linux-kernel - Re: [PATCH] net: calxeda: fix race condition in xgmac

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Message-ID: <CAJedcCw=XmZzP+wBQRmVrtM-ns9Gs0uvxGowTn-QfQ4QJ0Upyw@mail.gmail.com>
Date:   Thu, 9 Mar 2023 15:25:33 +0800
From:   Zheng Hacker <hackerzheng666@...il.com>
To:     Yunsheng Lin <linyunsheng@...wei.com>
Cc:     Zheng Wang <zyytlz.wz@....com>, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        1395428693sheep@...il.com, alex000young@...il.com
Subject: Re: [PATCH] net: calxeda: fix race condition in xgmac_remove due to
 unfinshed work

Yunsheng Lin <linyunsheng@...wei.com> 于2023年3月9日周四 14:24写道：
>
> On 2023/3/9 11:56, Zheng Wang wrote:
> > In xgmac_probe, the priv->tx_timeout_work is bound with
> > xgmac_tx_timeout_work. In xgmac_remove, if there is an
> > unfinished work, there might be a race condition that
> > priv->base was written byte after iounmap it.
> >
> > Fix it by finishing the work before cleanup.
>
> This should go to net branch, so title should be:
>
>  [PATCH net] net: calxeda: fix race condition in xgmac_remove due to unfinshed work
>

Sorry for the confusion.

> From history commit, it seems more common to use "net: calxedaxgmac" instead of
> "net: calxeda", I am not sure which one is better.
>
> Also there should be a Fixes tag for net branch, maybe:
>
> Fixes: 8746f671ef04 ("net: calxedaxgmac: fix race between xgmac_tx_complete and xgmac_tx_err")
>
>

Yes, I was eager to report the fix and ignored that. Thanks for
pointing that out.

> >
> > Signed-off-by: Zheng Wang <zyytlz.wz@....com>
> > ---
> >  drivers/net/ethernet/calxeda/xgmac.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/net/ethernet/calxeda/xgmac.c b/drivers/net/ethernet/calxeda/xgmac.c
> > index f4f87dfa9687..94c3804001e3 100644
> > --- a/drivers/net/ethernet/calxeda/xgmac.c
> > +++ b/drivers/net/ethernet/calxeda/xgmac.c
> > @@ -1831,6 +1831,7 @@ static int xgmac_remove(struct platform_device *pdev)
> >       /* Free the IRQ lines */
> >       free_irq(ndev->irq, ndev);
> >       free_irq(priv->pmt_irq, ndev);
> > +     cancel_work_sync(&priv->tx_timeout_work);
>
> It seems the blow function need to stop the dev_watchdog() from
> calling dev->netdev_ops->ndo_tx_timeout before calling
> cancel_work_sync(&priv->tx_timeout_work), otherwise the
> dev_watchdog() may trigger the priv->tx_timeout_work to run again.
>
>         netif_carrier_off(ndev);
>         netif_tx_disable(ndev);
>
> >
> >       unregister_netdev(ndev);
> >       netif_napi_del(&priv->napi);
> >

Yes, I agree with that. Thanks for your advice. I learned a lot from it.

Best regards,
Zheng