netdev - Re: broken behaviour of TC filter delete

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Date:   Fri, 24 Aug 2018 11:11:07 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Roman Mashak <mrv@...atatu.com>
Cc:     Jiri Pirko <jiri@...nulli.us>,
        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 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 am not sure how to fix this properly.