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Diffstat (limited to 'kernel')
-rw-r--r--kernel/kthread.c35
1 files changed, 24 insertions, 11 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 121a0e1fc659..0fccf7d0c6a1 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -1120,8 +1120,11 @@ static void kthread_cancel_delayed_work_timer(struct kthread_work *work,
}
/*
- * This function removes the work from the worker queue. Also it makes sure
- * that it won't get queued later via the delayed work's timer.
+ * This function removes the work from the worker queue.
+ *
+ * It is called under worker->lock. The caller must make sure that
+ * the timer used by delayed work is not running, e.g. by calling
+ * kthread_cancel_delayed_work_timer().
*
* The work might still be in use when this function finishes. See the
* current_work proceed by the worker.
@@ -1129,13 +1132,8 @@ static void kthread_cancel_delayed_work_timer(struct kthread_work *work,
* Return: %true if @work was pending and successfully canceled,
* %false if @work was not pending
*/
-static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork,
- unsigned long *flags)
+static bool __kthread_cancel_work(struct kthread_work *work)
{
- /* Try to cancel the timer if exists. */
- if (is_dwork)
- kthread_cancel_delayed_work_timer(work, flags);
-
/*
* Try to remove the work from a worker list. It might either
* be from worker->work_list or from worker->delayed_work_list.
@@ -1188,11 +1186,23 @@ bool kthread_mod_delayed_work(struct kthread_worker *worker,
/* Work must not be used with >1 worker, see kthread_queue_work() */
WARN_ON_ONCE(work->worker != worker);
- /* Do not fight with another command that is canceling this work. */
+ /*
+ * Temporary cancel the work but do not fight with another command
+ * that is canceling the work as well.
+ *
+ * It is a bit tricky because of possible races with another
+ * mod_delayed_work() and cancel_delayed_work() callers.
+ *
+ * The timer must be canceled first because worker->lock is released
+ * when doing so. But the work can be removed from the queue (list)
+ * only when it can be queued again so that the return value can
+ * be used for reference counting.
+ */
+ kthread_cancel_delayed_work_timer(work, &flags);
if (work->canceling)
goto out;
+ ret = __kthread_cancel_work(work);
- ret = __kthread_cancel_work(work, true, &flags);
fast_queue:
__kthread_queue_delayed_work(worker, dwork, delay);
out:
@@ -1214,7 +1224,10 @@ static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork)
/* Work must not be used with >1 worker, see kthread_queue_work(). */
WARN_ON_ONCE(work->worker != worker);
- ret = __kthread_cancel_work(work, is_dwork, &flags);
+ if (is_dwork)
+ kthread_cancel_delayed_work_timer(work, &flags);
+
+ ret = __kthread_cancel_work(work);
if (worker->current_work != work)
goto out_fast;