netdev - Re: [PATCH net] net: stmmac: fix completely hung TX when using TSO

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Date:   Tue, 6 Jun 2017 07:31:23 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Niklas Cassel <niklas.cassel@...s.com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>
Cc:     Niklas Cassel <niklass@...s.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: stmmac: fix completely hung TX when using TSO



On 06/06/2017 12:25 AM, Niklas Cassel wrote:
> stmmac_tso_allocator can fail to set the Last Descriptor bit
> on a descriptor that actually was the last descriptor.
> 
> This happens when the buffer of the last descriptor ends
> up having a size of exactly TSO_MAX_BUFF_SIZE.
> 
> When the IP eventually reaches the next last descriptor,
> which actually has the bit set, the DMA will hang.
> 
> When the DMA hangs, we get a tx timeout, however,
> since stmmac does not do a complete reset of the IP
> in stmmac_tx_timeout, we end up in a state with
> completely hung TX.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>

This should have:

Fixes: f748be531d70 ("stmmac: support new GMAC4")

right?

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 68a188e74c54..440bea049a7f 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -2723,7 +2723,7 @@ static void stmmac_tso_allocator(struct stmmac_priv *priv, unsigned int des,
>  
>  		priv->hw->desc->prepare_tso_tx_desc(desc, 0, buff_size,
>  			0, 1,
> -			(last_segment) && (buff_size < TSO_MAX_BUFF_SIZE),
> +			(last_segment) && (tmp_len <= TSO_MAX_BUFF_SIZE),
>  			0, 0);
>  
>  		tmp_len -= TSO_MAX_BUFF_SIZE;
> 

-- 
Florian