Changeset a1b7e80 in mainline for uspace/srv

Timestamp:

2011-09-02T16:54:18Z (14 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

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

Children:

f480d7e

Parents:

7a72ce1a (diff), 224c0e7 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge basic infrastructure for anticipated device removal from
lp:~jsvoboda/helenos/devrem

Location:

uspace/srv

Files:

• devman/devman.c (modified) (40 diffs)
• devman/devman.h (modified) (6 diffs)
• devman/main.c (modified) (29 diffs)
• loc/loc.c (modified) (1 diff)

uspace/srv/devman/devman.c

@@ -30 +30 @@
  * @{
  */
+/** @file Device Manager
+ *
+ * Locking order:
+ *   (1) driver_t.driver_mutex
+ *   (2) dev_tree_t.rwlock
+ *
+ * Synchronization:
+ *    - device_tree.rwlock protects:
+ *        - tree root, complete tree topology
+ *        - complete contents of device and function nodes
+ *    - dev_node_t.refcnt, fun_node_t.refcnt prevent nodes from
+ *      being deallocated
+ *    - find_xxx() functions increase reference count of returned object
+ *    - find_xxx_no_lock() do not increase reference count
+ *
+ * TODO
+ *    - Track all steady and transient device/function states
+ *    - Check states, wait for steady state on certain operations
+ */
 
 #include <errno.h>
@@ -43 +62 @@
 #include "devman.h"
 
-fun_node_t *find_node_child(fun_node_t *parent, const char *name);
+static fun_node_t *find_node_child(dev_tree_t *, fun_node_t *, const char *);
 
 /* hash table operations */
@@ -406 +425 @@
         }
         
+        fun_add_ref(fun);
         insert_fun_node(tree, fun, str_dup(""), NULL);
+        
         match_id_t *id = create_match_id();
         id->id = str_dup("root");
@@ -422 +443 @@
         }
         
+        dev_add_ref(dev);
         insert_dev_node(tree, dev, fun);
         
@@ -467 +489 @@
 /** Assign a driver to a device.
  *
+ * @param tree          Device tree
  * @param node          The device's node in the device tree.
  * @param drv           The driver.
  */
-void attach_driver(dev_node_t *dev, driver_t *drv)
+void attach_driver(dev_tree_t *tree, dev_node_t *dev, driver_t *drv)
 {
         log_msg(LVL_DEBUG, "attach_driver(dev=\"%s\",drv=\"%s\")",
@@ -476 +499 @@
         
         fibril_mutex_lock(&drv->driver_mutex);
+        fibril_rwlock_write_lock(&tree->rwlock);
         
         dev->drv = drv;
         list_append(&dev->driver_devices, &drv->devices);
         
+        fibril_rwlock_write_unlock(&tree->rwlock);
+        fibril_mutex_unlock(&drv->driver_mutex);
+}
+
+/** Detach driver from device.
+ *
+ * @param tree          Device tree
+ * @param node          The device's node in the device tree.
+ * @param drv           The driver.
+ */
+void detach_driver(dev_tree_t *tree, dev_node_t *dev)
+{
+        driver_t *drv = dev->drv;
+        
+        assert(drv != NULL);
+        
+        log_msg(LVL_DEBUG, "detach_driver(dev=\"%s\",drv=\"%s\")",
+            dev->pfun->pathname, drv->name);
+        
+        fibril_mutex_lock(&drv->driver_mutex);
+        fibril_rwlock_write_lock(&tree->rwlock);
+        
+        dev->drv = NULL;
+        list_remove(&dev->driver_devices);
+        
+        fibril_rwlock_write_unlock(&tree->rwlock);
         fibril_mutex_unlock(&drv->driver_mutex);
 }
@@ -556 +606 @@
         while (link != &driver->devices.head) {
                 dev = list_get_instance(link, dev_node_t, driver_devices);
+                fibril_rwlock_write_lock(&tree->rwlock);
+                
                 if (dev->passed_to_driver) {
+                        fibril_rwlock_write_unlock(&tree->rwlock);
                         link = link->next;
                         continue;
                 }
 
-                /*
-                 * We remove the device from the list to allow safe adding
-                 * of new devices (no one will touch our item this way).
-                 */
-                list_remove(link);
+                log_msg(LVL_DEBUG, "pass_devices_to_driver: dev->refcnt=%d\n",
+                    (int)atomic_get(&dev->refcnt));
+                dev_add_ref(dev);
 
                 /*
@@ -572 +623 @@
                  */
                 fibril_mutex_unlock(&driver->driver_mutex);
+                fibril_rwlock_write_unlock(&tree->rwlock);
 
                 add_device(driver, dev, tree);
+
+                dev_del_ref(dev);
 
                 /*
@@ -580 +634 @@
                  */
                 fibril_mutex_lock(&driver->driver_mutex);
-
-                /*
-                 * Insert the device back.
-                 * The order is not relevant here so no harm is done
-                 * (actually, the order would be preserved in most cases).
-                 */
-                list_append(link, &driver->devices);
 
                 /*
@@ -679 +726 @@
         char *loc_name = NULL;
         
+        assert(fibril_rwlock_is_locked(&tree->rwlock));
+        
         asprintf(&loc_name, "%s", fun->pathname);
         if (loc_name == NULL)
@@ -726 +775 @@
         
         ipc_call_t answer;
-        aid_t req = async_send_2(exch, DRIVER_ADD_DEVICE, dev->handle,
+        aid_t req = async_send_2(exch, DRIVER_DEV_ADD, dev->handle,
             parent_handle, &answer);
         
@@ -783 +832 @@
         
         /* Attach the driver to the device. */
-        attach_driver(dev, drv);
+        attach_driver(tree, dev, drv);
         
         fibril_mutex_lock(&drv->driver_mutex);
@@ -797 +846 @@
                 add_device(drv, dev, tree);
         
