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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Tue, 9 Mar 2021 12:39:59 -0800
Message-ID: <CAADnVQJe7GQjYvdBYvG3opeAdaY2EY2vtRafSp0zZ+Pe=Nnsdg@mail.gmail.com>
Subject: Re: [PATCH] net: add net namespace inode for all net_dev events
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     David Ahern <dsahern@gmail.com>,
        Tony Lu <tonylu@linux.alibaba.com>,
        "David S. Miller" <davem@davemloft.net>,
        Ingo Molnar <mingo@redhat.com>,
        Network Development <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, Mar 9, 2021 at 12:37 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> The size of the fields and order changes all the time in various events. I
> recommend doing so *all the time*. If you upgrade a kernel, then all the bpf
> programs you have for that kernel should also be updated. You can't rely on
> fields being the same, size or order. The best you can do is expect the
> field to continue to exist, and that's not even a guarantee.

+1. Tracing bpf progs already do that.
Old style tracing progs do it based on the kernel version.
New style is using CO-RE.