Kernel: Add Scheduler::is_initialized

Author: https://github.com/ccapitalK
Commit: https://github.com/SerenityOS/serenity/commit/cf1c8eb7786
Pull-request: https://github.com/SerenityOS/serenity/pull/7130
Reviewed-by: https://github.com/Dexesttp
Reviewed-by: https://github.com/IdanHo

Kernel/Scheduler.cpp

@@ -570,6 +570,12 @@ void Scheduler::dump_scheduler_state()
     dump_thread_list();
 }
 
+bool Scheduler::is_initialized()
+{
+    // The scheduler is initalized iff the idle thread exists
+    return Processor::idle_thread() != nullptr;
+}
+
 void dump_thread_list()
 {
     dbgln("Scheduler thread list for processor {}:", Processor::id());

Kernel/Scheduler.h

@@ -51,6 +51,7 @@ public:
     static bool dequeue_runnable_thread(Thread&, bool = false);
     static void queue_runnable_thread(Thread&);
     static void dump_scheduler_state();
+    static bool is_initialized();
 };
 
 }