On Fri, 5 Sep 2025 16:19:02 -0700
Guenter Roeck <[email protected]> wrote:
> > +++ 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);
>
> Is this really correct ? The pm notifier is only registered if
> ftrace_graph_active==1, but not if it is larger than that.
> The above code unregisters it unconditionally, even if
> ftrace_graph_active > 1. I can see that the resulting double
> unregistration in unregister_ftrace_graph() doesn't really
> matter since the error return will be ignored, but is it really
> irrelevant for the successful registered graphs no longer get the
> benefit of the pm notifier callback ?
Ah right, it should be:
error:
if (ret) {
ftrace_graph_active--;
gops->saved_func = NULL;
fgraph_lru_release_index(i);
if (!ftrace_graph_active)
unregister_pm_notifier(&ftrace_suspend_notifier);
}
return ret;
I missed that there's a:
ret = ftrace_startup_subops(&graph_ops, &gops->ops, command);
if (!ret)
fgraph_array[i] = gops;
Just before the error label, so the goto error isn't the only path there
that can affect the ret variable.
I could add a patch or you could send one.
-- Steve
