netdev - Re: [patch net-next v8 08/14] net: sched: add rt netlink message type for block get

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Date:   Mon, 15 Jan 2018 10:21:44 -0700
From:   David Ahern <dsahern@...il.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, jhs@...atatu.com,
        xiyou.wangcong@...il.com, mlxsw@...lanox.com, andrew@...n.ch,
        vivien.didelot@...oirfairelinux.com, f.fainelli@...il.com,
        michael.chan@...adcom.com, ganeshgr@...lsio.com,
        saeedm@...lanox.com, matanb@...lanox.com, leonro@...lanox.com,
        idosch@...lanox.com, jakub.kicinski@...ronome.com,
        simon.horman@...ronome.com, pieter.jansenvanvuuren@...ronome.com,
        john.hurley@...ronome.com, alexander.h.duyck@...el.com,
        ogerlitz@...lanox.com, john.fastabend@...il.com,
        daniel@...earbox.net
Subject: Re: [patch net-next v8 08/14] net: sched: add rt netlink message type
 for block get

On 1/15/18 10:08 AM, David Ahern wrote:
> On 1/15/18 10:03 AM, Jiri Pirko wrote:
>> Mon, Jan 15, 2018 at 05:56:31PM CET, dsahern@...il.com wrote:
>>> On 1/12/18 8:46 AM, Jiri Pirko wrote:
>>>> From: Jiri Pirko <jiri@...lanox.com>
>>>>
>>>> Add simple block get operation which primary purpose is to check the
>>>> block existence by block index.
>>>>
>>>> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
>>>> ---
>>>> v6->v7:
>>>> - new patch
>>>> ---
>>>>  include/uapi/linux/rtnetlink.h |  6 ++++
>>>>  net/sched/cls_api.c            | 64 ++++++++++++++++++++++++++++++++++++++++++
>>>>  security/selinux/nlmsgtab.c    |  5 +++-
>>>>  3 files changed, 74 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
>>>> index da878f2..4b1f626 100644
>>>> --- a/include/uapi/linux/rtnetlink.h
>>>> +++ b/include/uapi/linux/rtnetlink.h
>>>> @@ -150,6 +150,12 @@ enum {
>>>>  	RTM_NEWCACHEREPORT = 96,
>>>>  #define RTM_NEWCACHEREPORT RTM_NEWCACHEREPORT
>>>>  
>>>> +	RTM_NEWBLOCK = 100,
>>>> +#define RTM_NEWBLOCK RTM_NEWBLOCK
>>>> +	RTM_DELBLOCK,
>>>> +#define RTM_DELBLOCK RTM_DELBLOCK
>>>> +	RTM_GETBLOCK,
>>>> +#define RTM_GETBLOCK RTM_GETBLOCK
>>>>  	__RTM_MAX,
>>>>  #define RTM_MAX		(((__RTM_MAX + 3) & ~3) - 1)
>>>>  };
>>>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>>>> index d687e58..14e4f20 100644
>>>> --- a/net/sched/cls_api.c
>>>> +++ b/net/sched/cls_api.c
>>>> @@ -1553,6 +1553,69 @@ int tc_setup_cb_call(struct tcf_block *block, struct tcf_exts *exts,
>>>>  }
>>>>  EXPORT_SYMBOL(tc_setup_cb_call);
>>>>  
>>>> +static int block_notify_fill(struct net *net, struct sk_buff *skb,
>>>> +			     struct tcf_block *block, u32 portid, u32 seq,
>>>> +			     u16 flags, int event)
>>>> +{
>>>> +	struct nlmsghdr *nlh;
>>>> +	struct tcmsg *tcm;
>>>> +
>>>> +	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*tcm), flags);
>>>> +	if (!nlh)
>>>> +		return -EMSGSIZE;
>>>> +	tcm = nlmsg_data(nlh);
>>>> +	memset(tcm, 0, sizeof(*tcm));
>>>> +	tcm->tcm_family = AF_UNSPEC;
>>>> +	tcm->tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
>>>> +	tcm->tcm_block_index = block->index;
>>>> +	return 0;
>>>> +}
>>>
>>> Why can't this be done with RTM_GETQDISC?
>>
>> I don't follow. Could you please describe a bit more what do you think?
> 
> Why are you adding RTM_{NEW,GET,DEL}BLOCK? Can't you get the same
> information using RTM_GETQDISC and updating it to check for the
> 'tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK' path
> 

The above question is because a user specifies a shared block in a
'qdisc add'.

Alternatively, what about RTM_GETTFILTER? You already update
tc_ctl_tfilter to check for TCM_IFINDEX_MAGIC_BLOCK

My main question is why can't existing RTM_ commands be used?