+        fibril_mutex_lock(&drv->driver_mutex);
+        fibril_mutex_unlock(&drv->driver_mutex);
+
+        fibril_rwlock_write_lock(&tree->rwlock);
+        if (dev->pfun != NULL) {
+                dev->pfun->state = FUN_ON_LINE;
+        }
+        fibril_rwlock_write_unlock(&tree->rwlock);
         return true;
+}
+
+int driver_dev_remove(dev_tree_t *tree, dev_node_t *dev)
+{
+        async_exch_t *exch;
+        sysarg_t retval;
+        driver_t *drv;
+        devman_handle_t handle;
+        
+        assert(dev != NULL);
+        
+        log_msg(LVL_DEBUG, "driver_dev_remove(%p)", dev);
+        
+        fibril_rwlock_read_lock(&tree->rwlock);
+        drv = dev->drv;
+        handle = dev->handle;
+        fibril_rwlock_read_unlock(&tree->rwlock);
+        
+        exch = async_exchange_begin(drv->sess);
+        retval = async_req_1_0(exch, DRIVER_DEV_REMOVE, handle);
+        async_exchange_end(exch);
+        
+        return retval;
+
+}
+
+int driver_fun_online(dev_tree_t *tree, fun_node_t *fun)
+{
+        async_exch_t *exch;
+        sysarg_t retval;
+        driver_t *drv;
+        devman_handle_t handle;
+        
+        log_msg(LVL_DEBUG, "driver_fun_online(%p)", fun);
+
+        fibril_rwlock_read_lock(&tree->rwlock);
+        
+        if (fun->dev == NULL) {
+                /* XXX root function? */
+                fibril_rwlock_read_unlock(&tree->rwlock);
+                return EINVAL;
+        }
+        
+        drv = fun->dev->drv;
+        handle = fun->handle;
+        fibril_rwlock_read_unlock(&tree->rwlock);
+        
+        exch = async_exchange_begin(drv->sess);
+        retval = async_req_1_0(exch, DRIVER_FUN_ONLINE, handle);
+        loc_exchange_end(exch);
+        
+        return retval;
+}
+
+int driver_fun_offline(dev_tree_t *tree, fun_node_t *fun)
+{
+        async_exch_t *exch;
+        sysarg_t retval;
+        driver_t *drv;
+        devman_handle_t handle;
+        
+        log_msg(LVL_DEBUG, "driver_fun_offline(%p)", fun);
+
+        fibril_rwlock_read_lock(&tree->rwlock);
+        if (fun->dev == NULL) {
+                /* XXX root function? */
+                fibril_rwlock_read_unlock(&tree->rwlock);
+                return EINVAL;
+        }
+        
+        drv = fun->dev->drv;
+        handle = fun->handle;
+        fibril_rwlock_read_unlock(&tree->rwlock);
+        
+        exch = async_exchange_begin(drv->sess);
+        retval = async_req_1_0(exch, DRIVER_FUN_OFFLINE, handle);
+        loc_exchange_end(exch);
+        
+        return retval;
+
 }
 
@@ -826 +963 @@
         if (!create_root_nodes(tree))
                 return false;
-
+    
         /* Find suitable driver and start it. */
-        return assign_driver(tree->root_node->child, drivers_list, tree);
+        dev_node_t *rdev = tree->root_node->child;
+        dev_add_ref(rdev);
+        int rc = assign_driver(rdev, drivers_list, tree);
+        dev_del_ref(rdev);
+        
+        return rc;
 }
 
@@ -839 +981 @@
 dev_node_t *create_dev_node(void)
 {
-        dev_node_t *res = malloc(sizeof(dev_node_t));
-        
-        if (res != NULL) {
-                memset(res, 0, sizeof(dev_node_t));
-                list_initialize(&res->functions);
-                link_initialize(&res->driver_devices);
-                link_initialize(&res->devman_dev);
-        }
-        
-        return res;
+        dev_node_t *dev;
+        
+        dev = calloc(1, sizeof(dev_node_t));
+        if (dev == NULL)
+                return NULL;
+        
+        atomic_set(&dev->refcnt, 0);
+        list_initialize(&dev->functions);
+        link_initialize(&dev->driver_devices);
+        link_initialize(&dev->devman_dev);
+        
+        return dev;
 }
 
@@ -864 +1008 @@
 }
 
+/** Increase device node reference count.
+ *
+ * @param dev   Device node
+ */
+void dev_add_ref(dev_node_t *dev)
+{
+        atomic_inc(&dev->refcnt);
+}
+
+/** Decrease device node reference count.
+ *
+ * When the count drops to zero the device node is freed.
+ *
+ * @param dev   Device node
+ */
+void dev_del_ref(dev_node_t *dev)
+{
+        if (atomic_predec(&dev->refcnt) == 0)
+                delete_dev_node(dev);
+}
+
+
 /** Find the device node structure of the device witch has the specified handle.
  *
@@ -893 +1059 @@
         fibril_rwlock_read_lock(&tree->rwlock);
         dev = find_dev_node_no_lock(tree, handle);
+        if (dev != NULL)
+                dev_add_ref(dev);
+        
         fibril_rwlock_read_unlock(&tree->rwlock);
         
@@ -920 +1089 @@
                     list_get_instance(item, fun_node_t, dev_functions);
 
-                if (pos < buf_cnt)
+                if (pos < buf_cnt) {
                         hdl_buf[pos] = fun->handle;
+                }
+
                 pos++;
         }
@@ -937 +1108 @@
 fun_node_t *create_fun_node(void)
 {
-        fun_node_t *res = malloc(sizeof(fun_node_t));
-        
-        if (res != NULL) {
-                memset(res, 0, sizeof(fun_node_t));
-                link_initialize(&res->dev_functions);
-                list_initialize(&res->match_ids.ids);
-                link_initialize(&res->devman_fun);
-                link_initialize(&res->loc_fun);
-        }
-        
-        return res;
+        fun_node_t *fun;
+
+        fun = calloc(1, sizeof(fun_node_t));
+        if (fun == NULL)
+                return NULL;
+        
+        fun->state = FUN_INIT;
+        atomic_set(&fun->refcnt, 0);
+        link_initialize(&fun->dev_functions);
+        list_initialize(&fun->match_ids.ids);
+        link_initialize(&fun->devman_fun);
+        link_initialize(&fun->loc_fun);
+        
+        return fun;
 }
 
