On Fri, 31 Jul 2026 11:41:02 +0800
Michael Wu <[email protected]> wrote:
> An alternative of placing mutex_lock inside update_event_fields() was
> considered but rejected -- it would invert the established lock
> ordering (trace_event_sem -> event_mutex) and risk ABBA deadlock.
>
> Fixes: b3bc8547d3be ("tracing: Have TRACE_DEFINE_ENUM affect trace event
> types as well")
> Cc: [email protected]
> Signed-off-by: Michael Wu <[email protected]>
> ---
> kernel/trace/trace_events.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 956692856fa8..9632788da5af 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -3566,6 +3566,7 @@ void trace_event_update_all(struct trace_eval_map
> **map, int len)
> int last_i;
> int i;
>
> + mutex_lock(&event_mutex);
> down_write(&trace_event_sem);
> list_for_each_entry_safe(call, p, &ftrace_events, list) {
> /* events are usually grouped together with systems */
> @@ -3604,6 +3605,7 @@ void trace_event_update_all(struct trace_eval_map
> **map, int len)
> cond_resched();
> }
> up_write(&trace_event_sem);
> + mutex_unlock(&event_mutex);
> }
>
> static bool event_in_systems(struct trace_event_call *call,
You need to fix your email client to not mangle the output. It replaced
tabs with spaces and wrapped text, making it so I can not apply the patch.
-- Steve
