On Mon, Feb 25, 2019 at 08:39:27AM -0800, Eric Dumazet wrote:
> >> On 02/24/2019 08:12 PM, Hangbin Liu wrote:
> >>> ipv6_mod_enabled() is more safe and gentle to check if ipv6 is disabled
> >>> at running time.
> >>>
> >>
> >>
> >> Why is it better exactly ?
> >>
> >> IPv6 can be enabled on the host, but disabled per device
> >>
> >> /proc/sys/net/ipv6/conf/{name}/disable_ipv6
> >
> > Sorry, it looks I didn't make it clear in the commit description.
> > This issue only occurs when IPv6 is disabled at boot time as there is
> > no IPv6 route entry. Disable ipv6 on specific interface is not affected.
> > So check ipv6_mod_enabled() is enough and we don't need to worry about
> > the rcu_read_lock or the dev status.
> >
> > Should I update the commit description?
>
> Certainly. Are you telling us skb->dev could be NULL here ?
>
> Because rcu_read_lock() should already be asserted.
>
No. I know skb->dev is not NULL and we have rcu_read_lock() here. But can we
guarantee the skb->dev won't be NULL forever? Maybe I'm a little sensitive.
I mean for only checking if ipv6 is disable at boot time, use
ipv6_mod_enabled() is more suitable.
Thanks
Hangbin
