1 files changed, 113 insertions, 65 deletions

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 3fe5d60..57ca5be 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -99,65 +99,79 @@ __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
 	list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
 }
 
-static void rpc_rotate_queue_owner(struct rpc_wait_queue *queue)
-{
-	struct list_head *q = &queue->tasks[queue->priority];
-	struct rpc_task *task;
-
-	if (!list_empty(q)) {
-		task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
-		if (task->tk_owner == queue->owner)
-			list_move_tail(&task->u.tk_wait.list, q);
-	}
-}
-
 static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 {
 	if (queue->priority != priority) {
-		/* Fairness: rotate the list when changing priority */
-		rpc_rotate_queue_owner(queue);
 		queue->priority = priority;
+		queue->nr = 1U << priority;
 	}
 }
 
-static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
-{
-	queue->owner = pid;
-	queue->nr = RPC_BATCH_COUNT;
-}
-
 static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 {
 	rpc_set_waitqueue_priority(queue, queue->maxpriority);
-	rpc_set_waitqueue_owner(queue, 0);
 }
 
 /*
- * Add new request to a priority queue.
+ * Add a request to a queue list
  */
-static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
-		struct rpc_task *task,
-		unsigned char queue_priority)
+static void
+__rpc_list_enqueue_task(struct list_head *q, struct rpc_task *task)
 {
-	struct list_head *q;
 	struct rpc_task *t;
 
-	INIT_LIST_HEAD(&task->u.tk_wait.links);
-	if (unlikely(queue_priority > queue->maxpriority))
-		queue_priority = queue->maxpriority;
-	if (queue_priority > queue->priority)
-		rpc_set_waitqueue_priority(queue, queue_priority);
-	q = &queue->tasks[queue_priority];
 	list_for_each_entry(t, q, u.tk_wait.list) {
 		if (t->tk_owner == task->tk_owner) {
-			list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
+			list_add_tail(&task->u.tk_wait.links,
+					&t->u.tk_wait.links);
+			/* Cache the queue head in task->u.tk_wait.list */
+			task->u.tk_wait.list.next = q;
+			task->u.tk_wait.list.prev = NULL;
 			return;
 		}
 	}
+	INIT_LIST_HEAD(&task->u.tk_wait.links);
 	list_add_tail(&task->u.tk_wait.list, q);
 }
 
 /*
+ * Remove request from a queue list
+ */
+static void
+__rpc_list_dequeue_task(struct rpc_task *task)
+{
+	struct list_head *q;
+	struct rpc_task *t;
+
+	if (task->u.tk_wait.list.prev == NULL) {
+		list_del(&task->u.tk_wait.links);
+		return;
+	}
+	if (!list_empty(&task->u.tk_wait.links)) {
+		t = list_first_entry(&task->u.tk_wait.links,
+				struct rpc_task,
+				u.tk_wait.links);
+		/* Assume __rpc_list_enqueue_task() cached the queue head */
+		q = t->u.tk_wait.list.next;
+		list_add_tail(&t->u.tk_wait.list, q);
+		list_del(&task->u.tk_wait.links);
+	}
+	list_del(&task->u.tk_wait.list);
+}
+
+/*
+ * Add new request to a priority queue.
+ */
+static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
+		struct rpc_task *task,
+		unsigned char queue_priority)
+{
+	if (unlikely(queue_priority > queue->maxpriority))
+		queue_priority = queue->maxpriority;
+	__rpc_list_enqueue_task(&queue->tasks[queue_priority], task);
+}
+
+/*
  * Add new request to wait queue.
  *
  * Swapper tasks always get inserted at the head of the queue.
@@ -194,13 +208,7 @@ static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
  */
 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 {
-	struct rpc_task *t;
-
-	if (!list_empty(&task->u.tk_wait.links)) {
-		t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
-		list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
-		list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
-	}
+	__rpc_list_dequeue_task(task);
 }
 
