netdev - Re: [PATCH net 2/3] amd-xgbe: handle the corner-case during tx completion

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Message-ID: <8edf68af-f911-4c3f-ac37-9a9cfc820b50@intel.com>
Date: Wed, 22 Nov 2023 11:50:54 +0100
From: Wojciech Drewek <wojciech.drewek@...el.com>
To: Raju Rangoju <Raju.Rangoju@....com>, <netdev@...r.kernel.org>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <Thomas.Lendacky@....com>, <Shyam-sundar.S-k@....com>
Subject: Re: [PATCH net 2/3] amd-xgbe: handle the corner-case during tx
 completion



On 21.11.2023 20:14, Raju Rangoju wrote:
> The existing implementation uses software logic to accumulate tx
> completions until the specified time (1ms) is met and then poll them.
> However, there exists a tiny gap which leads to a race between
> resetting and checking the tx_activate flag. Due to this the tx
> completions are not reported to upper layer and tx queue timeout
> kicks-in restarting the device.
> 
> To address this, introduce a tx cleanup mechanism as part of the
> periodic maintenance process.
> 
> Fixes: c5aa9e3b8156 ("amd-xgbe: Initial AMD 10GbE platform driver")
> Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>
> Signed-off-by: Raju Rangoju <Raju.Rangoju@....com>
> ---

Reviewed-by: Wojciech Drewek <wojciech.drewek@...el.com>

>  drivers/net/ethernet/amd/xgbe/xgbe-drv.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> index 614c0278419b..6b73648b3779 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> @@ -682,10 +682,24 @@ static void xgbe_service(struct work_struct *work)
>  static void xgbe_service_timer(struct timer_list *t)
>  {
>  	struct xgbe_prv_data *pdata = from_timer(pdata, t, service_timer);
> +	struct xgbe_channel *channel;
> +	unsigned int i;
>  
>  	queue_work(pdata->dev_workqueue, &pdata->service_work);
>  
>  	mod_timer(&pdata->service_timer, jiffies + HZ);
> +
> +	if (!pdata->tx_usecs)
> +		return;
> +
> +	for (i = 0; i < pdata->channel_count; i++) {
> +		channel = pdata->channel[i];
> +		if (!channel->tx_ring || channel->tx_timer_active)
> +			break;
> +		channel->tx_timer_active = 1;
> +		mod_timer(&channel->tx_timer,
> +			  jiffies + usecs_to_jiffies(pdata->tx_usecs));
> +	}
>  }
>  
>  static void xgbe_init_timers(struct xgbe_prv_data *pdata)