Author: zml
Date: Fri Apr 30 16:29:05 2010
New Revision: 207439
URL: http://svn.freebsd.org/changeset/base/207439
Log:
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.flem...@isilon.com>
Reviewed by: jhb
Approved by: dfr (mentor)
Modified:
head/sys/kern/subr_taskqueue.c
head/sys/sys/_task.h
head/sys/sys/taskqueue.h
Modified: head/sys/kern/subr_taskqueue.c
==============================================================================
--- head/sys/kern/subr_taskqueue.c Fri Apr 30 16:20:14 2010
(r207438)
+++ head/sys/kern/subr_taskqueue.c Fri Apr 30 16:29:05 2010
(r207439)
@@ -51,7 +51,6 @@ struct taskqueue {
const char *tq_name;
taskqueue_enqueue_fn tq_enqueue;
void *tq_context;
- struct task *tq_running;
struct mtx tq_mutex;
struct thread **tq_threads;
int tq_tcount;
@@ -233,13 +232,13 @@ taskqueue_run(struct taskqueue *queue)
STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
pending = task->ta_pending;
task->ta_pending = 0;
- queue->tq_running = task;
+ task->ta_flags |= TA_FLAGS_RUNNING;
TQ_UNLOCK(queue);
task->ta_func(task->ta_context, pending);
TQ_LOCK(queue);
- queue->tq_running = NULL;
+ task->ta_flags &= ~TA_FLAGS_RUNNING;
wakeup(task);
}
@@ -256,14 +255,16 @@ taskqueue_drain(struct taskqueue *queue,
{
if (queue->tq_spin) { /* XXX */
mtx_lock_spin(&queue->tq_mutex);
- while (task->ta_pending != 0 || task == queue->tq_running)
+ while (task->ta_pending != 0 ||
+ (task->ta_flags & TA_FLAGS_RUNNING) != 0)
msleep_spin(task, &queue->tq_mutex, "-", 0);
mtx_unlock_spin(&queue->tq_mutex);
} else {
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
mtx_lock(&queue->tq_mutex);
- while (task->ta_pending != 0 || task == queue->tq_running)
+ while (task->ta_pending != 0 ||
+ (task->ta_flags & TA_FLAGS_RUNNING) != 0)
msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
mtx_unlock(&queue->tq_mutex);
}
Modified: head/sys/sys/_task.h
==============================================================================
--- head/sys/sys/_task.h Fri Apr 30 16:20:14 2010 (r207438)
+++ head/sys/sys/_task.h Fri Apr 30 16:29:05 2010 (r207439)
@@ -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_ */
Modified: head/sys/sys/taskqueue.h
==============================================================================
--- head/sys/sys/taskqueue.h Fri Apr 30 16:20:14 2010 (r207438)
+++ head/sys/sys/taskqueue.h Fri Apr 30 16:29:05 2010 (r207439)
@@ -75,6 +75,7 @@ void taskqueue_thread_enqueue(void *cont
(task)->ta_priority = (priority); \
(task)->ta_func = (func); \
(task)->ta_context = (context); \
+ (task)->ta_flags = 0; \
} while (0)
/*
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