 /*
@@ -212,7 +220,8 @@ static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_tas
 	__rpc_disable_timer(queue, task);
 	if (RPC_IS_PRIORITY(queue))
 		__rpc_remove_wait_queue_priority(task);
-	list_del(&task->u.tk_wait.list);
+	else
+		list_del(&task->u.tk_wait.list);
 	queue->qlen--;
 	dprintk("RPC: %5u removed from queue %p \"%s\"\n",
 			task->tk_pid, queue, rpc_qname(queue));
@@ -440,14 +449,28 @@ static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
 /*
  * Wake up a queued task while the queue lock is being held
  */
-static void rpc_wake_up_task_on_wq_queue_locked(struct workqueue_struct *wq,
-		struct rpc_wait_queue *queue, struct rpc_task *task)
+static struct rpc_task *
+rpc_wake_up_task_on_wq_queue_action_locked(struct workqueue_struct *wq,
+		struct rpc_wait_queue *queue, struct rpc_task *task,
+		bool (*action)(struct rpc_task *, void *), void *data)
 {
 	if (RPC_IS_QUEUED(task)) {
 		smp_rmb();
-		if (task->tk_waitqueue == queue)
-			__rpc_do_wake_up_task_on_wq(wq, queue, task);
+		if (task->tk_waitqueue == queue) {
+			if (action == NULL || action(task, data)) {
+				__rpc_do_wake_up_task_on_wq(wq, queue, task);
+				return task;
+			}
+		}
 	}
+	return NULL;
+}
+
+static void
+rpc_wake_up_task_on_wq_queue_locked(struct workqueue_struct *wq,
+		struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	rpc_wake_up_task_on_wq_queue_action_locked(wq, queue, task, NULL, NULL);
 }
 
 /*
@@ -465,6 +488,8 @@ void rpc_wake_up_queued_task_on_wq(struct workqueue_struct *wq,
 		struct rpc_wait_queue *queue,
 		struct rpc_task *task)
 {
+	if (!RPC_IS_QUEUED(task))
+		return;
 	spin_lock_bh(&queue->lock);
 	rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
 	spin_unlock_bh(&queue->lock);
@@ -475,12 +500,48 @@ void rpc_wake_up_queued_task_on_wq(struct workqueue_struct *wq,
  */
 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 {
+	if (!RPC_IS_QUEUED(task))
+		return;
 	spin_lock_bh(&queue->lock);
 	rpc_wake_up_task_queue_locked(queue, task);
 	spin_unlock_bh(&queue->lock);
 }
 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 
+static bool rpc_task_action_set_status(struct rpc_task *task, void *status)
+{
+	task->tk_status = *(int *)status;
+	return true;
+}
+
+static void
+rpc_wake_up_task_queue_set_status_locked(struct rpc_wait_queue *queue,
+		struct rpc_task *task, int status)
+{
+	rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
+			task, rpc_task_action_set_status, &status);
+}
+
+/**
+ * rpc_wake_up_queued_task_set_status - wake up a task and set task->tk_status
+ * @queue: pointer to rpc_wait_queue
+ * @task: pointer to rpc_task
+ * @status: integer error value
+ *
+ * If @task is queued on @queue, then it is woken up, and @task->tk_status is
+ * set to the value of @status.
+ */
+void
+rpc_wake_up_queued_task_set_status(struct rpc_wait_queue *queue,
+		struct rpc_task *task, int status)
+{
+	if (!RPC_IS_QUEUED(task))
+		return;
+	spin_lock_bh(&queue->lock);
+	rpc_wake_up_task_queue_set_status_locked(queue, task, status);
+	spin_unlock_bh(&queue->lock);
+}
+
 /*
  * Wake up the next task on a priority queue.
  */
@@ -493,17 +554,9 @@ static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *q
 	 * Service a batch of tasks from a single owner.
 	 */
 	q = &queue->tasks[queue->priority];
-	if (!list_empty(q)) {
-		task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
-		if (queue->owner == task->tk_owner) {
-			if (--queue->nr)
-				goto out;
-			list_move_tail(&task->u.tk_wait.list, q);
-		}
-		/*
-		 * Check if we need to switch queues.
-		 */
-		goto new_owner;
+	if (!list_empty(q) && --queue->nr) {
+		task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
+		goto out;
 	}
 
 	/*
@@ -515,7 +568,7 @@ static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *q
 		else
 			q = q - 1;
 		if (!list_empty(q)) {
-			task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
+			task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
 			goto new_queue;
 		}
 	} while (q != &queue->tasks[queue->priority]);
@@ -525,8 +578,6 @@ static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *q
 
 new_queue:
 	rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
-new_owner:
-	rpc_set_waitqueue_owner(queue, task->tk_owner);
 out:
 	return task;
 }
@@ -553,12 +604,9 @@ struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
 			queue, rpc_qname(queue));
 	spin_lock_bh(&queue->lock);
 	task = __rpc_find_next_queued(queue);
-	if (task != NULL) {
-		if (func(task, data))
-			rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
-		else
-			task = NULL;
-	}
+	if (task != NULL)
+		task = rpc_wake_up_task_on_wq_queue_action_locked(wq, queue,
+				task, func, data);
 	spin_unlock_bh(&queue->lock);
 
 	return task;