From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v2 net 2/2] tg3: Fix data corruption on 5725 with TSO
Date: Mon, 13 May 2013 14:14:04 -0700
Message-ID: <1368479644.13473.121.camel@edumazet-glaptop>
References: <1368479056-11780-1-git-send-email-nsujir@broadcom.com>
	 <1368479056-11780-3-git-send-email-nsujir@broadcom.com>
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Cc: davem@davemloft.net, netdev@vger.kernel.org,
	Michael Chan <mchan@broadcom.com>, stable@vger.kernel.org
To: Nithin Nayak Sujir <nsujir@broadcom.com>
Return-path: <stable-owner@vger.kernel.org>
In-Reply-To: <1368479056-11780-3-git-send-email-nsujir@broadcom.com>
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List-Id: netdev.vger.kernel.org

On Mon, 2013-05-13 at 14:04 -0700, Nithin Nayak Sujir wrote:
> From: Michael Chan <mchan@broadcom.com>
> 
> The 5725 family of devices (asic rev 5762), corrupts TSO packets where
> the buffer is within MSS bytes of a 4G boundary (4G, 8G etc.). Detect
> this condition and trigger the workaround path.
> 
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Michael Chan <mchan@broadcom.com>
> Signed-off-by: Nithin Nayak Sujir <nsujir@broadcom.com>
> ---
>  drivers/net/ethernet/broadcom/tg3.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
> index 781be76..e285d76 100644
> --- a/drivers/net/ethernet/broadcom/tg3.c
> +++ b/drivers/net/ethernet/broadcom/tg3.c
> @@ -7448,6 +7448,20 @@ static inline int tg3_4g_overflow_test(dma_addr_t mapping, int len)
>  	return (base > 0xffffdcc0) && (base + len + 8 < base);
>  }
>  
> +/* Test for TSO DMA buffers that cross into regions which are within MSS bytes
> + * of any 4GB boundaries: 4G, 8G, etc
> + */
> +static inline int tg3_4g_tso_overflow_test(struct tg3 *tp, dma_addr_t mapping,
> +					   u32 len, u32 mss)
> +{
> +	if (tg3_asic_rev(tp) == ASIC_REV_5762 && mss) {
> +		u32 base = (u32) mapping & 0xffffffff;
> +
> +		return ((base + len + (mss & 0x3fff)) < base);
> +	}
> +	return 0;
> +}
> +

I am curious : Does this condition even triggers ?