process removal: remove a few bugs and race conditions

src/sys/syscalls/exit.c

@@ -4,6 +4,7 @@
 #include <stdbool.h>
 #include <kernel/event.h>
 #include <kernel/alloc.h>
+#include <arch/interrupt.h>
 
 void syscall_exit(int status){
 	proc_t* proc = arch_getcls()->thread->proc;
@@ -44,10 +45,17 @@ void syscall_exit(int status){
 	}	
 
 	spinlock_release(&init->lock);
-	spinlock_release(&proc->lock);
-
 	event_signal(&proc->parent->childevent, true);
 
+        // context and thread destruction will happen in the waitpid()
+        // the pointer to this thread will reside in proc->threads
+
+        proc->threads = arch_getcls()->thread;
+	
+	arch_interrupt_disable();
+
+	spinlock_release(&proc->lock);
+
 	sched_dequeue();
 	
 	__builtin_unreachable();