MIME-Version: 1.0
From:   Benjamin Yim <yan2228598786@gmail.com>
Date:   Mon, 10 Jan 2022 10:07:33 +0800
Message-ID: <CALcyL7gK6xBLkuUAc6hJmiKwddjh8uhP1F1oCEdb+YTy-XTXiQ@mail.gmail.com>
Subject: Re: [PATCH] net: skb: introduce kfree_skb_reason()
To:     imagedong@tencent.com
Cc:     Jakub Kicinski <kuba@kernel.org>, netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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Precedence: bulk

On Thu,  6 Jan 2022 14:36:26 +0800 Menglong Dong wrote:

> Introduce the interface kfree_skb_reason(), which is able to pass
> the reason why the skb is dropped to 'kfree_skb' tracepoint.

> Add the 'reason' field to 'trace_kfree_skb', therefor user can get
> more detail information about abnormal skb with 'drop_monitor' or
> eBPF.

> All drop reasons are defined in the enum 'skb_drop_reason', and
> they will be print as string in 'kfree_skb' tracepoint in format
> of 'reason: XXX'.

> ( Maybe the reasons should be defined in a uapi header file, so that
> user space can use them? )

Since these drops are hardly hot path, why not simply use a string ?
An ENUM will not really help grep games.

tcp_drop(sk, skb, "csum error");


can refer to the previous discussion: https://lkml.org/lkml/2021/8/25/613