Re: [PATCH] bnx2: avoid flushing statistics when doing a MTU change

["Michael Chan" <mchan@broadcom.com>]

On Mon, 2009-11-30 at 06:05 -0800, Breno Leitao wrote:
> Eric Dumazet wrote:
> > I see nothing in the driver/patch that will consolidate bp->dev->stats 
> > before your memcpy(). DMA transfert doesnt touch bp->dev->stats.
> You're right, calling bnx2_get_stats() after the DMA should be enough, 
> as the following patch
> ---
> 
> [PATCH] bnx2: avoid flushing statistics when doing a MTU change
> 
> Actually when bnx2 changes the interface's MTU size, it resets
> the chip and consequently flushes the interface statistics.
> This patch saves the statistics in a temporary space in order to
> maintain the statistics correct after the chip reset.

Thanks Breno.  As I mentioned earlier, this does not save the ethtool -S
stats before reset.  The user may be confused when netstat does not
match ethtool -S.  I think we should save the statistics block so
everything will match up.  If you don't beat me to it, I'll work on the
patch later today.

> 
> Signed-off-by: Breno Leitao<leitao@linux.vnet.ibm.com>
> ---
>  drivers/net/bnx2.c |   57 ++++++++++++++++++++++++++++++++++++++-------------
>  drivers/net/bnx2.h |    1 +
>  2 files changed, 43 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c
> index 7fa4048..07c0376 100644
> --- a/drivers/net/bnx2.c
> +++ b/drivers/net/bnx2.c
> @@ -6221,6 +6221,8 @@ bnx2_open(struct net_device *dev)
>  	else if (bp->flags & BNX2_FLAG_USING_MSIX)
>  		printk(KERN_INFO PFX "%s: using MSIX\n", dev->name);
>  
> +	memset(&bp->stats_extra, 0, sizeof(struct net_device_stats));
> +
>  	netif_tx_start_all_queues(dev);
>  
>  	return 0;
> @@ -6469,46 +6471,58 @@ bnx2_get_stats(struct net_device *dev)
>  	net_stats->rx_packets =
>  		GET_NET_STATS(stats_blk->stat_IfHCInUcastPkts) +
>  		GET_NET_STATS(stats_blk->stat_IfHCInMulticastPkts) +
> -		GET_NET_STATS(stats_blk->stat_IfHCInBroadcastPkts);
> +		GET_NET_STATS(stats_blk->stat_IfHCInBroadcastPkts) + 
> +		bp->stats_extra.rx_packets;
>  
>  	net_stats->tx_packets =
>  		GET_NET_STATS(stats_blk->stat_IfHCOutUcastPkts) +
>  		GET_NET_STATS(stats_blk->stat_IfHCOutMulticastPkts) +
> -		GET_NET_STATS(stats_blk->stat_IfHCOutBroadcastPkts);
> +		GET_NET_STATS(stats_blk->stat_IfHCOutBroadcastPkts) +
> +		bp->stats_extra.tx_packets;
>  
>  	net_stats->rx_bytes =
> -		GET_NET_STATS(stats_blk->stat_IfHCInOctets);
> +		GET_NET_STATS(stats_blk->stat_IfHCInOctets) +
> +		bp->stats_extra.rx_bytes;
>  
>  	net_stats->tx_bytes =
> -		GET_NET_STATS(stats_blk->stat_IfHCOutOctets);
> +		GET_NET_STATS(stats_blk->stat_IfHCOutOctets) +
> +		bp->stats_extra.tx_bytes;
>  
>  	net_stats->multicast =
> -		GET_NET_STATS(stats_blk->stat_IfHCOutMulticastPkts);
> +		GET_NET_STATS(stats_blk->stat_IfHCOutMulticastPkts) +
> +		bp->stats_extra.multicast;
>  
>  	net_stats->collisions =
> -		(unsigned long) stats_blk->stat_EtherStatsCollisions;
> +		(unsigned long) stats_blk->stat_EtherStatsCollisions +
> +		bp->stats_extra.collisions;
>  
>  	net_stats->rx_length_errors =
>  		(unsigned long) (stats_blk->stat_EtherStatsUndersizePkts +
