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Date: Tue, 08 Dec 2020 01:19:09 -0700 From: subashab@...eaurora.org To: Jakub Kicinski <kuba@...nel.org>, Loic Poulain <loic.poulain@...aro.org> Cc: stranche@...eaurora.org, Network Development <netdev@...r.kernel.org> Subject: Re: [PATCH] net: rmnet: Adjust virtual device MTU on real device capability >> What about just returning an error on NETDEV_PRECHANGEMTU notification >> to prevent real device MTU change while virtual rmnet devices are >> linked? Not sure there is a more proper and thread safe way to manager >> that otherwise. > > Can't you copy what vlan devices do? That'd seem like a reasonable and > well tested precedent, no? Could you try this patch. I've tried addressing most of the conditions here. I haven't seen any issues with updating the MTU when rmnet devices are linked. diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c index fcdecdd..8d51b0c 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c @@ -26,7 +26,7 @@ static int rmnet_is_real_dev_registered(const struct net_device *real_dev) } /* Needs rtnl lock */ -static struct rmnet_port* +struct rmnet_port* rmnet_get_port_rtnl(const struct net_device *real_dev) { return rtnl_dereference(real_dev->rx_handler_data); @@ -253,7 +253,10 @@ static int rmnet_config_notify_cb(struct notifier_block *nb, netdev_dbg(real_dev, "Kernel unregister\n"); rmnet_force_unassociate_device(real_dev); break; - + case NETDEV_CHANGEMTU: + if (rmnet_vnd_validate_real_dev_mtu(real_dev)) + return NOTIFY_BAD; + break; default: break; } @@ -329,9 +332,17 @@ static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[], if (data[IFLA_RMNET_FLAGS]) { struct ifla_rmnet_flags *flags; + u32 old_data_format; + old_data_format = port->data_format; flags = nla_data(data[IFLA_RMNET_FLAGS]); port->data_format = flags->flags & flags->mask; + + if (rmnet_vnd_update_dev_mtu(port, real_dev)) { + port->data_format = old_data_format; + NL_SET_ERR_MSG_MOD(extack, "Invalid MTU on real dev"); + return -EINVAL; + } } return 0; diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h index be51598..8d8d469 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h @@ -73,4 +73,6 @@ int rmnet_add_bridge(struct net_device *rmnet_dev, struct netlink_ext_ack *extack); int rmnet_del_bridge(struct net_device *rmnet_dev, struct net_device *slave_dev); +struct rmnet_port* +rmnet_get_port_rtnl(const struct net_device *real_dev); #endif /* _RMNET_CONFIG_H_ */ diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c index d58b51d..df87883 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c @@ -58,9 +58,30 @@ static netdev_tx_t rmnet_vnd_start_xmit(struct sk_buff *skb, return NETDEV_TX_OK; } +static int rmnet_vnd_headroom(struct net_device *real_dev) +{ + struct rmnet_port *port; + u32 headroom; + + port = rmnet_get_port_rtnl(real_dev); + + headroom = sizeof(struct rmnet_map_header); + + if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) + headroom += sizeof(struct rmnet_map_dl_csum_trailer); + + return headroom; +} + static int rmnet_vnd_change_mtu(struct net_device *rmnet_dev, int new_mtu) { - if (new_mtu < 0 || new_mtu > RMNET_MAX_PACKET_SIZE) + struct rmnet_priv *priv = netdev_priv(rmnet_dev); + u32 headroom; + + headroom = rmnet_vnd_headroom(priv->real_dev); + + if (new_mtu < 0 || new_mtu > RMNET_MAX_PACKET_SIZE || + new_mtu > (priv->real_dev->mtu - headroom)) return -EINVAL; rmnet_dev->mtu = new_mtu; @@ -229,6 +250,7 @@ int rmnet_vnd_newlink(u8 id, struct net_device *rmnet_dev, { struct rmnet_priv *priv = netdev_priv(rmnet_dev); + u32 headroom; int rc; if (rmnet_get_endpoint(port, id)) { @@ -242,6 +264,13 @@ int rmnet_vnd_newlink(u8 id, struct net_device *rmnet_dev, priv->real_dev = real_dev; + headroom = rmnet_vnd_headroom(real_dev); + + if (rmnet_vnd_change_mtu(rmnet_dev, real_dev->mtu - headroom)) { + NL_SET_ERR_MSG_MOD(extack, "Invalid MTU on real dev"); + return -EINVAL; + } + rc = register_netdevice(rmnet_dev); if (!rc) { ep->egress_dev = rmnet_dev; @@ -283,3 +312,51 @@ int rmnet_vnd_do_flow_control(struct net_device *rmnet_dev, int enable) return 0; } + +int rmnet_vnd_validate_real_dev_mtu(struct net_device *real_dev) +{ + struct hlist_node *tmp_ep; + struct rmnet_endpoint *ep; + struct rmnet_port *port; + unsigned long bkt_ep; + u32 headroom; + + port = rmnet_get_port_rtnl(real_dev); + + headroom = sizeof(struct rmnet_map_header); + + if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) + headroom += sizeof(struct rmnet_map_dl_csum_trailer); + + hash_for_each_safe(port->muxed_ep, bkt_ep, tmp_ep, ep, hlnode) { + if (ep->egress_dev->mtu > (real_dev->mtu - headroom)) + return -1; + } + + return 0; +} + +int rmnet_vnd_update_dev_mtu(struct rmnet_port *port, + struct net_device *real_dev) +{ + struct hlist_node *tmp_ep; + struct rmnet_endpoint *ep; + unsigned long bkt_ep; + u32 headroom; + + headroom = sizeof(struct rmnet_map_header); + + if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) + headroom += sizeof(struct rmnet_map_dl_csum_trailer); + + hash_for_each_safe(port->muxed_ep, bkt_ep, tmp_ep, ep, hlnode) { + if (ep->egress_dev->mtu <= (real_dev->mtu - headroom)) + continue; + + if (rmnet_vnd_change_mtu(ep->egress_dev, + real_dev->mtu - headroom)) + return -1; + } + + return 0; +} \ No newline at end of file diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.h index 4967f34..dc3a444 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.h +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.h @@ -18,4 +18,7 @@ int rmnet_vnd_dellink(u8 id, struct rmnet_port *port, void rmnet_vnd_rx_fixup(struct sk_buff *skb, struct net_device *dev); void rmnet_vnd_tx_fixup(struct sk_buff *skb, struct net_device *dev); void rmnet_vnd_setup(struct net_device *dev); +int rmnet_vnd_validate_real_dev_mtu(struct net_device *real_dev); +int rmnet_vnd_update_dev_mtu(struct rmnet_port *port, + struct net_device *real_dev); #endif /* _RMNET_VND_H_ */ -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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