netdev - Re: Bug report (with fix) for DEC Tulip driver (de2104x.c)

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Message-ID: <20190920104353.GA10706@alpha.franken.de>
Date:   Fri, 20 Sep 2019 12:43:53 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Arlie Davis <arlied@...gle.com>
Cc:     netdev@...r.kernel.org, linux-parisc@...r.kernel.org
Subject: Re: Bug report (with fix) for DEC Tulip driver (de2104x.c)

On Mon, Sep 16, 2019 at 02:50:53PM -0700, Arlie Davis wrote:
>     See section 4.2.2 for the specs on the transfer descriptor.
> 
> Here's my patch that fixes it:
> 
> diff --git a/drivers/net/ethernet/dec/tulip/de2104x.c
> b/drivers/net/ethernet/dec/tulip/de2104x.c
> index f1a2da15dd0a..3a420ceb52e5 100644
> --- a/drivers/net/ethernet/dec/tulip/de2104x.c
> +++ b/drivers/net/ethernet/dec/tulip/de2104x.c
> @@ -545,6 +545,7 @@ static void de_tx (struct de_private *de)
>         while (tx_tail != tx_head) {
>                 struct sk_buff *skb;
>                 u32 status;
> +               u32 control;
> 
>                 rmb();
>                 status = le32_to_cpu(de->tx_ring[tx_tail].opts1);
> @@ -565,7 +566,8 @@ static void de_tx (struct de_private *de)
>                 pci_unmap_single(de->pdev, de->tx_skb[tx_tail].mapping,
>                                  skb->len, PCI_DMA_TODEVICE);
> 
> -               if (status & LastFrag) {
> +               control = le32_to_cpu(de->tx_ring[tx_tail].opts2);
> +               if (control & LastFrag) {

how about just remove the complete if ? We know that we always
use one descriptor per packet and chip doesn't touch control
field. So I see no reason to check it here. Tulip driver for
2114x cards doesn't check it neither.

Thomas.

-- 
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