> -		stats_blk->stat_EtherStatsOverrsizePkts);
> +		stats_blk->stat_EtherStatsOverrsizePkts) +
> +		bp->stats_extra.rx_length_errors;
>  
>  	net_stats->rx_over_errors =
>  		(unsigned long) (stats_blk->stat_IfInFTQDiscards +
> -		stats_blk->stat_IfInMBUFDiscards);
> +		stats_blk->stat_IfInMBUFDiscards) +
> +		bp->stats_extra.rx_over_errors;
>  
>  	net_stats->rx_frame_errors =
> -		(unsigned long) stats_blk->stat_Dot3StatsAlignmentErrors;
> +		(unsigned long) stats_blk->stat_Dot3StatsAlignmentErrors +
> +		bp->stats_extra.rx_frame_errors;
>  
>  	net_stats->rx_crc_errors =
> -		(unsigned long) stats_blk->stat_Dot3StatsFCSErrors;
> +		(unsigned long) stats_blk->stat_Dot3StatsFCSErrors +
> +		bp->stats_extra.rx_crc_errors;
>  
>  	net_stats->rx_errors = net_stats->rx_length_errors +
>  		net_stats->rx_over_errors + net_stats->rx_frame_errors +
> -		net_stats->rx_crc_errors;
> +		net_stats->rx_crc_errors +
> +		bp->stats_extra.rx_errors;
>  
>  	net_stats->tx_aborted_errors =
>      		(unsigned long) (stats_blk->stat_Dot3StatsExcessiveCollisions +
> -		stats_blk->stat_Dot3StatsLateCollisions);
> +		stats_blk->stat_Dot3StatsLateCollisions) +
> +		bp->stats_extra.tx_aborted_errors;
>  
>  	if ((CHIP_NUM(bp) == CHIP_NUM_5706) ||
>  	    (CHIP_ID(bp) == CHIP_ID_5708_A0))
> @@ -6516,7 +6530,8 @@ bnx2_get_stats(struct net_device *dev)
>  	else {
>  		net_stats->tx_carrier_errors =
>  			(unsigned long)
> -			stats_blk->stat_Dot3StatsCarrierSenseErrors;
> +			stats_blk->stat_Dot3StatsCarrierSenseErrors +
> +			bp->stats_extra.tx_carrier_errors;
>  	}
>  
>  	net_stats->tx_errors =
> @@ -6524,11 +6539,13 @@ bnx2_get_stats(struct net_device *dev)
>  		stats_blk->stat_emac_tx_stat_dot3statsinternalmactransmiterrors
>  		+
>  		net_stats->tx_aborted_errors +
> -		net_stats->tx_carrier_errors;
> +		net_stats->tx_carrier_errors +
> +		bp->stats_extra.tx_errors;
>  
>  	net_stats->rx_missed_errors =
>  		(unsigned long) (stats_blk->stat_IfInFTQDiscards +
> -		stats_blk->stat_IfInMBUFDiscards + stats_blk->stat_FwRxDrop);
> +		stats_blk->stat_IfInMBUFDiscards + stats_blk->stat_FwRxDrop) +
> +		bp->stats_extra.rx_missed_errors;
>  
>  	return net_stats;
>  }
> @@ -6989,6 +7006,16 @@ bnx2_change_ring_size(struct bnx2 *bp, u32 rx, u32 tx)
>  {
>  	if (netif_running(bp->dev)) {
>  		bnx2_netif_stop(bp);
> +
> +		/* Save statistics that is going to be reseted */
> +		REG_WR(bp, BNX2_HC_COMMAND, bp->hc_cmd |
> +				BNX2_HC_COMMAND_STATS_NOW);
> +		REG_RD(bp, BNX2_HC_COMMAND);
> +		udelay(5);
> +		bnx2_get_stats(bp->dev);
> +		memcpy(&bp->stats_extra, &bp->dev->stats,
> +			sizeof(struct net_device_stats));
> +
>  		bnx2_reset_chip(bp, BNX2_DRV_MSG_CODE_RESET);
>  		bnx2_free_skbs(bp);
>  		bnx2_free_mem(bp);
> diff --git a/drivers/net/bnx2.h b/drivers/net/bnx2.h
> index a4d8340..1063d1a 100644
> --- a/drivers/net/bnx2.h
> +++ b/drivers/net/bnx2.h
> @@ -6912,6 +6912,7 @@ struct bnx2 {
>  
>  	const struct firmware	*mips_firmware;
>  	const struct firmware	*rv2p_firmware;
> +	struct net_device_stats stats_extra;
>  };
>  
>  #define REG_RD(bp, offset)					\