workqueue: kick a worker in pwq_adjust_max_active()

If pwq_adjust_max_active() changes max_active from 0 to
saved_max_active, it needs to wakeup worker.  This is already done by
thaw_workqueues().

If pwq_adjust_max_active() increases max_active for an unbound wq,
while not strictly necessary for correctness, it's still desirable to
wake up a worker so that the requested concurrency level is reached
sooner.

Move wake_up_worker() call from thaw_workqueues() to
pwq_adjust_max_active() so that it can handle both of the above two
cases.  This also makes thaw_workqueues() simpler.

tj: Updated comments and description.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 6 insertions, 7 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index d2ac6cbfe8ab..79d1d347e690 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3598,6 +3598,12 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
                 while (!list_empty(&pwq->delayed_works) &&
                        pwq->nr_active < pwq->max_active)
                         pwq_activate_first_delayed(pwq);
+
+                /*
+                 * Need to kick a worker after thawed or an unbound wq's
+                 * max_active is bumped.  It's a slow path.  Do it always.
+                 */
+                wake_up_worker(pwq->pool);
         } else {
                 pwq->max_active = 0;
         }
@@ -4401,13 +4407,6 @@ void thaw_workqueues(void)
         }
         spin_unlock_irq(&pwq_lock);
 
-        /* kick workers */
-        for_each_pool(pool, pi) {
-                spin_lock_irq(&pool->lock);
-                wake_up_worker(pool);
-                spin_unlock_irq(&pool->lock);
-        }
-
         workqueue_freezing = false;
 out_unlock:
         mutex_unlock(&wq_mutex);