Re: [PATCH] ppp_generic.c: last_channel_index

[Alan Cox]

> get an Oops.  PPP daemon would try to allocate strange PPP interface numbers
> (ppp12, for example) and other sanity checks would fail (kind != INTERFACE
> || CHANNEL)
> 
> The last_channel_index wasn't being cleaned up when the channel was closed,
> leading to these problems the next time a PPP channel was opened.  This
> patch fixes the problem for me.

Im not convinced this is the actual problem I must admit

>         spin_lock_bh(&all_channels_lock);
> +       last_channel_index--;
>         list_del(&pch->file.list);
>         spin_unlock_bh(&all_channels_lock);

Suppose you open channel 0, then 1, then 2, then close 0. Your last_channel_index
is now wrong.

Certainly we should be reusing channel ids but I dont think its as simple as
your patch. The obvious question therefore is why does it work