Date:   Sun, 12 Mar 2023 12:32:19 -0700
From:   Cong Wang <xiyou.wangcong@gmail.com>
To:     Hsin-Wei Hung <hsinweih@uci.edu>
Cc:     John Fastabend <john.fastabend@gmail.com>,
        Jakub Sitnicki <jakub@cloudflare.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: A potential deadlock in sockhash map
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References: <CABcoxUayum5oOqFMMqAeWuS8+EzojquSOSyDA3J_2omY=2EeAg@mail.gmail.com>
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On Mon, Feb 20, 2023 at 07:39:59AM -0600, Hsin-Wei Hung wrote:
> DEFINE_BPF_MAP(map_0, BPF_MAP_TYPE_SOCKHASH, 0, uint32_t, uint32_t, 1005);
> SEC("tp/sched/sched_switch")
> int func(__u64 *ctx) {
>         uint32_t v0 = 0;
>         uint64_t v1 = 0;
>         v1 = bpf_map_delete_elem(&map_0, &v0);
>         return 0;
> }

It looks like we have to disable hardirq (instead of just softirq) in order to use
sockmap safely in interrupt context like sched/sched_switch.

Thanks.