Changeset 398c4d7 in mainline

Timestamp:

2010-12-01T23:51:29Z (13 years ago)

Author:

Vojtech Horky <vojtechhorky@…>

Branches:

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

Children:

c245f16e

Parents:

2edcb63

Message:

More conservative locking in devman

Add mutex guard when accessing driver_t structure during driver assigning.

Added missing async_wait_for and removed extra mutex_unlock.

To speed-up answer time, driver start is done in separate fibril to avoid
blocking IPC connection fibril.

Location:

uspace

Files:

• lib/c/generic/devman.c (modified) (1 diff)
• srv/devman/devman.c (modified) (5 diffs)
• srv/devman/main.c (modified) (3 diffs)

uspace/lib/c/generic/devman.c

@@ -116 +116 @@
 {
         ipc_call_t answer;
-        async_send_1(phone, DEVMAN_ADD_MATCH_ID, match_id->score, &answer);
+        aid_t req = async_send_1(phone, DEVMAN_ADD_MATCH_ID, match_id->score, &answer);
         int retval = async_data_write_start(phone, match_id->id, str_size(match_id->id));
-        return retval;  
+        async_wait_for(req, NULL);
+        return retval;
 }
 

uspace/srv/devman/devman.c

@@ -520 +520 @@
         fibril_mutex_lock(&driver->driver_mutex);
 
-        phone = ipc_connect_me_to(driver->phone, DRIVER_DEVMAN, 0, 0);
+        phone = async_connect_me_to(driver->phone, DRIVER_DEVMAN, 0, 0);
 
         if (phone < 0) {
@@ -583 +583 @@
          * immediately and possibly started here as well.
          */
+        printf(NAME ": driver %s goes into running state.\n", driver->name);
         driver->state = DRIVER_RUNNING;
 
@@ -712 +713 @@
                 /* TODO handle error */
         }
-        
+
         /* Wait for answer from the driver. */
         async_wait_for(req, &rc);
@@ -755 +756 @@
         attach_driver(node, drv);
         
+        fibril_mutex_lock(&drv->driver_mutex);
         if (drv->state == DRIVER_NOT_STARTED) {
                 /* Start the driver. */
                 start_driver(drv);
         }
-        
-        if (drv->state == DRIVER_RUNNING) {
+        fibril_mutex_unlock(&drv->driver_mutex);
+        
+        fibril_mutex_lock(&drv->driver_mutex);
+        bool is_running = drv->state == DRIVER_RUNNING;
+        fibril_mutex_unlock(&drv->driver_mutex);
+
+        if (is_running) {
                 /* Notify the driver about the new device. */
-                int phone = ipc_connect_me_to(drv->phone, DRIVER_DEVMAN, 0, 0);
+                int phone = async_connect_me_to(drv->phone, DRIVER_DEVMAN, 0, 0);
                 if (phone > 0) {
                         add_device(phone, drv, node, tree);
@@ -924 +931 @@
         node->name = dev_name;
         if (!set_dev_path(node, parent)) {
-                fibril_rwlock_write_unlock(&tree->rwlock);
                 return false;
         }

uspace/srv/devman/main.c

@@ -197 +197 @@
 }
 
+static int assign_driver_fibril(void *arg)
+{
+        node_t *node = (node_t *) arg;
+        assign_driver(node, &drivers_list, &device_tree);
+        return EOK;
+}
+
 /** Handle child device registration.
  *
@@ -237 +244 @@
         
         devman_receive_match_ids(match_count, &node->match_ids);
-        
+
+        /*
+         * Try to find suitable driver and assign it to the device.
+         * We do not want to block current fibril that is used to processing
+         * incoming calls: we will launch a separate fibril to handle
+         * the driver assigning. That is because assign_driver can actually
+         * include task spawning which could take some time.
+         */
+        fid_t assign_fibril = fibril_create(assign_driver_fibril, node);
+        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(node);
+        } else {
+                fibril_add_ready(assign_fibril);
+        }
+
         /* Return device handle to parent's driver. */
         ipc_answer_1(callid, EOK, node->handle);
-        
-        /* Try to find suitable driver and assign it to the device. */
-        assign_driver(node, &drivers_list, &device_tree);
 }
 
@@ -297 +319 @@
         printf(NAME ": device '%s' added to class '%s', class name '%s' was "
             "asigned to it\n", dev->pathname, class_name, class_info->dev_name);
-        
+
         ipc_answer_0(callid, EOK);
 }