workqueue: Cleanups around process_scheduled_works()

* Drop the trivial optimization in worker_thread() where it bypasses calling
  process_scheduled_works() if the first work item isn't linked. This is a
  mostly pointless micro optimization and gets in the way of improving the
  work processing path.

* Consolidate pool->watchdog_ts updates in the two callers into
  process_scheduled_works().

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 598009a..20722de 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2652,9 +2652,15 @@ __acquires(&pool->lock)
  */
 static void process_scheduled_works(struct worker *worker)
 {
-       while (!list_empty(&worker->scheduled)) {
-               struct work_struct *work = list_first_entry(&worker->scheduled,
-                                               struct work_struct, entry);
+       struct work_struct *work;
+       bool first = true;
+
+       while ((work = list_first_entry_or_null(&worker->scheduled,
+                                               struct work_struct, entry))) {
+               if (first) {
+                       worker->pool->watchdog_ts = jiffies;
+                       first = false;
+               }
                process_one_work(worker, work);
        }
 }
@@ -2735,17 +2741,8 @@ recheck:
                        list_first_entry(&pool->worklist,
                                         struct work_struct, entry);
 
-               pool->watchdog_ts = jiffies;
-
-               if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
-                       /* optimization path, not strictly necessary */
-                       process_one_work(worker, work);
-                       if (unlikely(!list_empty(&worker->scheduled)))
-                               process_scheduled_works(worker);
-               } else {
-                       move_linked_works(work, &worker->scheduled, NULL);
-                       process_scheduled_works(worker);
-               }
+               move_linked_works(work, &worker->scheduled, NULL);
+               process_scheduled_works(worker);
        } while (keep_working(pool));
 
        worker_set_flags(worker, WORKER_PREP);
@@ -2820,7 +2817,6 @@ repeat:
                                        struct pool_workqueue, mayday_node);
                struct worker_pool *pool = pwq->pool;
                struct work_struct *work, *n;
-               bool first = true;
 
                __set_current_state(TASK_RUNNING);
                list_del_init(&pwq->mayday_node);
@@ -2838,12 +2834,9 @@ repeat:
                WARN_ON_ONCE(!list_empty(scheduled));
                list_for_each_entry_safe(work, n, &pool->worklist, entry) {
                        if (get_work_pwq(work) == pwq) {
-                               if (first)
-                                       pool->watchdog_ts = jiffies;
                                move_linked_works(work, scheduled, &n);
                                pwq->stats[PWQ_STAT_RESCUED]++;
                        }
-                       first = false;
                }
 
                if (!list_empty(scheduled)) {