netdev - Re: [PATCH net] net: enetc: avoid deadlock in enetc_tx_onestep

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Message-ID: <20230112213629.4luzdpktiq7ho3pk@skbuf>
Date:   Thu, 12 Jan 2023 23:36:29 +0200
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        "Y . b . Lu" <yangbo.lu@....com>
Subject: Re: [PATCH net] net: enetc: avoid deadlock in
 enetc_tx_onestep_tstamp()

On Thu, Jan 12, 2023 at 01:29:21PM -0800, Alexander Duyck wrote:
> One other question I had. How do you handle the event that
> enetc_start_xmit returns NETDEV_TX_BUSY or causes the packet to go
> down the drop_packet_err path?

We don't. If the enetc_start_xmit() asks the qdisc to requeue the skb
via NETDEV_TX_BUSY, we aren't going to do that, because we aren't the
qdisc, or if the packet just gets dropped without being mapped into the
TX ring, ENETC_TX_ONESTEP_TSTAMP_IN_PROGRESS will remain set with no
possibility of ever becoming unset ever again.