Handle taskqueue_drain(9) correctly on a threaded taskqueue:

taskqueue_drain(9) will not correctly detect whether a task is
currently running.  The check is against a field in the taskqueue
struct, but for a threaded queue with more than one thread, multiple
threads can simultaneously be running a task, thus stomping over the
tq_running field.

Submitted by:       Matthew Fleming <matthew.fleming@isilon.com>
Reviewed by:        jhb
Approved by:        dfr (mentor)

1 files changed, 11 insertions, 5 deletions

diff --git a/sys/sys/_task.h b/sys/sys/_task.h
index 2a51e1b..781cd48 100644
--- a/sys/sys/_task.h
+++ b/sys/sys/_task.h
@@ -36,15 +36,21 @@
  * taskqueue_run().  The first argument is taken from the 'ta_context'
  * field of struct task and the second argument is a count of how many
  * times the task was enqueued before the call to taskqueue_run().
+ *
+ * List of locks
+ * (c)	const after init
+ * (q)	taskqueue lock
  */
 typedef void task_fn_t(void *context, int pending);
 
 struct task {
-	STAILQ_ENTRY(task) ta_link;	/* link for queue */
-	u_short	ta_pending;		/* count times queued */
-	u_short	ta_priority;		/* Priority */
-	task_fn_t *ta_func;		/* task handler */
-	void	*ta_context;		/* argument for handler */
+	STAILQ_ENTRY(task) ta_link;	/* (q) link for queue */
+	u_int	ta_flags;		/* (q) state of this task */
+#define	TA_FLAGS_RUNNING	0x01
+	u_short	ta_pending;		/* (q) count times queued */
+	u_short	ta_priority;		/* (c) Priority */
+	task_fn_t *ta_func;		/* (c) task handler */
+	void	*ta_context;		/* (c) argument for handler */
 };
 
 #endif /* !_SYS__TASK_H_ */