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From: "Jon Rosen (jrosen)" <jrosen@cisco.com>
To: Stephen Hemminger <stephen@networkplumber.org>
CC: "David S. Miller" <davem@davemloft.net>,
        Willem de Bruijn <willemb@google.com>,
        Eric Dumazet <edumazet@google.com>, Kees Cook <keescook@chromium.org>,
        David Windsor <dwindsor@gmail.com>,
        "Rosen, Rami" <rami.rosen@intel.com>,
        "Reshetova, Elena" <elena.reshetova@intel.com>,
        "Mike Maloney" <maloney@google.com>,
        Benjamin Poirier <bpoirier@suse.com>,
        "open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: RE: [RFC PATCH] packet: mark ring entry as in-use inside spin_lock to
 prevent RX ring overrun
Thread-Topic: [RFC PATCH] packet: mark ring entry as in-use inside spin_lock
 to prevent RX ring overrun
Thread-Index: AQHTy5aFtVi5IJ8ejEig7CpBQEL4WqPv73kAgAC8vKA=
Date: Wed, 4 Apr 2018 14:34:48 +0000
Message-ID: <54c7cbde468c45609e36738baa5ea084@XCH-RTP-016.cisco.com>
References: <20180403215526.15934-1-jrosen@cisco.com>
 <20180403161630.24f8339c@xeon-e3>
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> > diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> > index e0f3f4a..264d7b2 100644
> > --- a/net/packet/af_packet.c
> > +++ b/net/packet/af_packet.c
> > @@ -2287,6 +2287,15 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
> >  		if (po->stats.stats1.tp_drops)
> >  			status |= TP_STATUS_LOSING;
> >  	}
> > +
> > +        /*
> > +         * Mark this entry as TP_STATUS_IN_PROGRESS to prevent other
> > +         * kernel threads from re-using this same entry.
> > +         */
> > +#define TP_STATUS_IN_PROGRESS TP_STATUS_LOSING
> > +	if (po->tp_version <= TPACKET_V2)
> > +            __packet_set_status(po, h.raw, TP_STATUS_IN_PROGRESS);
> > +
> >  	po->stats.stats1.tp_packets++;
> >  	if (copy_skb) {
> >  		status |= TP_STATUS_COPY;
> 
> This patch looks correct. Please resend it with proper signed-off-by
> and with a kernel code indenting style (tabs).  Is this bug present
> since the beginning of af_packet and multiqueue devices or did it get
> introduced in some previous kernel?

Sorry about the tabs, I'll fix that and try to figure out what I did wrong with
the signed-off-by.

I've looked back as far as I could find online (2.6.11) and it would appear that
this bug has always been there.

Thanks, jon.