Re: [PATCH RFC net-next] net: Allow name change of IFF_UP interfaces

[åèèæ]

2017-08-09 19:42 GMT+09:00 Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>:
> What happens is: __netvsc_vf_setup() does dev_open() for the VF device and
> the consecutive dev_change_name() fails with -EBUSY because of the
> (dev->flags & IFF_UP) check. The history of this code predates git so I
> wasn't able to figure out when and why the check was added, everything
> seems to work fine without it. dev_change_name() has only two call sites,
> both hold rtnl_lock.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
>  RFC: I'm probably miossing something obvious and the check can't be just
>  dropped. Stephen suggested a different solution to the isuue:
>  https://www.spinics.net/lists/netdev/msg448243.html but it has its own
>  drawbacks.
> ---
>  net/core/dev.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 1d75499add72..c608e233a78a 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1186,8 +1186,6 @@ int dev_change_name(struct net_device *dev, const char *newname)
>         BUG_ON(!dev_net(dev));
>
>         net = dev_net(dev);
> -       if (dev->flags & IFF_UP)
> -               return -EBUSY;
>
>         write_seqcount_begin(&devnet_rename_seq);

I think people expect the name won't change while up
and I don't think it is a good idea to allow changing the
name while the interface is up.

--yoshfuji


>
> --
> 2.13.4
>