Re: [PATCH] perf record: Fix BTF type checks in the off-cpu profiling

[Song Liu]

On Fri, Sep 22, 2023 at 4:44 PM Namhyung Kim <namhyung@xxxxxxxxxx> 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@xxxxxxxxxx>
> Cc: Hao Luo <haoluo@xxxxxxxxxx>
> CC: bpf@xxxxxxxxxxxxxxx
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Acked-by: Song Liu <song@xxxxxxxxxx>