Environment variables WIP, fix waiting scheduling issues + CE cancel proc

kernel/id/id_alloc.c

@@ -31,14 +31,20 @@ int id_alloc (struct id_alloc* ida) {
 
   spin_lock (&ida->lock, &fid);
 
-  for (size_t bit = 0; bit < ida->bm.nbits; bit++) {
-    if (!bm_test (&ida->bm, bit)) {
-      bm_set (&ida->bm, bit);
+  size_t start = ida->next_id;
+  size_t current = start;
+  do {
+    if (!bm_test (&ida->bm, current)) {
+      bm_set (&ida->bm, current);
+
+      ida->next_id = (current + 1) % ida->bm.nbits;
 
       spin_unlock (&ida->lock, fid);
-      return (int)bit;
+      return (int)current;
     }
-  }
+
+    current = (current + 1) % ida->bm.nbits;
+  } while (current != start);
 
   spin_unlock (&ida->lock, fid);
   return -ST_OOM_ERROR;

kernel/id/id_alloc.h

@@ -8,6 +8,7 @@
 struct id_alloc {
   struct bm bm;
   spin_lock_t lock;
+  int next_id;
 };
 
 int id_alloc (struct id_alloc* ida);