From: Steffen Klassert <steffen.klassert@secunet.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>, netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH] inetpeer: fix a race in inetpeer_gc_worker()
Date: Tue, 5 Jun 2012 14:42:57 +0200 [thread overview]
Message-ID: <20120605124257.GE27795@secunet.com> (raw)
In-Reply-To: <1338898752.2760.2482.camel@edumazet-glaptop>
On Tue, Jun 05, 2012 at 02:19:12PM +0200, Eric Dumazet wrote:
> On Tue, 2012-06-05 at 13:56 +0200, Steffen Klassert wrote:
> > On Tue, Jun 05, 2012 at 11:28:27AM +0200, Eric Dumazet wrote:
> > > From: Eric Dumazet <edumazet@google.com>
> > >
> > > commit 5faa5df1fa2024 (inetpeer: Invalidate the inetpeer tree along with
> > > the routing cache) added a race :
> > >
> > > Before freeing an inetpeer, we must respect a RCU grace period, and make
> > > sure no user will attempt to increase refcnt.
> > >
> >
> > As already mentioned in the other mail. In this case, I think
> > we can just delete the inetpeer once the refcount got zero.
> >
>
> Nope, a concurrent lookup can find an entry about to be freed.
Hm, I agree that we need rcu protection when we remove single entries
from an inetpeer tree. But in this case we invalidate the entire tree.
The first lookup after inetpeer_invalidate_tree() was invoked should
find an empty tree, base->root initialized to peer_avl_empty_rcu.
Maybe I'm wrong, but I don't see how a lookup should find such an
old invalidated tree.
next prev parent reply other threads:[~2012-06-05 12:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-05 9:28 [PATCH] inetpeer: fix a race in inetpeer_gc_worker() Eric Dumazet
2012-06-05 11:56 ` Steffen Klassert
2012-06-05 12:19 ` Eric Dumazet
2012-06-05 12:42 ` Steffen Klassert [this message]
2012-06-05 12:56 ` Eric Dumazet
2012-06-05 13:01 ` Steffen Klassert
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