netdev - Re: [PATCH net 1/1] net sched filters: pass netlink message flags in event notification

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Date:   Thu, 17 Nov 2016 13:02:24 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Roman Mashak <mrv@...atatu.com>
Cc:     David Miller <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [PATCH net 1/1] net sched filters: pass netlink message flags in
 event notification

On Wed, Nov 16, 2016 at 2:16 PM, Roman Mashak <mrv@...atatu.com> wrote:
> Userland client should be able to read an event, and reflect it back to
> the kernel, therefore it needs to extract complete set of netlink flags.
>
> For example, this will allow "tc monitor" to distinguish Add and Replace
> operations.
>
> Signed-off-by: Roman Mashak <mrv@...atatu.com>
> Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
> ---
>  net/sched/cls_api.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 2b2a797..8e93d4a 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -112,7 +112,7 @@ static void tfilter_notify_chain(struct net *net, struct sk_buff *oskb,
>
>         for (it_chain = chain; (tp = rtnl_dereference(*it_chain)) != NULL;
>              it_chain = &tp->next)
> -               tfilter_notify(net, oskb, n, tp, 0, event, false);
> +               tfilter_notify(net, oskb, n, tp, n->nlmsg_flags, event, false);


I must miss something, why does it make sense to pass n->nlmsg_flags
as 'fh' to tfilter_notify()??


>  }
>
>  /* Select new prio value from the range, managed by kernel. */
> @@ -430,7 +430,8 @@ static int tfilter_notify(struct net *net, struct sk_buff *oskb,
>         if (!skb)
>                 return -ENOBUFS;
>
> -       if (tcf_fill_node(net, skb, tp, fh, portid, n->nlmsg_seq, 0, event) <= 0) {
> +       if (tcf_fill_node(net, skb, tp, fh, portid, n->nlmsg_seq,
> +                         n->nlmsg_flags, event) <= 0) {


This part makes sense.