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-rw-r--r--kernel/kthread.c28
1 files changed, 20 insertions, 8 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index f874300dfce5..524dfc8247d7 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -578,6 +578,9 @@ EXPORT_SYMBOL_GPL(__kthread_init_worker);
* The works are not allowed to keep any locks, disable preemption or interrupts
* when they finish. There is defined a safe point for freezing when one work
* finishes and before a new one is started.
+ *
+ * Also the works must not be handled by more than one worker at the same time,
+ * see also kthread_queue_work().
*/
int kthread_worker_fn(void *worker_ptr)
{
@@ -714,12 +717,21 @@ kthread_create_worker_on_cpu(int cpu, const char namefmt[], ...)
}
EXPORT_SYMBOL(kthread_create_worker_on_cpu);
+static void kthread_insert_work_sanity_check(struct kthread_worker *worker,
+ struct kthread_work *work)
+{
+ lockdep_assert_held(&worker->lock);
+ WARN_ON_ONCE(!list_empty(&work->node));
+ /* Do not use a work with >1 worker, see kthread_queue_work() */
+ WARN_ON_ONCE(work->worker && work->worker != worker);
+}
+
/* insert @work before @pos in @worker */
static void kthread_insert_work(struct kthread_worker *worker,
- struct kthread_work *work,
- struct list_head *pos)
+ struct kthread_work *work,
+ struct list_head *pos)
{
- lockdep_assert_held(&worker->lock);
+ kthread_insert_work_sanity_check(worker, work);
list_add_tail(&work->node, pos);
work->worker = worker;
@@ -735,6 +747,9 @@ static void kthread_insert_work(struct kthread_worker *worker,
* Queue @work to work processor @task for async execution. @task
* must have been created with kthread_worker_create(). Returns %true
* if @work was successfully queued, %false if it was already pending.
+ *
+ * Reinitialize the work if it needs to be used by another worker.
+ * For example, when the worker was stopped and started again.
*/
bool kthread_queue_work(struct kthread_worker *worker,
struct kthread_work *work)
@@ -779,16 +794,13 @@ void kthread_flush_work(struct kthread_work *work)
struct kthread_worker *worker;
bool noop = false;
-retry:
worker = work->worker;
if (!worker)
return;
spin_lock_irq(&worker->lock);
- if (work->worker != worker) {
- spin_unlock_irq(&worker->lock);
- goto retry;
- }
+ /* Work must not be used with >1 worker, see kthread_queue_work(). */
+ WARN_ON_ONCE(work->worker != worker);
if (!list_empty(&work->node))
kthread_insert_work(worker, &fwork.work, work->node.next);