This warning was triggered during testing on v6.16:
notifier callback ftrace_suspend_notifier_call already registered
WARNING: CPU: 2 PID: 86 at kernel/notifier.c:23
notifier_chain_register+0x44/0xb0
...
Call Trace:
<TASK>
blocking_notifier_chain_register+0x34/0x60
register_ftrace_graph+0x330/0x410
ftrace_profile_write+0x1e9/0x340
vfs_write+0xf8/0x420
? filp_flush+0x8a/0xa0
? filp_close+0x1f/0x30
? do_dup2+0xaf/0x160
ksys_write+0x65/0xe0
do_syscall_64+0xa4/0x260
entry_SYSCALL_64_after_hwframe+0x77/0x7f
When writing to the function_profile_enabled interface, the notifier was
not unregistered after start_graph_tracing failed, causing a warning the
next time function_profile_enabled was written.
Fixed by adding unregister_pm_notifier in the exception path.
Fixes: 4a2b8dda3f870 ("tracing/function-graph-tracer: fix a regression while
suspend to disk")
Signed-off-by: Ye Weihua <yeweih...@huawei.com>
---
kernel/trace/fgraph.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index c5b207992fb4..dac2d58f3949 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -1391,10 +1391,11 @@ int register_ftrace_graph(struct fgraph_ops *gops)
error:
if (ret) {
ftrace_graph_active--;
gops->saved_func = NULL;
fgraph_lru_release_index(i);
+ unregister_pm_notifier(&ftrace_suspend_notifier);
}
return ret;
}
void unregister_ftrace_graph(struct fgraph_ops *gops)
--
2.34.1
