netdev - Re: [PATCH net-next 1/2] gianfar: remove largely unused gfar

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Date:	Wed, 13 Feb 2013 15:13:08 +0200
From:	Claudiu Manoil <claudiu.manoil@...escale.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
CC:	David Miller <davem@...emloft.net>, <netdev@...r.kernel.org>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net-next 1/2] gianfar: remove largely unused gfar_stats
 struct

On 2/13/2013 2:24 AM, Paul Gortmaker wrote:
> The gfar_stats struct is only used in copying out data
> via ethtool.  It is declared as the extra stats, followed
> by the rmon stats.  However, the rmon stats are never
> actually ever used in the driver; instead the rmon data
> is a u32 register read that is cast directly into the
> ethtool buf.
>
> It seems the only reason rmon is in the struct at all is
> to give the offset(s) at which it should be exported into
> the ethtool buffer.  But note gfar_stats doesn't contain
> a gfar_extra_stats as a substruct -- instead it contains
> a u64 array of equal element count.  This implicitly means
> we have two independent declarations of what gfar_extra_stats
> really is.  Rather than have this duality, we already have
> defines which give us the offset directly, and hence do not
> need the struct at all.
>
> Further, since we know the extra_stats is unconditionally
> always present, we can write it out to the ethtool buf
> 1st, and then optionally write out the rmon data.  There
> is no need for two independent loops, both of which are
> simply copying out the extra_stats to buf offset zero.
>
> This also helps pave the way towards allowing the extra
> stats fields to be converted to atomic64_t values, without
> having their types directly influencing the ethtool stats
> export code (gfar_fill_stats) that expects to deal with u64.
>
> Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>

Reviewed-by: Claudiu Manoil <claudiu.manoil@...escale.com>

> ---
>   drivers/net/ethernet/freescale/gianfar.h         |  8 +-------
>   drivers/net/ethernet/freescale/gianfar_ethtool.c | 15 ++++++---------
>   2 files changed, 7 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/gianfar.h b/drivers/net/ethernet/freescale/gianfar.h
> index 71793f4..61b1785 100644
> --- a/drivers/net/ethernet/freescale/gianfar.h
> +++ b/drivers/net/ethernet/freescale/gianfar.h
> @@ -646,15 +646,9 @@ struct gfar_extra_stats {
>   #define GFAR_RMON_LEN ((sizeof(struct rmon_mib) - 16)/sizeof(u32))
>   #define GFAR_EXTRA_STATS_LEN (sizeof(struct gfar_extra_stats)/sizeof(u64))
>
> -/* Number of stats in the stats structure (ignore car and cam regs)*/
> +/* Number of stats exported via ethtool */
>   #define GFAR_STATS_LEN (GFAR_RMON_LEN + GFAR_EXTRA_STATS_LEN)
>
> -struct gfar_stats {
> -	u64 extra[GFAR_EXTRA_STATS_LEN];
> -	u64 rmon[GFAR_RMON_LEN];
> -};
> -
> -
>   struct gfar {
>   	u32	tsec_id;	/* 0x.000 - Controller ID register */
>   	u32	tsec_id2;	/* 0x.004 - Controller ID2 register */
> diff --git a/drivers/net/ethernet/freescale/gianfar_ethtool.c b/drivers/net/ethernet/freescale/gianfar_ethtool.c
> index 45e59d5..172acb9 100644
> --- a/drivers/net/ethernet/freescale/gianfar_ethtool.c
> +++ b/drivers/net/ethernet/freescale/gianfar_ethtool.c
> @@ -151,18 +151,15 @@ static void gfar_fill_stats(struct net_device *dev, struct ethtool_stats *dummy,
>   	struct gfar __iomem *regs = priv->gfargrp[0].regs;
>   	u64 *extra = (u64 *) & priv->extra_stats;
>
> +	for (i = 0; i < GFAR_EXTRA_STATS_LEN; i++)
> +		buf[i] = extra[i];
> +
>   	if (priv->device_flags & FSL_GIANFAR_DEV_HAS_RMON) {
>   		u32 __iomem *rmon = (u32 __iomem *) &regs->rmon;
> -		struct gfar_stats *stats = (struct gfar_stats *) buf;
> -
> -		for (i = 0; i < GFAR_RMON_LEN; i++)
> -			stats->rmon[i] = (u64) gfar_read(&rmon[i]);
>
> -		for (i = 0; i < GFAR_EXTRA_STATS_LEN; i++)
> -			stats->extra[i] = extra[i];
> -	} else
> -		for (i = 0; i < GFAR_EXTRA_STATS_LEN; i++)
> -			buf[i] = extra[i];
> +		for (; i < GFAR_STATS_LEN; i++, rmon++)
> +			buf[i] = (u64) gfar_read(rmon);
> +	}
>   }
>
>   static int gfar_sset_count(struct net_device *dev, int sset)
>



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