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From:   Song Liu <song@kernel.org>
Date:   Wed, 27 Sep 2023 09:09:38 -0700
Message-ID: <CAPhsuW6mEWJcZdYbPbqt5ArBMznzQYwHBqTpKCcsB4B0o=PSGA@mail.gmail.com>
Subject: Re: [PATCH] perf record: Fix BTF type checks in the off-cpu profiling
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-perf-users@vger.kernel.org, Hao Luo <haoluo@google.com>,
        bpf@vger.kernel.org
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On Fri, Sep 22, 2023 at 4:44=E2=80=AFPM Namhyung Kim <namhyung@kernel.org> =
wrote:
>
> The BTF func proto for a tracepoint has one more argument than the
> actual tracepoint function since it has a context argument at the
> begining.  So it should compare to 5 when the tracepoint has 4
> arguments.
>
>   typedef void (*btf_trace_sched_switch)(void *, bool, struct task_struct=
 *, struct task_struct *, unsigned int);
>
> Also, recent change in the perf tool would use a hand-written minimal
> vmlinux.h to generate BTF in the skeleton.  So it won't have the info
> of the tracepoint.  Anyway it should use the kernel's vmlinux BTF to
> check the type in the kernel.
>
> Fixes: b36888f71c85 ("perf record: Handle argument change in sched_switch=
")
> Cc: Song Liu <song@kernel.org>
> Cc: Hao Luo <haoluo@google.com>
> CC: bpf@vger.kernel.org
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Acked-by: Song Liu <song@kernel.org>