@@ -965 +1139 @@
 }
 
+/** Increase function node reference count.
+ *
+ * @param fun   Function node
+ */
+void fun_add_ref(fun_node_t *fun)
+{
+        atomic_inc(&fun->refcnt);
+}
+
+/** Decrease function node reference count.
+ *
+ * When the count drops to zero the function node is freed.
+ *
+ * @param fun   Function node
+ */
+void fun_del_ref(fun_node_t *fun)
+{
+        if (atomic_predec(&fun->refcnt) == 0)
+                delete_fun_node(fun);
+}
+
 /** Find the function node with the specified handle.
  *
@@ -975 +1170 @@
         unsigned long key = handle;
         link_t *link;
+        fun_node_t *fun;
         
         assert(fibril_rwlock_is_locked(&tree->rwlock));
@@ -982 +1178 @@
                 return NULL;
         
-        return hash_table_get_instance(link, fun_node_t, devman_fun);
+        fun = hash_table_get_instance(link, fun_node_t, devman_fun);
+        
+        return fun;
 }
 
@@ -996 +1194 @@
         
         fibril_rwlock_read_lock(&tree->rwlock);
+        
         fun = find_fun_node_no_lock(tree, handle);
+        if (fun != NULL)
+                fun_add_ref(fun);
+        
         fibril_rwlock_read_unlock(&tree->rwlock);
         
@@ -1004 +1206 @@
 /** Create and set device's full path in device tree.
  *
+ * @param tree          Device tree
  * @param node          The device's device node.
  * @param parent        The parent device node.
@@ -1009 +1212 @@
  *                      resources etc.).
  */
-static bool set_fun_path(fun_node_t *fun, fun_node_t *parent)
-{
+static bool set_fun_path(dev_tree_t *tree, fun_node_t *fun, fun_node_t *parent)
+{
+        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
         assert(fun->name != NULL);
         
@@ -1037 +1241 @@
  *
  * @param tree          The device tree.
- * @param node          The newly added device node. 
- * @param dev_name      The name of the newly added device.
- * @param parent        The parent device node.
+ * @param dev           The newly added device node.
+ * @param pfun          The parent function node.
  *
  * @return              True on success, false otherwise (insufficient resources
@@ -1046 +1249 @@
 bool insert_dev_node(dev_tree_t *tree, dev_node_t *dev, fun_node_t *pfun)
 {
-        assert(dev != NULL);
-        assert(tree != NULL);
         assert(fibril_rwlock_is_write_locked(&tree->rwlock));
         
@@ -1065 +1266 @@
 }
 
+/** Remove device from device tree.
+ *
+ * @param tree          Device tree
+ * @param dev           Device node
+ */
+void remove_dev_node(dev_tree_t *tree, dev_node_t *dev)
+{
+        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
+        
+        log_msg(LVL_DEBUG, "remove_dev_node(dev=%p)", dev);
+        
+        /* Remove node from the handle-to-node map. */
+        unsigned long key = dev->handle;
+        hash_table_remove(&tree->devman_devices, &key, 1);
+        
+        /* Unlink from parent function. */
+        dev->pfun->child = NULL;
+        dev->pfun = NULL;
+        
+        dev->state = DEVICE_REMOVED;
+}
+
+
 /** Insert new function into device tree.
  *
  * @param tree          The device tree.
- * @param node          The newly added function node. 
- * @param dev_name      The name of the newly added function.
- * @param parent        Owning device node.
+ * @param fun           The newly added function node. 
+ * @param fun_name      The name of the newly added function.
+ * @param dev           Owning device node.
  *
  * @return              True on success, false otherwise (insufficient resources
@@ -1080 +1304 @@
         fun_node_t *pfun;
         
-        assert(fun != NULL);
-        assert(tree != NULL);
         assert(fun_name != NULL);
         assert(fibril_rwlock_is_write_locked(&tree->rwlock));
@@ -1092 +1314 @@
         
         fun->name = fun_name;
-        if (!set_fun_path(fun, pfun)) {
+        if (!set_fun_path(tree, fun, pfun)) {
                 return false;
         }
@@ -1116 +1338 @@
 void remove_fun_node(dev_tree_t *tree, fun_node_t *fun)
 {
-        assert(tree != NULL);
-        assert(fun != NULL);
         assert(fibril_rwlock_is_write_locked(&tree->rwlock));
         
@@ -1127 +1347 @@
         if (fun->dev != NULL)
                 list_remove(&fun->dev_functions);
+        
+        fun->dev = NULL;
+        fun->state = FUN_REMOVED;
 }
 
@@ -1148 +1371 @@
         
         fun_node_t *fun = tree->root_node;
+        fun_add_ref(fun);
         /*
          * Relative path to the function from its parent (but with '/' at the
@@ -1165 +1389 @@
                 }
                 
-                fun = find_node_child(fun, rel_path + 1);
+                fun_node_t *cfun = find_node_child(tree, fun, rel_path + 1);
+                fun_del_ref(fun);
+                fun = cfun;
                 
                 if (cont) {
@@ -1183 +1409 @@
  * Device tree rwlock should be held at least for reading.
  *
+ * @param tree Device tree
  * @param dev Device the function belongs to.
  * @param name Function name (not path).
@@ -1188 +1415 @@
  * @retval NULL No function with given name.
  */
-fun_node_t *find_fun_node_in_device(dev_node_t *dev, const char *name)
-{
-        assert(dev != NULL);
+fun_node_t *find_fun_node_in_device(dev_tree_t *tree, dev_node_t *dev,
+    const char *name)
+{
         assert(name != NULL);
+        assert(fibril_rwlock_is_locked(&tree->rwlock));
 
         fun_node_t *fun;
@@ -1198 +1426 @@
                 fun = list_get_instance(link, fun_node_t, dev_functions);
 
-                if (str_cmp(name, fun->name) == 0)
+                if (str_cmp(name, fun->name) == 0) {
+                        fun_add_ref(fun);
                         return fun;
+                }
         }
 
