netdev - Re: [net-next 02/15] ethtool: Add support for configuring PFC stall prevention in ethtool

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Message-ID: <20180324145703.GC31941@lunn.ch>
Date:   Sat, 24 Mar 2018 15:57:03 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Saeed Mahameed <saeedm@...lanox.com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Inbar Karmy <inbark@...lanox.com>,
        Michal Kubecek <mkubecek@...e.cz>
Subject: Re: [net-next 02/15] ethtool: Add support for configuring PFC stall
 prevention in ethtool

On Fri, Mar 23, 2018 at 03:39:12PM -0700, Saeed Mahameed wrote:
> From: Inbar Karmy <inbark@...lanox.com>
> 
> In the event where the device unexpectedly becomes unresponsive
> for a long period of time, flow control mechanism may propagate
> pause frames which will cause congestion spreading to the entire
> network.
> To prevent this scenario, when the device is stalled for a period
> longer than a pre-configured timeout, flow control mechanisms are
> automatically disabled.
> 
> This patch adds support for the ETHTOOL_PFC_STALL_PREVENTION
> as a tunable.
> This API provides support for configuring flow control storm prevention
> timeout (msec).
> 
> Signed-off-by: Inbar Karmy <inbark@...lanox.com>
> Cc: Michal Kubecek <mkubecek@...e.cz>
> Cc: Andrew Lunn <andrew@...n.ch>
> Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
> ---
>  include/uapi/linux/ethtool.h | 4 ++++
>  net/core/ethtool.c           | 6 ++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
> index 20da156aaf64..9dc63a14a747 100644
> --- a/include/uapi/linux/ethtool.h
> +++ b/include/uapi/linux/ethtool.h
> @@ -217,10 +217,14 @@ struct ethtool_value {
>  	__u32	data;
>  };
>  
> +#define PFC_STORM_PREVENTION_AUTO	0xffff
> +#define PFC_STORM_PREVENTION_DISABLE	0
> +
>  enum tunable_id {
>  	ETHTOOL_ID_UNSPEC,
>  	ETHTOOL_RX_COPYBREAK,
>  	ETHTOOL_TX_COPYBREAK,
> +	ETHTOOL_PFC_PREVENTION_TOUT,

Hi Inbar

Please could you add a comment here about the units. Ideally we want
this file to be self documenting.

     Andrew