ftrace: Set callback to ftrace_stub when no ops are registered (f7aad4e1) · Commits · 戴 / test

The clean up that adds the helper function ftrace_ops_get_func() caused the default function to not change when DYNAMIC_FTRACE was not set and no ftrace_ops were registered. Although static tracing is not very useful (not having DYNAMIC_FTRACE set), it is still supported and we don't want to break it. Clean up the if statement even more to specifically have the default function call ftrace_stub when no ftrace_ops are registered. This fixes the small bug for static tracing as well as makes the code a bit more understandable. Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

kernel/trace/ftrace.c

+13 −6

Original line number	Diff line number	Diff line
		@@ -253,18 +253,25 @@ static void update_ftrace_function(void)
		{
		ftrace_func_t func;

		/*
		* Prepare the ftrace_ops that the arch callback will use.
		* If there's only one ftrace_ops registered, the ftrace_ops_list
		* will point to the ops we want.
		*/
		set_function_trace_op = ftrace_ops_list;

		/* If there's no ftrace_ops registered, just call the stub function */
		if (ftrace_ops_list == &ftrace_list_end) {
		func = ftrace_stub;

		/*
		* If we are at the end of the list and this ops is
		* recursion safe and not dynamic and the arch supports passing ops,
		* then have the mcount trampoline call the function directly.
		*/
		if (ftrace_ops_list == &ftrace_list_end \|\|
		(ftrace_ops_list->next == &ftrace_list_end)) {

		/* Set the ftrace_ops that the arch callback uses */
		set_function_trace_op = ftrace_ops_list;

		} else if (ftrace_ops_list->next == &ftrace_list_end) {
		func = ftrace_ops_get_func(ftrace_ops_list);

		} else {
		/* Just use the default ftrace_ops */
		set_function_trace_op = &ftrace_list_end;

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