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-rw-r--r--kernel/workqueue.c60
1 files changed, 59 insertions, 1 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e785b0f..8ee6ec8 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -932,6 +932,38 @@ static void insert_work(struct cpu_workqueue_struct *cwq,
wake_up_worker(gcwq);
}
+/*
+ * Test whether @work is being queued from another work executing on the
+ * same workqueue. This is rather expensive and should only be used from
+ * cold paths.
+ */
+static bool is_chained_work(struct workqueue_struct *wq)
+{
+ unsigned long flags;
+ unsigned int cpu;
+
+ for_each_gcwq_cpu(cpu) {
+ struct global_cwq *gcwq = get_gcwq(cpu);
+ struct worker *worker;
+ struct hlist_node *pos;
+ int i;
+
+ spin_lock_irqsave(&gcwq->lock, flags);
+ for_each_busy_worker(worker, i, pos, gcwq) {
+ if (worker->task != current)
+ continue;
+ spin_unlock_irqrestore(&gcwq->lock, flags);
+ /*
+ * I'm @worker, no locking necessary. See if @work
+ * is headed to the same workqueue.
+ */
+ return worker->current_cwq->wq == wq;
+ }
+ spin_unlock_irqrestore(&gcwq->lock, flags);
+ }
+ return false;
+}
+
static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
struct work_struct *work)
{
@@ -943,7 +975,9 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
debug_work_activate(work);
- if (WARN_ON_ONCE(wq->flags & WQ_DYING))
+ /* if dying, only works from the same workqueue are allowed */
+ if (unlikely(wq->flags & WQ_DYING) &&
+ WARN_ON_ONCE(!is_chained_work(wq)))
return;
/* determine gcwq to use */
@@ -2936,11 +2970,35 @@ EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
*/
void destroy_workqueue(struct workqueue_struct *wq)
{
+ unsigned int flush_cnt = 0;
unsigned int cpu;
+ /*
+ * Mark @wq dying and drain all pending works. Once WQ_DYING is
+ * set, only chain queueing is allowed. IOW, only currently
+ * pending or running work items on @wq can queue further work
+ * items on it. @wq is flushed repeatedly until it becomes empty.
+ * The number of flushing is detemined by the depth of chaining and
+ * should be relatively short. Whine if it takes too long.
+ */
wq->flags |= WQ_DYING;
+reflush:
flush_workqueue(wq);
+ for_each_cwq_cpu(cpu, wq) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+ if (!cwq->nr_active && list_empty(&cwq->delayed_works))
+ continue;
+
+ if (++flush_cnt == 10 ||
+ (flush_cnt % 100 == 0 && flush_cnt <= 1000))
+ printk(KERN_WARNING "workqueue %s: flush on "
+ "destruction isn't complete after %u tries\n",
+ wq->name, flush_cnt);
+ goto reflush;
+ }
+
/*
* wq list is used to freeze wq, remove from list after
* flushing is complete in case freeze races us.
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