@@ -1209 +1439 @@
  * Device tree rwlock should be held at least for reading.
  *
+ * @param tree          Device tree
  * @param parent        The parent function node.
  * @param name          The name of the child function.
  * @return              The child function node.
  */
-fun_node_t *find_node_child(fun_node_t *pfun, const char *name)
-{
-        return find_fun_node_in_device(pfun->child, name);
+static fun_node_t *find_node_child(dev_tree_t *tree, fun_node_t *pfun,
+    const char *name)
+{
+        return find_fun_node_in_device(tree, pfun->child, name);
 }
 
@@ -1228 +1460 @@
         fibril_rwlock_read_lock(&tree->rwlock);
         link = hash_table_find(&tree->loc_functions, &key);
-        if (link != NULL)
+        if (link != NULL) {
                 fun = hash_table_get_instance(link, fun_node_t, loc_fun);
+                fun_add_ref(fun);
+        }
         fibril_rwlock_read_unlock(&tree->rwlock);
         
@@ -1237 +1471 @@
 void tree_add_loc_function(dev_tree_t *tree, fun_node_t *fun)
 {
+        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
+        
         unsigned long key = (unsigned long) fun->service_id;
-        fibril_rwlock_write_lock(&tree->rwlock);
         hash_table_insert(&tree->loc_functions, &key, &fun->loc_fun);
-        fibril_rwlock_write_unlock(&tree->rwlock);
 }
 

uspace/srv/devman/devman.h

@@ -118 +118 @@
 } driver_list_t;
 
-/** The state of the device. */
+/** Device state */
 typedef enum {
         DEVICE_NOT_INITIALIZED = 0,
         DEVICE_USABLE,
         DEVICE_NOT_PRESENT,
-        DEVICE_INVALID
+        DEVICE_INVALID,
+        /** Device node has been removed from the tree */
+        DEVICE_REMOVED
 } device_state_t;
 
 /** Device node in the device tree. */
 struct dev_node {
+        /** Reference count */
+        atomic_t refcnt;
+        
         /** The global unique identifier of the device. */
         devman_handle_t handle;
@@ -154 +159 @@
 };
 
+/** Function state */
+typedef enum {
+        FUN_INIT = 0,
+        FUN_OFF_LINE,
+        FUN_ON_LINE,
+        /** Function node has been removed from the tree */
+        FUN_REMOVED
+} fun_state_t;
+
 /** Function node in the device tree. */
 struct fun_node {
+        /** Reference count */
+        atomic_t refcnt;
+        /** State */
+        fun_state_t state;
+        
         /** The global unique identifier of the function */
         devman_handle_t handle;
@@ -239 +258 @@
 
 extern void add_driver(driver_list_t *, driver_t *);
-extern void attach_driver(dev_node_t *, driver_t *);
+extern void attach_driver(dev_tree_t *, dev_node_t *, driver_t *);
+extern void detach_driver(dev_tree_t *, dev_node_t *);
 extern void add_device(driver_t *, dev_node_t *, dev_tree_t *);
 extern bool start_driver(driver_t *);
+extern int driver_dev_remove(dev_tree_t *, dev_node_t *);
+extern int driver_fun_online(dev_tree_t *, fun_node_t *);
+extern int driver_fun_offline(dev_tree_t *, fun_node_t *);
 
 extern driver_t *find_driver(driver_list_t *, const char *);
@@ -254 +277 @@
 extern dev_node_t *create_dev_node(void);
 extern void delete_dev_node(dev_node_t *node);
+extern void dev_add_ref(dev_node_t *);
+extern void dev_del_ref(dev_node_t *);
 extern dev_node_t *find_dev_node_no_lock(dev_tree_t *tree,
     devman_handle_t handle);
@@ -263 +288 @@
 extern fun_node_t *create_fun_node(void);
 extern void delete_fun_node(fun_node_t *);
+extern void fun_add_ref(fun_node_t *);
+extern void fun_del_ref(fun_node_t *);
 extern fun_node_t *find_fun_node_no_lock(dev_tree_t *tree,
     devman_handle_t handle);
 extern fun_node_t *find_fun_node(dev_tree_t *tree, devman_handle_t handle);
 extern fun_node_t *find_fun_node_by_path(dev_tree_t *, char *);
-extern fun_node_t *find_fun_node_in_device(dev_node_t *, const char *);
+extern fun_node_t *find_fun_node_in_device(dev_tree_t *tree, dev_node_t *,
+    const char *);
 
 /* Device tree */
@@ -274 +302 @@
 extern bool create_root_nodes(dev_tree_t *);
 extern bool insert_dev_node(dev_tree_t *, dev_node_t *, fun_node_t *);
+extern void remove_dev_node(dev_tree_t *, dev_node_t *);
 extern bool insert_fun_node(dev_tree_t *, fun_node_t *, char *, dev_node_t *);
 extern void remove_fun_node(dev_tree_t *, fun_node_t *);

uspace/srv/devman/main.c

@@ -234 +234 @@
         dev_node_t *dev_node = (dev_node_t *) arg;
         assign_driver(dev_node, &drivers_list, &device_tree);
+
+        /* Delete one reference we got from the caller. */
+        dev_del_ref(dev_node);
         return EOK;
 }
 
