netdev - Re: broken behaviour of TC filter delete

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Message-ID: <CAM_iQpU44vdR_aRSpYkBf+awVfwHGG3_j4hJbU2wV3zoHy9cwg@mail.gmail.com>
Date:   Mon, 27 Aug 2018 11:30:07 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     Roman Mashak <mrv@...atatu.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jiri Pirko <jiri@...lanox.com>,
        Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: broken behaviour of TC filter delete

On Sat, Aug 25, 2018 at 6:06 AM Jiri Pirko <jiri@...nulli.us> wrote:
>
> Fri, Aug 24, 2018 at 08:11:07PM CEST, xiyou.wangcong@...il.com wrote:
> >On Fri, Aug 24, 2018 at 9:21 AM Roman Mashak <mrv@...atatu.com> wrote:
> >>
> >> So _before_ commit f71e0ca4db187af7c44987e9d21e9042c3046070 step 6 would
> >> return -ENOENT with "Error: Filter with specified priority/protocol not
> >> found." and _after_ the commit it returns -EINVAL (Error: Cannot find
> >> specified filter chain.)
> >>
> >> ENOENT seems to be more logical to return when there's no more filter to delete.
> >
> >Yeah, at least we should keep ENOENT for compatibility.
> >
> >The bug here is chain 0 is gone after the last filter is gone,
> >so when you delete the filter again, it treats it as you specify
> >chain 0 which does not exist, so it hits EINVAL before ENOENT.
>
> I understand. My concern is about consistency with other chains. Perhaps
> -ENOENT for all chains in this case would be doable. What do you think?

Yeah, I think -ENOENT makes more sense than EINVAL here too.