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SubjectRe: [PATCH] tracing: Skip software disabled event at __synth_event_trace_end()
On Wed, 12 Feb 2020 14:54:19 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> When the synthetic event is software disabled,
> __synth_event_trace_start() does not allocate an event buffer.
> In this case __synth_event_trace_end() also should not commit
> the buffer.
>
> Check the trace_state->disabled at __synth_event_trace_end()
> and if it is disabled, skip it.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> kernel/trace/trace_events_hist.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 483b3fd1094f..781e4b55e117 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -1847,6 +1847,9 @@ __synth_event_trace_start(struct trace_event_file *file,
> static inline void
> __synth_event_trace_end(struct synth_event_trace_state *trace_state)
> {
> + if (trace_state->disabled)
> + return;
> +

Aah, I assumed that trace_state should be initialized with 0, but
in really, it could be just allocated on the stack.
We has to set trace_state->disabled = false in __synth_event_trace_start().

Thank you,

> trace_event_buffer_commit(&trace_state->fbuffer);
>
> ring_buffer_nest_end(trace_state->buffer);
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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