Kernel: Various context switch fixes

These changes solve a number of problems with the software
context swithcing:

* The scheduler lock really should be held throughout context switches
* Transitioning from the initial (idle) thread to another needs to
  hold the scheduler lock
* Transitioning from a dying thread to another also needs to hold
  the scheduler lock
* Dying threads cannot necessarily be finalized if they haven't
  switched out of it yet, so flag them as active while a processor
  is running it (the Running state may be switched to Dying while
  it still is actually running)

1 files changed, 3 insertions, 1 deletions

diff --git a/Kernel/Scheduler.h b/Kernel/Scheduler.h
index bec0d27b89..5ffb57d201 100644
--- a/Kernel/Scheduler.h
+++ b/Kernel/Scheduler.h
@@ -58,11 +58,13 @@ public:
     static timeval time_since_boot();
     static bool yield();
     static bool donate_to(Thread*, const char* reason);
-    static bool context_switch(Thread&);
+    static bool context_switch(Thread*);
+    static void enter_current(Thread& prev_thread);
     static Process* colonel();
     static void beep();
     static void idle_loop();
     static void invoke_async();
+    static void notify_finalizer();
 
     template<typename Callback>
     static inline IterationDecision for_each_runnable(Callback);