WebSVN – HelenOS – Diff – /branches/tracing/kernel/generic/src/udebug/udebug.c

     mutex_unlock(&TASK->udebug.lock);
     udebug_wait_for_go(&THREAD->udebug.go_wq);
+}
-/** Thread-creation event hook.
+/** Thread-creation event hook combined with attaching the thread.
+ *
  * Must be called when a new userspace thread is created in the debugged
+ * task. Generates a THREAD_B event. Also attaches the thread @a t
+ * to the task @a ta.
+ *
+ * This is necessary to avoid a race condition where the BEGIN and THREAD_READ
+ * requests would be handled inbetween attaching the thread and checking it
+ * for being in a debugging session to send the THREAD_B event. We could then
+ * either miss threads or get some threads both in the thread list
- * task. Generates a THREAD_B event.
+ * and get a THREAD_B event for them.
+ *
  * @param t Structure of the thread being created. Not locked, as the
  *      thread is not executing yet.
+ * @param ta    Task to which the thread should be attached.
  */
-void udebug_thread_b_event(struct thread *t)
+void udebug_thread_b_event_attach(struct thread *t, struct task *ta)
+{
     call_t *call;
     mutex_lock(&TASK->udebug.lock);
     mutex_lock(&THREAD->udebug.lock);
+    thread_attach(t, ta);
     LOG("udebug_thread_b_event\n");
     LOG("- check state\n");
     /* Must only generate events when in debugging session */
     if (THREAD->udebug.debug_active != true) {

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