workqueue: drop WQ_RESCUER and test workqueue->rescuer for NULL instead
WQ_RESCUER is superflous. WQ_MEM_RECLAIM indicates that the user
wants a rescuer and testing wq->rescuer for NULL can answer whether a
given workqueue has a rescuer or not. Drop WQ_RESCUER and test
wq->rescuer directly.
This will help simplifying __alloc_workqueue_key() failure path by
allowing it to use destroy_workqueue() on a partially constructed
workqueue, which in turn will help implementing dynamic management of
pool_workqueues.
While at it, clear wq->rescuer after freeing it in
destroy_workqueue(). This is a precaution as scheduled changes will
make destruction more complex.
This patch doesn't introduce any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index a8b86f7..7ff2b9c 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1827,7 +1827,7 @@
lockdep_assert_held(&workqueue_lock);
- if (!(wq->flags & WQ_RESCUER))
+ if (!wq->rescuer)
return;
/* mayday mayday mayday */
@@ -2285,7 +2285,7 @@
* @__rescuer: self
*
* Workqueue rescuer thread function. There's one rescuer for each
- * workqueue which has WQ_RESCUER set.
+ * workqueue which has WQ_MEM_RECLAIM set.
*
* Regular work processing on a pool may block trying to create a new
* worker which uses GFP_KERNEL allocation which has slight chance of
@@ -2769,7 +2769,7 @@
* flusher is not running on the same workqueue by verifying write
* access.
*/
- if (pwq->wq->saved_max_active == 1 || pwq->wq->flags & WQ_RESCUER)
+ if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)
lock_map_acquire(&pwq->wq->lockdep_map);
else
lock_map_acquire_read(&pwq->wq->lockdep_map);
@@ -3412,13 +3412,6 @@
va_end(args);
va_end(args1);
- /*
- * Workqueues which may be used during memory reclaim should
- * have a rescuer to guarantee forward progress.
- */
- if (flags & WQ_MEM_RECLAIM)
- flags |= WQ_RESCUER;
-
max_active = max_active ?: WQ_DFL_ACTIVE;
max_active = wq_clamp_max_active(max_active, flags, wq->name);
@@ -3449,7 +3442,11 @@
}
local_irq_enable();
- if (flags & WQ_RESCUER) {
+ /*
+ * Workqueues which may be used during memory reclaim should
+ * have a rescuer to guarantee forward progress.
+ */
+ if (flags & WQ_MEM_RECLAIM) {
struct worker *rescuer;
wq->rescuer = rescuer = alloc_worker();
@@ -3533,9 +3530,10 @@
spin_unlock_irq(&workqueue_lock);
- if (wq->flags & WQ_RESCUER) {
+ if (wq->rescuer) {
kthread_stop(wq->rescuer->task);
kfree(wq->rescuer);
+ wq->rescuer = NULL;
}
/*