-/** Handle function registration.
- *
- * Child devices are registered by their parent's device driver.
- */
-static void devman_add_function(ipc_callid_t callid, ipc_call_t *call)
-{
-        fun_type_t ftype = (fun_type_t) IPC_GET_ARG1(*call);
-        devman_handle_t dev_handle = IPC_GET_ARG2(*call);
-        sysarg_t match_count = IPC_GET_ARG3(*call);
-        dev_tree_t *tree = &device_tree;
-        
-        fibril_rwlock_write_lock(&tree->rwlock);
-
-        dev_node_t *dev = NULL;
-        dev_node_t *pdev = find_dev_node_no_lock(&device_tree, dev_handle);
-        
-        if (pdev == NULL) {
-                fibril_rwlock_write_unlock(&tree->rwlock);
-                async_answer_0(callid, ENOENT);
-                return;
-        }
-        
-        if (ftype != fun_inner && ftype != fun_exposed) {
-                /* Unknown function type */
-                log_msg(LVL_ERROR, 
-                    "Unknown function type %d provided by driver.",
-                    (int) ftype);
-
-                fibril_rwlock_write_unlock(&tree->rwlock);
-                async_answer_0(callid, EINVAL);
-                return;
-        }
-        
-        char *fun_name = NULL;
-        int rc = async_data_write_accept((void **)&fun_name, true, 0, 0, 0, 0);
-        if (rc != EOK) {
-                fibril_rwlock_write_unlock(&tree->rwlock);
-                async_answer_0(callid, rc);
-                return;
-        }
-        
-        /* Check that function with same name is not there already. */
-        if (find_fun_node_in_device(pdev, fun_name) != NULL) {
-                fibril_rwlock_write_unlock(&tree->rwlock);
-                async_answer_0(callid, EEXISTS);
-                printf(NAME ": Warning, driver tried to register `%s' twice.\n",
-                    fun_name);
-                free(fun_name);
-                return;
-        }
-        
-        fun_node_t *fun = create_fun_node();
-        fun->ftype = ftype;
-        
-        if (!insert_fun_node(&device_tree, fun, fun_name, pdev)) {
-                fibril_rwlock_write_unlock(&tree->rwlock);
-                delete_fun_node(fun);
-                async_answer_0(callid, ENOMEM);
-                return;
-        }
-
-        if (ftype == fun_inner) {
+static int online_function(fun_node_t *fun)
+{
+        dev_node_t *dev;
+        
+        fibril_rwlock_write_lock(&device_tree.rwlock);
+
+        if (fun->state == FUN_ON_LINE) {
+                fibril_rwlock_write_unlock(&device_tree.rwlock);
+                log_msg(LVL_WARN, "Function %s is already on line.",
+                    fun->pathname);
+                return EOK;
+        }
+        
+        if (fun->ftype == fun_inner) {
                 dev = create_dev_node();
                 if (dev == NULL) {
-                        fibril_rwlock_write_unlock(&tree->rwlock);
-                        delete_fun_node(fun);
-                        async_answer_0(callid, ENOMEM);
-                        return;
+                        fibril_rwlock_write_unlock(&device_tree.rwlock);
+                        return ENOMEM;
                 }
 
-                insert_dev_node(tree, dev, fun);
-        }
-
-        fibril_rwlock_write_unlock(&tree->rwlock);
+                insert_dev_node(&device_tree, dev, fun);
+                dev_add_ref(dev);
+        }
         
         log_msg(LVL_DEBUG, "devman_add_function(fun=\"%s\")", fun->pathname);
         
-        devman_receive_match_ids(match_count, &fun->match_ids);
-
-        if (ftype == fun_inner) {
+        if (fun->ftype == fun_inner) {
+                dev = fun->child;
                 assert(dev != NULL);
+                
+                /* Give one reference over to assign_driver_fibril(). */
+                dev_add_ref(dev);
                 /*
                  * Try to find a suitable driver and assign it to the device.  We do
@@ -327 +281 @@
                 fid_t assign_fibril = fibril_create(assign_driver_fibril, dev);
                 if (assign_fibril == 0) {
-                        /*
-                         * Fallback in case we are out of memory.
-                         * Probably not needed as we will die soon anyway ;-).
-                         */
-                        (void) assign_driver_fibril(fun);
-                } else {
-                        fibril_add_ready(assign_fibril);
+                        log_msg(LVL_ERROR, "Failed to create fibril for "
+                            "assigning driver.");
+                        /* XXX Cleanup */
+                        fibril_rwlock_write_unlock(&device_tree.rwlock);
+                        return ENOMEM;
+                }
+                fibril_add_ready(assign_fibril);
+        } else {
+                loc_register_tree_function(fun, &device_tree);
+        }
+        
+        fibril_rwlock_write_unlock(&device_tree.rwlock);
+        
+        return EOK;
+}
+
+static int offline_function(fun_node_t *fun)
+{
+        int rc;
+        
+        fibril_rwlock_write_lock(&device_tree.rwlock);
+        
+        if (fun->state == FUN_OFF_LINE) {
+                fibril_rwlock_write_unlock(&device_tree.rwlock);
+                log_msg(LVL_WARN, "Function %s is already off line.",
+                    fun->pathname);
+                return EOK;
+        }
+        
+        if (fun->ftype == fun_inner) {
+                log_msg(LVL_DEBUG, "Offlining inner function %s.",
+                    fun->pathname);
+                
+                if (fun->child != NULL) {
+                        dev_node_t *dev = fun->child;
+                        
+                        dev_add_ref(dev);
+                        fibril_rwlock_write_unlock(&device_tree.rwlock);
+                        
+                        rc = driver_dev_remove(&device_tree, dev);
+                        if (rc != EOK) {
+                                dev_del_ref(dev);
+                                return ENOTSUP;
+                        }
+                        
+                        detach_driver(&device_tree, dev);
+                        
+                        fibril_rwlock_write_lock(&device_tree.rwlock);
+                        remove_dev_node(&device_tree, dev);
+                        
+                        /* Delete ref created when node was inserted */
+                        dev_del_ref(dev);
+                        /* Delete ref created by dev_add_ref(dev) above */
+                        dev_del_ref(dev);
                 }
         } else {
-                loc_register_tree_function(fun, tree);
+                /* Unregister from location service */
+                rc = loc_service_unregister(fun->service_id);
+                if (rc != EOK) {
+                        fibril_rwlock_write_unlock(&device_tree.rwlock);
+                        log_msg(LVL_ERROR, "Failed unregistering tree service.");
+                        return EIO;
+                }
+                
+                fun->service_id = 0;
+        }
+        
+        fun->state = FUN_OFF_LINE;
+        fibril_rwlock_write_unlock(&device_tree.rwlock);
+        
+        return EOK;
+}
+
+/** Handle function registration.
+ *
+ * Child devices are registered by their parent's device driver.
+ */
+static void devman_add_function(ipc_callid_t callid, ipc_call_t *call)
+{
+        fun_type_t ftype = (fun_type_t) IPC_GET_ARG1(*call);
+        devman_handle_t dev_handle = IPC_GET_ARG2(*call);
+        sysarg_t match_count = IPC_GET_ARG3(*call);
+        dev_tree_t *tree = &device_tree;
+        
+        dev_node_t *pdev = find_dev_node(&device_tree, dev_handle);
+        if (pdev == NULL) {
+                async_answer_0(callid, ENOENT);
+                return;
+        }
+        
+        if (ftype != fun_inner && ftype != fun_exposed) {
+                /* Unknown function type */
+                log_msg(LVL_ERROR, 
+                    "Unknown function type %d provided by driver.",
+                    (int) ftype);
+
+                dev_del_ref(pdev);
+                async_answer_0(callid, EINVAL);
+                return;
+        }
+        
+        char *fun_name = NULL;
+        int rc = async_data_write_accept((void **)&fun_name, true, 0, 0, 0, 0);
+        if (rc != EOK) {
+                dev_del_ref(pdev);
+                async_answer_0(callid, rc);
+                return;
+        }
+        
+        fibril_rwlock_write_lock(&tree->rwlock);
+        
+        /* Check device state */
+        if (pdev->state == DEVICE_REMOVED) {
+                fibril_rwlock_write_unlock(&tree->rwlock);
+                dev_del_ref(pdev);
+                async_answer_0(callid, ENOENT);
+                return;
+        }
+        
+        /* Check that function with same name is not there already. */
+        if (find_fun_node_in_device(tree, pdev, fun_name) != NULL) {
+                fibril_rwlock_write_unlock(&tree->rwlock);
+                dev_del_ref(pdev);
+                async_answer_0(callid, EEXISTS);
+                printf(NAME ": Warning, driver tried to register `%s' twice.\n",
+                    fun_name);
+                free(fun_name);
+                return;
+        }
+        
+        fun_node_t *fun = create_fun_node();
+        fun_add_ref(fun);
+        fun->ftype = ftype;
+        
+        if (!insert_fun_node(&device_tree, fun, fun_name, pdev)) {
+                fibril_rwlock_write_unlock(&tree->rwlock);
+                dev_del_ref(pdev);
+                delete_fun_node(fun);
+                async_answer_0(callid, ENOMEM);
+                return;
+        }
+        
+        fibril_rwlock_write_unlock(&tree->rwlock);
+        dev_del_ref(pdev);
+        
+        devman_receive_match_ids(match_count, &fun->match_ids);
+        
+        rc = online_function(fun);
+        if (rc != EOK) {
+                /* XXX clean up */
+                async_answer_0(callid, rc);
+                return;
         }
         
