Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fixes from Tejun Heo:
 "Two workqueue fixes.  One for an unlikely but possible critical bug
  during kworker shutdown and the other to make lockdep names a bit more
  descriptive"

* 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: ensure @task is valid across kthread_stop()
  workqueue: add args to workqueue lockdep name

2 files changed, 8 insertions, 4 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 594521ba0d43..704f4f652d0a 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -419,10 +419,7 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
         static struct lock_class_key __key;                             \
         const char *__lock_name;                                        \
                                                                         \
-        if (__builtin_constant_p(fmt))                                  \
-                __lock_name = (fmt);                                    \
-        else                                                            \
-                __lock_name = #fmt;                                     \
+        __lock_name = #fmt#args;                                        \
                                                                         \
         __alloc_workqueue_key((fmt), (flags), (max_active),             \
                               &__key, __lock_name, ##args);             \
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 82ef9f3b7473..193e977a10ea 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1851,6 +1851,12 @@ static void destroy_worker(struct worker *worker)
         if (worker->flags & WORKER_IDLE)
                 pool->nr_idle--;
 
+        /*
+         * Once WORKER_DIE is set, the kworker may destroy itself at any
+         * point.  Pin to ensure the task stays until we're done with it.
+         */
+        get_task_struct(worker->task);
+
         list_del_init(&worker->entry);
         worker->flags |= WORKER_DIE;
 
@@ -1859,6 +1865,7 @@ static void destroy_worker(struct worker *worker)
         spin_unlock_irq(&pool->lock);
 
         kthread_stop(worker->task);
+        put_task_struct(worker->task);
         kfree(worker);
 
         spin_lock_irq(&pool->lock);