Use RW spin locks

kernel/proc/proc.h

@@ -15,10 +15,12 @@
 #include <amd64/proc.h> /* USTACK_SIZE */
 #endif
 
-/// Process is ready to run
+/* Process is ready to run */
 #define PROC_READY 0
-/// Process marked garbage collection
+/* Process marked garbage collection */
 #define PROC_DEAD 1
+/* Process is suspended */
+#define PROC_SUSPENDED 2
 
 #define PROC_RESOURCES_MAX 1024
 
@@ -36,6 +38,7 @@ struct proc {
   int pid;
   struct rb_node_link proc_tree_link;
   struct rb_node_link cpu_run_q_link;
+  struct rb_node_link suspension_link;
 
   struct list_node_link* mappings; /* pd.lock implicitly protects this field */
   struct proc_platformdata pdata;
@@ -45,8 +48,15 @@ struct proc {
   atomic_int state;
   struct rb_node_link* resource_tree;
   atomic_int rids;
+  struct proc_suspension_q* suspension_q;
 };
 
+struct proc_suspension_q {
+  struct rb_node_link* proc_tree;
+  spin_lock_t lock;
+};
+
+void proc_suspend (struct proc* proc, struct proc_suspension_q* sq);
 void proc_sched (void);
 void proc_kill (struct proc* proc);
 bool proc_map (struct proc* proc, uintptr_t start_paddr, uintptr_t start_vaddr, size_t pages,