function_graph: Do not update pid func if CONFIG_DYNAMIC_FTRACE not enabled

The ftrace subops is only defined if CONFIG_DYNAMIC_FTRACE is enabled. If
it is not, function tracing is extremely limited, and the subops in the
ftrace_ops structure is not defined (and will fail to compile). If
DYNAMIC_FTRACE is not enabled, then function graph filtering will not
work (as it shouldn't).

Link: https://lore.kernel.org/linux-trace-kernel/20240605202709.096020676@goodmis.org

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: df3ec5da ("function_graph: Add pid tracing back to function graph tracer")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406051855.9VIYXbTB-lkp@intel.com/Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/fgraph.c

@@ -1177,6 +1177,7 @@ void fgraph_update_pid_func(void)
 	if (!(graph_ops.flags & FTRACE_OPS_FL_INITIALIZED))
 		return;
 
+#ifdef CONFIG_DYNAMIC_FTRACE
 	list_for_each_entry(op, &graph_ops.subop_list, list) {
 		if (op->flags & FTRACE_OPS_FL_PID) {
 			gops = container_of(op, struct fgraph_ops, ops);
@@ -1186,6 +1187,7 @@ void fgraph_update_pid_func(void)
 				static_call_update(fgraph_func, gops->entryfunc);
 		}
 	}
+#endif
 }
 
 /* Allocate a return stack for each task */