Changeset 48bcf49 in mainline for kernel/generic/src/cap/cap.c

Timestamp:

2017-09-28T22:08:15Z (7 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

6636fb19

Parents:

dd20cbb

Message:

Introduce reference-counted kobjects

Capabilities are thus reduced to task-local names for references to kobjects.

File:

• kernel/generic/src/cap/cap.c (modified) (7 diffs)

kernel/generic/src/cap/cap.c

@@ -40 +40 @@
 #include <adt/list.h>
 
-void cap_initialize(cap_t *cap, int handle)
-{
-        cap->type = CAP_TYPE_INVALID;
+static kobject_t *cap_unpublish_locked(task_t *, cap_handle_t, kobject_type_t);
+
+void cap_initialize(cap_t *cap, cap_handle_t handle)
+{
+        cap->state = CAP_STATE_FREE;
         cap->handle = handle;
-        cap->can_reclaim = NULL;
         link_initialize(&cap->link);
 }
@@ -58 +59 @@
         mutex_initialize(&task->cap_info->lock, MUTEX_PASSIVE);
 
-        for (int i = 0; i < CAP_TYPE_MAX; i++)
-                list_initialize(&task->cap_info->type_list[i]);
-
-        for (int i = 0; i < MAX_CAPS; i++)
-                cap_initialize(&task->cap_info->caps[i], i);
+        for (kobject_type_t t = 0; t < KOBJECT_TYPE_MAX; t++)
+                list_initialize(&task->cap_info->type_list[t]);
+
+        for (cap_handle_t h = 0; h < MAX_CAPS; h++)
+                cap_initialize(&task->cap_info->caps[h], h);
 }
 
@@ -71 +72 @@
 }
 
-bool caps_apply_to_type(task_t *task, cap_type_t type,
+bool caps_apply_to_kobject_type(task_t *task, kobject_type_t type,
     bool (*cb)(cap_t *, void *), void *arg)
 {
@@ -88 +89 @@
 }
 
-void caps_lock(task_t *task)
-{
-        mutex_lock(&task->cap_info->lock);
-}
-
-void caps_unlock(task_t *task)
-{
-        mutex_unlock(&task->cap_info->lock);
-}
-
-cap_t *cap_get(task_t *task, int handle, cap_type_t type)
+static cap_t *cap_get(task_t *task, cap_handle_t handle, cap_state_t state)
 {
         assert(mutex_locked(&task->cap_info->lock));
@@ -104 +95 @@
         if ((handle < 0) || (handle >= MAX_CAPS))
                 return NULL;
-        if (task->cap_info->caps[handle].type != type)
+        if (task->cap_info->caps[handle].state != state)
                 return NULL;
         return &task->cap_info->caps[handle];
 }
 
-int cap_alloc(task_t *task)
-{
-        int handle;
-
-        mutex_lock(&task->cap_info->lock);
-        for (handle = 0; handle < MAX_CAPS; handle++) {
+cap_handle_t cap_alloc(task_t *task)
+{
+        mutex_lock(&task->cap_info->lock);
+        for (cap_handle_t handle = 0; handle < MAX_CAPS; handle++) {
                 cap_t *cap = &task->cap_info->caps[handle];
-                if (cap->type > CAP_TYPE_ALLOCATED) {
-                        if (cap->can_reclaim && cap->can_reclaim(cap)) {
-                                list_remove(&cap->link);
-                                cap_initialize(cap, handle);
-                        }
-                }
-                if (cap->type == CAP_TYPE_INVALID) {
-                        cap->type = CAP_TYPE_ALLOCATED;
+                /* See if the capability should be garbage-collected */
+                if (cap->state == CAP_STATE_PUBLISHED &&
+                    cap->kobject->ops->reclaim &&
+                    cap->kobject->ops->reclaim(cap->kobject)) {
+                        kobject_t *kobj = cap_unpublish_locked(task, handle,
+                            cap->kobject->type);
+                        kobject_put(kobj);
+                        cap_initialize(&task->cap_info->caps[handle], handle);
+                }
+                if (cap->state == CAP_STATE_FREE) {
+                        cap->state = CAP_STATE_ALLOCATED;
                         mutex_unlock(&task->cap_info->lock);
                         return handle;
@@ -133 +125 @@
 }
 
