From: David Carlier <devnexen@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lee Jones <lee@kernel.org>,
linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org,
David Carlier <devnexen@gmail.com>,
stable@vger.kernel.org
Subject: [PATCH] tracing: Drop the synthetic event ref when clearing hist triggers
Date: Thu, 22 Oct 2026 21:53:16 +0100 [thread overview]
Message-ID: <20261022205405.1228742-1-devnexen@gmail.com> (raw)
clear_event_triggers() frees a hist trigger on a synthetic event without
dropping the se->ref taken by event_hist_trigger_parse(). Removing an
instance with such a trigger leaves the synthetic event busy forever.
Fixes: 4b147936fa50 ("tracing: Add support for 'synthetic' events")
Cc: stable@vger.kernel.org
Signed-off-by: David Carlier <devnexen@gmail.com>
---
Applies on trace/for-next, depends on 3403d9bb27eb ("tracing/histograms: Verify event_call identity when updating synth_event refcount").
kernel/trace/trace.h | 2 ++
kernel/trace/trace_events_hist.c | 20 +++++++++++++-------
kernel/trace/trace_events_trigger.c | 2 ++
3 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 0f0786700f99..e108f95fd609 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1915,9 +1915,11 @@ extern const struct file_operations event_inject_fops;
#ifdef CONFIG_HIST_TRIGGERS
extern int register_trigger_hist_cmd(void);
extern int register_trigger_hist_enable_disable_cmds(void);
+extern void hist_put_synth_event(struct trace_event_file *file);
#else
static inline int register_trigger_hist_cmd(void) { return 0; }
static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
+static inline void hist_put_synth_event(struct trace_event_file *file) { }
#endif
extern int register_trigger_cmds(void);
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index f39fa8942673..9419edfd1b67 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6756,6 +6756,17 @@ static bool hist_trigger_check_refs(struct event_trigger_data *data,
return false;
}
+void hist_put_synth_event(struct trace_event_file *file)
+{
+ struct synth_event *se;
+
+ lockdep_assert_held(&event_mutex);
+
+ se = find_synth_event_call(file->event_call);
+ if (se)
+ se->ref--;
+}
+
static void hist_unregister_trigger(char *glob,
struct event_trigger_data *data,
struct trace_event_file *file)
@@ -6811,7 +6822,6 @@ static void hist_unreg_all(struct trace_event_file *file)
{
struct event_trigger_data *test, *n;
struct hist_trigger_data *hist_data;
- struct synth_event *se;
lockdep_assert_held(&event_mutex);
@@ -6824,9 +6834,7 @@ static void hist_unreg_all(struct trace_event_file *file)
list_del_rcu(&test->list);
trace_event_trigger_enable_disable(file, 0);
- se = find_synth_event_call(file->event_call);
- if (se)
- se->ref--;
+ hist_put_synth_event(file);
update_cond_flag(file);
if (hist_data->enable_timestamps)
@@ -6941,9 +6949,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
}
event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
- se = find_synth_event_call(file->event_call);
- if (se)
- se->ref--;
+ hist_put_synth_event(file);
ret = 0;
goto out_free;
}
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 4d2fde996c0f..a2487ad7fef8 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -643,6 +643,8 @@ clear_event_triggers(struct trace_array *tr)
list_for_each_entry_safe(data, n, &file->triggers, list) {
trace_event_trigger_enable_disable(file, 0);
list_del_rcu(&data->list);
+ if (data->cmd_ops->trigger_type == ETT_EVENT_HIST)
+ hist_put_synth_event(file);
if (data->cmd_ops->free)
data->cmd_ops->free(data);
}
--
2.55.0
reply other threads:[~2026-10-22 20:54 UTC|newest]
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