Re: [RTnet-developers] [PATCH] Keep arp cache when new IP addr. is on same subnet as old IP, addr. Delete loopback route when changing IP address.

[Jan K. <jan...@si...>]

Please follow the format

[PATCH] Subject line

Patch description lines, specifically explaining the "why".

Signed-off
(see also
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=Documentation/SubmittingPatches;h=689e2371095cc5dfea9927120009341f369159aa;hb=f6f94e2ab1b33f0082ac22d71f66385a60d8157f#l297)

The comments below apply if you can explain the use case to me. The
standard Linux networking stack seems to behave like current RTnet.

On 2011-12-13 17:22, Jesper Christensen wrote:
> 
> 
> diff --git a/stack/ipv4/af_inet.c b/stack/ipv4/af_inet.c
> index 8b394be..18754cf 100644
> --- a/stack/ipv4/af_inet.c
> +++ b/stack/ipv4/af_inet.c
> @@ -239,7 +239,16 @@ static void rt_ip_ifup(struct rtnet_device *rtdev,
>      int                 i;
>  
>  
> -    rt_ip_route_del_all(rtdev); /* cleanup routing table */
> +    /* Only delete our own address if the new address is
> +       on the same subnet */
> +    if (rtdev->broadcast_ip == up_cmd->args.up.broadcast_ip)
> +        rt_ip_route_del_host(rtdev->local_ip, rtdev);
> +    else
> +        rt_ip_route_del_all(rtdev); /* cleanup routing table */
> +
> +    /* Delete our loopback route for the device */

The following block should be moved into the selective deletion path
above (as del_all already does it for us).

> +    if ((tmp = rtdev_get_loopback()) != NULL)

Please split up assignment and comparison into two lines (yes, that used
to be done differently in past here as well).

> +        rt_ip_route_del_host(rtdev->local_ip, tmp);

rtdev_dereference(tmp) is missing.

>  
>      if (up_cmd->args.up.ip_addr != 0xFFFFFFFF) {
>          rtdev->local_ip     = up_cmd->args.up.ip_addr;

Thanks,
Jan

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