Implement Mutexes and supporting syscalls, cleanup/optimize scheduler

kernel/proc/mutex.c

@@ -0,0 +1,42 @@
+#include <libk/assert.h>
+#include <libk/rbtree.h>
+#include <libk/std.h>
+#include <proc/mutex.h>
+#include <proc/proc.h>
+#include <sync/spin_lock.h>
+#include <sys/debug.h>
+
+void proc_mutex_lock (struct proc* proc, struct proc_mutex* mutex) {
+  while (atomic_flag_test_and_set_explicit (&mutex->flag, memory_order_acquire))
+    proc_suspend (proc, &mutex->suspension_q);
+
+  /* taken */
+
+  mutex->owner = proc;
+}
+
+bool proc_mutex_unlock (struct proc* proc, struct proc_mutex* mutex) {
+  if (mutex->owner != proc)
+    return false;
+
+  atomic_flag_clear_explicit (&mutex->flag, memory_order_release);
+
+  struct proc* resumed_proc;
+  struct rb_node_link* node;
+  rbtree_first (&mutex->suspension_q.proc_tree, node);
+
+  while (node) {
+    struct rb_node_link* next;
+    rbtree_next (node, next);
+
+    resumed_proc = rbtree_entry (node, struct proc, suspension_link);
+
+    proc_resume (resumed_proc);
+
+    node = next;
+  }
+
+  assert (mutex->suspension_q.proc_tree == NULL);
+
+  return true;
+}