netdev - RE: [PATCH net-next v7 2/2] qede: Add driver support for PTP

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Date:   Thu, 16 Feb 2017 12:38:19 +0000
From:   "Mintz, Yuval" <Yuval.Mintz@...ium.com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        "richardcochran@...il.com" <richardcochran@...il.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Kalluru, Sudarsana" <Sudarsana.Kalluru@...ium.com>
Subject: RE: [PATCH net-next v7 2/2] qede: Add driver support for PTP

> > +void qede_ptp_tx_ts(struct qede_dev *edev, struct sk_buff *skb) {
> > +	struct qede_ptp *ptp;
> > +
> > +	ptp = edev->ptp;
> > +	if (!ptp)
> > +		return;
> > +
> > +	if (unlikely(!(edev->flags & QEDE_TX_TIMESTAMPING_EN))) {
> > +		DP_NOTICE(edev,
> > +			  "Tx timestamping was not enabled, this packet will
> not be timestamped\n");
> > +	} else if (unlikely(ptp->tx_skb)) {
> > +		DP_NOTICE(edev,
> > +			  "The device supports only a single outstanding
> packet to timestamp, this packet will not be timestamped\n");
> > +	} else {
> > +		skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
> > +		/* schedule check for Tx timestamp */
> > +		ptp->tx_skb = skb_get(skb);
> > +		schedule_work(&ptp->work);
> > +	}
> > +}
> 
> 
> This is a multi queue device.
> 
> Therefore multiple cpus could call this function at the same time.
> 
> ptp->tx_skb needs some kind of SMP protection.

IIs it a real issue or odd corner-case in actual scenario?
Regardless, I assume it's a theoretical breach waiting for an
adversary to exploit, so better fix it now.

I'll send a fix later today. Thanks.