trace/fgraph: Fix error handling

[ Upstream commit ab1396af7595e7d49a3850481b24d7fe7cbdfd31 ]

Commit edede7a6dcd7 ("trace/fgraph: Fix the warning caused by missing
unregister notifier") added a call to unregister the PM notifier if
register_ftrace_graph() failed. It does so unconditionally. However,
the PM notifier is only registered with the first call to
register_ftrace_graph(). If the first registration was successful and
a subsequent registration failed, the notifier is now unregistered even
if ftrace graphs are still registered.

Fix the problem by only unregistering the PM notifier during error handling
if there are no active fgraph registrations.

Fixes: edede7a6dcd7 ("trace/fgraph: Fix the warning caused by missing unregister notifier")
Closes: https://lore.kernel.org/all/63b0ba5a-a928-438e-84f9-93028dd72e54@roeck-us.net/
Cc: Ye Weihua <yeweihua4@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250906050618.2634078-1-linux@roeck-us.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 2eed8bc672f913f79a75c3cc176bcf4e7c4169d2..988a4c4ba97bc85edd2bb2472cd34ad9e854c908 100644 (file)
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -1316,7 +1316,8 @@ error:
                ftrace_graph_active--;
                gops->saved_func = NULL;
                fgraph_lru_release_index(i);
-               unregister_pm_notifier(&ftrace_suspend_notifier);
+               if (!ftrace_graph_active)
+                       unregister_pm_notifier(&ftrace_suspend_notifier);
        }
        return ret;
 }