@@ -356 +452 @@
                 async_answer_0(callid, rc);
                 return;
-        }       
+        }
         
         fun_node_t *fun = find_fun_node(&device_tree, handle);
         if (fun == NULL) {
+                async_answer_0(callid, ENOENT);
+                return;
+        }
+        
+        fibril_rwlock_read_lock(&device_tree.rwlock);
+        
+        /* Check function state */
+        if (fun->state == FUN_REMOVED) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
                 async_answer_0(callid, ENOENT);
                 return;
@@ -375 +480 @@
             fun->pathname, cat_name);
 
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+        fun_del_ref(fun);
+
         async_answer_0(callid, EOK);
+}
+
+/** Online function by driver request.
+ *
+ */
+static void devman_drv_fun_online(ipc_callid_t iid, ipc_call_t *icall,
+    driver_t *drv)
+{
+        fun_node_t *fun;
+        int rc;
+
+        printf("devman_drv_fun_online()\n");
+        fun = find_fun_node(&device_tree, IPC_GET_ARG1(*icall));
+        if (fun == NULL) {
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        
+        fibril_rwlock_read_lock(&device_tree.rwlock);
+        if (fun->dev == NULL || fun->dev->drv != drv) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+                fun_del_ref(fun);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+        
+        rc = online_function(fun);
+        if (rc != EOK) {
+                printf("devman_drv_fun_online() online_fun->ERROR\n");
+                fun_del_ref(fun);
+                async_answer_0(iid, (sysarg_t) rc);
+                return;
+        }
+        
+        fun_del_ref(fun);
+        printf("devman_drv_fun_online() online_fun->OK\n");
+        
+        async_answer_0(iid, (sysarg_t) EOK);
+}
+
+
+/** Offline function by driver request.
+ *
+ */
+static void devman_drv_fun_offline(ipc_callid_t iid, ipc_call_t *icall,
+    driver_t *drv)
+{
+        fun_node_t *fun;
+        int rc;
+
+        fun = find_fun_node(&device_tree, IPC_GET_ARG1(*icall));
+        if (fun == NULL) {
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        
+        fibril_rwlock_write_lock(&device_tree.rwlock);
+        if (fun->dev == NULL || fun->dev->drv != drv) {
+                fun_del_ref(fun);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        fibril_rwlock_write_unlock(&device_tree.rwlock);
+        
+        rc = offline_function(fun);
+        if (rc != EOK) {
+                fun_del_ref(fun);
+                async_answer_0(iid, (sysarg_t) rc);
+                return;
+        }
+        
+        fun_del_ref(fun);
+        async_answer_0(iid, (sysarg_t) EOK);
 }
 
@@ -385 +567 @@
         int rc;
         
+        
+        fun_node_t *fun = find_fun_node(&device_tree, fun_handle);
+        if (fun == NULL) {
+                async_answer_0(callid, ENOENT);
+                return;
+        }
+        
         fibril_rwlock_write_lock(&tree->rwlock);
         
-        fun_node_t *fun = find_fun_node_no_lock(&device_tree, fun_handle);
-        if (fun == NULL) {
+        log_msg(LVL_DEBUG, "devman_remove_function(fun='%s')", fun->pathname);
+        
+        /* Check function state */
+        if (fun->state == FUN_REMOVED) {
                 fibril_rwlock_write_unlock(&tree->rwlock);
                 async_answer_0(callid, ENOENT);
@@ -394 +585 @@
         }
         
