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trace/fgraph: Fix error handling 

Commit edede7a6dc ("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: edede7a6dc ("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>
This commit is contained in:
Guenter Roeck 2025-09-05 22:06:18 -07:00 committed by Steven Rostedt (Google)
parent 80d03a4083
commit ab1396af75
1 changed files with 2 additions and 1 deletions
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3
kernel/trace/fgraph.c
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@ -1397,7 +1397,8 @@ 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;
}