Changeset 3954961e in mainline for kernel/generic/src/synch/waitq.c

Timestamp:

2012-07-10T17:34:22Z (12 years ago)

Author:

Adam Hraska <adam.hraska+hos@…>

Branches:

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

Children:

e0c80f66

Parents:

ff90f5f

Message:

waitq: Added ability to wait for the completion of a running wakeup.

File:

• kernel/generic/src/synch/waitq.c (modified) (1 diff)

kernel/generic/src/synch/waitq.c

@@ -442 +442 @@
         irq_spinlock_unlock(&wq->lock, true);
 }
+
+/** If there is a wakeup in progress actively waits for it to complete.
+ * 
+ * The function returns once the concurrently running waitq_wakeup()
+ * exits. It returns immediately if there are no concurrent wakeups 
+ * at the time.
+ * 
+ * Example usage:
+ * @code
+ * void callback(waitq *wq)
+ * {
+ *     // Do something and notify wait_for_completion() that we're done.
+ *     waitq_wakeup(wq);
+ * }
+ * void wait_for_completion(void) 
+ * {
+ *     waitq wg;
+ *     waitq_initialize(&wq);
+ *     // Run callback() in the background, pass it wq.
+ *     do_asynchronously(callback, &wq);
+ *     // Wait for callback() to complete its work.
+ *     waitq_sleep(&wq);
+ *     // callback() completed its work, but it may still be accessing 
+ *     // wq in waitq_wakeup(). Therefore it is not yet safe to return 
+ *     // or it would clobber up our stack (where wq is stored).
+ *     waitq_complete_wakeup(&wq);
+ *     // waitq_wakeup() is complete, it is safe to free wq.
+ * }
+ * @endcode
+ * 
+ * @param wq  Pointer to a wait queue.
+ */
+void waitq_complete_wakeup(waitq_t *wq)
+{
+        irq_spinlock_lock(&wq->lock, true);
+        irq_spinlock_unlock(&wq->lock, true);
+}
+
 
 /** Internal SMP- and IRQ-unsafe version of waitq_wakeup()