-        log_msg(LVL_DEBUG, "devman_remove_function(fun='%s')", fun->pathname);
-        
         if (fun->ftype == fun_inner) {
                 /* Handle possible descendants */
-                /* TODO */
-                log_msg(LVL_WARN, "devman_remove_function(): not handling "
-                    "descendants\n");
+                /* TODO - This is a surprise removal */
+                if (fun->child != NULL) {
+                        log_msg(LVL_WARN, "devman_remove_function(): not handling "
+                            "descendants\n");
+                }
         } else {
-                /* Unregister from location service */
-                rc = loc_service_unregister(fun->service_id);
-                if (rc != EOK) {
-                        log_msg(LVL_ERROR, "Failed unregistering tree service.");
-                        fibril_rwlock_write_unlock(&tree->rwlock);
-                        async_answer_0(callid, EIO);
-                        return;
+                if (fun->service_id != 0) {
+                        /* Unregister from location service */
+                        rc = loc_service_unregister(fun->service_id);
+                        if (rc != EOK) {
+                                log_msg(LVL_ERROR, "Failed unregistering tree "
+                                    "service.");
+                                fibril_rwlock_write_unlock(&tree->rwlock);
+                                fun_del_ref(fun);
+                                async_answer_0(callid, EIO);
+                                return;
+                        }
                 }
         }
@@ -414 +609 @@
         remove_fun_node(&device_tree, fun);
         fibril_rwlock_write_unlock(&tree->rwlock);
-        delete_fun_node(fun);
+        
+        /* Delete ref added when inserting function into tree */
+        fun_del_ref(fun);
+        /* Delete ref added above when looking up function */
+        fun_del_ref(fun);
         
         log_msg(LVL_DEBUG, "devman_remove_function() succeeded.");
@@ -485 +684 @@
                         devman_add_function_to_cat(callid, &call);
                         break;
+                case DEVMAN_DRV_FUN_ONLINE:
+                        devman_drv_fun_online(callid, &call, driver);
+                        break;
+                case DEVMAN_DRV_FUN_OFFLINE:
+                        devman_drv_fun_offline(callid, &call, driver);
+                        break;
                 case DEVMAN_REMOVE_FUNCTION:
                         devman_remove_function(callid, &call);
                         break;
                 default:
-                        async_answer_0(callid, EINVAL); 
+                        async_answer_0(callid, EINVAL);
                         break;
                 }
@@ -500 +705 @@
 {
         char *pathname;
+        devman_handle_t handle;
         
         int rc = async_data_write_accept((void **) &pathname, true, 0, 0, 0, 0);
@@ -516 +722 @@
         }
 
-        async_answer_1(iid, EOK, fun->handle);
+        fibril_rwlock_read_lock(&device_tree.rwlock);
+
+        /* Check function state */
+        if (fun->state == FUN_REMOVED) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        handle = fun->handle;
+
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+
+        /* Delete reference created above by find_fun_node_by_path() */
+        fun_del_ref(fun);
+
+        async_answer_1(iid, EOK, handle);
 }
 
@@ -534 +755 @@
         if (!async_data_read_receive(&data_callid, &data_len)) {
                 async_answer_0(iid, EINVAL);
+                fun_del_ref(fun);
                 return;
         }
@@ -541 +763 @@
                 async_answer_0(data_callid, ENOMEM);
                 async_answer_0(iid, ENOMEM);
+                fun_del_ref(fun);
+                return;
+        }
+
+        fibril_rwlock_read_lock(&device_tree.rwlock);
+
+        /* Check function state */
+        if (fun->state == FUN_REMOVED) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+                free(buffer);
+
+                async_answer_0(data_callid, ENOENT);
+                async_answer_0(iid, ENOENT);
+                fun_del_ref(fun);
                 return;
         }
@@ -552 +788 @@
         async_answer_0(iid, EOK);
 
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+        fun_del_ref(fun);
         free(buffer);
 }
@@ -571 +809 @@
         if (!async_data_read_receive(&data_callid, &data_len)) {
                 async_answer_0(iid, EINVAL);
+                fun_del_ref(fun);
                 return;
         }
@@ -578 +817 @@
                 async_answer_0(data_callid, ENOMEM);
                 async_answer_0(iid, ENOMEM);
-                return;
-        }
-
+                fun_del_ref(fun);
+                return;
+        }
+        
+        fibril_rwlock_read_lock(&device_tree.rwlock);
+        
+        /* Check function state */
+        if (fun->state == FUN_REMOVED) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+                free(buffer);
+
+                async_answer_0(data_callid, ENOENT);
+                async_answer_0(iid, ENOENT);
+                fun_del_ref(fun);
+                return;
+        }
+        
         size_t sent_length = str_size(fun->pathname);
         if (sent_length > data_len) {
@@ -589 +842 @@
         async_answer_0(iid, EOK);
 
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+        fun_del_ref(fun);
         free(buffer);
 }
@@ -609 +864 @@
         dev_node_t *dev = find_dev_node_no_lock(&device_tree,
             IPC_GET_ARG1(*icall));
-        if (dev == NULL) {
+        if (dev == NULL || dev->state == DEVICE_REMOVED) {
                 fibril_rwlock_read_unlock(&device_tree.rwlock);
                 async_answer_0(callid, ENOENT);
@@ -648 +903 @@
         fibril_rwlock_read_lock(&device_tree.rwlock);
         
