From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: netdev@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
Rik van Riel <riel@redhat.com>,
Daniel Borkmann <borkmann@iogearbox.net>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
brouer@redhat.com
Subject: Re: [net-next PATCH] bpf: cpumap fix potential lost wake-up problem
Date: Tue, 24 Oct 2017 06:46:32 +0200 [thread overview]
Message-ID: <20171024064632.56a668eb@redhat.com> (raw)
In-Reply-To: <59EE525D.6090903@iogearbox.net>
On Mon, 23 Oct 2017 22:34:37 +0200
Daniel Borkmann <daniel@iogearbox.net> wrote:
> On 10/23/2017 07:39 PM, Jesper Dangaard Brouer wrote:
> > As pointed out by Michael, commit 1c601d829ab0 ("bpf: cpumap xdp_buff
> > to skb conversion and allocation") contains a classical example of the
> > potential lost wake-up problem.
> >
> > We need to recheck the condition __ptr_ring_empty() after changing
> > current->state to TASK_INTERRUPTIBLE, this avoids a race between
> > wake_up_process() and schedule(). After this, a race with
> > wake_up_process() will simply change the state to TASK_RUNNING, and
> > the schedule() call not really put us to sleep.
> >
> > Fixes: 1c601d829ab0 ("bpf: cpumap xdp_buff to skb conversion and allocation")
> > Reported-by: "Michael S. Tsirkin" <mst@redhat.com>
>
> SOB missing ...
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Damn... DaveM do I need to resubmit? Or will patchwork pickup above SOB?
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2017-10-24 4:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-23 17:39 [net-next PATCH] bpf: cpumap fix potential lost wake-up problem Jesper Dangaard Brouer
2017-10-23 20:34 ` Daniel Borkmann
2017-10-24 4:46 ` Jesper Dangaard Brouer [this message]
2017-10-24 9:40 ` David Miller
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