Major restructure

kern/libkern/spinlock.h

@@ -0,0 +1,51 @@
+#ifndef KERNEL_Spinlock_H
+#define KERNEL_Spinlock_H
+
+#include <stdint.h>
+
+/** Mutual exclusion spin lock */
+struct Spinlock {
+    u32 locked; // Is the lock held?
+
+    // NOTE: Perhaps feature gate this?
+
+    // For debugging:
+    char       *name; // Name of lock.
+    struct Cpu *cpu;  // The cpu holding the lock.
+};
+
+/**
+ * Acquire the lock.
+ * Loops (spins) until the lock is acquired.
+ * Panics if the lock is already held by this cpu.
+ */
+void acquire(struct Spinlock *);
+
+/**
+ * Check whether this cpu is holding the lock.
+ * Interrupts must be off.
+ */
+int holding(struct Spinlock *);
+
+/**
+ * Initialize Spinlock
+ */
+void initlock(struct Spinlock *, char *);
+
+/**
+ * Release the lock.
+ * Panics if the lock is not held.
+ */
+void release(struct Spinlock *);
+
+/**
+ * @brief push_off/pop_off are like intr_off()/intr_on() except that they are
+ * matched: it takes two pop_off()s to undo two push_off()s.  Also, if
+ * interrupts are initially off, then push_off, pop_off leaves them off.
+ */
+void push_off(void);
+
+/** @copydoc pop_off */
+void pop_off(void);
+
+#endif