workqueue: fix possible stall on try_to_grab_pending() of a delayed work item

[platform/adaptation/renesas_rcar/renesas_kernel.git] / kernel / workqueue.c

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 48becab..d2fe8e7 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -977,10 +977,9 @@ static void move_linked_works(struct work_struct *work, struct list_head *head,
                *nextp = n;
 }
 
-static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
+static void cwq_activate_delayed_work(struct work_struct *work)
 {
-       struct work_struct *work = list_first_entry(&cwq->delayed_works,
-                                                   struct work_struct, entry);
+       struct cpu_workqueue_struct *cwq = get_work_cwq(work);
 
        trace_workqueue_activate_work(work);
        move_linked_works(work, &cwq->pool->worklist, NULL);
@@ -988,6 +987,14 @@ static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
        cwq->nr_active++;
 }
 
+static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
+{
+       struct work_struct *work = list_first_entry(&cwq->delayed_works,
+                                                   struct work_struct, entry);
+
+       cwq_activate_delayed_work(work);
+}
+
 /**
  * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
  * @cwq: cwq of interest
@@ -1106,6 +1113,18 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
                smp_rmb();
                if (gcwq == get_work_gcwq(work)) {
                        debug_work_deactivate(work);
+
+                       /*
+                        * A delayed work item cannot be grabbed directly
+                        * because it might have linked NO_COLOR work items
+                        * which, if left on the delayed_list, will confuse
+                        * cwq->nr_active management later on and cause
+                        * stall.  Make sure the work item is activated
+                        * before grabbing.
+                        */
+                       if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
+                               cwq_activate_delayed_work(work);
+
                        list_del_init(&work->entry);
                        cwq_dec_nr_in_flight(get_work_cwq(work),
                                get_work_color(work),