[ovs-dev] [PATCH 2/3] netdev-linux: make tap devices persistent.

[Flavio Leitner]

On Wed, Jun 07, 2017 at 09:39:16AM +0000, Vishal Deep Ajmera wrote:
> Hi Flavio,
> 
> If the tap-device is persistent but the 'netdev' datapath is not yet
> started then will it create any issues in the system ? What happens
> if we start sending packets on this interface whereas data-path is
> not present ?

The link goes down and packets are dropped.
fbl

> 
> Regards,
> Vishal
> 
> -----Original Message-----
> From: ovs-dev-bounces at openvswitch.org [mailto:ovs-dev-bounces at openvswitch.org] On Behalf Of Flavio Leitner
> Sent: Tuesday, May 30, 2017 1:10 AM
> To: dev at openvswitch.org
> Cc: Flavio Leitner <fbl at redhat.com>
> Subject: [ovs-dev] [PATCH 2/3] netdev-linux: make tap devices persistent.
> 
> When using data path type "netdev", bridge port is a tun device and when OVS restarts, that device and its network configuration is lost.
> 
> This patch enables the tap device to persist instead.
> 
> Signed-off-by: Flavio Leitner <fbl at redhat.com>
> ---
>  lib/netdev-linux.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c index 3ad3d45..d181e4f 100644
> --- a/lib/netdev-linux.c
> +++ b/lib/netdev-linux.c
> @@ -866,6 +866,13 @@ netdev_linux_construct_tap(struct netdev *netdev_)
>          goto error_close;
>      }
>  
> +    if (ioctl(netdev->tap_fd, TUNSETPERSIST, 1)) {
> +        VLOG_WARN("%s: creating tap device failed (persist): %s", name,
> +                  ovs_strerror(errno));
> +        error = errno;
> +        goto error_close;
> +    }
> +
>      return 0;
>  
>  error_close:
> @@ -885,6 +892,7 @@ netdev_linux_destruct(struct netdev *netdev_)
>      if (netdev_get_class(netdev_) == &netdev_tap_class
>          && netdev->tap_fd >= 0)
>      {
> +        ioctl(netdev->tap_fd, TUNSETPERSIST, 0);
>          close(netdev->tap_fd);
>      }
>  
> --
> 2.9.4
> 
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-- 
Flavio