tracing: fix return value in __ftrace_event_enable_disable for TRACE_REG_UNREGISTER

When __ftrace_event_enable_disable invokes the class callback to
unregister the event, the return value is not reported up to the
caller, hence leading to event unregister failures being silently
ignored.

This patch assigns the ret variable to the invocation of the
event unregister callback, so that its return value is stored
and reported to the caller, and it raises a warning in case
of error.

Link: https://lore.kernel.org/20250321170821.101403-1-gpaoloni@redhat.com
Signed-off-by: Gabriele Paoloni <gpaoloni@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 513de9ceb80ef0ada33f494e5b1c94d9ab383e33..8e7603acca210db6ee5e684e7c2493b0b20a9040 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -790,7 +790,9 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
                                clear_bit(EVENT_FILE_FL_RECORDED_TGID_BIT, &file->flags);
                        }
 
-                       call->class->reg(call, TRACE_REG_UNREGISTER, file);
+                       ret = call->class->reg(call, TRACE_REG_UNREGISTER, file);
+
+                       WARN_ON_ONCE(ret);
                }
                /* If in SOFT_MODE, just set the SOFT_DISABLE_BIT, else clear it */
                if (file->flags & EVENT_FILE_FL_SOFT_MODE)