On Thu, 9 Nov 2023 21:18:48 -0500 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Fri, 10 Nov 2023 10:51:54 +0900 > Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> wrote: > > > So this patch registers ftrace_ops for each fgraph_ops to ftrace. > > This means that the ftrace_graph_func() will be called twice or more > > on the same function. > > Thus should I call ftrace_startup() once when the first fgraph_ops > > is registered? > > No, it's not enough. Actually each fgraph_ops can have different filters. > > We need to define a shared filter and combine new filters to one and > > use it. We also need to do it when a fgraph is unregistered. > > > > Is there any function which makes a new filter from two (or more) filters? > > So I'm guessing that we need to have a fgraph_set_filter*() operations? > > When one gets added, it needs to update the ftrace_ops to include the added > functions. Or we need to have a way to create a new hash from all the > registered fgraph_ops, and have that for the ftrace_ops. Then when it gets > called, if it has more than one registered function, it needs to iterate > over the list? Yes, that is one option, update a global common hash and introduce a new common ftrace function to run function_graph_enter(). Or, I think keep the current one but iterate ftrace_ops to callback the function_graph_enter() with ftrace_ops. Then we can get appropriate fgraph_ops. Ftrace push return trace can skip pushing if ret == return_to_handler. (maybe this is better to reuse ftrace) Thank you, > > -- Steve > > > > > > Or, maybe we can make the common callback to find the previous ret entry on > > the ret_stack and reuse it. (In this case we don't need loop on each > > fgraph_array entry) > -- Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
