return (NULL);
}
+/*
+ * Theory for the taskq_wait_id(), taskq_wait_outstanding(), and
+ * taskq_wait() functions below.
+ *
+ * Taskq waiting is accomplished by tracking the lowest outstanding task
+ * id and the next available task id. As tasks are dispatched they are
+ * added to the tail of the pending, priority, or delay lists. As worker
+ * threads become available the tasks are removed from the heads of these
+ * lists and linked to the worker threads. This ensures the lists are
+ * kept sorted by lowest to highest task id.
+ *
+ * Therefore the lowest outstanding task id can be quickly determined by
+ * checking the head item from all of these lists. This value is stored
+ * with the taskq as the lowest id. It only needs to be recalculated when
+ * either the task with the current lowest id completes or is canceled.
+ *
+ * By blocking until the lowest task id exceeds the passed task id the
+ * taskq_wait_outstanding() function can be easily implemented. Similarly,
+ * by blocking until the lowest task id matches the next task id taskq_wait()
+ * can be implemented.
+ *
+ * Callers should be aware that when there are multiple worked threads it
+ * is possible for larger task ids to complete before smaller ones. Also
+ * when the taskq contains delay tasks with small task ids callers may
+ * block for a considerable length of time waiting for them to expire and
+ * execute.
+ */
static int
taskq_wait_id_check(taskq_t *tq, taskqid_t id)
{
}
EXPORT_SYMBOL(taskq_wait_id);
-/*
- * The taskq_wait() function will block until all previously submitted
- * tasks have been completed. A previously submitted task is defined as
- * a task with a lower task id than the current task queue id. Note that
- * all task id's are assigned monotonically at dispatch time.
- *
- * Waiting for all previous tasks to complete is accomplished by tracking
- * the lowest outstanding task id. As tasks are dispatched they are added
- * added to the tail of the pending, priority, or delay lists. And as
- * worker threads become available the tasks are removed from the heads
- * of these lists and linked to the worker threads. This ensures the
- * lists are kept in lowest to highest task id order.
- *
- * Therefore the lowest outstanding task id can be quickly determined by
- * checking the head item from all of these lists. This value is stored
- * with the task queue as the lowest id. It only needs to be recalculated
- * when either the task with the current lowest id completes or is canceled.
- *
- * By blocking until the lowest task id exceeds the current task id when
- * the function was called we ensure all previous tasks have completed.
- *
- * NOTE: When there are multiple worked threads it is possible for larger
- * task ids to complete before smaller ones. Conversely when the task
- * queue contains delay tasks with small task ids, you may block for a
- * considerable length of time waiting for them to expire and execute.
- */
static int
-taskq_wait_check(taskq_t *tq, taskqid_t id)
+taskq_wait_outstanding_check(taskq_t *tq, taskqid_t id)
{
int rc;
return (rc);
}
+/*
+ * The taskq_wait_outstanding() function will block until all tasks with a
+ * lower taskqid than the passed 'id' have been completed. Note that all
+ * task id's are assigned monotonically at dispatch time. Zero may be
+ * passed for the id to indicate all tasks dispatch up to this point,
+ * but not after, should be waited for.
+ */
void
-taskq_wait_all(taskq_t *tq, taskqid_t id)
+taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
{
- wait_event(tq->tq_wait_waitq, taskq_wait_check(tq, id));
+ wait_event(tq->tq_wait_waitq,
+ taskq_wait_outstanding_check(tq, id ? id : tq->tq_next_id - 1));
}
-EXPORT_SYMBOL(taskq_wait_all);
+EXPORT_SYMBOL(taskq_wait_outstanding);
-void
-taskq_wait(taskq_t *tq)
+static int
+taskq_wait_check(taskq_t *tq)
{
- taskqid_t id;
-
- ASSERT(tq);
+ int rc;
- /* Wait for the largest outstanding taskqid */
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
- id = tq->tq_next_id - 1;
+ rc = (tq->tq_lowest_id == tq->tq_next_id);
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
- taskq_wait_all(tq, id);
+ return (rc);
+}
+
+/*
+ * The taskq_wait() function will block until the taskq is empty.
+ * This means that if a taskq re-dispatches work to itself taskq_wait()
+ * callers will block indefinitely.
+ */
+void
+taskq_wait(taskq_t *tq)
+{
+ wait_event(tq->tq_wait_waitq, taskq_wait_check(tq));
}
EXPORT_SYMBOL(taskq_wait);
* next pending task as soon as it completes its current task. This
* means that tasks do not strictly complete in order in which they
* were dispatched (increasing task id). This is fine but we need to
- * verify that taskq_wait_all() blocks until the passed task id and all
- * lower task ids complete. We do this by dispatching the following
+ * verify taskq_wait_outstanding() blocks until the passed task id and
+ * all lower task ids complete. We do this by dispatching the following
* specific sequence of tasks each of which block for N time units.
- * We then use taskq_wait_all() to unblock at specific task id and
+ * We then use taskq_wait_outstanding() to unblock at specific task id and
* verify the only the expected task ids have completed and in the
* correct order. The two cases of interest are:
*
*
* The following table shows each task id and how they will be
* scheduled. Each rows represent one time unit and each column
- * one of the three worker threads. The places taskq_wait_all()
+ * one of the three worker threads. The places taskq_wait_outstanding()
* must unblock for a specific id are identified as well as the
* task ids which must have completed and their order.
*
- * +-----+ <--- taskq_wait_all(tq, 8) unblocks
+ * +-----+ <--- taskq_wait_outstanding(tq, 8) unblocks
* | | Required Completion Order: 1,2,4,5,3,8,6,7
* +-----+ |
* | | |
* | | +-----+
* | | | 8 |
- * | | +-----+ <--- taskq_wait_all(tq, 3) unblocks
+ * | | +-----+ <--- taskq_wait_outstanding(tq, 3) unblocks
* | | 7 | | Required Completion Order: 1,2,4,5,3
* | +-----+ |
* | 6 | | |
splat_vprint(file, SPLAT_TASKQ_TEST5_NAME, "Taskq '%s' "
"waiting for taskqid %d completion\n", tq_arg.name, 3);
- taskq_wait_all(tq, 3);
+ taskq_wait_outstanding(tq, 3);
if ((rc = splat_taskq_test_order(&tq_arg, order1)))
goto out;
splat_vprint(file, SPLAT_TASKQ_TEST5_NAME, "Taskq '%s' "
"waiting for taskqid %d completion\n", tq_arg.name, 8);
- taskq_wait_all(tq, 8);
+ taskq_wait_outstanding(tq, 8);
rc = splat_taskq_test_order(&tq_arg, order2);
out:
splat_vprint(file, SPLAT_TASKQ_TEST6_NAME, "Taskq '%s' "
"waiting for taskqid %d completion\n", tq_arg.name,
SPLAT_TASKQ_ORDER_MAX);
- taskq_wait_all(tq, SPLAT_TASKQ_ORDER_MAX);
+ taskq_wait_outstanding(tq, SPLAT_TASKQ_ORDER_MAX);
rc = splat_taskq_test_order(&tq_arg, order);
out:
if (tq_arg->flag == 0) {
splat_vprint(file, SPLAT_TASKQ_TEST7_NAME,
"Taskq '%s' waiting\n", tq_arg->name);
- taskq_wait_all(tq, SPLAT_TASKQ_DEPTH_MAX);
+ taskq_wait_outstanding(tq, SPLAT_TASKQ_DEPTH_MAX);
}
error = (tq_arg->depth == SPLAT_TASKQ_DEPTH_MAX ? 0 : -EINVAL);
projects / mirror_spl.git / commitdiff