netdev - Re: [PATCH v5] bfin_mac: convert bfin Ethernet driver to NAPI framework

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Date:	Wed, 16 Jul 2014 15:17:29 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Sonic Zhang <sonic.adi@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	Varka Bhadram <varkabhadram@...il.com>,
	adi-buildroot-devel@...ts.sourceforge.net,
	Sonic Zhang <sonic.zhang@...log.com>
Subject: Re: [PATCH v5] bfin_mac: convert bfin Ethernet driver to NAPI
 framework

On Wed, 2014-07-16 at 17:51 +0800, Sonic Zhang wrote:
> From: Sonic Zhang <sonic.zhang@...log.com>
> 
> Ethernet RX DMA buffers are polled in NAPI work queue other than received
> directly in DMA RX interrupt handler.
> 
> Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>
> 
> ---
> v2-changes:
> - avoid test NAPI_STATE_NPSVC bit in net device driver
> 
> v3-changes:
> - use tabs while indenting the code
> 
> v4-changes:
> - unconditionally complete the NAPI poll and re-enable the MAC_RX IRQ
> 
> v5-changes:
> - should match open parenthesis
> 
> Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>
> ---
>  drivers/net/ethernet/adi/bfin_mac.c | 80 +++++++++++++++++++++++--------------
>  drivers/net/ethernet/adi/bfin_mac.h |  1 +
>  2 files changed, 51 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/net/ethernet/adi/bfin_mac.c b/drivers/net/ethernet/adi/bfin_mac.c
> index 7ae74d4..6dde102 100644
> --- a/drivers/net/ethernet/adi/bfin_mac.c
> +++ b/drivers/net/ethernet/adi/bfin_mac.c
> @@ -1218,11 +1218,14 @@ out:
>  #define RX_ERROR_MASK (RX_LONG | RX_ALIGN | RX_CRC | RX_LEN | \
>  	RX_FRAG | RX_ADDR | RX_DMAO | RX_PHY | RX_LATE | RX_RANGE)
>  
> -static void bfin_mac_rx(struct net_device *dev)
> +static void bfin_mac_rx(struct napi_struct *napi, int budget)


budget seems unused in this function.

>  {
> +	struct bfin_mac_local *lp = container_of(napi,
> +						 struct bfin_mac_local,
> +						 napi);
> +	struct net_device *dev = lp->ndev;
>  	struct sk_buff *skb, *new_skb;
>  	unsigned short len;
> -	struct bfin_mac_local *lp __maybe_unused = netdev_priv(dev);
>  #if defined(BFIN_MAC_CSUM_OFFLOAD)
>  	unsigned int i;
>  	unsigned char fcs[ETH_FCS_LEN + 1];
> @@ -1256,7 +1259,7 @@ static void bfin_mac_rx(struct net_device *dev)
>  	current_rx_ptr->skb = new_skb;
>  	current_rx_ptr->desc_a.start_addr = (unsigned long)new_skb->data - 2;
>  
> -	len = (unsigned short)((current_rx_ptr->status.status_word) & RX_FRLEN);
> +	len = (unsigned short)(current_rx_ptr->status.status_word & RX_FRLEN);
>  	/* Deduce Ethernet FCS length from Ethernet payload length */
>  	len -= ETH_FCS_LEN;
>  	skb_put(skb, len);
> @@ -1294,7 +1297,8 @@ static void bfin_mac_rx(struct net_device *dev)
>  	}
>  #endif
>  
> -	netif_rx(skb);
> +	napi_gro_receive(&lp->napi, skb);
> +
>  	dev->stats.rx_packets++;
>  	dev->stats.rx_bytes += len;
>  out:
> @@ -1302,41 +1306,51 @@ out:
>  	current_rx_ptr = current_rx_ptr->next;
>  }
>  
> +static int bfin_mac_poll(struct napi_struct *napi, int budget)
> +{
> +	int i = 0;
> +	unsigned long flags;
> +
> +	while (current_rx_ptr->status.status_word != 0 && i < budget) {
> +		bfin_mac_rx(napi, budget);
> +		i++;
> +	}
> +
> +	if (i < budget) {
> +		napi_gro_flush(napi, false);
> +		local_irq_save(flags);
> +		__napi_complete(napi);
> +		local_irq_restore(flags);
> +		enable_irq(IRQ_MAC_RX);

I have no idea why you open-code napi_complete();

Why cant you just copy/paste what other drivers do here ?

	if (i < budget) {
		napi_complete(napi);
		enable_irq(IRQ_MAC_RX);
	}



...

>  
> @@ -1689,6 +1704,8 @@ static int bfin_mac_probe(struct platform_device *pdev)
>  	lp->tx_reclaim_timer.data = (unsigned long)lp;
>  	lp->tx_reclaim_timer.function = tx_reclaim_skb_timeout;
>  
> +	netif_napi_add(ndev, &lp->napi, bfin_mac_poll, CONFIG_BFIN_RX_DESC_NUM);


Have you checked kernel log ?

You should have hit :

        if (weight > NAPI_POLL_WEIGHT)
                pr_err_once("netif_napi_add() called with weight %d on device %s\n",
                            weight, dev->name);





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