netdev - RE: [Intel-wired-lan] [net PATCH 2/2] e1000: Double Tx descriptors needed check for 82544

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Date:	Wed, 9 Mar 2016 23:51:47 +0000
From:	"Brown, Aaron F" <aaron.f.brown@...el.com>
To:	Alexander Duyck <aduyck@...antis.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"jogreene@...hat.com" <jogreene@...hat.com>,
	"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"sassmann@...hat.com" <sassmann@...hat.com>
Subject: RE: [Intel-wired-lan] [net PATCH 2/2] e1000: Double Tx descriptors
	needed check for 82544

> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@...ts.osuosl.org] On
> Behalf Of Alexander Duyck
> Sent: Wednesday, March 2, 2016 1:16 PM
> To: netdev@...r.kernel.org; jogreene@...hat.com; intel-wired-
> lan@...ts.osuosl.org; Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>;
> sassmann@...hat.com
> Subject: [Intel-wired-lan] [net PATCH 2/2] e1000: Double Tx descriptors
> needed check for 82544
> 
> The 82544 has code that adds one additional descriptor per data buffer.
> However we weren't taking that into acount when determining the
> descriptors
> needed for the next transmit at the end of the xmit_frame path.
> 
> This change takes that into account by doubling the number of descriptors
> needed for the 82544 so that we can avoid a potential issue where we could
> hang the Tx ring by loading frames with xmit_more enabled and then
> stopping
> the ring without writing the tail.
> 
> In addition it adds a few more descriptors to account for some additional
> workarounds that have been added over time.
> 
> Signed-off-by: Alexander Duyck <aduyck@...antis.com>
> ---
>  drivers/net/ethernet/intel/e1000/e1000_main.c |   19
> ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)

Tested-by: Aaron Brown <aaron.f.brown@...el.com>