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Diffstat (limited to 'kernel/kthread.c')
-rw-r--r--kernel/kthread.c88
1 files changed, 52 insertions, 36 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 3d3de633702e..b579af57ea10 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -360,16 +360,12 @@ repeat:
struct kthread_work, node);
list_del_init(&work->node);
}
+ worker->current_work = work;
spin_unlock_irq(&worker->lock);
if (work) {
__set_current_state(TASK_RUNNING);
work->func(work);
- smp_wmb(); /* wmb worker-b0 paired with flush-b1 */
- work->done_seq = work->queue_seq;
- smp_mb(); /* mb worker-b1 paired with flush-b0 */
- if (atomic_read(&work->flushing))
- wake_up_all(&work->done);
} else if (!freezing(current))
schedule();
@@ -378,6 +374,19 @@ repeat:
}
EXPORT_SYMBOL_GPL(kthread_worker_fn);
+/* insert @work before @pos in @worker */
+static void insert_kthread_work(struct kthread_worker *worker,
+ struct kthread_work *work,
+ struct list_head *pos)
+{
+ lockdep_assert_held(&worker->lock);
+
+ list_add_tail(&work->node, pos);
+ work->worker = worker;
+ if (likely(worker->task))
+ wake_up_process(worker->task);
+}
+
/**
* queue_kthread_work - queue a kthread_work
* @worker: target kthread_worker
@@ -395,10 +404,7 @@ bool queue_kthread_work(struct kthread_worker *worker,
spin_lock_irqsave(&worker->lock, flags);
if (list_empty(&work->node)) {
- list_add_tail(&work->node, &worker->work_list);
- work->queue_seq++;
- if (likely(worker->task))
- wake_up_process(worker->task);
+ insert_kthread_work(worker, work, &worker->work_list);
ret = true;
}
spin_unlock_irqrestore(&worker->lock, flags);
@@ -406,6 +412,18 @@ bool queue_kthread_work(struct kthread_worker *worker,
}
EXPORT_SYMBOL_GPL(queue_kthread_work);
+struct kthread_flush_work {
+ struct kthread_work work;
+ struct completion done;
+};
+
+static void kthread_flush_work_fn(struct kthread_work *work)
+{
+ struct kthread_flush_work *fwork =
+ container_of(work, struct kthread_flush_work, work);
+ complete(&fwork->done);
+}
+
/**
* flush_kthread_work - flush a kthread_work
* @work: work to flush
@@ -414,39 +432,37 @@ EXPORT_SYMBOL_GPL(queue_kthread_work);
*/
void flush_kthread_work(struct kthread_work *work)
{
- int seq = work->queue_seq;
-
- atomic_inc(&work->flushing);
+ struct kthread_flush_work fwork = {
+ KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
+ COMPLETION_INITIALIZER_ONSTACK(fwork.done),
+ };
+ struct kthread_worker *worker;
+ bool noop = false;
- /*
- * mb flush-b0 paired with worker-b1, to make sure either
- * worker sees the above increment or we see done_seq update.
- */
- smp_mb__after_atomic_inc();
+retry:
+ worker = work->worker;
+ if (!worker)
+ return;
- /* A - B <= 0 tests whether B is in front of A regardless of overflow */
- wait_event(work->done, seq - work->done_seq <= 0);
- atomic_dec(&work->flushing);
+ spin_lock_irq(&worker->lock);
+ if (work->worker != worker) {
+ spin_unlock_irq(&worker->lock);
+ goto retry;
+ }
- /*
- * rmb flush-b1 paired with worker-b0, to make sure our caller
- * sees every change made by work->func().
- */
- smp_mb__after_atomic_dec();
-}
-EXPORT_SYMBOL_GPL(flush_kthread_work);
+ if (!list_empty(&work->node))
+ insert_kthread_work(worker, &fwork.work, work->node.next);
+ else if (worker->current_work == work)
+ insert_kthread_work(worker, &fwork.work, worker->work_list.next);
+ else
+ noop = true;
-struct kthread_flush_work {
- struct kthread_work work;
- struct completion done;
-};
+ spin_unlock_irq(&worker->lock);
-static void kthread_flush_work_fn(struct kthread_work *work)
-{
- struct kthread_flush_work *fwork =
- container_of(work, struct kthread_flush_work, work);
- complete(&fwork->done);
+ if (!noop)
+ wait_for_completion(&fwork.done);
}
+EXPORT_SYMBOL_GPL(flush_kthread_work);
/**
* flush_kthread_worker - flush all current works on a kthread_worker