+        fun = find_fun_node_no_lock(&device_tree, IPC_GET_ARG1(*icall));
+        if (fun == NULL || fun->state == FUN_REMOVED) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        
+        if (fun->child == NULL) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        
+        async_answer_1(iid, EOK, fun->child->handle);
+        
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+}
+
+/** Online function.
+ *
+ * Send a request to online a function to the responsible driver.
+ * The driver may offline other functions if necessary (i.e. if the state
+ * of this function is linked to state of another function somehow).
+ */
+static void devman_fun_online(ipc_callid_t iid, ipc_call_t *icall)
+{
+        fun_node_t *fun;
+        int rc;
+
         fun = find_fun_node(&device_tree, IPC_GET_ARG1(*icall));
         if (fun == NULL) {
-                fibril_rwlock_read_unlock(&device_tree.rwlock);
-                async_answer_0(iid, ENOENT);
-                return;
-        }
-        
-        if (fun->child == NULL) {
-                fibril_rwlock_read_unlock(&device_tree.rwlock);
-                async_answer_0(iid, ENOENT);
-                return;
-        }
-        
-        async_answer_1(iid, EOK, fun->child->handle);
-        
-        fibril_rwlock_read_unlock(&device_tree.rwlock);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        
+        rc = driver_fun_online(&device_tree, fun);
+        fun_del_ref(fun);
+        
+        async_answer_0(iid, (sysarg_t) rc);
+}
+
+/** Offline function.
+ *
+ * Send a request to offline a function to the responsible driver. As
+ * a result the subtree rooted at that function should be cleanly
+ * detatched. The driver may offline other functions if necessary
+ * (i.e. if the state of this function is linked to state of another
+ * function somehow).
+ */
+static void devman_fun_offline(ipc_callid_t iid, ipc_call_t *icall)
+{
+        fun_node_t *fun;
+        int rc;
+
+        fun = find_fun_node(&device_tree, IPC_GET_ARG1(*icall));
+        if (fun == NULL) {
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        
+        rc = driver_fun_offline(&device_tree, fun);
+        fun_del_ref(fun);
+        
+        async_answer_0(iid, (sysarg_t) rc);
 }
 
@@ -678 +981 @@
         }
 
+        fibril_rwlock_read_lock(&device_tree.rwlock);
+
+        /* Check function state */
+        if (fun->state == FUN_REMOVED) {
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+
         async_answer_1(iid, EOK, fun->handle);
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+        fun_del_ref(fun);
 }
 
@@ -710 +1024 @@
                         devman_fun_get_path(callid, &call);
                         break;
+                case DEVMAN_FUN_ONLINE:
+                        devman_fun_online(callid, &call);
+                        break;
+                case DEVMAN_FUN_OFFLINE:
+                        devman_fun_offline(callid, &call);
+                        break;
                 case DEVMAN_FUN_SID_TO_HANDLE:
                         devman_fun_sid_to_handle(callid, &call);
@@ -730 +1050 @@
         if (fun == NULL)
                 dev = find_dev_node(&device_tree, handle);
-        else
+        else {
+                fibril_rwlock_read_lock(&device_tree.rwlock);
                 dev = fun->dev;
+                if (dev != NULL)
+                        dev_add_ref(dev);
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
+        }
 
         /*
@@ -743 +1068 @@
                     "function with handle %" PRIun " was found.", handle);
                 async_answer_0(iid, ENOENT);
-                return;
+                goto cleanup;
         }
 
@@ -751 +1076 @@
                     handle);
                 async_answer_0(iid, ENOENT);
-                return;
+                goto cleanup;
         }
         
         driver_t *driver = NULL;
+        
+        fibril_rwlock_read_lock(&device_tree.rwlock);
         
         if (drv_to_parent) {
@@ -769 +1096 @@
         }
         
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+        
         if (driver == NULL) {
                 log_msg(LVL_ERROR, "IPC forwarding refused - " \
                     "the device %" PRIun " is not in usable state.", handle);
                 async_answer_0(iid, ENOENT);
-                return;
+                goto cleanup;
         }
         
@@ -786 +1115 @@
                     "Could not forward to driver `%s'.", driver->name);
                 async_answer_0(iid, EINVAL);
-                return;
+                goto cleanup;
         }
 
@@ -802 +1131 @@
         async_forward_fast(iid, exch, method, fwd_h, 0, IPC_FF_NONE);
         async_exchange_end(exch);
+
+cleanup:
+        if (dev != NULL)
+                dev_del_ref(dev);
+        if (fun != NULL)
+                fun_del_ref(fun);
 }
 
@@ -811 +1146 @@
         fun_node_t *fun;
         dev_node_t *dev;
+        devman_handle_t handle;
+        driver_t *driver;
 
         fun = find_loc_tree_function(&device_tree, service_id);
         
-        if (fun == NULL || fun->dev->drv == NULL) {
+        fibril_rwlock_read_lock(&device_tree.rwlock);
+        
+        if (fun == NULL || fun->dev == NULL || fun->dev->drv == NULL) {
                 log_msg(LVL_WARN, "devman_connection_loc(): function "
                     "not found.\n");
+                fibril_rwlock_read_unlock(&device_tree.rwlock);
                 async_answer_0(iid, ENOENT);
                 return;
@@ -822 +1162 @@
         
         dev = fun->dev;
-        
-        async_exch_t *exch = async_exchange_begin(dev->drv->sess);
-        async_forward_fast(iid, exch, DRIVER_CLIENT, fun->handle, 0,
+        driver = dev->drv;
+        handle = fun->handle;
+        
+        fibril_rwlock_read_unlock(&device_tree.rwlock);
+        
+        async_exch_t *exch = async_exchange_begin(driver->sess);
+        async_forward_fast(iid, exch, DRIVER_CLIENT, handle, 0,
             IPC_FF_NONE);
         async_exchange_end(exch);
@@ -830 +1174 @@
         log_msg(LVL_DEBUG,
             "Forwarding loc service request for `%s' function to driver `%s'.",
-            fun->pathname, dev->drv->name);
+            fun->pathname, driver->name);
+
+        fun_del_ref(fun);
 }
 

uspace/srv/loc/loc.c

@@ -1231 +1231 @@
         svc = loc_service_find_id(svc_id);
         
+        if (cat == NULL || svc == NULL) {
+                fibril_mutex_unlock(&cdir.mutex);
+                fibril_mutex_unlock(&services_list_mutex);
+                async_answer_0(iid, ENOENT);
+                return;
+        }
+        
         fibril_mutex_lock(&cat->mutex);
         retval = category_add_service(cat, svc);