[ovs-dev] [PATCH v5] gre: Rename fallback devices to avoid udev's interference

[Gregory Rose]

On 9/18/2018 10:35 AM, Yifeng Sun wrote:
> On certain kernel versions, when openvswitch kernel module creates
> a gre0 interface, the kernel’s gre module will jump out and compete
> to control the gre0 interface. This will cause the failure of
> openvswitch kernel module loading.
>
> This fix renames fallback devices by adding a prefix "ovs-".
>
> Signed-off-by: Yifeng Sun <pkusunyifeng at gmail.com>
> VMware Issue: #2162866
> ---

LGTM.  Thanks Yifeng!

Reviewed-by: Greg Rose <gvrose8192 at gmail.com>
Tested-by: Greg Rose <gvrose8192 at gmail.com>

> Please backport this patch to upstream OVS down to 2.9, thanks.
>
> v1->v2: Added sanity check for device names, thanks Justin.
> v2->v3: Fix an indent error.
> v3->v4: Fix by code review, also fix a potenial bug.
> v4->v5: Remove unnecessary code by code review, thanks Greg!
>
>   datapath/linux/compat/ip6_gre.c    | 5 +++--
>   datapath/linux/compat/ip6_tunnel.c | 6 +++---
>   datapath/linux/compat/ip_gre.c     | 2 +-
>   3 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/datapath/linux/compat/ip6_gre.c b/datapath/linux/compat/ip6_gre.c
> index 00dbefc9b099..182785273c6f 100644
> --- a/datapath/linux/compat/ip6_gre.c
> +++ b/datapath/linux/compat/ip6_gre.c
> @@ -377,7 +377,7 @@ static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
>   	if (parms->name[0])
>   		strlcpy(name, parms->name, IFNAMSIZ);
>   	else
> -		strcpy(name, "ip6gre%d");
> +		strlcpy(name, "ovs-ip6gre%d", IFNAMSIZ);
>   
>   	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
>   			   ip6gre_tunnel_setup);
> @@ -1712,7 +1712,8 @@ static int __net_init ip6gre_init_net(struct net *net)
>   	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
>   	int err;
>   
> -	ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0",
> +	ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl),
> +					  "ovs-ip6gre0",
>   					  NET_NAME_UNKNOWN,
>   					  ip6gre_tunnel_setup);
>   	if (!ign->fb_tunnel_dev) {
> diff --git a/datapath/linux/compat/ip6_tunnel.c b/datapath/linux/compat/ip6_tunnel.c
> index 56fd8b4dd342..9f4bae7dd3d1 100644
> --- a/datapath/linux/compat/ip6_tunnel.c
> +++ b/datapath/linux/compat/ip6_tunnel.c
> @@ -355,7 +355,7 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
>   	if (p->name[0])
>   		strlcpy(name, p->name, IFNAMSIZ);
>   	else
> -		sprintf(name, "ip6tnl%%d");
> +		strlcpy(name, "ovs-ip6tnl%d", IFNAMSIZ);
>   
>   	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
>   			   ip6_tnl_dev_setup);
> @@ -1410,7 +1410,7 @@ ip6_tnl_parm_to_user(struct ip6_tnl_parm *u, const struct __ip6_tnl_parm *p)
>    *     %SIOCCHGTUNNEL: change tunnel parameters to those given
>    *     %SIOCDELTUNNEL: delete tunnel
>    *
> - *   The fallback device "ip6tnl0", created during module
> + *   The fallback device "ovs-ip6tnl0", created during module
>    *   initialization, can be used for creating other tunnel devices.
>    *
>    * Return:
> @@ -2093,7 +2093,7 @@ static int __net_init ip6_tnl_init_net(struct net *net)
>   	ip6n->tnls[1] = ip6n->tnls_r_l;
>   
>   	err = -ENOMEM;
> -	ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6tnl0",
> +	ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ovs-ip6tnl0",
>   					NET_NAME_UNKNOWN, ip6_tnl_dev_setup);
>   
>   	if (!ip6n->fb_tnl_dev)
> diff --git a/datapath/linux/compat/ip_gre.c b/datapath/linux/compat/ip_gre.c
> index 05132ba9494a..b7322c58e420 100644
> --- a/datapath/linux/compat/ip_gre.c
> +++ b/datapath/linux/compat/ip_gre.c
> @@ -1463,7 +1463,7 @@ static struct pernet_operations erspan_net_ops = {
>   
>   static int __net_init ipgre_tap_init_net(struct net *net)
>   {
> -	return ip_tunnel_init_net(net, gre_tap_net_id, &ipgre_tap_ops, "gretap0");
> +	return ip_tunnel_init_net(net, gre_tap_net_id, &ipgre_tap_ops, "ovs-gretap0");
>   }
>   
>   static void __net_exit ipgre_tap_exit_net(struct net *net)