Changeset 121966e in mainline

Timestamp:

2009-08-07T21:37:20Z (16 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

9732e98

Parents:

e31c2c5

Message:

task_done() should not kill tasks one by one and wait until each dies.
Instead, the kill needs to be signalled to all tasks and repeated as
long as there are any user tasks. Otherwise completion of a task kill
may depend on death of another task with a higher ID due to unanswered
calls.

File:

• kernel/generic/src/proc/task.c (modified) (6 diffs)

kernel/generic/src/proc/task.c

@@ -75 +75 @@
 static task_id_t task_counter = 0;
 
+/* Forward declarations. */
+static void task_kill_internal(task_t *);
+
 /** Initialize kernel tasks support. */
 void task_init(void)
@@ -83 +86 @@
 
 /*
- * The idea behind this walker is to remember a single task different from
+ * The idea behind this walker is to kill and count all tasks different from
  * TASK.
  */
@@ -89 +92 @@
 {
         task_t *t = avltree_get_instance(node, task_t, tasks_tree_node);
-        task_t **tp = (task_t **) arg;
-
-        if (t != TASK) { 
-                *tp = t;
-                return false;   /* stop walking */
+        unsigned *cnt = (unsigned *) arg;
+
+        if (t != TASK) {
+                (*cnt)++;
+#ifdef CONFIG_DEBUG
+                printf("[%"PRIu64"] ", t->taskid);
+#endif
+                task_kill_internal(t);
         }
 
@@ -102 +108 @@
 void task_done(void)
 {
-        task_t *t;
+        unsigned tasks_left;
+
         do { /* Repeat until there are any tasks except TASK */
-                
                 /* Messing with task structures, avoid deadlock */
+#ifdef CONFIG_DEBUG
+                printf("Killing tasks... ");
+#endif
                 ipl_t ipl = interrupts_disable();
                 spinlock_lock(&tasks_lock);
-                
-                t = NULL;
-                avltree_walk(&tasks_tree, task_done_walker, &t);
-                
-                if (t != NULL) {
-                        task_id_t id = t->taskid;
-                        
-                        spinlock_unlock(&tasks_lock);
-                        interrupts_restore(ipl);
-                        
+                tasks_left = 0;
+                avltree_walk(&tasks_tree, task_done_walker, &tasks_left);
+                spinlock_unlock(&tasks_lock);
+                interrupts_restore(ipl);
+                thread_sleep(1);
 #ifdef CONFIG_DEBUG
-                        printf("Killing task %" PRIu64 "\n", id);
-#endif                  
-                        task_kill(id);
-                        thread_usleep(10000);
-                } else {
-                        spinlock_unlock(&tasks_lock);
-                        interrupts_restore(ipl);
-                }
-                
-        } while (t != NULL);
+                printf("\n");
+#endif
+        } while (tasks_left);
 }
 
@@ -350 +347 @@
 }
 
-/** Kill task.
- *
- * This function is idempotent.
- * It signals all the task's threads to bail it out.
- *
- * @param id            ID of the task to be killed.
- *
- * @return              Zero on success or an error code from errno.h.
- */
-int task_kill(task_id_t id)
-{
-        ipl_t ipl;
-        task_t *ta;
+static void task_kill_internal(task_t *ta)
+{
         link_t *cur;
 
-        if (id == 1)
-                return EPERM;
-        
-        ipl = interrupts_disable();
-        spinlock_lock(&tasks_lock);
-        if (!(ta = task_find_by_id(id))) {
-                spinlock_unlock(&tasks_lock);
-                interrupts_restore(ipl);
-                return ENOENT;
-        }
-        spinlock_unlock(&tasks_lock);
-        
         /*
          * Interrupt all threads.
@@ -397 +371 @@
         }
         spinlock_unlock(&ta->lock);
+}
+
+/** Kill task.
+ *
+ * This function is idempotent.
+ * It signals all the task's threads to bail it out.
+ *
+ * @param id            ID of the task to be killed.
+ *
+ * @return              Zero on success or an error code from errno.h.
+ */
+int task_kill(task_id_t id)
+{
+        ipl_t ipl;
+        task_t *ta;
+
+        if (id == 1)
+                return EPERM;
+        
+        ipl = interrupts_disable();
+        spinlock_lock(&tasks_lock);
+        if (!(ta = task_find_by_id(id))) {
+                spinlock_unlock(&tasks_lock);
+                interrupts_restore(ipl);
+                return ENOENT;
+        }
+        task_kill_internal(ta);
+        spinlock_unlock(&tasks_lock);
         interrupts_restore(ipl);
-        
         return 0;
 }