On Tue, Jul 18, 2017 at 4:33 PM, Girish Moodalbail
<girish.moodalb...@oracle.com> wrote:
> This patch adds changelink rtnl operation support for geneve devices
> and the code changes involve:
>
> - add geneve_quiesce() which quiesces the geneve device data path
> for both TX and RX. This lets us perform the changelink operation
> atomically w.r.t data path. Also add geneve_unquiesce() to
> reverse the operation of geneve_quiesce().
>
> - refactor geneve_newlink into geneve_nl2info to be used by both
> geneve_newlink and geneve_changelink
>
> - geneve_nl2info takes a changelink boolean argument to isolate
> changelink checks.
>
> - Allow changing only a few attributes (ttl, tos, and remote tunnel
> endpoint IP address (within the same address family)):
> - return -EOPNOTSUPP for attributes that cannot be changed for
> now. Incremental patches can make the non-supported one
> available in the future if needed.
>
> Signed-off-by: Girish Moodalbail <girish.moodalb...@oracle.com>
> ---
> v0 -> v1:
> - added geneve_quiesce() and geneve_unquiesce() functions to
> perform the changelink operation atomically w.r.t data path
> ---
> drivers/net/geneve.c | 192
> +++++++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 157 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
> index de8156c..829f541 100644
> --- a/drivers/net/geneve.c
> +++ b/drivers/net/geneve.c
...
...
> +/* Quiesces the geneve device data path for both TX and RX. */
> +static inline void geneve_quiesce(struct geneve_dev *geneve,
> + struct geneve_sock **gs4,
> + struct geneve_sock **gs6)
> +{
> + *gs4 = rtnl_dereference(geneve->sock4);
> + rcu_assign_pointer(geneve->sock4, NULL);
> +
> +#if IS_ENABLED(CONFIG_IPV6)
> + *gs6 = rtnl_dereference(geneve->sock6);
> + rcu_assign_pointer(geneve->sock6, NULL);
> +#else
> + *gs6 = NULL;
> +#endif
> + synchronize_net();
> +}
> +
> +/* Resumes the geneve device data path for both TX and RX. */
> +static inline void geneve_unquiesce(struct geneve_dev *geneve,
> + struct geneve_sock *gs4,
> + struct geneve_sock __maybe_unused *gs6)
> +{
> + rcu_assign_pointer(geneve->sock4, gs4);
> +#if IS_ENABLED(CONFIG_IPV6)
> + rcu_assign_pointer(geneve->sock6, gs6);
> +#endif
> + synchronize_net();
> +}
> +
> +static int geneve_changelink(struct net_device *dev, struct nlattr *tb[],
> + struct nlattr *data[],
> + struct netlink_ext_ack *extack)
> +{
> + struct geneve_dev *geneve = netdev_priv(dev);
> + struct geneve_sock *gs4, *gs6;
> + struct ip_tunnel_info info;
> + bool metadata;
> + bool use_udp6_rx_checksums;
> + int err;
> +
> + /* If the geneve device is configured for metadata (or externally
> + * controlled, for example, OVS), then nothing can be changed.
> + */
> + if (geneve->collect_md)
> + return -EOPNOTSUPP;
> +
> + /* Start with the existing info. */
> + memcpy(&info, &geneve->info, sizeof(info));
> + metadata = geneve->collect_md;
> + use_udp6_rx_checksums = geneve->use_udp6_rx_checksums;
> + err = geneve_nl2info(dev, tb, data, &info, &metadata,
> + &use_udp6_rx_checksums, true);
> + if (err)
> + return err;
> +
> + if (!geneve_dst_addr_equal(&geneve->info, &info))
> + dst_cache_reset(&info.dst_cache);
> +
> + geneve_quiesce(geneve, &gs4, &gs6);
> + geneve->info = info;
> + geneve->collect_md = metadata;
> + geneve->use_udp6_rx_checksums = use_udp6_rx_checksums;
> + geneve_unquiesce(geneve, gs4, gs6);
> +
This is nice trick. But it adds check for the socket in datapath. did
you explore updating entire device state in single atomic transaction?
> + return 0;
> +}
> +
> static void geneve_dellink(struct net_device *dev, struct list_head *head)
> {
> struct geneve_dev *geneve = netdev_priv(dev);
> @@ -1375,6 +1496,7 @@ static int geneve_fill_info(struct sk_buff *skb, const
> struct net_device *dev)
> .setup = geneve_setup,
> .validate = geneve_validate,
> .newlink = geneve_newlink,
> + .changelink = geneve_changelink,
> .dellink = geneve_dellink,
> .get_size = geneve_get_size,
> .fill_info = geneve_fill_info,
> --
> 1.8.3.1
>
