if (err)
> return;
>
> + be->netif->frontend_connected = 1;
> + xen_net_adjust_mtu(be->netif);
> err = xen_net_read_mac(dev, be->netif->fe_dev_addr);
> if (err) {
> xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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