Changes in kernel/generic/src/cap/cap.c [9fc776c7:5a6cc679] in mainline

File:

• kernel/generic/src/cap/cap.c (modified) (2 diffs)

kernel/generic/src/cap/cap.c

@@ -235 +235 @@
 }
 
+static bool cap_reclaimer(ht_link_t *link, void *arg)
+{
+        cap_t **result = (cap_t **) arg;
+        cap_t *cap = hash_table_get_inst(link, cap_t, caps_link);
+
+        if (cap->state == CAP_STATE_PUBLISHED && cap->kobject->ops->reclaim &&
+            cap->kobject->ops->reclaim(cap->kobject)) {
+                kobject_t *kobj = cap_unpublish(cap->task, cap->handle,
+                    cap->kobject->type);
+                kobject_put(kobj);
+                cap_initialize(cap, cap->task, cap->handle);
+                *result = cap;
+                return false;
+        }
+
+        return true;
+}
+
 /** Allocate new capability
  *
@@ -245 +263 @@
 errno_t cap_alloc(task_t *task, cap_handle_t *handle)
 {
-        mutex_lock(&task->cap_info->lock);
-        cap_t *cap = slab_alloc(cap_cache, FRAME_ATOMIC);
+        cap_t *cap = NULL;
+
+        /*
+         * First of all, see if we can reclaim a capability. Note that this
+         * feature is only temporary and capability reclamaition will eventually
+         * be phased out.
+         */
+        mutex_lock(&task->cap_info->lock);
+        hash_table_apply(&task->cap_info->caps, cap_reclaimer, &cap);
+
+        /*
+         * If we don't have a capability by now, try to allocate a new one.
+         */
         if (!cap) {
-                mutex_unlock(&task->cap_info->lock);
-                return ENOMEM;
-        }
-        uintptr_t hbase;
-        if (!ra_alloc(task->cap_info->handles, 1, 1, &hbase)) {
-                slab_free(cap_cache, cap);
-                mutex_unlock(&task->cap_info->lock);
-                return ENOMEM;
-        }
-        cap_initialize(cap, task, (cap_handle_t) hbase);
-        hash_table_insert(&task->cap_info->caps, &cap->caps_link);
+                cap = slab_alloc(cap_cache, FRAME_ATOMIC);
+                if (!cap) {
+                        mutex_unlock(&task->cap_info->lock);
+                        return ENOMEM;
+                }
+                uintptr_t hbase;
+                if (!ra_alloc(task->cap_info->handles, 1, 1, &hbase)) {
+                        slab_free(cap_cache, cap);
+                        mutex_unlock(&task->cap_info->lock);
+                        return ENOMEM;
+                }
+                cap_initialize(cap, task, (cap_handle_t) hbase);
+                hash_table_insert(&task->cap_info->caps, &cap->caps_link);
+        }
 
         cap->state = CAP_STATE_ALLOCATED;