linux-kernel - Re: [PATCH bpf v2] bpf: fix nested bpf tracepoints with per-cpu data

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Date:   Sat, 15 Jun 2019 16:35:12 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Matt Mullins <mmullins@...com>
Cc:     Andrew Hall <hall@...com>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>
Subject: Re: [PATCH bpf v2] bpf: fix nested bpf tracepoints with per-cpu data

On Tue, Jun 11, 2019 at 2:54 PM Matt Mullins <mmullins@...com> wrote:
>
> BPF_PROG_TYPE_RAW_TRACEPOINTs can be executed nested on the same CPU, as
> they do not increment bpf_prog_active while executing.
>
> This enables three levels of nesting, to support
>   - a kprobe or raw tp or perf event,
>   - another one of the above that irq context happens to call, and
>   - another one in nmi context
> (at most one of which may be a kprobe or perf event).
>
> Fixes: 20b9d7ac4852 ("bpf: avoid excessive stack usage for perf_sample_data")
> Signed-off-by: Matt Mullins <mmullins@...com>

Applied. Thanks