From: Guenter Roeck <linux@roeck-us.net> mainline inclusion from mainline-v6.17-rc4 commit ab1396af7595e7d49a3850481b24d7fe7cbdfd31 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ICYBCS Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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> Conflicts: kernel/trace/fgraph.c [Context conflict, need to integrate the two err handling codes together] Signed-off-by: Tengda Wu <wutengda2@huawei.com> --- kernel/trace/fgraph.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 7956a799b5e8..35d14657a28b 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -646,11 +646,8 @@ int register_ftrace_graph(struct fgraph_ops *gops) ftrace_graph_active++; ret = start_graph_tracing(); - if (ret) { - ftrace_graph_active--; - unregister_pm_notifier(&ftrace_suspend_notifier); - goto out; - } + if (ret) + goto out_err; ftrace_graph_return = gops->retfunc; @@ -665,8 +662,12 @@ int register_ftrace_graph(struct fgraph_ops *gops) update_function_graph_func(); ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET); - if (ret) - unregister_pm_notifier(&ftrace_suspend_notifier); +out_err: + if (ret) { + ftrace_graph_active--; + if (!ftrace_graph_active) + unregister_pm_notifier(&ftrace_suspend_notifier); + } out: mutex_unlock(&ftrace_lock); return ret; -- 2.34.1