Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fix from Tejun Heo:
 "Another fix for a really old bug.

  It only affects drain_workqueue() which isn't used often and even then
  triggers only during a pretty small race window, so it isn't too
  surprising that it stayed hidden for so long.

  The fix is straight-forward and low-risk. Kudos to Li Bin for
  reporting and fixing the bug"

* 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Fix NULL pointer dereference

Author: torvalds

kernel/workqueue_internal.h

@@ -10,6 +10,7 @@
 
 #include <linux/workqueue.h>
 #include <linux/kthread.h>
+#include <linux/preempt.h>
 
 struct worker_pool;
 
@@ -60,7 +61,7 @@ struct worker {
  */
 static inline struct worker *current_wq_worker(void)
 {
-	if (current->flags & PF_WQ_WORKER)
+	if (in_task() && (current->flags & PF_WQ_WORKER))
 		return kthread_data(current);
 	return NULL;
 }