netdev - RE: [PATCH NET] ethtool: silence warning on bit loss

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Date:   Fri, 14 Oct 2016 09:26:45 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Jesse Brandeburg' <jesse.brandeburg@...el.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH NET] ethtool: silence warning on bit loss

From: Jesse Brandeburg
> Sent: 14 October 2016 00:14
> Sparse was complaining when we went to prototype some code
> using ethtool_cmd_speed_set and SPEED_100000, which uses
> the upper 16 bits of __u32 speed for the first time.
...
> Reported-by: Preethi Banala <preethi.banala@...el.com>
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
> ---
>  include/uapi/linux/ethtool.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
> index 099a420..8e54723 100644
> --- a/include/uapi/linux/ethtool.h
> +++ b/include/uapi/linux/ethtool.h
> @@ -119,8 +119,7 @@ struct ethtool_cmd {
>  static inline void ethtool_cmd_speed_set(struct ethtool_cmd *ep,
>  					 __u32 speed)
>  {
> -
> -	ep->speed = (__u16)speed;
> +	ep->speed = (__u16)(speed & 0xFFFF);
>  	ep->speed_hi = (__u16)(speed >> 16);

I suspect that deleting both (__u16) casts also fixes it?

	David