netdev - Re: [Patch bpf] selftests/bpf: Retry for EAGAIN in udp_redir_to

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Date:   Fri, 21 May 2021 14:49:26 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     John Fastabend <john.fastabend@...il.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, Cong Wang <cong.wang@...edance.com>,
        Jiang Wang <jiang.wang@...edance.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: Re: [Patch bpf] selftests/bpf: Retry for EAGAIN in udp_redir_to_connected()

On Thu, May 20, 2021 at 10:12 PM Andrii Nakryiko
<andrii.nakryiko@...il.com> wrote:
> It doesn't matter. Instead of having an endless loop, please add a
> counter and limit the number of iterations to some reasonable number.
> That's all, no one is asking you to do something impossible, just
> prevent looping forever in some unforeseen situations and just fail
> the test instead.

Well, in a non-hostile environment, the packet will not be dropped
as it is sent via a loopback, hence the loop is not endless.

"my memcg kicks in for some unknown reason" is pretty much
a hostile environment, for which we should not consider. The counter
argument is simply not to run selftests in such a hostile environment.

Thanks.