Hi David,
thanks for your reply.
On Tue, Feb 04, 2014 at 08:32:03PM -0800, David Miller wrote:
> From: Alexander Aring <alex.ar...@gmail.com>
> Date: Tue, 4 Feb 2014 11:57:53 +0100
>
> > @@ -197,7 +197,9 @@ static void lowpan_fragment_timer_expired(unsigned long
> > entry_addr)
> >
> > pr_debug("timer expired for frame with tag %d\n", entry->tag);
> >
> > + spin_lock_bh(&flist_lock);
> > list_del(&entry->list);
> > + spin_unlock_bh(&flist_lock);
> > dev_kfree_skb(entry->skb);
> > kfree(entry);
> > }
>
> This will deadlock, because the other code path holding flist_lock calls
> del_timer_sync() to wait for this timer to return.
>
ok. I detected this some months ago and I talked with Werner Almesberger
about that. He talked something about del_timer_sync too and other
issues, but I didn't understand that I open a new deadlock case. Now I
learned something new things, thanks. :-)
> The synchornization in this code is really a big mess.
That is one thing which I also detected so I decide to make a new
implementation based on net/ipv6/reassembly.c which also used the
inet_frag api.
I will bring these patches mainline and I hope it will remove the most
of the race condigition. But then it's only solved in net-next branch.
- Alex
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