6.16-stable review patch. If anyone has any objections, please let me know.
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From: Guenter Roeck linux@roeck-us.net
[ 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.ne... 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 --- kernel/trace/fgraph.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index dac2d58f39490..db40ec5cc9d73 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -1393,7 +1393,8 @@ int register_ftrace_graph(struct fgraph_ops *gops) 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; }