From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Jakub Kicinski <kubakici@wp.pl>,
davem@davemloft.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 3/3] tap: XDP support
Date: Fri, 28 Jul 2017 06:46:40 +0300 [thread overview]
Message-ID: <20170728064603-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <7d1cb7bf-43c1-3993-be00-04e4676dd917@redhat.com>
On Fri, Jul 28, 2017 at 11:28:54AM +0800, Jason Wang wrote:
> > > + old_prog = rtnl_dereference(tun->xdp_prog);
> > > + if (old_prog)
> > > + bpf_prog_put(old_prog);
> > > + rcu_assign_pointer(tun->xdp_prog, prog);
> > Is this OK? Could this lead to the program getting freed and then
> > datapath accessing a stale pointer? I mean in the scenario where the
> > process gets pre-empted between the bpf_prog_put() and
> > rcu_assign_pointer()?
>
> Will call bpf_prog_put() after rcu_assign_pointer().
I suspect you need to sync RCU or something before that.
next prev parent reply other threads:[~2017-07-28 3:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-27 9:25 [PATCH net-next 0/3] XDP support for tap Jason Wang
2017-07-27 9:25 ` [PATCH net-next 1/3] tap: use build_skb() for small packet Jason Wang
2017-07-27 9:25 ` [PATCH net-next 2/3] net: export some generic xdp helpers Jason Wang
2017-07-27 9:25 ` [PATCH net-next 3/3] tap: XDP support Jason Wang
2017-07-28 3:13 ` Jakub Kicinski
2017-07-28 3:28 ` Jason Wang
2017-07-28 3:46 ` Michael S. Tsirkin [this message]
2017-07-28 3:50 ` Jason Wang
2017-07-28 4:05 ` Michael S. Tsirkin
2017-07-28 3:51 ` Jakub Kicinski
2017-07-28 15:11 ` Daniel Borkmann
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