On Sun, Mar 19, 2023 at 02:27:44PM -0700, Haiyang Zhang wrote:
> During probe, get the hardware allowed max MTU by querying the device
> configuration. Users can select MTU up to the device limit. Also,
> when XDP is in use, we currently limit the buffer size to one page.
>
> Updated RX data path to allocate and use RX queue DMA buffers with
> proper size based on the MTU setting.
>
> Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> ---
> .../net/ethernet/microsoft/mana/mana_bpf.c | 22 +-
> drivers/net/ethernet/microsoft/mana/mana_en.c | 229 ++++++++++++------
> include/net/mana/gdma.h | 4 +
> include/net/mana/mana.h | 18 +-
> 4 files changed, 183 insertions(+), 90 deletions(-)
<...>
> +static int mana_change_mtu(struct net_device *ndev, int new_mtu)
> +{
> + unsigned int old_mtu = ndev->mtu;
> + int err, err2;
> +
> + err = mana_detach(ndev, false);
> + if (err) {
> + netdev_err(ndev, "mana_detach failed: %d\n", err);
> + return err;
> + }
> +
> + ndev->mtu = new_mtu;
> +
> + err = mana_attach(ndev);
> + if (!err)
> + return 0;
> +
> + netdev_err(ndev, "mana_attach failed: %d\n", err);
> +
> + /* Try to roll it back to the old configuration. */
> + ndev->mtu = old_mtu;
> + err2 = mana_attach(ndev);
I second to Francois and agree with him that it is very questionable.
If mana_attach() failed for first try, you should bail out and not
retry with some hope that it will pass.
Thanks
> + if (err2)
> + netdev_err(ndev, "mana re-attach failed: %d\n", err2);
> +
> + return err;
