[ofa-general] Re: [ewg] [PATCH] IB/ipoib: avoid WARN_ON on NULL path->ah
eli at dev.mellanox.co.il
Tue Sep 23 04:07:58 PDT 2008
On Tue, Sep 23, 2008 at 02:01:00PM +0300, Moni Shoua wrote:
> Eli Cohen wrote:
> > Commit ee1e2c82c245a5fb2864e9dbcdaab3390fde3fcc introduced an
> > optimization on path flushing. This caused a new possible scenario in
> > which unicast_arp_send triggers path query which could fail, causing
> > path->ah to become NULL. A successive successfull path query will then
> > trigger WARN_ON() in path_rec_completion(). This fix requires old_ah
> > to differ from NULL as a prerequsite to trigger the WARN_ON().
> > Moreover, that commit also allowed path resolution to be triggered for
> > an invalid path; if that path resolution failed, old_ah would be freed
> > outside priv->lock violating the assumption that dropping references
> > inside the lock are guaranteed not to reach zero reference.
> Eli Roland,
> I understand that this patch is going to be in OFED.
> What about upstream kernel?
> I'd like to add improvements to commit ee1e2c82c245a5fb2864e9dbcdaab3390fde3fcc (the one you referred to) and it will probably be on top of your fix.
> I'm sorry if I missed Roland's answer.
I don't think Roland responded to this patch yet. Still, I think it is
important that this patch is reviewed since we have a regression
relative to 2.6.26.
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