Subject: Re: [PATCH] net: calxeda: fix race condition in xgmac_remove due to
 unfinshed work
From:   Yunsheng Lin <linyunsheng@huawei.com>
To:     Zheng Wang <zyytlz.wz@163.com>, <davem@davemloft.net>,
        <edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>,
        <netdev@vger.kernel.org>
CC:     <linux-kernel@vger.kernel.org>, <hackerzheng666@gmail.com>,
        <1395428693sheep@gmail.com>, <alex000young@gmail.com>
References: <20230309035641.3439953-1-zyytlz.wz@163.com>
 <ec579c96-9955-f317-b37a-4f3fcd0c206e@huawei.com>
Message-ID: <c9bafa3d-12ba-e9fe-8606-8160a8c42517@huawei.com>
Date:   Thu, 9 Mar 2023 14:27:20 +0800
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On 2023/3/9 14:23, Yunsheng Lin wrote:
> 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

typo error:
unfinshed -> unfinished

> 
>>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")
> 
> 
>>
>> Signed-off-by: Zheng Wang <zyytlz.wz@163.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);
>>
> .
>