workqueue: Make worker_attach/detach_pool() update worker->pool

For historical reasons, the worker attach/detach functions don't currently manage worker->pool and the callers are manually and inconsistently updating it. This patch moves worker->pool updates into the worker attach/detach functions. This makes worker->pool consistent and clearly defines how worker->pool updates are synchronized. This will help later workqueue visibility improvements by allowing safe access to workqueue information from worker->task.

Tejun Heo committed 8 years ago

Commit a2d812a1 parent 1258fae2 files · +9 −9Browse files

Showing the changes to kernel/workqueue.c (1 of 2 files). Show all

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kernel/workqueue.c+8−8

 		worker->flags |= WORKER_UNBOUND;
 	list_add_tail(&worker->node, &pool->workers);
+	worker->pool = pool;
 	mutex_unlock(&wq_pool_attach_mutex);
 }
 /**
  * worker_detach_from_pool() - detach a worker from its pool
  * @worker: worker which is attached to its pool
- * @pool: the pool @worker is attached to
  *
  * Undo the attaching which had been done in worker_attach_to_pool().  The
  * caller worker shouldn't access to the pool after detached except it has
  * other reference to the pool.
  */
-static void worker_detach_from_pool(struct worker *worker,
+static void worker_detach_from_pool(struct worker *worker)
-				    struct worker_pool *pool)
 {
+	struct worker_pool *pool = worker->pool;
 	struct completion *detach_completion = NULL;
 	mutex_lock(&wq_pool_attach_mutex);
 	list_del(&worker->node);
+	worker->pool = NULL;
 	if (list_empty(&pool->workers))
 		detach_completion = pool->detach_completion;
 	mutex_unlock(&wq_pool_attach_mutex);
 	if (!worker)
 		goto fail;
-	worker->pool = pool;
 	worker->id = id;
 	if (pool->cpu >= 0)
 		set_task_comm(worker->task, "kworker/dying");
 		ida_simple_remove(&pool->worker_ida, worker->id);
-		worker_detach_from_pool(worker, pool);
+		worker_detach_from_pool(worker);
 		kfree(worker);
 		return 0;
 	}
 		worker_attach_to_pool(rescuer, pool);
 		spin_lock_irq(&pool->lock);
-		rescuer->pool = pool;
 		/*
 		 * Slurp in all works issued via this workqueue and
 		if (need_more_worker(pool))
 			wake_up_worker(pool);
-		rescuer->pool = NULL;
 		spin_unlock_irq(&pool->lock);
-		worker_detach_from_pool(rescuer, pool);
+		worker_detach_from_pool(rescuer);
 		spin_lock_irq(&wq_mayday_lock);
 	}