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Date:   Fri, 27 Sep 2019 14:44:48 +0200
From:   Daniel Borkmann <daniel@iogearbox.net>
To:     Allan Zhang <allanzhang@google.com>
Cc:     songliubraving@fb.com, netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org, Stanislav Fomichev <sdf@google.com>,
        Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH 1/1] bpf: Fix bpf_event_output re-entry issue
Message-ID: <20190927124448.GA22184@pc-66.home>
References: <20190925234312.94063-1-allanzhang@google.com>
 <20190925234312.94063-2-allanzhang@google.com>
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On Wed, Sep 25, 2019 at 04:43:12PM -0700, Allan Zhang wrote:
> BPF_PROG_TYPE_SOCK_OPS program can reenter bpf_event_output because it can
> be called from atomic and non-atomic contexts since we don't have
> bpf_prog_active to prevent it happen.
> 
> This patch enables 3 level of nesting to support normal, irq and nmi
> context.
> 
> We can easily reproduce the issue by running neper crr mode with 100 flows
> and 10 threads from neper client side.
> 
> Here is the whole stack dump:
[...]
> 
> Fixes: a5a3a828cd00 ("bpf: add perf event notificaton support for sock_ops")
> 
> Effort: BPF
> Signed-off-by: Allan Zhang <allanzhang@google.com>
> Reviewed-by: Stanislav Fomichev <sdf@google.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>

Applied, thanks!