Hi Andrew > -----Original Message----- > From: Andrew Lunn [mailto:andrew@xxxxxxx] > Sent: Friday, August 18, 2017 2:31 PM > To: Salil Mehta > Cc: davem@xxxxxxxxxxxxx; Zhuangyuzeng (Yisen); lipeng (Y); > dan.carpenter@xxxxxxxxxx; mehta.salil.lnk@xxxxxxxxx; > netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux- > rdma@xxxxxxxxxxxxxxx; Linuxarm > Subject: Re: [PATCH net-next] net: hns3: Add support to change MTU in > hardware & netdev > > On Fri, Aug 18, 2017 at 12:35:58PM +0100, Salil Mehta wrote: > > This patch adds the following support to the HNS3 driver: > > 1. Support to change the Maximum Transmission Unit of a > > netdevice and of a port in hardware . > > 2. Initializes the supported MTU range for the netdevice. > > > > Signed-off-by: lipeng <lipeng321@xxxxxxxxxx> > > Signed-off-by: Salil Mehta <salil.mehta@xxxxxxxxxx> > > --- > > .../net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c | 46 > ++++++++++++++++++++++ > > .../net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.h | 1 + > > 2 files changed, 47 insertions(+) > > > > diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c > b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c > > index e731f87..8e3711e 100644 > > --- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c > > +++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c > > @@ -1278,11 +1278,53 @@ static int hns3_ndo_set_vf_vlan(struct > net_device *netdev, int vf, u16 vlan, > > return ret; > > } > > > > +static int hns3_nic_change_mtu(struct net_device *netdev, int > new_mtu) > > +{ > > + struct hns3_nic_priv *priv = netdev_priv(netdev); > > + struct hnae3_handle *h = priv->ae_handle; > > + bool if_running = netif_running(netdev); > > + int ret; > > + > > + /* no change in MTU */ > > + if (new_mtu == netdev->mtu) > > + return 0; > > Hi Salil > > It is worth reading the core code: > > http://elixir.free- > electrons.com/linux/latest/source/net/core/dev.c#L6713 Right. Looks like it is already being done since 4.10-rc1 because of the patches Floated by Jarod Wilson <jarod@xxxxxxxxxx>. Link: https://lkml.org/lkml/2016/10/13/270 Will remove this duplicate check! Thanks Salil > + > > + if (!h->ae_algo->ops->set_mtu) > > + return -ENOTSUPP; > > + > > + /* if this was called with netdev up then bring netdevice down */ > > + if (if_running) { > > + (void)hns3_nic_net_stop(netdev); > > + msleep(100); > > + } > > + > > + ret = h->ae_algo->ops->set_mtu(h, new_mtu); > > + if (ret) { > > + netdev_err(netdev, "failed to change MTU in hardware %d\n", > > + ret); > > + return ret; > > + } > > + > > + /* assign newly changed mtu to netdevice as well */ > > + netdev->mtu = new_mtu; > > http://elixir.free- > electrons.com/linux/latest/source/net/core/dev.c#L6698 Again, it is being done by core now since 4.10-rc1. Link: https://lkml.org/lkml/2016/10/13/270 Will remove this duplicate code! Thanks Salil > > > + > > + /* if the netdev was running earlier, bring it up again */ > > + if (if_running) { > > + if (hns3_nic_net_open(netdev)) { > > + netdev_err(netdev, "MTU, couldnt up netdev again\n"); > > + ret = -EINVAL; > > + } > > + } > > + > > + return ret; > > +} > > + > > static const struct net_device_ops hns3_nic_netdev_ops = { > > .ndo_open = hns3_nic_net_open, > > .ndo_stop = hns3_nic_net_stop, > > .ndo_start_xmit = hns3_nic_net_xmit, > > .ndo_set_mac_address = hns3_nic_net_set_mac_address, > > + .ndo_change_mtu = hns3_nic_change_mtu, > > .ndo_set_features = hns3_nic_set_features, > > .ndo_get_stats64 = hns3_nic_get_stats64, > > .ndo_setup_tc = hns3_nic_setup_tc, > > @@ -2752,6 +2794,10 @@ static int hns3_client_init(struct > hnae3_handle *handle) > > goto out_reg_netdev_fail; > > } > > > > + /* MTU range: 68 - 9706 */ > > + netdev->min_mtu = ETH_MIN_MTU; > > http://elixir.free- > electrons.com/linux/latest/source/net/ethernet/eth.c#L361 Supported range of Min and Max MTU should be at the discretion of the driver. Therefore, initialization looks fine to me. I could not clearly understand the problem being highlighted over here. Could you further clarify? Thanks Salil > > > + netdev->max_mtu = HNS3_MAX_MTU - (ETH_HLEN + ETH_FCS_LEN + > VLAN_HLEN); > > + > > return ret; > > > > out_reg_netdev_fail: > > diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.h > b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.h > > index a6e8f15..7e87461 100644 > > --- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.h > > +++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.h > > @@ -76,6 +76,7 @@ enum hns3_nic_state { > > #define HNS3_RING_NAME_LEN 16 > > #define HNS3_BUFFER_SIZE_2048 2048 > > #define HNS3_RING_MAX_PENDING 32768 > > +#define HNS3_MAX_MTU 9728 > > It seems odd that it does not already exists somewhere. The core does > not enforce the MTU. You could be passed a frame which is bigger. So > you should check before trying to pass something to the hardware which > the hardware cannot handle. There is a check already in place for this as well since 4.10-rc1. But perhaps this time there is no change required as it is being taken care by the core. Thanks to sharp eyes of Jarod. Link: https://lkml.org/lkml/2016/10/13/270 [...] if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) { net_err_ratelimited("%s: Invalid MTU %d requested, hw max %d\n", dev->name, new_mtu, dev->max_mtu); [...] I think I missed this patch entirely so those rest above checks & assignments were repeated. Thanks Salil > > Andrew -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
