On Mon, 14 Sep 2026 05:31:56 +0900
Donggeun Yoo <[email protected]> wrote:
> diff --git a/kernel/trace/trace_events_hist.c
> b/kernel/trace/trace_events_hist.c
> index 963e0d6b61fd..4676dc6d9146 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -806,9 +806,12 @@ static void last_cmd_set(struct trace_event_file *file,
> char *str)
> snprintf(last_cmd_loc, MAX_FILTER_STR_VAL, HIST_PREFIX "%s:%s",
> system, name);
> }
>
> +/* Set while a field lookup may fail silently; the parse path is serialized.
> */
> +static bool hist_err_silent;
> +
> static void hist_err(struct trace_array *tr, u8 err_type, u16 err_pos)
> {
> - if (!last_cmd)
> + if (!last_cmd || hist_err_silent)
> return;
>
> tracing_log_err(tr, last_cmd_loc, last_cmd, err_text,
> @@ -4003,7 +4006,9 @@ trace_action_create_field_var(struct hist_trigger_data
> *hist_data,
> * unqualified fields on the target event, or if qualified,
> * target fields that have qualified names matching the target.
> */
> + hist_err_silent = true;
> field_var = create_target_field_var(hist_data, system, event, var);
> + hist_err_silent = false;
>
> if (field_var && !IS_ERR(field_var)) {
> save_field_var(hist_data, field_var);
I applied this patch then I unapplied it after looking at it.
This looks racy as hist_err_silent is global. The parse path is serialized
but we should add a lockdep assert in hist_err() to make sure the event
mutex is held, as well as by the setting of the hist_err_silent to prove
that the code is serialized.
-- Steve
