netdev - Re: [Patch net-next 02/13] ipv4: introduce tracepoint trace_ip_queue

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Message-ID: <CAM_iQpV42D3HHESF62tmUHn=gB-a-6fqiRJGYaoVp0HyRH=xEA@mail.gmail.com>
Date:   Wed, 11 Aug 2021 17:37:35 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Martin KaFai Lau <kafai@...com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Qitao Xu <qitao.xu@...edance.com>,
        Cong Wang <cong.wang@...edance.com>, bpf <bpf@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [Patch net-next 02/13] ipv4: introduce tracepoint trace_ip_queue_xmit()

On Wed, Aug 11, 2021 at 4:08 PM Martin KaFai Lau <kafai@...com> wrote:
> Some of the function names are hardly changed.

This is obviously wrong for two reasons:

1. Kernel developers did change them. As a quick example,
tcp_retransmit_skb() has been changed, we do have reasons to only trace
__tcp_retransmit_skb() instead.

2. Even if kernel developers never did, compilers can do inline too. For
example, I see nothing to stop compiler to inline tcp_transmit_skb()
which is static and only calls __tcp_transmit_skb(). You explicitly
mark bpf_fentry_test1() as noinline, don't you?

I understand you are eager to promote ebpf, however, please keep
reasonable on facts.

Thanks.