Merge branch 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue updates from Tejun Heo:
 "Over the lockdep cross-release churn, workqueue lost some of the
  existing annotations. Johannes Berg restored it and also improved
  them"

* 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: re-add lockdep dependencies for flushing
  workqueue: skip lockdep wq dependency in cancel_work_sync()

1 files changed, 30 insertions, 15 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 78b192071ef7..60e80198c3df 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2652,6 +2652,9 @@ void flush_workqueue(struct workqueue_struct *wq)
         if (WARN_ON(!wq_online))
                 return;
 
+        lock_map_acquire(&wq->lockdep_map);
+        lock_map_release(&wq->lockdep_map);
+
         mutex_lock(&wq->mutex);
 
         /*
@@ -2843,7 +2846,8 @@ reflush:
 }
 EXPORT_SYMBOL_GPL(drain_workqueue);
 
-static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
+static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
+                             bool from_cancel)
 {
         struct worker *worker = NULL;
         struct worker_pool *pool;
@@ -2885,7 +2889,8 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
          * workqueues the deadlock happens when the rescuer stalls, blocking
          * forward progress.
          */
-        if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) {
+        if (!from_cancel &&
+            (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) {
                 lock_map_acquire(&pwq->wq->lockdep_map);
                 lock_map_release(&pwq->wq->lockdep_map);
         }
@@ -2896,6 +2901,27 @@ already_gone:
         return false;
 }
 
+static bool __flush_work(struct work_struct *work, bool from_cancel)
+{
+        struct wq_barrier barr;
+
+        if (WARN_ON(!wq_online))
+                return false;
+
+        if (!from_cancel) {
+                lock_map_acquire(&work->lockdep_map);
+                lock_map_release(&work->lockdep_map);
+        }
+
+        if (start_flush_work(work, &barr, from_cancel)) {
+                wait_for_completion(&barr.done);
+                destroy_work_on_stack(&barr.work);
+                return true;
+        } else {
+                return false;
+        }
+}
+
 /**
  * flush_work - wait for a work to finish executing the last queueing instance
  * @work: the work to flush
@@ -2909,18 +2935,7 @@ already_gone:
  */
 bool flush_work(struct work_struct *work)
 {
-        struct wq_barrier barr;
-
-        if (WARN_ON(!wq_online))
-                return false;
-
-        if (start_flush_work(work, &barr)) {
-                wait_for_completion(&barr.done);
-                destroy_work_on_stack(&barr.work);
-                return true;
-        } else {
-                return false;
-        }
+        return __flush_work(work, false);
 }
 EXPORT_SYMBOL_GPL(flush_work);
 
@@ -2986,7 +3001,7 @@ static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
          * isn't executing.
          */
         if (wq_online)
-                flush_work(work);
+                __flush_work(work, true);
 
         clear_work_data(work);