netdev - Re: [PATCH net] net/sched: cls_u32: fix cls

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Date:   Thu, 08 Feb 2018 15:29:05 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     ivecera@...hat.com
Cc:     netdev@...r.kernel.org, ogerlitz@...lanox.com, jiri@...nulli.us,
        xiyou.wangcong@...il.com, jhs@...atatu.com
Subject: Re: [PATCH net] net/sched: cls_u32: fix cls_u32 on filter replace

From: Ivan Vecera <ivecera@...hat.com>
Date: Thu,  8 Feb 2018 16:10:39 +0100

> The following sequence is currently broken:
> 
>  # tc qdisc add dev foo ingress
>  # tc filter replace dev foo protocol all ingress \
>    u32 match u8 0 0 action mirred egress mirror dev bar1
>  # tc filter replace dev foo protocol all ingress \
>    handle 800::800 pref 49152 \
>    u32 match u8 0 0 action mirred egress mirror dev bar2
>  Error: cls_u32: Key node flags do not match passed flags.
>  We have an error talking to the kernel, -1
> 
> The error comes from u32_change() when comparing new and
> existing flags. The existing ones always contains one of
> TCA_CLS_FLAGS_{,NOT}_IN_HW flag depending on offloading state.
> These flags cannot be passed from userspace so the condition
> (n->flags != flags) in u32_change() always fails.
> 
> Fix the condition so the flags TCA_CLS_FLAGS_NOT_IN_HW and
> TCA_CLS_FLAGS_IN_HW are not taken into account.
> 
> Fixes: 24d3dc6d27ea ("net/sched: cls_u32: Reflect HW offload status")
> Signed-off-by: Ivan Vecera <ivecera@...hat.com>

Ugh, private kernel flags are always troublesome for this reason.

Applied and queued up for -stable.