From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: [patch net-next v7 07/13] net: sched: use block index as a handle
 instead of qdisc when block is shared
Date: Wed, 10 Jan 2018 11:12:44 -0700
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References: <20180109140731.1022-1-jiri@resnulli.us>
 <20180109140731.1022-8-jiri@resnulli.us>
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To: Jiri Pirko <jiri@resnulli.us>, netdev@vger.kernel.org
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On 1/9/18 7:07 AM, Jiri Pirko wrote:
> diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
> index 843e29a..9c026d9 100644
> --- a/include/uapi/linux/rtnetlink.h
> +++ b/include/uapi/linux/rtnetlink.h
> @@ -541,9 +541,15 @@ struct tcmsg {
>  	int		tcm_ifindex;
>  	__u32		tcm_handle;
>  	__u32		tcm_parent;
> +/* tcm_block_index is used instead of tcm_parent
> + * in case tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK
> + */
> +#define tcm_block_index tcm_parent
>  	__u32		tcm_info;
>  };
>  
> +#define TCM_IFINDEX_MAGIC_BLOCK (0xFFFFFFFFU)
> +
>  enum {
>  	TCA_UNSPEC,
>  	TCA_KIND,


This could be more clearly documented for anyone wanting to write an app
against the API. Something like:

For shared blocks, tcm_ifindex is set to TCM_IFINDEX_MAGIC_BLOCK, and
tcm_parent is aliased to tcm_block_index which is the block index.