-void cap_publish(task_t *task, int handle, cap_type_t type, void *kobject)
-{
-        mutex_lock(&task->cap_info->lock);
-        cap_t *cap = cap_get(task, handle, CAP_TYPE_ALLOCATED);
+void
+cap_publish(task_t *task, cap_handle_t handle, kobject_t *kobj)
+{
+        mutex_lock(&task->cap_info->lock);
+        cap_t *cap = cap_get(task, handle, CAP_STATE_ALLOCATED);
         assert(cap);
-        cap->type = type;
-        cap->kobject = kobject;
-        list_append(&cap->link, &task->cap_info->type_list[type]);
-        mutex_unlock(&task->cap_info->lock);
-}
-
-cap_t *cap_unpublish(task_t *task, int handle, cap_type_t type)
-{
-        cap_t *cap;
-
-        mutex_lock(&task->cap_info->lock);
-        cap = cap_get(task, handle, type);
+        cap->state = CAP_STATE_PUBLISHED;
+        /* Hand over kobj's reference to cap */
+        cap->kobject = kobj;
+        list_append(&cap->link, &task->cap_info->type_list[kobj->type]);
+        mutex_unlock(&task->cap_info->lock);
+}
+
+static kobject_t *
+cap_unpublish_locked(task_t *task, cap_handle_t handle, kobject_type_t type)
+{
+        kobject_t *kobj = NULL;
+
+        cap_t *cap = cap_get(task, handle, CAP_STATE_PUBLISHED);
         if (cap) {
-                list_remove(&cap->link);
-                cap->type = CAP_TYPE_ALLOCATED;
-        }
-        mutex_unlock(&task->cap_info->lock);
-
-        return cap;
-}
-
-void cap_free(task_t *task, int handle)
+                if (cap->kobject->type == type) {
+                        /* Hand over cap's reference to kobj */
+                        kobj = cap->kobject;
+                        cap->kobject = NULL;
+                        list_remove(&cap->link);
+                        cap->state = CAP_STATE_ALLOCATED;
+                }
+        }
+
+        return kobj;
+}
+kobject_t *cap_unpublish(task_t *task, cap_handle_t handle, kobject_type_t type)
+{
+
+        mutex_lock(&task->cap_info->lock);
+        kobject_t *kobj = cap_unpublish_locked(task, handle, type);
+        mutex_unlock(&task->cap_info->lock);
+
+        return kobj;
+}
+
+void cap_free(task_t *task, cap_handle_t handle)
 {
         assert(handle >= 0);
         assert(handle < MAX_CAPS);
-        assert(task->cap_info->caps[handle].type == CAP_TYPE_ALLOCATED);
+        assert(task->cap_info->caps[handle].state == CAP_STATE_ALLOCATED);
 
         mutex_lock(&task->cap_info->lock);
@@ -170 +177 @@
 }
 
+void kobject_initialize(kobject_t *kobj, kobject_type_t type, void *raw,
+    kobject_ops_t *ops)
+{
+        atomic_set(&kobj->refcnt, 1);
+        kobj->type = type;
+        kobj->raw = raw;
+        kobj->ops = ops;
+}
+
+kobject_t *
+kobject_get(struct task *task, cap_handle_t handle, kobject_type_t type)
+{
+        kobject_t *kobj = NULL;
+
+        mutex_lock(&task->cap_info->lock);
+        cap_t *cap = cap_get(task, handle, CAP_STATE_PUBLISHED);
+        if (cap) {
+                if (cap->kobject->type == type) {
+                        kobj = cap->kobject;
+                        atomic_inc(&kobj->refcnt);
+                }
+        }
+        mutex_unlock(&task->cap_info->lock);
+
+        return kobj;
+}
+
+void kobject_put(kobject_t *kobj)
+{
+        if (atomic_postdec(&kobj->refcnt) == 1) {
+                kobj->ops->destroy(kobj->raw);
+                free(kobj);
+        }
+}
+
 /** @}
  */